Subject: Re: Seismograph for school From: ChrisAtUpw@....... Date: Sat, 30 Sep 2006 22:15:14 EDT In a message dated 2006/09/30, tchannel@.............. writes: > Hi Folks, I have a question about the coil and magnet portion of a sensor. > I have seen very small coils and magnets used and very large ones. I guess > the common one is about a 25# pull magnet and a coil of about 500 ohms? I am > going to rebuild my assembly for two reasons, first I have been told my cow > magnet and small coil is just too small. > The second reason is I just found a great cheap powerful magnet. It is the > size of a deck of cards, about 50# pull and about $8.00 at Harbor Freight. > > Using the same (everything) but three different magnet/coils, undersized, > just right, and oversized, what effects would they have, on the gain, final > image, etc? > > I would create a "pancake" coil about the same size as the magnet, square > in shape and thin. > > Your thought or suggestions please. If this is a good magnet to use in a > coil assembly or using two in a damper assembly, I can give you the part > number etc. They are welding assembly magnets, two in a package. Hi Ted, You don't need this size or bulk. You need quite a few thousand turns on a coil with the ID clear of the OD of the magnet, if you use a cow magnet. You do need a coil of 350 to 1000 Ohms to match your opamp input impedance. The greater the number of turns and the greater the change of flux (= area x field) through the coil, the greater the output. If you put an unshielded magnet on the arm of a seismometer, you are likely to detect every pulse on the house utility power wiring, fridges switching on and off, passing cars and trucks and changes in the Earth's field.... The signal is likely to be very noisy. The sensitivity of a seismic detection system needs to be very high. The usual coil / magnet system involves mounting the coil on the arm, sitting your magnet on the baseplate and using a non magnetic mass - brass is easy to use, but you can also use lead or copper. You need a linear high sensitivity response. You have to allow for tilt drift over the week of about 3/8" with a Lehman and the sensitivity needs to stay constant and linear within this range. This can be provided with a rectangular coil of maybe 2000 turns and a quad NdFeB magnet system on mild steel backing plates. I have described my detector system using four 1" square x 1/8" thick NdFeB magnets on 1/4" thick mild steel backing plates in the second half of http://jclahr.com/science/psn/chapman/lehman/index.html You may be able to extract the primary winding from a small low power mains transformer and use that? This is the sort which has side by side, not overlapping, P & S windings and a square / rectangular former. I don't know what is available to you? Larry sells round relay coils, but I prefer a larger rectangular form. You may also be able to buy 'spare' mains coils for timers and water flow valves on washing machines. Some have a suitable pancake form. The coil needs to have an internal rectangular measurement in the direction of motion of maybe 1/2" to 3/4" so that its output will be constant, allowing for the tilt drift on the seismometer. I also use an identical mild steel adjustable frame for the damping, but it uses a 1/16" copper plate and 1" x 1/2" x 1/4" thick NdFeB bar magnets. The damping tongue is mounted horizontally and the damping magnet block is simply slid further over it until you get ~0.7 critical damping. If you deflect the arm 10 mm and release it, it should swing 0.5 mm beyond the balance point before returning to balance. The damping force that you need decreases as the period set is increased, and increases with the seismic mass, so it needs to be easily adjustable. This construction is easy to set up and use and it is NOT temperature sensitive. This magnet + tongue damping arrangement is very effective. You can buy suitable NdFeB magnets from www.kjmagnetics.com. Regards, Chris Chapman In a me= ssage dated 2006/09/30, tchannel@.............. writes:

Hi Folks,  I have a questi= on about the coil and magnet portion of a sensor. I have seen very small coi= ls and magnets used and very large ones. I guess the common one is about a 2= 5# pull magnet and a coil of about 500 ohms? I am going to rebuild my assemb= ly for two reasons, first I have been told my cow magnet and small coil is j= ust too small. 
The second reason is I just found a great cheap powerful magnet.  It i= s the size of a deck of cards, about 50# pull and about $8.00 at Harbor Frei= ght.

Using the same (everything) but three different magnet/coils, undersized,=20= just right, and oversized, what effects would they have, on the gain, final=20= image, etc?

 I would create a "pancake" coil about the same size as the magnet, square=20= in shape and thin. 

Your thought or suggestions please.  If this is a good magnet to use=20= in a coil assembly or using two in a damper assembly, I can give you the par= t number etc.  They are welding assembly magnets, two in a package.


Hi Ted,

       You don't need this size or bulk.

       You need quite a few thousand turns on=20= a coil with the ID clear of the OD of the magnet, if you use a cow magnet. <= BR>
       You do need a coil of 350 to 1000 Ohms=20= to match your opamp input impedance.

       The greater the number of turns and the= greater the change of flux (=3D area x field) through the coil, the greater= the output.

       If you put an unshielded magnet on the=20= arm of a seismometer, you are likely to detect every pulse on the house util= ity power wiring, fridges switching on and off, passing cars and trucks and=20= changes in the Earth's field.... The signal is likely to be very noisy. The=20= sensitivity of a seismic detection system needs to be very high.

       The usual coil / magnet system involves= mounting the coil on the arm, sitting your magnet on the baseplate and usin= g a non magnetic mass - brass is easy to use, but you can also use lead or c= opper. You need a linear high sensitivity response. You have to allow for ti= lt drift over the week of about 3/8" with a Lehman and the sensitivity needs= to stay constant and linear within this range. This can be provided with a=20= rectangular coil of maybe 2000 turns and a quad NdFeB magnet system on mild=20= steel backing plates.

       I have described my detector system usi= ng four 1" square x 1/8" thick NdFeB magnets on 1/4" thick mild steel backin= g plates in the second half of  http://jclahr.com/science/psn/chapman/l= ehman/index.html

       You may be able to extract the primary=20= winding from a small low power mains transformer and use that? This is the s= ort which has side by side, not overlapping, P & S windings and a square= / rectangular former. I don't know what is available to you? Larry sells ro= und relay coils, but I prefer a larger rectangular form. You may also be abl= e to buy 'spare' mains coils for timers and water flow valves on washing mac= hines. Some have a suitable pancake form.

       The coil needs to have an internal rect= angular measurement in the direction of motion of maybe 1/2" to 3/4" so that= its output will be constant, allowing for the tilt drift on the seismometer= ..

       I also use an identical mild steel adju= stable frame for the damping, but it uses a 1/16" copper plate and 1" x 1/2"= x 1/4" thick NdFeB bar magnets. The damping tongue is mounted horizontally=20= and the damping magnet block is simply slid further over it until you get ~0= ..7 critical damping. If you deflect the arm 10 mm and release it, it should=20= swing 0.5 mm beyond the balance point before returning to balance. The dampi= ng force that you need decreases as the period set is increased, and increas= es with the seismic mass, so it needs to be easily adjustable. This construc= tion is easy to set up and use and it is NOT temperature sensitive. This mag= net + tongue damping arrangement is very effective.

       You can buy suitable NdFeB magnets from= www.kjmagnetics.com.

       Regards,

       Chris Chapman Subject: Re: Seismograph for school From: "Geoffrey" gmvoeth@........... Date: Sat, 30 Sep 2006 19:27:59 -0700 Hello Chris; Can you tell us how to get a uniform magnetic field to cut the coil at right angles (normal) to the windings ? can you use two opposing horse shoe magnets with a coil in the middle ? i should imagine a sturdy custom built non magnetic bracket is needed as well as great care not to let the magnets clap together or the impact might weaken the magnets. i think those horshoe magnets with a hole in the middle of the u is the way to go. regards; geoff __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Seismograph for school From: ChrisAtUpw@....... Date: Sat, 30 Sep 2006 23:58:52 EDT In a message dated 2006/10/01, gmvoeth@........... writes: > Hello Chris; > Can you tell us how to get a uniform magnetic field > to cut the coil at right angles (normal) to the windings ? Hi Geoff, I use 4 off 1" sq x 1/8" rectangular NdFeB magnets on two 3.5" x 2" x 1/4" thick mild steel backing plates and mount the coil in between. You have N+S magnets on one face opposite to S+N magnets on the other face. This gives a high central field and a linear movement response. I use a rectangular pancake coil of about 2000 turns. It is quite effective! See http://jclahr.com/science/psn/chapman/lehman/index.html > can you use two opposing horse shoe magnets > with a coil in the middle ? This is likely to give a lower sensitivity and is more difficult to make / mount. Large Alnico U magnets are quite expensive. You benefit from the relatively high flux of the NdFeB magnets. Regards, Chris Chapman In a me= ssage dated 2006/10/01, gmvoeth@........... writes:

Hello Chris;
Can you tell us how to get a uniform magnetic field
to cut the coil at right angles (normal) to the windings ?


Hi Geoff,

       I use 4 off 1" sq x 1/8" rectangular Nd= FeB magnets on two 3.5" x 2" x 1/4" thick mild steel backing plates and moun= t the coil in between. You have N+S magnets on one face opposite to S+N magn= ets on the other face. This gives a high central field and a linear movement= response. I use a rectangular pancake coil of about 2000 turns. It is quite= effective!

       See  http://jclahr.com/science/psn= /chapman/lehman/index.html

can you use two opposing horse=20= shoe magnets
with a coil in the middle ?


       This is likely to give a lower sensitiv= ity and is more difficult to make / mount. Large Alnico U magnets are quite=20= expensive. You benefit from the relatively high flux of the NdFeB magnets.
       Regards,

       Chris Chapman Subject: Re: Seismograph for school From: "Geoffrey" gmvoeth@........... Date: Sun, 1 Oct 2006 00:40:52 -0700 Hello Chris; http://jclahr.com/science/psn/chapman/lehman/index.html Yes, I like that design very much. Do you make a vertical version of that with a spring where the wire is ? I would like very much to either buy a kit or the plans from you to build my own vertical. I lack talent in your area I need help to make a decent sensor. Vertical is my only interest unless I can get a planer type sensor in the horizontal. Meaning a single sensor for both EW/NS. Please email me the details. gmvoeth@........... gmvoeth@......... gmvoeth@......... any one of those three addresses. I have seen a novel sensor at ASU about 1985 where two masses are N/S and E/W but vertically at a 45 degree angle or so making it possible to reproduce three dimensional motion with only two sensors. Or so it seemed to me. I have never seen that design on the Internet. regards; geoff __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Seismograph for school From: ChrisAtUpw@....... Date: Sun, 1 Oct 2006 15:39:26 EDT In a message dated 2006/10/01, gmvoeth@........... writes: > Hello Chris; > http://jclahr.com/science/psn/chapman/lehman/index.html > Yes, I like that design very much. > > Do you make a vertical version of that > with a spring where the wire is ? Hi Geoff, Not at the moment. Long period verticals are much more difficult to make than long period horizontals. The essential properties to give a 'zero length extension spring' were worked out by LaCoste in the mid 1930's. See http://psn.quake.net/bibliography.html To balance the vertical force of gravity on the mass requires a very constant force. You need a Ni-SpanC spring and a lot of careful design to enable you to get stable periods over about 10 secs. The elastic properties of steel springs are much too temperature sensitive. One alternative is to use a steel leaf spring, but to provide electronic force feedback to both compensate for incoming signals and to remove the drift. The feedback essentially tries to hold the mass stationary. See great example at http://www.bryantlabs.net/seismo.html Another alternative is to use a steel spring to produce a vertical with a period of 1 to 3 seconds, which is not too difficult to do and then extend the response electronically by x10 to x20 - as you can for a geophone (Roberts' circuit). You could probably extend the period of your 1 Hz geophone to about ~20 sec this way, but you would likely see some increase in sensor noise. This period extension method is attempted on the AS-1. See http://jclahr.com/science/psn/as1/index.html The basic period is about 1.5 sec and a response from 3Hz to 20 sec is claimed, but the manufactured item costs about US $600. Regards, Chris Chapman In a me= ssage dated 2006/10/01, gmvoeth@........... writes:

Hello Chris;
http://jclahr.com/science/psn/chapman/lehman/index.html
Yes, I like that design very much.

Do you make a vertical version of that
with a spring where the wire is ?


Hi Geoff,

       Not at the moment.

       Long period verticals are much more dif= ficult to make than long period horizontals. The essential properties to giv= e a 'zero length extension spring' were worked out by LaCoste in the mid 193= 0's. See http://psn.quake.net/bibliography.html To balance the vertical forc= e of gravity on the mass requires a very constant force. You need a Ni-SpanC= spring and a lot of careful design to enable you to get stable periods over= about 10 secs. The elastic properties of steel springs are much too tempera= ture sensitive.

       One alternative is to use a steel leaf=20= spring, but to provide electronic force feedback to both compensate for inco= ming signals and to remove the drift. The feedback essentially tries to hold= the mass stationary. See great example at http://www.bryantlabs.net/seismo.= html

       Another alternative is to use a steel s= pring to produce a vertical with a period of 1 to 3 seconds, which is not to= o difficult to do and then extend the response electronically by x10 to x20=20= - as you can for a geophone (Roberts' circuit). You could probably extend th= e period of your 1 Hz geophone to about ~20 sec this way, but you would like= ly see some increase in sensor noise.

       This period extension method is attempt= ed on the AS-1. See http://jclahr.com/science/psn/as1/index.html The basic p= eriod is about 1.5 sec and a response from 3Hz to 20 sec is claimed, but the= manufactured item costs about US $600.

       Regards,

       Chris Chapman Subject: Re: Seismograph for school From: "meredith lamb" paleoartifact@......... Date: Sun, 1 Oct 2006 14:04:12 -0600 Hi all, There is a choice of magnet distributors one can entertain for purchasing magnets of course. "Magnets4less" Lists magnets roughly for alot less (~1/3 to 1/4) the price of KJMagnetics. The problem with Magnet4less is they have a minimum order of ~$30.00.....and....their shipping/handling charge of ~$8 or so, is afew dollars more, and its the ultra slow UPS, and their personnel at that place. KJMagnetics ships fast, and usually a flat rate via USPS. KJMagnetics also has a minimum quantity order (~usually 10 of whatever size), as does Magnets4less which can get up to 20 minimum ....for the sizes entertained here. Its worth comparison shopping I suppose .....for example: KJMagnetics: 1x1x1/8"= qty of 10 @ 29.15 ($2.91 each) Magnets4less: 1x1x1/8"= qty of 20 @..... ($0.98 each) Well made horizontal Chris! Still trying to quess what the boom pivot actually is.....perhaps a single wire vertical between the blocks and the boom end center pivots on such?? (can't see on the photo) Take care, Meredith Lamb On 9/30/06, ChrisAtUpw@....... wrote: > > In a message dated 2006/10/01, gmvoeth@........... writes: > > Hello Chris; > Can you tell us how to get a uniform magnetic field > to cut the coil at right angles (normal) to the windings ? > > > > Hi Geoff, > > I use 4 off 1" sq x 1/8" rectangular NdFeB magnets on two 3.5" x 2" > x 1/4" thick mild steel backing plates and mount the coil in between. You > have N+S magnets on one face opposite to S+N magnets on the other face. This > gives a high central field and a linear movement response. I use a > rectangular pancake coil of about 2000 turns. It is quite effective! > > See http://jclahr.com/science/psn/chapman/lehman/index.html > > can you use two opposing horse shoe magnets > with a coil in the middle ? > > > > This is likely to give a lower sensitivity and is more difficult to > make / mount. Large Alnico U magnets are quite expensive. You benefit from > the relatively high flux of the NdFeB magnets. > > Regards, > > Chris Chapman Hi all,

There is a choice of magnet distributors one can entertain for purchasing
magnets of course.  "Magnets4less" Lists magnets roughly for alot less
(~1/3 to 1/4) the price of KJMagnetics.  The problem with Magnet4less
is they have a minimum order of ~$30.00.....and....their shipping/handling
charge of ~$8 or so, is afew dollars more, and its the ultra slow UPS, and
their personnel at that place.  KJMagnetics ships fast, and usually a flat rate
via USPS.  KJMagnetics also has a minimum quantity order (~usually 10
of whatever size), as does Magnets4less which can get up to 20 minimum
....for the sizes entertained here.  Its worth comparison shopping I suppose
.....for example:

KJMagnetics:    1x1x1/8"= qty of 10 @ 29.15 ($2.91 each)
Magnets4less:   1x1x1/8"= qty of 20 @..... ($0.98 each)

Well made horizontal Chris!  Still trying to quess what the boom
pivot actually is.....perhaps a single wire vertical between the blocks and
the boom end center pivots on such?? (can't see on the photo)

Take care, Meredith Lamb

 
On 9/30/06, ChrisAtUpw@....... <ChrisAtUpw@.......> wrote:
In a message dated 2006/10/01, gmvoeth@........... writes:

Hello Chris;
Can you tell us how to get a uniform magnetic field
to cut the coil at right angles (normal) to the windings ?


Hi Geoff,

       I use 4 off 1" sq x 1/8" rectangular NdFeB magnets on two 3.5" x 2" x 1/4" thick mild steel backing plates and mount the coil in between. You have N+S magnets on one face opposite to S+N magnets on the other face. This gives a high central field and a linear movement response. I use a rectangular pancake coil of about 2000 turns. It is quite effective!

       See  http://jclahr.com/science/psn/chapman/lehman/index.html

can you use two opposing horse shoe magnets
with a coil in the middle ?


        This is likely to give a lower sensitivity and is more difficult to make / mount. Large Alnico U magnets are quite expensive. You benefit from the relatively high flux of the NdFeB magnets.

       Regards,

       Chris Chapman

Subject: Re: Seismograph for school From: Bobhelenmcclure@....... Date: Sun, 1 Oct 2006 21:21:16 EDT Hi all, I agree with Chris Chapman on the design of magnets and coils for horizontal sensors. Those who have an interest in building their own sensors should take a look at mine on John Lahr's web site, especially page _http://www.jclahr.com/science/psn/mcclure/horiz2.html_ (http://www.jclahr.com/science/psn/mcclure/horiz2.html) I operate three sensors for Z, N, and E. They are adjusted to fairly short natural periods, ranging from 5 to 14 seconds. I extend their effective period to 24 seconds by a digital filter of my own design, with excellent results. The magnets I recommend are available for $5.50 each, 50mm x 18mm x 6mm block magnet, from _http://www.gaussboys.com_ (http://www.gaussboys.com) You will need four of them and two pieces of 1/4 inch flat steel, two inches by three inches, and four steel bolts to make a magnet assembly. You do not necessarily need separate damping magnets. Just shunt the pickup coil with the appropriate resistance. Bob McClure Locust Valley, NY
Hi all,
 
  I agree with Chris Chapman on the design of magnets and coils fo= r=20 horizontal sensors. Those who have an interest in building their own sensors= =20 should take a look at mine on John Lahr's web site, especially page http://www.jc= lahr.com/science/psn/mcclure/horiz2.html
 
  I operate three sensors for Z, N, and E. They are adjusted to fa= irly=20 short natural periods, ranging from 5 to 14 seconds. I extend their effectiv= e=20 period to 24 seconds by a digital filter of my own design, with excellent=20 results.
 
  The magnets I recommend are available for $5.50 each, 50mm x 18m= m x=20 6mm block magnet, from http://www.gaussboys.com  You wil= l need=20 four of them and two pieces of 1/4 inch flat steel, two inches by three inch= es,=20 and four steel bolts to make a magnet assembly. You do not necessarily need=20 separate damping magnets. Just shunt the pickup coil with the appropriate=20 resistance.
 
Bob McClure
Locust Valley, NY
 Subject: Re: Seismograph for school From: ChrisAtUpw@....... Date: Sun, 1 Oct 2006 22:58:49 EDT In a message dated 2006/10/02, Bobhelenmcclure@....... writes: > I agree with Chris Chapman on the design of magnets and coils for > horizontal sensors. Hi Bob, Thanks! Chris In a me= ssage dated 2006/10/02, Bobhelenmcclure@....... writes:

I agree with Chris Chapman on=20= the design of magnets and coils for horizontal sensors.


Hi Bob,

       Thanks!

       Chris Subject: Re: Seismograph for school From: "tchannel" tchannel@.............. Date: Sun, 1 Oct 2006 22:12:06 -0600 Hi Bob, Thanks for the great picture. I really liked your ideas and = also the great one that Chris made. Chris posted a drawing showing the magnet layout. Two magnets on top, = end to end N to S, I think, and on the bottom two magnets end to end S = to N. I find they make these magnets with the N and S poles in various = arrangement. I don't remember the terms but are your poles on the ends or on the Axially (through 6mm = thickness)? In other words, laying flat, face up, North and flip it = over and that side is South? I made my first sensor, using a cow magnet and a coil in the shape of a = spool, the cow magnet's, North pole, only fits into the spool hole, to = the center point. If the pendulum move right, the North pole moves from = center to the end of the spool, if it move left the North pole moves = from the center of the spool to the entrance of the spool. It does = work, but I see these are much better arrangement. After reading these postings, I have a much better ideas about the coil = size and proper wire size. On the other hand I see picture of huge huge = magnets and coil. Is there a measurement in mv's or other test to tell = if one has made a coil/magnet arrangement which is proper in output? Thanks, for the ideas, Ted ----- Original Message -----=20 From: Bobhelenmcclure@.......... To: psn-l@................. Sent: Sunday, October 01, 2006 7:21 PM Subject: Re: Seismograph for school Hi all, I agree with Chris Chapman on the design of magnets and coils for = horizontal sensors. Those who have an interest in building their own = sensors should take a look at mine on John Lahr's web site, especially = page http://www.jclahr.com/science/psn/mcclure/horiz2.html I operate three sensors for Z, N, and E. They are adjusted to fairly = short natural periods, ranging from 5 to 14 seconds. I extend their = effective period to 24 seconds by a digital filter of my own design, = with excellent results. The magnets I recommend are available for $5.50 each, 50mm x 18mm x = 6mm block magnet, from http://www.gaussboys.com You will need four of = them and two pieces of 1/4 inch flat steel, two inches by three inches, = and four steel bolts to make a magnet assembly. You do not necessarily = need separate damping magnets. Just shunt the pickup coil with the = appropriate resistance. Bob McClure Locust Valley, NY
Hi Bob,  Thanks for the great picture.  I really liked = your ideas=20 and also the great one that Chris made.
Chris posted a drawing showing the magnet layout.  Two magnets = on top,=20 end to end N to S, I think, and on the bottom two magnets end to end S = to=20 N.   I find they make these magnets with the N and S poles in = various=20 arrangement.  I don't remember the terms
but are your poles on the ends or on the Axially (through 6mm=20 thickness)?   In other words, laying flat, face up, North and = flip it=20 over and that side is South?
 
I made my first sensor, using a cow magnet and a coil in the shape = of a=20 spool,  the cow magnet's, North pole, only fits into the spool = hole, to the=20 center point.  If the pendulum move right, the North pole = moves from=20 center to the end of the spool, if it move left the North pole moves = from the=20 center of the spool to the entrance of the spool.   It does = work, but=20 I see these are much better arrangement.
 
After reading these postings, I have a much better ideas about the = coil=20 size and proper wire size.  On the other hand I see picture of huge = huge=20 magnets and coil.   Is there a measurement in mv's or other = test to=20 tell if one has made a coil/magnet arrangement which is proper in = output?
 
Thanks, for the ideas,  Ted
----- Original Message -----
From:=20 Bobhelenmcclure@....... =
Sent: Sunday, October 01, 2006 = 7:21=20 PM
Subject: Re: Seismograph for = school

Hi all,
 
  I agree with Chris Chapman on the design of magnets and = coils for=20 horizontal sensors. Those who have an interest in building their own = sensors=20 should take a look at mine on John Lahr's web site, especially page http://www= ..jclahr.com/science/psn/mcclure/horiz2.html
 
  I operate three sensors for Z, N, and E. They are adjusted = to=20 fairly short natural periods, ranging from 5 to 14 seconds. I extend = their=20 effective period to 24 seconds by a digital filter of my own design, = with=20 excellent results.
 
  The magnets I recommend are available for $5.50 each, 50mm = x 18mm=20 x 6mm block magnet, from http://www.gaussboys.com  = You will=20 need four of them and two pieces of 1/4 inch flat steel, two inches by = three=20 inches, and four steel bolts to make a magnet assembly. You do not = necessarily=20 need separate damping magnets. Just shunt the pickup coil with the = appropriate=20 resistance.
 
Bob McClure
Locust Valley, NY
Subject: Magnests and coil for PVC seismometer & more From: jonfr500@......... Date: Mon, 2 Oct 2006 05:45:38 +0000 Hi all My Gentoo Linux hard drive is dieing on me (it's not dead, it's giving erro= rs), so I have to use webmail until I can replace it and get my system back= up. I am going to start to build my PVC seismometer this month, what I am hopef= ully going to buy this month are three things. Pair of magnets (no larger t= hen 4 cm in diamater), a coil and a resistance (like they use in geophones)= .. I need a suggestions on the magets, the coil and the resistance. The natr= ual frequancy of the PVC seismometer is ment to be 1Hz, that is a good plac= e for me to start. Regards. J=F3n Fr=EDmann. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Sensor calibration From: Bobhelenmcclure@....... Date: Mon, 2 Oct 2006 22:00:43 EDT I have been asked about sensor calibration. For my thoughts, please go to _http://www.seismicnet.com/psnlist/index04.html_ (http://www.seismicnet.com/psnlist/index04.html) to see my letter on the subject, submitted on Tue. 13 Jul 2004 19:33:44 GMT. I have used both the methods described there for my own sensors. Cheers, Bob McClure
  I have been asked about sensor calibration. For my thoughts, ple= ase=20 go to
http://www.seismicne= t.com/psnlist/index04.html to=20 see my letter on the subject, submitted on Tue. 13 Jul 2004 19:33:44 GMT. I=20= have=20 used both the methods described there for my own sensors.
 
Cheers,
 
Bob McClure
 Subject: Re: Seismograph for school From: "tchannel" tchannel@.............. Date: Tue, 3 Oct 2006 10:28:57 -0600 Hi Bob, I have questions about your great Horz. sensor and the picture. 1. You used solder for the mass, is the mass volume fixed or is there a = wide range of weights, one could use. I guess the mass is to overcome = the friction of the hinge and stay stationary. The reason I ask is I = see a wide range of masses, but most around 5#. What is yours? and what = is your beam length? 2. Again the solder, is non magnetic is this important as I see many = things use as mass including iron? 3. I see you used a resistor as a damp, and not a external damper = device. I have read about doing this, but could not understand the = values for the resistor. You used 94k (in parallal?) acrossed the coil? = How did you arrive at that value? 4. You indicate to use a 100k in place of the 10k when using Larry's = amp, which I will be using. Why is that? 5. The placement of the sensor: Could it be on other than a concrete = floor, a normal wood floor? Could it be on carpet? I know that is not = the best choice, but many schools have such floors. Or should one not = bother with any other surface but a concrete floor? Thanks for your advise, and "well done!" Ted ----- Original Message -----=20 From: Bobhelenmcclure@.......... To: psn-l@................. Sent: Sunday, October 01, 2006 7:21 PM Subject: Re: Seismograph for school Hi all, I agree with Chris Chapman on the design of magnets and coils for = horizontal sensors. Those who have an interest in building their own = sensors should take a look at mine on John Lahr's web site, especially = page http://www.jclahr.com/science/psn/mcclure/horiz2.html I operate three sensors for Z, N, and E. They are adjusted to fairly = short natural periods, ranging from 5 to 14 seconds. I extend their = effective period to 24 seconds by a digital filter of my own design, = with excellent results. The magnets I recommend are available for $5.50 each, 50mm x 18mm x = 6mm block magnet, from http://www.gaussboys.com You will need four of = them and two pieces of 1/4 inch flat steel, two inches by three inches, = and four steel bolts to make a magnet assembly. You do not necessarily = need separate damping magnets. Just shunt the pickup coil with the = appropriate resistance. Bob McClure Locust Valley, NY
Hi Bob,  I have questions about your great Horz. sensor and = the=20 picture.
 
1. You used solder for the mass,  is the mass volume fixed or = is there=20 a wide range of weights, one could use.  I guess the mass is to = overcome=20 the friction of the hinge and stay stationary.  The reason I ask is = I see a=20 wide range of masses, but most around 5#.  What is yours? and what = is your=20 beam length?
 
2. Again the solder, is non magnetic is this important as I see = many things=20 use as mass including iron?
 
3.  I see you used a resistor as a damp, and not a external = damper=20 device.  I have read about doing this, but could not understand the = values=20 for the resistor.  You used 94k (in parallal?) acrossed the = coil?  How=20 did you arrive at that value?
 
4. You indicate to use a 100k in place of the 10k when using = Larry's=20 amp,  which I will be using.  Why is that?
 
5.  The placement of the sensor:  Could it be on other = than a=20 concrete floor, a normal wood floor?  Could it be on carpet?  = I know=20 that is not the best choice, but many schools have such floors.  Or = should=20 one not bother with any other surface but a concrete floor?
 
Thanks for your advise, and "well done!"   Ted
----- Original Message -----
From:=20 Bobhelenmcclure@....... =
Sent: Sunday, October 01, 2006 = 7:21=20 PM
Subject: Re: Seismograph for = school

Hi all,
 
  I agree with Chris Chapman on the design of magnets and = coils for=20 horizontal sensors. Those who have an interest in building their own = sensors=20 should take a look at mine on John Lahr's web site, especially page http://www= ..jclahr.com/science/psn/mcclure/horiz2.html
 
  I operate three sensors for Z, N, and E. They are adjusted = to=20 fairly short natural periods, ranging from 5 to 14 seconds. I extend = their=20 effective period to 24 seconds by a digital filter of my own design, = with=20 excellent results.
 
  The magnets I recommend are available for $5.50 each, 50mm = x 18mm=20 x 6mm block magnet, from http://www.gaussboys.com  = You will=20 need four of them and two pieces of 1/4 inch flat steel, two inches by = three=20 inches, and four steel bolts to make a magnet assembly. You do not = necessarily=20 need separate damping magnets. Just shunt the pickup coil with the = appropriate=20 resistance.
 
Bob McClure
Locust Valley, NY
Subject: Locating earthqukes with winquake From: jonfr500@......... Date: Tue, 3 Oct 2006 18:20:26 +0000 Hi Is it possible for me to locate earthquakes with Winquake ? Becose I am goi= ng to setup a remote station soon, problay after 2 - 3 months (depending on= few things). The remote station won't be internet connected, but I will co= llect data from it once a month. Sometimes next week I will also get one sensor reading regarding a earthqua= ke that I did detect this summer, I am going to attemt to locate that earth= quake to some exstent just by using two stations. Regards. J=F3n Fr=EDmann. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Locating earthqukes with winquake From: ChrisAtUpw@....... Date: Tue, 3 Oct 2006 18:53:16 EDT In a message dated 2006/10/03, jonfr500@......... writes: > Is it possible for me to locate earthquakes with Winquake ? Because I am > going to setup a remote station soon, probably after 2 - 3 months (depending on > few things). The remote station won't be internet connected, but I will > collect data from it once a month. > > Sometimes next week I will also get one sensor reading regarding an > earthquake that I did detect this summer, I am going to attempt to locate that > earthquake to some existent just by using two stations. Hi Jon, Before you spend any money.... The P wave may travel at ~8 km /sec. You are going to need fairly widely separated stations to get a reasonably accurate angle estimate, depending on the distance. You can determine the approximate distance from the P-S interval. Can you get on-line signals from one of the Icelandic seismic stations as your second source? At least to try out? If you are going to use this method, you will need precision timing at all times, about 0.1 sec or better. You are lucky if the software clock on a computer is accurate to 30 sec / day! They are hopeless for seismic work. This is likely to need a GPS receiver at both stations. Could you use an internet link? What sort of sensors were you planning to use? Regional and teleseismic quakes need a response down to 0.5 Hz. Regards, Chris Chapman In a me= ssage dated 2006/10/03, jonfr500@......... writes:

Is it possible for me to locate= earthquakes with Winquake ? Because I am going to setup a remote station so= on, probably after 2 - 3 months (depending on few things). The remote statio= n won't be internet connected, but I will collect data from it once a month.=

Sometimes next week I will also get one sensor reading regarding an earthqua= ke that I did detect this summer, I am going to attempt to locate that earth= quake to some existent just by using two stations.


Hi Jon,

       Before you spend any money....

       The P wave may travel at ~8 km /sec. Yo= u are going to need fairly widely separated stations to get a reasonably acc= urate angle estimate, depending on the distance. You can determine the appro= ximate distance from the P-S interval. Can you get on-line signals from one=20= of the Icelandic seismic stations as your second source? At least to try out= ?

       If you are going to use this method, yo= u will need precision timing at all times, about 0.1 sec or better. You are=20= lucky if the software clock on a computer is accurate to 30 sec / day! They=20= are hopeless for seismic work. This is likely to need a GPS receiver at both= stations.

       Could you use an internet link?

       What sort of sensors were you planning=20= to use? Regional and teleseismic quakes need a response down to 0.5 Hz.

       Regards,

       Chris Chapman Subject: Re: Locating earthqukes with winquake From: jonfr500@......... Date: Tue, 3 Oct 2006 23:23:37 +0000 Hi The distanst between the stations is going to be ~11 km. I am going to use = gps clock on both stations, it is a standard that I have implimented at cur= rent date. All IMO stations are digital stations and I cannot lisen to them. They also= use there own specalised decoding software, that I don't have accsess to. = But I can request a data from IMO and then I get a sac binary format files,= that I convert to psn format. The second station is going to use 4.5Hz geophone, like the one I have. The= second station is going to sit directly on a bedrock, no sand, nothing of = such short. I cannot have a internet connection, becose this is out in the = country side and the location doesn't have a fone line. Even then the only = connection option is a ISDN at 9.6kbps as speed, if I don't want to pay pr = min, charge. Regards. J=F3n Fr=EDmann. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Seismograph for school From: ChrisAtUpw@....... Date: Tue, 3 Oct 2006 21:00:29 EDT In a message dated 2006/10/03, tchannel@.............. writes: > 1. You used solder for the mass, is the mass volume fixed or is there a > wide range of weights, one could use. I guess the mass is to overcome the > friction of the hinge and stay stationary. The reason I ask is I see a wide range > of masses, but most around 5#. What is yours? and what is your beam length? Hi Ted, The period of a simple pendulum T = 2 x Pi x sqrt(L / g) where L is t he length in m and g = 9.81 m / sec^2. With a garden gate arrangement you can extend the period by x20 or more, but this gets increasingly difficult since the suspension angles get tiny and you may get dimensional / temperature associated lack of stability. Make the cross bar width ~1/3 the base length. There are pendulum design sheets on John Lahr's website. If A is the angle between the vertical and the rotation axis of the gate, you multiply g in the equation above by sine A. You will be using tilts of less than 1 degree. A 22" arm (1.5 ec) set to 20 sec requires an angle of 0.322 deg; set to 30 sec it requires 0.143 deg. The period is independent of the mass of the pendulum, but depends on the 'radius of gyration' of the whole moving system. A heavy connecting beam can significantly reduce this. A reasonable mass is 1 to 2 lbs with about a 2 ft arm - 1.5 sec. If you use more weight than this, you will need a strong top suspension. I suggest that you work out this force and look up the strength of your wire? The idea behind the suspension is that there should be as little friction as possible. Pre electronic seismometers used mechanical lever gain linkages to move the pen and hence needed a large mass to overcome the friction. > 2. Again the solder, is non magnetic is this important as I see many things > use as mass including iron? I don't use any magnetic materials on the boom 'in principle'. You won't know for sure what is a magnetic interaction and what is seismic. If I am taking the time and effort to build a seismometer, avoiding obvious problems just makes good sense. Like put the pickup coil on the arm and the magnets on the baseplate! > 3. I see you used a resistor as a damp, and not a external damper device. > I have read about doing this, but could not understand the values for the > resistor. You used 94k (in parallel?) acrossed the coil? How did you arrive > at that value? Experiment. Exactly the same principle - any relative movement induces a voltage in the coil proportionate to the magnetic field, the number of turns on the coil, the velocity and the circuit resistance provides the damping loss. The lower this resistance, the greater the loss, but this also reduces the output voltage. Not significantly in this design, since the magnetic field and coupling are very high and the mass is low. > 4. You indicate to use a 100k in place of the 10k when using Larry's amp, > which I will be using. Why is that? Because an input resistor of 10 K is less than the required damping resistor for this particular sensor design. > 5. The placement of the sensor: Could it be on other than a concrete > floor, a normal wood floor? Could it be on carpet? I know that is not the best > choice, but many schools have such floors. Or should one not bother with any > other surface but a concrete floor? You are likely to find wood floors both noisy and lacking tilt stability - can be critical for a long period Lehman. I can't say no, but try it with little expectation of success? You can put wide melamine shelving on a carpet and add weight to hold it firm, but the thicker the carpet the lower the stability. Expect drift with temperature, humidity and time. Bricks? On a concrete floor, I stick on 2" squares of 1/8" SS plate with pool adhesive to provide a good base for the adjusting screws. Regards, Chris Chapman In a me= ssage dated 2006/10/03, tchannel@.............. writes:

1. You used solder for the mass= ,  is the mass volume fixed or is there a wide range of weights, one co= uld use. I guess the mass is to overcome the friction of the hinge and stay=20= stationary. The reason I ask is I see a wide range of masses, but most aroun= d 5#.  What is yours? and what is your beam length?


Hi Ted,

       The period of a simple pendulum T =3D 2= x Pi x sqrt(L / g) where L is the length in m and g =3D 9.81 m / sec^2. Wit= h a garden gate arrangement you can extend the period by x20 or more, but th= is gets increasingly difficult since the suspension angles get tiny and you=20= may get dimensional / temperature associated lack of stability. Make the cro= ss bar width ~1/3 the base length. There are pendulum design sheets on John=20= Lahr's website. If A is the angle between the vertical and the rotation axis= of the gate, you multiply g in the equation above by sine A.  You will= be using tilts of less than 1 degree. A 22" arm (1.5 ec) set to 20 sec requ= ires an angle of 0.322 deg; set to 30 sec it requires 0.143 deg.
       The period is independent of the mass o= f the pendulum, but depends on the 'radius of gyration' of the whole moving=20= system. A heavy connecting beam can significantly reduce this. A reasonable=20= mass is 1 to 2 lbs with about a 2 ft arm - 1.5 sec. If you use more weight t= han this, you will need a strong top suspension. I suggest that you work out= this force and look up the strength of your wire?
       The idea behind the suspension is that=20= there should be as little friction as possible. Pre electronic seismometers=20= used mechanical lever gain linkages to move the pen and hence needed a large= mass to overcome the friction.

2. Again the solder, is non mag= netic is this important as I see many things use as mass including iron?

       I don't use any magnetic materials on=20= the boom 'in principle'. You won't know for sure what is a magnetic interact= ion and what is seismic. If I am taking the time and effort to build a seism= ometer, avoiding obvious problems just makes good sense. Like put the pickup= coil on the arm and the magnets on the baseplate!

3.  I see you used a resis= tor as a damp, and not a external damper device.  I have read about doi= ng this, but could not understand the values for the resistor.  You use= d 94k (in parallel?) acrossed the coil?  How did you arrive at that val= ue?


       Experiment. Exactly the same principle= - any relative movement induces a voltage in the coil proportionate to the=20= magnetic field, the number of turns on the coil, the velocity and the circui= t resistance provides the damping loss. The lower this resistance, the great= er the loss, but this also reduces the output voltage. Not significantly in=20= this design, since the magnetic field and coupling are very high and the mas= s is low.

4. You indicate to use a 100k i= n place of the 10k when using Larry's amp, which I will be using. Why is tha= t?


       Because an input resistor of 10 K is l= ess than the required damping resistor for this particular sensor design.
5.  The placement of the=20= sensor: Could it be on other than a concrete floor, a normal wood floor? Cou= ld it be on carpet? I know that is not the best choice, but many schools hav= e such floors. Or should one not bother with any other surface but a concret= e floor?


       You are likely to find wood floors both= noisy and lacking tilt stability - can be critical for a long period Lehman= ..  I can't say no, but try it with little expectation of success? You c= an put wide melamine shelving on a carpet and add weight to hold it firm, bu= t the thicker the carpet the lower the stability. Expect drift with temperat= ure, humidity and time. Bricks? On a concrete floor, I stick on 2" squares o= f 1/8" SS plate with pool adhesive to provide a good base for the adjusting=20= screws.

       Regards,

       Chris Chapman Subject: Re: Locating earthqukes with winquake From: "Thomas Dick" dickthomas01@............. Date: Tue, 3 Oct 2006 20:20:07 -0500 what about using radio to connect to you computer like they are doing in Washington State, USA? __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Locating earthqukes with winquake From: jonfr500@......... Date: Wed, 4 Oct 2006 01:51:45 +0000 Hi There is a big mountin in between. I can't brodcast over it. I also think t= hat I might need a premission for such type of radio transmission, it probl= ay costs money. Regards. J=F3n Fr=EDmann. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Seismograph for school From: Ben Bradley benbradley@............... Date: Tue, 03 Oct 2006 21:59:10 -0400 ChrisAtUpw@....... wrote: > In a message dated 2006/10/03, tchannel@.............. writes: >>2. Again the solder, is non magnetic is this important as I see many things >>use as mass including iron? > > > I don't use any magnetic materials on the boom 'in principle'. You > won't know for sure what is a magnetic interaction and what is seismic. If I am > taking the time and effort to build a seismometer, avoiding obvious problems > just makes good sense. Like put the pickup coil on the arm and the magnets on > the baseplate! This makes good sense for eliminating magnetic effects on the boom, but you then have electric connections to something on the boom. How do you do connect to the coil and minimize friction and "spring"-type interference to the boom from the connecting wires? I have my own ideas in this area that I think are good, but I'd like to hear what others do for this. > Regards, > > Chris Chapman > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Building a lehman seismometer From: jonfr500@......... Date: Wed, 4 Oct 2006 02:18:59 +0000 Hi In my planning of building a PVC seimsmometer, I also plan to build a Lehma= n seismometer, if I can keep it small enugh. But I need a suggestion for ma= terial and some mesurements and proper drawings before I can start. I also = want to keep the frequancy of the Lehman seismometer around 1Hz. Regards. J=F3n Fr=EDmann. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Seismograph for school From: ChrisAtUpw@....... Date: Tue, 3 Oct 2006 22:54:19 EDT In a message dated 2006/10/04, benbradley@............... writes: > How do you do connect to the coil and minimize friction and "spring"-type > interference to the boom from the connecting wires? Hi Ben, The usual method is to use two small coils, or 'hairpins' maybe 2" long, of the finest insulated copper wire that you can get, which is likely to be 36 gauge, 5 thou, across the lower bearing. If you mount them vertically, they have the least torque. A small torque which is constant will not matter and it is balanced out during levelling. The electrical resistance will be very small compared to that of the coil. If you use wire like Beldsol, it has polyurethane insulation. You wrap it around the terminal post, apply a hot soldering iron and resin cored solder and the insulation just melts. You do not need to 'strip' the wire. Regards, Chris Chapman In a me= ssage dated 2006/10/04, benbradley@............... writes:

How do you do connect to the co= il and minimize friction and "spring"-type
interference to the boom from the connecting wires?


Hi Ben,

       The usual method is to use two small co= ils, or 'hairpins' maybe 2" long, of the finest insulated copper wire that y= ou can get, which is likely to be 36 gauge, 5 thou, across the lower bearing= .. If you mount them vertically, they have the least torque. A small torqu= e which is constant will not matter and it is balanced out during levell= ing. The electrical resistance will be very small compared to that of the co= il. If you use wire like Beldsol, it has polyurethane insulation. You wrap i= t around the terminal post, apply a hot soldering iron and resin cored solde= r and the insulation just melts. You do not need to 'strip' the wire.

       Regards,

       Chris Chapman Subject: Re: Building a lehman seismometer From: ChrisAtUpw@....... Date: Tue, 3 Oct 2006 23:23:14 EDT In a message dated 2006/10/04, jonfr500@......... writes: > I also plan to build a Lehman seismometer, if I can keep it small enough. > But I need a suggestion for material and some mesurements and proper drawings > before I can start. I also want to keep the frequency of the Lehman > seismometer around 1Hz. Hi Jon, The whole point about a Lehman type seismometer is that you take a pedulum which would have a period of about 1.3 to 1.5 sec if mounted vertically and extend the period to maybe 20 sec. The sensor will respond from 20 sec to the 10 Hz of your amplifier filter. I suspect that an arm of between 45 and 60 cm would be fine for you. Don't try to make it smaller. This should pick up your seismic signals very well. I make a T / L frame with U channel Al with 5 mm Al plate for the corner supports. I don't know what materials are available to you. You can use 50 x 25 mm, but I prefer 75 x 25 mm section. Regards, Chris Chapman In a me= ssage dated 2006/10/04, jonfr500@......... writes:

I also plan to build a Lehman s= eismometer, if I can keep it small enough. But I need a suggestion for mater= ial and some mesurements and proper drawings before I can start. I also want= to keep the frequency of the Lehman seismometer around 1Hz.

Hi Jon,

       The  whole point about a Lehman ty= pe seismometer is that you take a pedulum which would have a period of about= 1.3 to 1.5 sec if mounted vertically and extend the period to maybe 20 sec.= The sensor will respond from 20 sec to the 10 Hz of your amplifier filter.=20= I suspect that an arm of between 45 and 60 cm would be fine for you. Don't t= ry to make it smaller. This should pick up your seismic signals very well.
       I make a T / L frame with U channel Al=20= with 5 mm Al plate for the corner supports. I don't know what materials are=20= available to you. You can use 50 x 25 mm, but I prefer 75 x 25 mm section.
       Regards,

       Chris Chapman Subject: ebay auction From: Bob Barns royb1@........... Date: Wed, 04 Oct 2006 09:50:06 -0400 INTENSITRON Earthquake Intensity Computer (seismometer) Item number: 160037359005 ends Oct 8 Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Building a lehman seismometer From: "tchannel" tchannel@.............. Date: Wed, 4 Oct 2006 11:00:34 -0600 Hi Everyone, I did find some 38 gauge magnet wire, but thought you = might like to see this on ebay. 37 gauge Item number: 290035960569 one = pound. Thanks, Ted ----- Original Message ----- From: ChrisAtUpw@.......... To: psn-l@................. Sent: Tuesday, October 03, 2006 9:23 PM Subject: Re: Building a lehman seismometer In a message dated 2006/10/04, jonfr500@......... writes: I also plan to build a Lehman seismometer, if I can keep it small = enough. But I need a suggestion for material and some mesurements and = proper drawings before I can start. I also want to keep the frequency of = the Lehman seismometer around 1Hz. Hi Jon,=20 The whole point about a Lehman type seismometer is that you = take a pedulum which would have a period of about 1.3 to 1.5 sec if = mounted vertically and extend the period to maybe 20 sec. The sensor = will respond from 20 sec to the 10 Hz of your amplifier filter. I = suspect that an arm of between 45 and 60 cm would be fine for you. Don't = try to make it smaller. This should pick up your seismic signals very = well. I make a T / L frame with U channel Al with 5 mm Al plate for = the corner supports. I don't know what materials are available to you. = You can use 50 x 25 mm, but I prefer 75 x 25 mm section. Regards, Chris Chapman
Hi Everyone,  I did find some 38 = gauge magnet=20 wire, but thought you might like to see this on ebay.  37 gauge = Item=20 number: 290035960569 one pound.
 
Thanks, Ted
 
----- Original Message ----- = From: ChrisAtUpw@.......
Sent: Tuesday, October 03, 2006 = 9:23=20 PM
Subject: Re: Building a lehman=20 seismometer

In a=20 message dated 2006/10/04, jonfr500@......... = writes:

I also plan to build a Lehman seismometer, if I can keep = it=20 small enough. But I need a suggestion for material and some = mesurements and=20 proper drawings before I can start. I also want to keep the = frequency of the=20 Lehman seismometer around 1Hz.


Hi Jon,=20

       The  whole point = about a=20 Lehman type seismometer is that you take a pedulum which would have a = period=20 of about 1.3 to 1.5 sec if mounted vertically and extend the period to = maybe=20 20 sec. The sensor will respond from 20 sec to the 10 Hz of your = amplifier=20 filter. I suspect that an arm of between 45 and 60 cm would be fine = for you.=20 Don't try to make it smaller. This should pick up your seismic signals = very=20 well.

       I make a T / L frame = with U=20 channel Al with 5 mm Al plate for the corner supports. I don't know = what=20 materials are available to you. You can use 50 x 25 mm, but I prefer = 75 x 25=20 mm section.

      =20 Regards,

       Chris Chapman=20
Subject: Maine US Quakes From: "Thomas Dick" dickthomas01@............. Date: Thu, 5 Oct 2006 09:36:31 -0500 Thsi in our local paper this morning ... I quote Bar Harbor, Maine title of article "Water table drops after quake" Moinday's earthquake lowered the water level by 3 1/2 feet at one lo0cation in a national park but wasn't expected to hurt the water supply, officials said. By Wednesday, the water level was still falling but beginning to level off, said Gregory Stewart, a hydrologist water level was observed at one of the ageny's monitoring wells in Acadia National Park. The earthquake registered a magnitude of 3.9 and followed quakes with magnitudes of 3.5 and 2.5 on Sept. 22 and 26. and Maine was one place they felt safe putting atomic generating plants! __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Building a lehman seismometer From: "tchannel" tchannel@.............. Date: Thu, 5 Oct 2006 09:46:28 -0600 Hi Chris, A few questions: 1 Does your coil and damper assemblies just set on the aluminum base, = free to move for adjustment, or are they fixed to the base? 2 You cleaned the plates, which hold the magnets, and then painted the = exterior, but not the surface the magnets touch. Would the paint = interfere with something on that surface? 3 This is a hard question. Assuming I have finished my sensor, and = leveled it, what is the procedure for adjusting the period? I know the = target angle. I would guess one would have to start at that point, with the base = level, the pendulum level, and everything plumb. You mentioned the formula for determining the angle of the hinge, I have = that information. Not knowing the correct procedure, and not being able = to measure that small of an angle, I would have converted the angle into = a decimal of inches, and measured the difference from the top hinge to = the bottom hinge. Maybe you could walk me through this procedure? 4 I get confused with many of these terms, so I hope you understand this = question. If the target period is say 10 seconds, would the arm move, = when pulled 10mm, verrrrrrrrrry slowly, taking 10 seconds to complete = one cycle? 5 After it is leveled and the period is set, Is it then that you can = check the damp, by moving the arm 10mm and releasing it? I know what an underdamped situation would look like. But is there way = to tell if it is over damped? Thanks, Ted ----- Original Message -----=20 From: ChrisAtUpw@.......... To: psn-l@................. Sent: Tuesday, October 03, 2006 9:23 PM Subject: Re: Building a lehman seismometer In a message dated 2006/10/04, jonfr500@......... writes: I also plan to build a Lehman seismometer, if I can keep it small = enough. But I need a suggestion for material and some mesurements and = proper drawings before I can start. I also want to keep the frequency of = the Lehman seismometer around 1Hz. Hi Jon,=20 The whole point about a Lehman type seismometer is that you = take a pedulum which would have a period of about 1.3 to 1.5 sec if = mounted vertically and extend the period to maybe 20 sec. The sensor = will respond from 20 sec to the 10 Hz of your amplifier filter. I = suspect that an arm of between 45 and 60 cm would be fine for you. Don't = try to make it smaller. This should pick up your seismic signals very = well. I make a T / L frame with U channel Al with 5 mm Al plate for = the corner supports. I don't know what materials are available to you. = You can use 50 x 25 mm, but I prefer 75 x 25 mm section. Regards, Chris Chapman
Hi Chris,   A few = questions:
 
1 Does your coil and damper = assemblies just=20 set on the aluminum base, free to move for adjustment, or are they fixed = to the=20 base?
 
2 You cleaned the plates, which = hold the=20 magnets, and then painted the exterior, but not the surface the magnets=20 touch.  Would the paint interfere with something on that=20 surface?
 
3 This is a hard question.  = Assuming I=20 have finished my sensor, and leveled it, what is the procedure for = adjusting the=20 period?  I know the target angle.
I would guess one would have to start = at that=20 point, with the base level, the pendulum level, and everything=20 plumb.
You mentioned the formula for = determining the angle=20 of the hinge, I have that information.  Not knowing the correct = procedure,=20 and not being able to measure that small of an angle, I would have = converted the=20 angle into a decimal of inches, and measured the difference from the top = hinge=20 to the bottom hinge.  Maybe you could walk me through this=20 procedure?
 
4 I = get confused=20 with many of these terms, so I hope you understand this question.  = If the=20 target period is say 10 seconds, would the arm move, when pulled 10mm,=20 verrrrrrrrrry slowly, taking 10 seconds to complete one = cycle?
 
5  After it is leveled and the = period is set,=20 Is it then that you can check the damp, by moving the arm 10mm and = releasing=20 it?
I know what an underdamped situation = would look=20 like.  But is there way to tell if it is over damped?
 
Thanks, Ted
 
 
 
 
----- Original Message -----
From:=20 ChrisAtUpw@.......
Sent: Tuesday, October 03, 2006 = 9:23=20 PM
Subject: Re: Building a lehman=20 seismometer

In a=20 message dated 2006/10/04, jonfr500@......... = writes:

I also plan to build a Lehman seismometer, if I can keep = it=20 small enough. But I need a suggestion for material and some = mesurements and=20 proper drawings before I can start. I also want to keep the = frequency of the=20 Lehman seismometer around 1Hz.

Hi Jon,=20

       The  whole point = about a=20 Lehman type seismometer is that you take a pedulum which would have a = period=20 of about 1.3 to 1.5 sec if mounted vertically and extend the period to = maybe=20 20 sec. The sensor will respond from 20 sec to the 10 Hz of your = amplifier=20 filter. I suspect that an arm of between 45 and 60 cm would be fine = for you.=20 Don't try to make it smaller. This should pick up your seismic signals = very=20 well.

       I make a T / L frame = with U=20 channel Al with 5 mm Al plate for the corner supports. I don't know = what=20 materials are available to you. You can use 50 x 25 mm, but I prefer = 75 x 25=20 mm section.

      =20 Regards,

       Chris Chapman=20 Subject: Re: Building a lehman seismometer From: ChrisAtUpw@....... Date: Thu, 5 Oct 2006 15:26:42 EDT In a message dated 2006/10/05, tchannel@.............. writes: > 1 Does your coil and damper assemblies just set on the aluminum base, free > to move for adjustment, or are they fixed to the base? Hi Ted, My arm has a support wire fixture and then a mass right at the end of the arm. The support fixture carries a damping tongue in the direction of the hinge and a coil on the mass side. Both the sensor and damper magnets slide on the base strip, for mounting and adjustment of their position. They have small guide strips underneath which hold them parallel. > 2 You cleaned the plates, which hold the magnets, and then painted the > exterior, but not the surface the magnets touch. Would the paint interfere with > something on that surface? I suggest that you paint everything with Hammerite or similar, but try to get it smooth and level. I etch coated the magnet position with phosphoric acid, allowed it to react and dry overnight and then put CL anticorrosion car grease on it. I was not certain that I could get enough damping initially, but I found that I could overdamp the system quite easily, so I increased the damper magnet spacing. > 3 This is a hard question. Assuming I have finished my sensor, and levelled > it, what is the procedure for adjusting the period? Maybe you could walk me > through this procedure? You first lower the base plate / strip at the mass end. Then you mount the arm and make any necessary solder connections for the coil wiring. Then you put the magnet units on the base and adjust the top wire so that both the coil and the damping plate are central within the magnet spacings. The first time, you may need to make adjustments of the magnet block heights, so that the arm is parallel to the base. Then you slide the damper free and adjust the cross levels so that the arm is stable in the central position. If you can't get a stable central position, you need to adjust the suspension so that the top hinge is nearer the mass end - or the bottom fitting is further away. You may mark the end of the arm with an inkline and also put a central mark on the base. You deflect the arm and time a swing. It may be about 5 sec initially. Then you slowly raise the base at the mass end of the arm with the adjusting screw, testing to determine the period, until you get the period you want. As the period is lengthened, you will probably need to trim the cross level slightly. Then you slide the damping magnet over edge of the tongue, deflect the arm 10 mm and release it. It may help to stick a bit of graph paper to the base to be able the measure the position of the damping block. 0.7 damping is obtained when the arm swings 0.5 mm past the zero position and then falls back again. The amount of damping decreases as the set period increases, so it needs to be easily adjustable. If the critical position is obtained with the tongue less that half covering the magnets, increase the damper magnet spacing. > 4 I get confused with many of these terms, so I hope you understand this > question. If the target period is say 10 seconds, would the arm move, when > pulled 10mm, very slowly, taking 10 seconds to complete one cycle? That is correct. Assuming that the arm is not damped, you deflect it and then release it. It takes 2.5 sec to get to zero, overshoots and comes back to zero in 5 sec, overshoots again and comes back to zero from the initial direction in another 5 sec. Total 5 + 5 = 10 sec. The period is the time for one complete oscillation cycle. You want at least twice this. > 5 After it is leveled and the period is set, Is it then that you can check > the damp, by moving the arm 10mm and releasing it? Correct, you set up the period first and then you slide the damper further over the tongue in small steps until it is just a bit under critical. > I know what an underdamped situation would look like. But is there way > to tell if it is over damped? As you increase the damping from zero, the time that the arm takes to fall back through / to the balance position increases slightly. If you overdamp the arm, it never swings through the zero position and the more you damp it, the longer it takes to get there. Look for the arm swinging just past the zero line, but without another oscillation. Regards, Chris Chapman In a me= ssage dated 2006/10/05, tchannel@.............. writes:

1 Does your coil and damper ass= emblies just set on the aluminum base, free to move for adjustment, or are t= hey fixed to the base?


Hi Ted,

       My arm has a support wire fixture and t= hen a mass right at the end of the arm.
       The support fixture carries a damping t= ongue in the direction of the hinge and a coil on the mass side.
       Both the sensor and damper magnets slid= e on the base strip, for mounting and adjustment of their position. They hav= e small guide strips underneath which hold them parallel.  

2 You cleaned the plates, whic= h hold the magnets, and then painted the exterior, but not the surface the m= agnets touch.  Would the paint interfere with something on that surface= ?


       I suggest that you paint everything wi= th Hammerite or similar, but try to get it smooth and level. I etch coated t= he magnet position with phosphoric acid, allowed it to react and dry overnig= ht and then put CL anticorrosion car grease on it. I was not certain that I=20= could get enough damping initially, but I found that I could overdamp the sy= stem quite easily, so I increased the damper magnet spacing.

3 This is a hard question. Ass= uming I have finished my sensor, and levelled it, what is the procedure for=20= adjusting the period? Maybe you could walk me through this procedure?=

       You first lower the base plate / strip= at the mass end. Then you mount the arm and make any necessary solder conne= ctions for the coil wiring. Then you put the magnet units on the base and ad= just the top wire so that both the coil and the damping plate are central wi= thin the magnet spacings. The first time, you may need to make adjustments o= f the magnet block heights, so that the arm is parallel to the base.
       Then you slide the damper free and adju= st the cross levels so that the arm is stable in the central position. If yo= u can't get a stable central position, you need to adjust the suspension so=20= that the top hinge is nearer the mass end - or the bottom fitting is further= away. You may mark the end of the arm with an inkline and also put a centra= l mark on the base. You deflect the arm and time a swing. It may be about 5=20= sec initially. Then you slowly raise the base at the mass end of the arm wit= h the adjusting screw, testing to determine the period, until you get the pe= riod you want. As the period is lengthened, you will probably need to trim t= he cross level slightly.
       Then you slide the damping magnet o= ver edge of the tongue, deflect the arm 10 mm and release it. It may help to= stick a bit of graph paper to the base to be able the measure the position=20= of the damping block. 0.7 damping is obtained when the arm swings 0.5 mm pas= t the zero position and then falls back again.
       The amount of damping decreases as the=20= set period increases, so it needs to be easily adjustable. If the critical p= osition is obtained with the tongue less that half covering the magnets, inc= rease the damper magnet spacing.

4 I get confused with many of=20= these terms, so I hope you understand this question.  If the target per= iod is say 10 seconds, would the arm move, when pulled 10mm, very slowly, ta= king 10 seconds to complete one cycle?


       That is correct. Assuming that the arm= is not damped, you deflect it and then release it. It takes 2.5 sec to get=20= to zero, overshoots and comes back to zero in 5 sec, overshoots again and co= mes back to zero from the initial direction in another 5 sec. Total 5 + 5=20= =3D 10 sec. The period is the time for one complete oscillation cycle. You w= ant at least twice this.

5  After it is leveled an= d the period is set, Is it then that you can check the damp, by moving the a= rm 10mm and releasing it?


       Correct, you set up the period first a= nd then you slide the damper further over the tongue in small steps until it= is just a bit under critical.

    I know what= an underdamped situation would look like.  But is there way to tell if= it is over damped?


       As you increase the damping from zero,=20= the time that the arm takes to fall back through / to the balance position i= ncreases slightly. If you overdamp the arm, it never swings through the zero= position and the more you damp it, the longer it takes to get there. Look f= or the arm swinging just past the zero line, but without another oscillation= ..

       Regards,

       Chris Chapman Subject: Sensor magnet and coil design From: Bobhelenmcclure@....... Date: Thu, 5 Oct 2006 16:11:35 EDT I submitting this note in order to give others the benefits of my own sometimes trial-and-error efforts to build a seismic sensor. I am sure that Chris Chapman will continue to contribute, as well. Both Chris Chapman and I favor the use of Neodymium Iron Boron magnets arranged in a four-pole structure for generating the magnetic field needed for velocity sensing and damping in seismic sensors. The magnets are powerful, relatively cheap, and easily obtained. The magnets I favor are block magnets, 6 mm thick, 18 mm wide, and 50 mm long. They are magnetized in the thickness direction and are of the composition known as N38. They have a coercive force of about 12,000 Oersteds (CGS units), corresponding to 1.2 Teslas in the SI system. Construction of a four-pole magnet assembly is very simple, but also very hazardous. These magnets are attracted to steel and to each other with a force of about 57 pounds per square inch, and any skin caught between them can be badly nipped. You must keep loose magnets very far away from steel or each other and wear heavy leather work gloves when handling them. The magnets are brittle, and will break if they crash together or with steel. The pole plates are mild steel, thick enough to carry the flux of the magnetic circuit. More on that later. One of the plates must have clearance holes for 3/16" bolts, one hole in each corner. The plates, for the above magnet dimensions, should measure two inches by at least three inches. Slide two magnets onto each plate, with opposite poling on each plate. When you have one magnet in position on a plate, carefully hold the second magnet above the first. You will feel either an attraction or a repulsion of the second magnet toward the one on the plate. Make sure the force is repulsive, then slide the second magnet into place beside the first. When the magnets are positioned on each plate, make a wooden or plastic shim somewhat thinner than the final magnet gap you intend to use. I would use a shim about six inches long and the same width as the paired magnets, which would be about 1.5 inches for the example. With the shim covering the magnets of one plate, hold the second plate over it, getting no closer than enough to determine if the force between them is attractive or repulsive. The correct alignment is indicated by an attractive force. You now place the upper plate (magnets down) on the shim at one end of the lower plate and slide the upper plate and magnets up over the lower magnets. You now have a sandwich of upper and lower assemblies tightly squeezing the shim in between. Place four bolts in the plate with the holes. Note than these bolts are used to hold the plates apart, not together. Use the bolts to jack the plates apart to get the desired gap spacing, and then you can withdraw the shim. If each of your plates have clearance holes drilled in them, you will need two nuts for each screw. Now it is time to discuss what field strength you get, and what thickness of steel is required. Suppose for my example using 6 mm thick magnets, I use a gap of 6 mm. The resulting distance between plates is 18 mm, 12 mm filled with magnet, and 6 mm with air. I call the ratio of total magnet thickness to total plate separation the filling factor. To a first approximation, the gap field the coercive force of the magnetic material multiplied by the filling factor. In this example, the coercive force is 12 KOe and the filling factor is 2/3, so the gap field is 8 KOe. The accuracy of this estimate depends on the magnet width compared to the gap size. If the gap becomes appreciable compared to the width, you will get more fringing field and less-than-expected gap field. I have written a program that solves LaPlace's equation by iteration which lets me estimate more exactly what the penalty is for any geometry. For my example magnet structure, I use 1/4 inch thick steel plates. I find that there is a very slight saturation of the plates in the region between magnet pairs. When I use 24 mm wide magnets, there is a lot of saturation and a lot of external stray field around the whole assembly. I have to put steel side plates on the assembly to eliminate the saturation and the stray field. Steel can carry a flux density of about 20 to 24 KOe without saturation. Without saturation, the magnetic circuit of a 4-pole structure consists of a closed rectangular flux path, with lines traveling through magnets, gaps, and steel. The steel must carry the same total number of lines of flux as the gap and magnets. The number of lines is proportional to the gap flux density multiplied by the magnet width. In the example of 8 KOe and 18 mm width, this corresponds to 8,000 times 1.8, or 14,000 lines per lineal centimeter of magnet structure. The quarter-inch-thick steel (0.625 cm) must carry a flux density of 22,000 KOe. It does so, barely. The next topic is coil design. By following the above magnet assembly design principles, you know the approximate gap field, so by also knowing the magnet length you will be able to estimate the number of coil turns you will need to achieve a given output sensitivity in volts per meter per second. If the end loops of the coil extend beyond the ends of the magnet, each turn is immersed in a total field length of twice the magnet length. In the example design, the magnet length is 50 mm, so L per turn is 0.1 m. The output voltage generated by the moving coil is Volts = B * N * L * Vel, where B is field strength in Teslas, N is number of turns, L is length per turn in the field, and Vel is velocity in meters per second. One Tesla corresponds to 10,000 Oersteds. Suppose n = 1100, B = 0.8 Tesla, and L = 0.1 meter. Then Volts/Vel = 0.8 * 1100 * 0.1 = 88 v-s/m, which is a good number to strive for. A wire size of #38 or less will allow this number of turns to fit comfortably within the gap field cross-section. The coil will have a resistance low enough to permit resistive shunt damping of a pendulum weighing up to a kilogram, in my opinion. My sensors have a pendulum mass of about 0.1Kg, and critical damping is achieved at about 30 kOhms. Since the coil resistance is only 340 Ohms, the shunt damping imposes negligible loss on output sensitivity. Even a kilogram mass would require only about 10% loss of output using shunt damping. There is one significant complication to this type of magnet and coil design, having to do with the fact that pure copper is diamagnetic, and coil and its pendulum are subject to forces other than the desired restoring force of a garden gate pendulum. In the example design this diamagnetic force is a decentering force, making it very difficult to adjust the sensor to a state of stable long period equilibrium. I reduce this effect by essentially potting the coil in acrylic plastic, which is also diamagnetic, and having the boundaries of the plastic extend well outside the edges of the magnetic field. Using a heavier pendulum would be of great benefit, as well. Bob McClure
  I submitting this note in order to give others the benefits of m= y=20 own sometimes trial-and-error efforts to build a seismic sensor. I am sure t= hat=20 Chris Chapman will continue to contribute, as well.
 
  Both Chris Chapman and I favor the use of Neodymium Iron Boron=20 magnets arranged in a four-pole structure for generating the magnetic field=20 needed for velocity sensing and damping in seismic sensors. The magnets are=20 powerful, relatively cheap, and easily obtained. The magnets I favor ar= e=20 block magnets, 6 mm thick, 18 mm wide, and 50 mm long. They are magnetized i= n=20 the thickness direction and are of the composition known as N38. They have a= =20 coercive force of about 12,000 Oersteds (CGS units), corresponding to 1.2 Te= slas=20 in the SI system.
 
  Construction of a four-pole magnet assembly is very simple, but=20= also=20 very hazardous. These magnets are attracted to steel and to each other with=20= a=20 force of about 57 pounds per square inch, and any skin caught between them c= an=20 be badly nipped. You must keep loose magnets very far away from steel or eac= h=20 other and wear heavy leather work gloves when handling them. The magnets are= =20 brittle, and will break if they crash together or with steel. The pole plate= s=20 are mild steel, thick enough to carry the flux of the magnetic circuit. More= on=20 that later. One of the plates must have clearance holes for 3/16" bolts, one= =20 hole in each corner. The plates, for the above magnet dimensions, should mea= sure=20 two inches by at least three inches.
 
  Slide two magnets onto each plate, with opposite poling on each=20 plate. When you have one magnet in position on a plate, carefully hold the=20 second magnet above the first. You will feel either an attraction or a repul= sion=20 of the second magnet toward the one on the plate. Make sure the force is=20 repulsive, then slide the second magnet into place beside the first. When th= e=20 magnets are positioned on each plate, make a wooden or plastic shim somewhat= =20 thinner than the final magnet gap you intend to use. I would use a shim abou= t=20 six inches long and the same width as the paired magnets, which would be abo= ut=20 1.5 inches for the example. With the shim covering the magnets of one plate,= =20 hold the second plate over it, getting no closer than enough to determine if= the=20 force between them is attractive or repulsive. The correct alignment is=20 indicated by an attractive force. You now place the upper plate (magnets dow= n)=20 on the shim at one end of the lower plate and slide the upper plate and magn= ets=20 up over the lower magnets. You now have a sandwich of upper and lower assemb= lies=20 tightly squeezing the shim in between.
 
  Place four bolts in the plate with the holes. Note than these bo= lts=20 are used to hold the plates apart, not together. Use the bolts to jack the=20 plates apart to get the desired gap spacing, and then you can withdraw the s= him.=20 If each of your plates have clearance holes drilled in them, you will need t= wo=20 nuts for each screw.
 
  Now it is time to discuss what field strength you get, and what=20 thickness of steel is required. Suppose for my example using 6 mm thick magn= ets,=20 I use a gap of 6 mm. The resulting distance between plates is 18 mm, 12 mm=20 filled with magnet, and 6 mm with air. I call the ratio of total magnet=20 thickness to total plate separation the filling factor. To a first=20 approximation, the gap field the coercive force of the magnetic material=20 multiplied by the filling factor. In this example, the coercive force is 12=20= KOe=20 and the filling factor is 2/3, so the gap field is 8 KOe. The accuracy of th= is=20 estimate depends on the magnet width compared to the gap size. If the gap=20 becomes appreciable compared to the width, you will get more fringing field=20= and=20 less-than-expected gap field. I have written a program that solves LaPlace's= =20 equation by iteration which lets me estimate more exactly what the penalty i= s=20 for any geometry.
 
  For my example magnet structure, I use 1/4 inch thick steel plat= es.=20 I find that there is a very slight saturation of the plates in the region=20 between magnet pairs. When I use 24 mm wide magnets, there is a lot of=20 saturation and a lot of external stray field around the whole assembly. I ha= ve=20 to put steel side plates on the assembly to eliminate the saturation and the= =20 stray field. Steel can carry a flux density of about 20 to 24 KOe without=20 saturation. Without saturation, the magnetic circuit of a 4-pole structure=20 consists of a closed rectangular flux path, with lines traveling through=20 magnets, gaps, and steel. The steel must carry the same total number of line= s of=20 flux as the gap and magnets. The number of lines is proportional to the gap=20= flux=20 density multiplied by the magnet width. In the example of 8 KOe and 18 mm wi= dth,=20 this corresponds to 8,000 times 1.8, or 14,000 lines per lineal centime= ter=20 of magnet structure. The quarter-inch-thick steel (0.625 cm) must carry a fl= ux=20 density of 22,000 KOe. It does so, barely.
 
  The next topic is coil design. By following the above magnet=20 assembly design principles, you know the approximate gap field, so by also=20 knowing the magnet length you will be able to estimate the number of coil tu= rns=20 you will need to achieve a given output sensitivity in volts per meter per=20 second. If the end loops of the coil extend beyond the ends of the magnet, e= ach=20 turn is immersed in a total field length of twice the magnet length. In the=20 example design, the magnet length is 50 mm, so L per turn is 0.1 m.
 
  The output voltage generated by the moving coil is Volts =3D B *= N * L=20 * Vel, where B is field strength in Teslas, N is number of turns, L is lengt= h=20 per turn in the field, and Vel is velocity in meters per second. One Tesla=20 corresponds to 10,000 Oersteds. Suppose n =3D 1100, B =3D 0.8 Tesla, and L=20= =3D 0.1=20 meter. Then Volts/Vel =3D 0.8 * 1100 * 0.1 =3D 88 v-s/m, which is a good num= ber to=20 strive for.
 
  A wire size of #38 or less will allow this number of turns to fi= t=20 comfortably within the gap field cross-section. The coil will have a resista= nce=20 low enough to permit resistive shunt damping of a pendulum weighing up to a=20 kilogram, in my opinion. My sensors have a pendulum mass of about 0.1Kg, and= =20 critical damping is achieved at about 30 kOhms. Since the coil resistance is= =20 only 340 Ohms, the shunt damping imposes negligible loss on output sensitivi= ty.=20 Even a kilogram mass would require only about 10% loss of output using shunt= =20 damping.
 
  There is one significant complication to this type of magnet and= =20 coil design, having to do with the fact that pure copper is diamagnetic, and= =20 coil and its pendulum are subject to forces other than the desired restoring= =20 force of a garden gate pendulum. In the example design this diamagnetic forc= e is=20 a decentering force, making it very difficult to adjust the sensor to a stat= e of=20 stable long period equilibrium. I reduce this effect by essentially potting=20= the=20 coil in acrylic plastic, which is also diamagnetic, and having the boundarie= s of=20 the plastic extend well outside the edges of the magnetic field. Using a hea= vier=20 pendulum would be of great benefit, as well.
 
Bob McClure
 Subject: Re: Building a lehman seismometer From: "tchannel" tchannel@.............. Date: Thu, 5 Oct 2006 15:50:06 -0600 Thanks, Chris for your reply. Most helpful I am in the process of building a sensor bases on your prototype, and = great drawings. I have most of the parts located, again with your help = and others on the mailing list. I will send pictures as I go along, if = you like, and if you tell me how to send them. I regards to the angle between the bottom and top hinge, a fraction of a = degree, how do you measure for that? Or do you adjust and measure the = period, instead? Chris, I see on your drawing you did not need to brace the vertical arm = of your device. Looks very strong. How did you attach that vertical to = the cross member? Many Thanks, Ted ----- Original Message -----=20 From: ChrisAtUpw@.......... To: psn-l@................. Sent: Thursday, October 05, 2006 1:26 PM Subject: Re: Building a lehman seismometer In a message dated 2006/10/05, tchannel@.............. writes: 1 Does your coil and damper assemblies just set on the aluminum = base, free to move for adjustment, or are they fixed to the base? Hi Ted, My arm has a support wire fixture and then a mass right at the = end of the arm. The support fixture carries a damping tongue in the direction = of the hinge and a coil on the mass side. Both the sensor and damper magnets slide on the base strip, for = mounting and adjustment of their position. They have small guide strips = underneath which hold them parallel. =20 2 You cleaned the plates, which hold the magnets, and then painted = the exterior, but not the surface the magnets touch. Would the paint = interfere with something on that surface? I suggest that you paint everything with Hammerite or similar, = but try to get it smooth and level. I etch coated the magnet position = with phosphoric acid, allowed it to react and dry overnight and then put = CL anticorrosion car grease on it. I was not certain that I could get = enough damping initially, but I found that I could overdamp the system = quite easily, so I increased the damper magnet spacing. 3 This is a hard question. Assuming I have finished my sensor, and = levelled it, what is the procedure for adjusting the period? Maybe you = could walk me through this procedure? You first lower the base plate / strip at the mass end. Then = you mount the arm and make any necessary solder connections for the coil = wiring. Then you put the magnet units on the base and adjust the top = wire so that both the coil and the damping plate are central within the = magnet spacings. The first time, you may need to make adjustments of the = magnet block heights, so that the arm is parallel to the base. Then you slide the damper free and adjust the cross levels so = that the arm is stable in the central position. If you can't get a = stable central position, you need to adjust the suspension so that the = top hinge is nearer the mass end - or the bottom fitting is further = away. You may mark the end of the arm with an inkline and also put a = central mark on the base. You deflect the arm and time a swing. It may = be about 5 sec initially. Then you slowly raise the base at the mass end = of the arm with the adjusting screw, testing to determine the period, = until you get the period you want. As the period is lengthened, you will = probably need to trim the cross level slightly. Then you slide the damping magnet over edge of the tongue, = deflect the arm 10 mm and release it. It may help to stick a bit of = graph paper to the base to be able the measure the position of the = damping block. 0.7 damping is obtained when the arm swings 0.5 mm past = the zero position and then falls back again. The amount of damping decreases as the set period increases, so = it needs to be easily adjustable. If the critical position is obtained = with the tongue less that half covering the magnets, increase the damper = magnet spacing.=20 4 I get confused with many of these terms, so I hope you understand = this question. If the target period is say 10 seconds, would the arm = move, when pulled 10mm, very slowly, taking 10 seconds to complete one = cycle? That is correct. Assuming that the arm is not damped, you = deflect it and then release it. It takes 2.5 sec to get to zero, = overshoots and comes back to zero in 5 sec, overshoots again and comes = back to zero from the initial direction in another 5 sec. Total 5 + 5 = =3D 10 sec. The period is the time for one complete oscillation cycle. = You want at least twice this. 5 After it is leveled and the period is set, Is it then that you = can check the damp, by moving the arm 10mm and releasing it? Correct, you set up the period first and then you slide the = damper further over the tongue in small steps until it is just a bit = under critical. I know what an underdamped situation would look like. But is = there way to tell if it is over damped? As you increase the damping from zero, the time that the arm = takes to fall back through / to the balance position increases slightly. = If you overdamp the arm, it never swings through the zero position and = the more you damp it, the longer it takes to get there. Look for the arm = swinging just past the zero line, but without another oscillation. Regards, Chris Chapman
Thanks, Chris for your reply. Most=20 helpful
 
   I am in the process of = building a=20 sensor bases on your prototype, and great drawings.   I have = most of=20 the parts located, again with your help and others on the mailing = list.  I=20 will send pictures as I go along, if you like, and if you tell me how to = send=20 them.
 
I regards to the angle between the = bottom and top=20 hinge, a fraction of a degree, how do you measure for that? Or do you = adjust and=20 measure the period, instead?
 
Chris, I see on your drawing you did = not need to=20 brace the vertical arm of your device. Looks very strong.  How did = you=20 attach that vertical to the cross member?
 
Many Thanks, Ted
 
 
----- Original Message -----
From:=20 ChrisAtUpw@.......
Sent: Thursday, October 05, = 2006 1:26=20 PM
Subject: Re: Building a lehman=20 seismometer

In a=20 message dated 2006/10/05, tchannel@..............=20 writes:

1 Does your coil and damper assemblies just set on the = aluminum=20 base, free to move for adjustment, or are they fixed to the=20 base?


Hi=20 Ted,

       My arm has a support = wire=20 fixture and then a mass right at the end of the=20 arm.
       The support fixture = carries a=20 damping tongue in the direction of the hinge and a coil on the mass=20 side.
       Both the sensor and = damper=20 magnets slide on the base strip, for mounting and adjustment of their=20 position. They have small guide strips underneath which hold them=20 parallel.  

2 You cleaned the plates, which hold the magnets, and = then=20 painted the exterior, but not the surface the magnets touch.  = Would the=20 paint interfere with something on that surface?

       I=20 suggest that you paint everything with Hammerite or similar, but try = to get it=20 smooth and level. I etch coated the magnet position with phosphoric = acid,=20 allowed it to react and dry overnight and then put CL anticorrosion = car grease=20 on it. I was not certain that I could get enough damping initially, = but I=20 found that I could overdamp the system quite easily, so I increased = the damper=20 magnet spacing.

 3 This is a hard question. Assuming I have finished my = sensor,=20 and levelled it, what is the procedure for adjusting the period? = Maybe you=20 could walk me through this procedure?

       You=20 first lower the base plate / strip at the mass end. Then you mount the = arm and=20 make any necessary solder connections for the coil wiring. Then you = put the=20 magnet units on the base and adjust the top wire so that both the coil = and the=20 damping plate are central within the magnet spacings. The first time, = you may=20 need to make adjustments of the magnet block heights, so that the arm = is=20 parallel to the base.
       Then you = slide=20 the damper free and adjust the cross levels so that the arm is stable = in the=20 central position. If you can't get a stable central position, you need = to=20 adjust the suspension so that the top hinge is nearer the mass end - = or the=20 bottom fitting is further away. You may mark the end of the arm with = an=20 inkline and also put a central mark on the base. You deflect the arm = and time=20 a swing. It may be about 5 sec initially. Then you slowly raise the = base at=20 the mass end of the arm with the adjusting screw, testing to determine = the=20 period, until you get the period you want. As the period is = lengthened, you=20 will probably need to trim the cross level slightly.
      =20 Then you = slide the=20 damping magnet over edge of the tongue, deflect the arm 10 mm and = release it.=20 It may help to stick a bit of graph paper to the base to be able the = measure=20 the position of the damping block. 0.7 damping is obtained when the = arm swings=20 0.5 mm past the zero position and then falls back=20 again.
       The amount of damping = decreases=20 as the set period increases, so it needs to be easily adjustable. If = the=20 critical position is obtained with the tongue less that half covering = the=20 magnets, increase the damper magnet spacing.

4 I get confused with many of these terms, so I hope you = understand this question.  If the target period is say 10 = seconds,=20 would the arm move, when pulled 10mm, very slowly, taking 10 seconds = to=20 complete one cycle?

       That is=20 correct. Assuming that the arm is not damped, you deflect it and then = release=20 it. It takes 2.5 sec to get to zero, overshoots and comes back to zero = in 5=20 sec, overshoots again and comes back to zero from the initial = direction in=20 another 5 sec. Total 5 + 5 =3D 10 sec. The period is the time for one = complete=20 oscillation cycle. You want at least twice this.

 5  After it is leveled and the period is set, Is it = then=20 that you can check the damp, by moving the arm 10mm and releasing=20 it?

      =20 Correct, you set up the period first and then you slide the damper = further=20 over the tongue in small steps until it is just a bit under=20 critical.

     I know what an underdamped situation = would=20 look like.  But is there way to tell if it is over=20 damped?

       As = you=20 increase the damping from zero, the time that the arm takes to fall = back=20 through / to the balance position increases slightly. If you overdamp = the arm,=20 it never swings through the zero position and the more you damp it, = the longer=20 it takes to get there. Look for the arm swinging just past the zero = line, but=20 without another = oscillation.

      =20 Regards,

       Chris = Chapman=20 Subject: Re: Building a lehman seismometer From: ChrisAtUpw@....... Date: Thu, 5 Oct 2006 22:59:04 EDT In a message dated 2006/10/05, tchannel@.............. writes: > I am in the process of building a sensor bases on your prototype, and > great drawings. I have most of the parts located, again with your help and > others on the mailing list. I will send pictures as I go along, if you like, and > if you tell me how to send them. Hi Ted, gif or jpg images would do fine to my EMail address. > I regards to the angle between the bottom and top hinge, a fraction of a > degree, how do you measure for that? Or do you adjust and measure the period, > instead? I don't measure it, I calculate it. Then I make the structure so that there is a small amount of adjustment. The axis is defined by the centre of the ball and the edge of the top wire clamp. You vary the slope of the long horizontal baseplate to set the period accurately, using the end adjustment screw, but you keep the arm parallel to the baseplate. > Chris, I see on your drawing you did not need to brace the vertical arm of > your device. Looks very strong. How did you attach that vertical to the > cross member? In my case the bottom of the vertical was milled flat and then the centre sections were milled out ~15 thou so that there were four longitudinal narrow strips about 1/16" wide x 3/4" long at the corners. Then two bolts were put through the cross bar, the long base and threaded into the vertical at the front and back ends. If you don't mill out / file out the centre sections, the clamp force will be at the centre, not at the edges where you want it and it will rock just enough to give trouble. An alternative is to use a flat end and 3 or 4 shim strips. You can also make three point suspensions, or you can glue the vertical to the long base with two part modified acrylic glue. This is strong and tough, unlike epoxy which is brittle. However you have to be very quick as it has a gel time of about a couple of minutes in a warm room. An alternative construction might be to use a 3" dia tube for the vertical? This can be held on either with a central vertical threaded rod and a top plate, or by mounting a 3/4" circular rod horizontally through two holes in the vertical tube, drilling and tapping this and putting a vertical bolt up through the baseplate. You would make three contact strip suspension flats at 120 deg. You can use an SS ball on a carbide flat lower hinge or crossed cylinders. You can buy 1/8" solid tungsten carbide drills from www.Smallparts.com or www.Digikey.com and cut the shanks to length with a carbide disk. Glue one to the head of an SS bolt and the other to the end of the arm with two part modified acrylic glue. I usually file a shallow V first to locate the shank mechanically. Mount the vertical rod or the ball on vertical support and the horizontal rod or the flat on the arm, NOT the other way around! 8 thou Nickel plated piano wire is available for mandolin strings at a music shop. See www.daddario.com Another method of construction which you might wish to consider? In this I used Al alloy U channel, 3" wide x 1" high and three triangular 3/16" to 1/4" thick corner plates at the end T / L joint. The vertical is attached to the long horizontal base with two 5" corner plates and four SS bolts per plate. I use two plain SS washers and a spring washer per bolt to prevent it digging into the softer Al. The open U is on the inside of the 90 deg joint. The cross bar is attached to the outside of the vertical with four bolts and a 7" triangle. It seems to work OK and makes quite a neat job. I bought it cut / chopped to size, from a local metals supermarket. You maybe able to get 2" x 1" U channel from building supplies / DIY. I tend to make things more massive than absolutely necessary. The secret of the rigidity is mostly in the three large triangular joint plates. I tend to use 18" to 24" long tubular arms. 22" gives a 1.5 sec basic pendulum which you can extend by x20 to 30 sec. 3 ft is a bit bulky, but it gives maybe 40 sec or more? You can get compression fittings for most tube. I use 1/2" SS water pipe and brass water fittings, 15mm OD, but the tube may not be widely available? It is light but rigid and non magnetic. Hard drawn Cu or brass are alternatives. You can also buy general purpose brass compression 'engineering' fittings for a wide range of standard pipe sizes, but these may only be available through a few more specialist suppliers and they tend to be more expensive than water fittings. Check on the availabilty of thin wall welded SS water pipe? Regards, Chris Chapman In a me= ssage dated 2006/10/05, tchannel@.............. writes:

   I am in the proces= s of building a sensor bases on your prototype, and great drawings. I have m= ost of the parts located, again with your help and others on the mailing lis= t. I will send pictures as I go along, if you like, and if you tell me how t= o send them.


Hi Ted,

       gif or jpg images would do fine to my E= Mail address.

I regards to the angle between= the bottom and top hinge, a fraction of a degree, how do you measure for th= at? Or do you adjust and measure the period, instead?


       I don't measure it, I calculate it. Th= en I make the structure so that there is a small amount of adjustment. The a= xis is defined by the centre of the ball and the edge of the top wire clamp.= You vary the slope of the long horizontal baseplate to set the period accur= ately, using the end adjustment screw, but you keep the arm parallel to the=20= baseplate.

Chris, I see on your drawing y= ou did not need to brace the vertical arm of your device. Looks very strong.=   How did you attach that vertical to the cross member?

       In my case the bottom of the vertical=20= was milled flat and then the centre sections were milled out ~15 thou so tha= t there were four longitudinal narrow strips about 1/16" wide x 3/4" long at= the corners. Then two bolts were put through the cross bar, the long base a= nd threaded into the vertical at the front and back ends. If you don't mill=20= out / file out the centre sections, the clamp force will be at the centre, n= ot at the edges where you want it and it will rock just enough to give troub= le. An alternative is to use a flat end and 3 or 4 shim strips.
       You can also make three point suspensio= ns, or you can glue the vertical to the long base with two part modified acr= ylic glue. This is strong and tough, unlike epoxy which is brittle. However=20= you have to be very quick as it has a gel time of about a couple of minutes=20= in a warm room.
       An alternative construction might be to= use a 3" dia tube for the vertical? This can be held on either with a centr= al vertical threaded rod and a top plate, or by mounting a 3/4" circular rod= horizontally through two holes in the vertical tube, drilling and tapping t= his and putting a vertical bolt up through the baseplate. You would make thr= ee contact strip suspension flats at 120 deg.
       You can use an SS ball on a carbide fla= t lower hinge or crossed cylinders. You can buy 1/8" solid tungsten carbide=20= drills from www.Smallparts.com or www.Digikey.com and cut the shanks to leng= th with a carbide disk. Glue one to the head of an SS bolt and the other to=20= the end of the arm with two part modified acrylic glue. I usually file a sha= llow V first to locate the shank mechanically. Mount the vertical rod or the= ball on vertical support and the horizontal rod or the flat on the arm, NOT= the other way around! 8 thou Nickel plated piano wire is available for mand= olin strings at a music shop. See www.daddario.com
    Another method of construction which you might wish t= o consider? In this I used Al alloy U channel, 3" wide x 1" high and three t= riangular 3/16" to 1/4" thick corner plates at the end T / L joint. The vert= ical is attached to the long horizontal base with two 5" corner plates and f= our SS bolts per plate. I use two plain SS washers and a spring washer per b= olt to prevent it digging into the softer Al. The open U is on the inside of= the 90 deg joint. The cross bar is attached to the outside of the vertical=20= with four bolts and a 7" triangle. It seems to work OK and makes quite a nea= t job. I bought it cut / chopped to size, from a local metals supermarket. Y= ou maybe able to get 2" x 1" U channel from building supplies / DIY. I tend=20= to make things more massive than absolutely necessary. The secret of the rig= idity is mostly in the three large triangular joint plates.
    I tend to use 18" to 24" long tubular arms. 22" gives a 1= ..5 sec basic pendulum which you can extend by x20 to 30 sec. 3 ft is a bit b= ulky, but it gives maybe 40 sec or more? You can get compression fittings fo= r most tube. I use 1/2" SS water pipe and brass water fittings, 15mm OD, but= the tube may not be widely available? It is light but rigid and non magneti= c. Hard drawn Cu or brass are alternatives. You can also buy general purpose= brass compression 'engineering' fittings for a wide range of standard pipe=20= sizes, but these may only be available through a few more specialist supplie= rs and they tend to be more expensive than water fittings. Check on the avai= labilty of thin wall welded SS water pipe?

    Regards,

    Chris Chapman   
Subject: Re: Sensor magnet and coil design From: ChrisAtUpw@....... Date: Fri, 6 Oct 2006 06:18:14 EDT In a message dated 2006/10/05, Bobhelenmcclure@....... writes: > I submitting this note in order to give others the benefits of my own > sometimes trial-and-error efforts to build a seismic sensor. I am sure that > Chris Chapman will continue to contribute, as well. Hi Bob, Is that meant to be an invitation? > Both Chris Chapman and I favor the use of Neodymium Iron Boron magnets > arranged in a four-pole structure for generating the magnetic field needed for > velocity sensing and damping in seismic sensors. The magnets are powerful, > relatively cheap, and easily obtained. The magnets I favor are block magnets, 6 > mm thick, 18 mm wide, and 50 mm long. They are magnetized in the thickness > direction and are of the composition known as N38. They have a coercive force > of about 12,000 Oersteds (CGS units), corresponding to 1.2 Teslas in the SI > system. > > Construction of a four-pole magnet assembly is very simple, but also very > hazardous. These magnets are attracted to steel and to each other with a > force of about 57 pounds per square inch, and any skin caught between them can be > badly nipped. You must keep loose magnets very far away from steel or each > other and wear heavy leather work gloves when handling them. The magnets are > brittle, and will break if they crash together or with steel. The pole plates > are mild steel, thick enough to carry the flux of the magnetic circuit. More > on that later. One of the plates must have clearance holes for 3/16" bolts, > one hole in each corner. The plates, for the above magnet dimensions, should > measure two inches by at least three inches. So just two of these magnets could probably lift you right off the floor...... You need to plan your assembly, place the magnets over a 3 ft away and be very careful. You will likely sometime get a pinched finger, but with care you can avoid broken bones or a crushed finger joint. I am not being alarmist. You MUST avoid flying magnets! Which is one reason why my designs favour rather smaller magnets and separate the damping and detector functions. The other reason for this is that the systems were designed for school use and you then want to separate out the two functions for educational / demonstration purposes. You already have a large field increase by using the NdFeB magnets in comparison with Alnico and a more sensitive and flexible orientation with the quad magnet arrangement, so you can cut down on total coil turns and still get better performance. This can reduce the resistance and may allow ~more signal amplification. The minimum noise is determined by the input noise impedance characteristics of the opamp. You ~match the coil resistance to this notional resistance figure to get the best performance. In amateur seismic work, you are usually limited in practice by the ambient environmental noise. I prefer zinc plated 1/4" OD set screws to 3/16" OD. Mostly personal choice, but they are a bit more rigid and it also increases the magnetic coupling between the two backing plates, which can carry stray fields. You won't get the total flux of any two magnets matching exactly. > Slide two magnets onto each plate, with opposite poling on each plate. > When you have one magnet in position on a plate, carefully hold the second > magnet above the first. You will feel either an attraction or a repulsion of the > second magnet toward the one on the plate. Make sure the force is repulsive, > then slide the second magnet into place beside the first. When the magnets > are positioned on each plate, make a wooden or plastic shim somewhat thinner > than the final magnet gap you intend to use. I would use a shim about six > inches long and the same width as the paired magnets, which would be about 1.5 > inches for the example. With the shim covering the magnets of one plate, hold > the second plate over it, getting no closer than enough to determine if the > force between them is attractive or repulsive. The correct alignment is > indicated by an attractive force. You now place the upper plate (magnets down) on the > shim at one end of the lower plate and slide the upper plate and magnets up > over the lower magnets. You now have a sandwich of upper and lower assemblies > tightly squeezing the shim in between. If you are doing it this way, I suggest that you attach the plastic shim or preferably a wood block firmly to the first magnet with PVC or gaffer tape. This can help prevent accidents. The forces can be really dangerous. > Place four bolts in the plate with the holes. Note than these bolts are > used to hold the plates apart, not together. Use the bolts to jack the plates > apart to get the desired gap spacing, and then you can withdraw the shim. If > each of your plates have clearance holes drilled in them, you will need two > nuts for each screw. I mount the two magnets on the first block. Then I fit the four bolts with two nuts each. The inner one I do up finger tight, the outer one I leave at ~ 1.5" along the thread. Then I prepare the second plate. I grip the first plate with my hand to prevent the plates getting too close and slide the second plate onto the bolts. With Bob's more powerful magnets, I would use a wood safety block and adhesive tape in place of my hand. I rock this plate till it contacts the nuts and then back off the nuts sequentially about a turn at a time till I get the desired central magnet separation. > Now it is time to discuss what field strength you get, and what thickness > of steel is required. Suppose for my example using 6 mm thick magnets, I use > a gap of 6 mm. The resulting distance between plates is 18 mm, 12 mm filled > with magnet, and 6 mm with air. I call the ratio of total magnet thickness to > total plate separation the filling factor. To a first approximation, the gap > field the coercive force of the magnetic material multiplied by the filling > factor. In this example, the coercive force is 12 KOe and the filling factor > is 2/3, so the gap field is 8 KOe. The accuracy of this estimate depends on > the magnet width compared to the gap size. If the gap becomes appreciable > compared to the width, you will get more fringing field and less-than-expected > gap field. Can you run through the maths and assumptions of this please? > For my example magnet structure, I use 1/4 inch thick steel plates. I > find that there is a very slight saturation of the plates in the region between > magnet pairs. When I use 24 mm wide magnets, there is a lot of saturation > and a lot of external stray field around the whole assembly. I have to put > steel side plates on the assembly to eliminate the saturation and the stray > field. Steel can carry a flux density of about 20 to 24 KOe without saturation. > Without saturation, the magnetic circuit of a 4-pole structure consists of a > closed rectangular flux path, with lines traveling through magnets, gaps, and > steel. The steel must carry the same total number of lines of flux as the gap > and magnets. The number of lines is proportional to the gap flux density > multiplied by the magnet width. In the example of 8 KOe and 18 mm width, this > corresponds to 8,000 times 1.8, or 14,000 lines per lineal centimeter of magnet > structure. The quarter-inch-thick steel (0.625 cm) must carry a flux density > of 22,000 KOe. It does so, barely. Kaye and Laby list the flux density of mild steel at 21.5 k Oer at saturation. If you made the backing plate to just cover the magnets, all the flux would have to go through the centre of the mild steel plate. If you increase the backing plate area, flux can go through this surrounding strip, reducing the overall thickness required, down to about 1/2 minimum, before you have to increase the thickness. I leave a 1/2" wide border around my magnets. The closer the two plates, the greater the field in the gap, so the more flux that the plates have to carry in the critical central area. I put a rounded corner of the magnet just onto the backing plate, rotate it till one edge is on the plate, reduce the angle till maybe 1/4 of the magnet is flat on the plate and then slide the magnet into position. > The next topic is coil design. By following the above magnet assembly > design principles, you know the approximate gap field, so by also knowing the > magnet length you will be able to estimate the number of coil turns you will > need to achieve a given output sensitivity in volts per meter per second. If > the end loops of the coil extend beyond the ends of the magnet, each turn is > immersed in a total field length of twice the magnet length. In the example > design, the magnet length is 50 mm, so L per turn is 0.1 m. > > The output voltage generated by the moving coil is Volts = B * N * L * > Vel, where B is field strength in Teslas, N is number of turns, L is length per > turn in the field, and Vel is velocity in meters per second. One Tesla > corresponds to 10,000 Oersteds. Suppose n = 1100, B = 0.8 Tesla, and L = 0.1 meter. > Then Volts/Vel = 0.8 * 1100 * 0.1 = 88 v-s/m, which is a good number to > strive for. > > A wire size of #38 or less will allow this number of turns to fit > comfortably within the gap field cross-section. The coil will have a resistance low > enough to permit resistive shunt damping of a pendulum weighing up to a > kilogram, in my opinion. My sensors have a pendulum mass of about 0.1Kg, and > critical damping is achieved at about 30 kOhms. Since the coil resistance is only > 340 Ohms, the shunt damping imposes negligible loss on output sensitivity. > Even a kilogram mass would require only about 10% loss of output using shunt > damping. The damping force required also depends on the set period. What period are you using? What effect does this damping current have on the input noise in practice? Can it be significant? Looking at the commonly available lists of insulated wire, the Beldsol polyurethane coated copper wire which you can solder directly without stripping is stocked in sizes down to 36 AWG. You may have to hunt hard / go to professional suppliers for 38 AWG and smaller diameters - higher numbers. The properties of copper wire are listed in the www under AWG copper wire. > There is one significant complication to this type of magnet and coil > design, having to do with the fact that pure copper is diamagnetic, and coil and > its pendulum are subject to forces other than the desired restoring force of > a garden gate pendulum. In the example design this diamagnetic force is a > decentering force, making it very difficult to adjust the sensor to a state of > stable long period equilibrium. I reduce this effect by essentially potting > the coil in acrylic plastic, which is also diamagnetic, and having the > boundaries of the plastic extend well outside the edges of the magnetic field. Using > a heavier pendulum would be of great benefit, as well. Pure copper is diamagnetic, but some copper wire contains a tiny amount of iron, which is strongly paramagnetic. The properties may vary in practice. This is even more of a pest and can result in the coil being attracted by the strong field gradient at the edge of the magnets. With these high fields, you can get the situation where the coil has two stable positions over the edges of the magnets, with an unstable region in between. You may need to check your reel, or your wound coil, or wind a sample coil for a repulsion / attraction test. You may get an even stronger effect when the winding is close to / over the central N/S magnet join. You can reduce this type of problem by increasing the separation between the coil and the edges of the magnets a bit, but this reduces the sensitivity; by limiting the travel of the arm so that the coil does not get too close to the edges of the magnets and by increasing the magnet area and hence the available coil travel, but this may require a thicker backing plate and gives a higher coil resistance. The force on the winding is proportional to H x dH/dr, which falls off very rapidly with increasing r at the edges of the magnet. I appreciate the value of using a wider plastic plate to reduce the change of susceptibility with position. I suspect that it may be important to have a solid plastic core to the coil to reduce forces associated with the cental magnet join. Also, the less copper that is used, the lower the force. Regards, Chris Chapman In a me= ssage dated 2006/10/05, Bobhelenmcclure@....... writes:

  I submitting this note i= n order to give others the benefits of my own sometimes trial-and-error effo= rts to build a seismic sensor. I am sure that Chris Chapman will continue to= contribute, as well.


Hi Bob,

       Is that meant to be an invitation?

  Both Chris Chapman and I= favor the use of Neodymium Iron Boron magnets arranged in a four-pole struc= ture for generating the magnetic field needed for velocity sensing and dampi= ng in seismic sensors. The magnets are powerful, relatively cheap, and easil= y obtained. The magnets I favor are block magnets, 6 mm thick, 18 mm wide, a= nd 50 mm long. They are magnetized in the thickness direction and are of the= composition known as N38. They have a coercive force of about 12,000 Oerste= ds (CGS units), corresponding to 1.2 Teslas in the SI system.

  Construction of a four-pole magnet assembly is very simple, but also=20= very hazardous. These magnets are attracted to steel and to each other with=20= a force of about 57 pounds per square inch, and any skin caught between them= can be badly nipped. You must keep loose magnets very far away from steel o= r each other and wear heavy leather work gloves when handling them. The magn= ets are brittle, and will break if they crash together or with steel. The po= le plates are mild steel, thick enough to carry the flux of the magnetic cir= cuit. More on that later. One of the plates must have clearance holes for 3/= 16" bolts, one hole in each corner. The plates, for the above magnet dimensi= ons, should measure two inches by at least three inches.


       So just two of these magnets coul= d probably lift you right off the floor......
       You need to plan your assembly, place t= he magnets over a 3 ft away and be very careful. You will likely sometime ge= t a pinched finger, but with care you can avoid broken bones or a crushed fi= nger joint. I am not being alarmist.
       You MUST avoid flying magnets! &nb= sp; 

       Which is one reason why my designs favo= ur rather smaller magnets and separate the damping and detector functions. T= he other reason for this is that the systems were designed for school use an= d you then want to separate out the two functions for educational / demonstr= ation purposes. You already have a large field increase by using the NdFeB m= agnets in comparison with Alnico and a more sensitive and flexible orientati= on with the quad magnet arrangement, so you can cut down on total coil turns= and still get better performance. This can reduce the resistance and may al= low ~more signal amplification. The minimum noise is determined by the input= noise impedance characteristics of the opamp. You ~match the coil resistanc= e to this notional resistance figure to get the best performance. In amateur= seismic work, you are usually limited in practice by the ambient environmen= tal noise.

       I prefer zinc plated 1/4" OD set screws= to 3/16" OD. Mostly personal choice, but they are a bit more rigid and it a= lso increases the magnetic coupling between the two backing plates, which ca= n carry stray fields. You won't get the total flux of any two magnets matchi= ng exactly.

  Slide two magnets onto e= ach plate, with opposite poling on each plate. When you have one magnet in p= osition on a plate, carefully hold the second magnet above the first. You wi= ll feel either an attraction or a repulsion of the second magnet toward the=20= one on the plate. Make sure the force is repulsive, then slide the second ma= gnet into place beside the first. When the magnets are positioned on each pl= ate, make a wooden or plastic shim somewhat thinner than the final magnet ga= p you intend to use. I would use a shim about six inches long and the same w= idth as the paired magnets, which would be about 1.5 inches for the example.= With the shim covering the magnets of one plate, hold the second plate over= it, getting no closer than enough to determine if the force between them is= attractive or repulsive. The correct alignment is indicated by an attractiv= e force. You now place the upper plate (magnets down) on the shim at one end= of the lower plate and slide the upper plate and magnets up over the lower=20= magnets. You now have a sandwich of upper and lower assemblies tightly squee= zing the shim in between.


       If you are doing it this way, I suggest= that you attach the plastic shim or preferably a wood block firmly to the f= irst magnet with PVC or gaffer tape. This can help prevent accidents. The fo= rces can be really dangerous.

  Place four bolts in the=20= plate with the holes. Note than these bolts are used to hold the plates apar= t, not together. Use the bolts to jack the plates apart to get the desired g= ap spacing, and then you can withdraw the shim. If each of your plates have=20= clearance holes drilled in them, you will need two nuts for each screw.

       I mount the two magnets on the first bl= ock. Then I fit the four bolts with two nuts each. The inner one I do up fin= ger tight, the outer one I leave at ~ 1.5" along the thread. Then I prepare=20= the second plate. I grip the first plate with my hand to prevent the plates=20= getting too close and slide the second plate onto the bolts. With Bob's more= powerful magnets, I would use a wood safety block and adhesive tape in plac= e of my hand. I rock this plate till it contacts the nuts and then back off=20= the nuts sequentially about a turn at a time till I get the desired central=20= magnet separation.

  Now it is time to discus= s what field strength you get, and what thickness of steel is required. Supp= ose for my example using 6 mm thick magnets, I use a gap of 6 mm. The result= ing distance between plates is 18 mm, 12 mm filled with magnet, and 6 mm wit= h air. I call the ratio of total magnet thickness to total plate separation=20= the filling factor. To a first approximation, the gap field the coercive for= ce of the magnetic material multiplied by the filling factor. In this exampl= e, the coercive force is 12 KOe and the filling factor is 2/3, so the gap fi= eld is 8 KOe. The accuracy of this estimate depends on the magnet width comp= ared to the gap size. If the gap becomes appreciable compared to the width,=20= you will get more fringing field and less-than-expected gap field.

       Can you run through the maths and assum= ptions of this please?

   For my example mag= net structure, I use 1/4 inch thick steel plates. I find that there is a ver= y slight saturation of the plates in the region between magnet pairs. When I= use 24 mm wide magnets, there is a lot of saturation and a lot of external=20= stray field around the whole assembly. I have to put steel side plates on th= e assembly to eliminate the saturation and the stray field. Steel can carry=20= a flux density of about 20 to 24 KOe without saturation. Without saturation,= the magnetic circuit of a 4-pole structure consists of a closed rectangular= flux path, with lines traveling through magnets, gaps, and steel. The steel= must carry the same total number of lines of flux as the gap and magnets. T= he number of lines is proportional to the gap flux density multiplied by the= magnet width. In the example of 8 KOe and 18 mm width, this corresponds to=20= 8,000 times 1.8, or 14,000 lines per lineal centimeter of magnet structure.=20= The quarter-inch-thick steel (0.625 cm) must carry a flux density of 22,000=20= KOe. It does so, barely.


       Kaye and Laby list the flux density of=20= mild steel at 21.5 k Oer at saturation.
      If you made the backing plate to just cover t= he magnets, all the flux would have to go through the centre of the mild ste= el plate. If you increase the backing plate area, flux can go through this s= urrounding strip, reducing the overall thickness required, down to about 1/2= minimum, before you have to increase the thickness. I leave a 1/2" wide bor= der around my magnets.
       The closer the two plates, the greater=20= the field in the gap, so the more flux that the plates have to carry in the=20= critical central area. 
       I put a rounded corner of the magnet ju= st onto the backing plate, rotate it till one edge is on the plate, reduce t= he angle till maybe 1/4 of the magnet is flat on the plate and then slide th= e magnet into position.

  The next topic is coil d= esign. By following the above magnet assembly design principles, you know th= e approximate gap field, so by also knowing the magnet length you will be ab= le to estimate the number of coil turns you will need to achieve a given out= put sensitivity in volts per meter per second. If the end loops of the coil=20= extend beyond the ends of the magnet, each turn is immersed in a total field= length of twice the magnet length. In the example design, the magnet length= is 50 mm, so L per turn is 0.1 m.

  The output voltage generated by the moving coil is Volts =3D B * N *=20= L * Vel, where B is field strength in Teslas, N is number of turns, L is len= gth per turn in the field, and Vel is velocity in meters per second. One Tes= la corresponds to 10,000 Oersteds. Suppose n =3D 1100, B =3D 0.8 Tesla, and=20= L =3D 0.1 meter. Then Volts/Vel =3D 0.8 * 1100 * 0.1 =3D 88 v-s/m, which is=20= a good number to strive for.

  A wire size of #38 or less will allow this number of turns to fit com= fortably within the gap field cross-section. The coil will have a resistance= low enough to permit resistive shunt damping of a pendulum weighing up to a= kilogram, in my opinion. My sensors have a pendulum mass of about 0.1Kg, an= d critical damping is achieved at about 30 kOhms. Since the coil resistance=20= is only 340 Ohms, the shunt damping imposes negligible loss on output sensit= ivity. Even a kilogram mass would require only about 10% loss of output usin= g shunt damping.


       The damping force required also depends= on the set period. What period are you using?
       What effect does this damping current h= ave on the input noise in practice? Can it be significant?
       Looking at the commonly available lists= of insulated wire, the Beldsol polyurethane coated copper wire which you ca= n solder directly without stripping is stocked in sizes down to 36 AWG. You=20= may have to hunt hard / go to professional suppliers for 38 AWG and smaller=20= diameters - higher numbers. The properties of copper wire are listed in the=20= www under AWG copper wire.

  There is one significant= complication to this type of magnet and coil design, having to do with the=20= fact that pure copper is diamagnetic, and coil and its pendulum are subject=20= to forces other than the desired restoring force of a garden gate pendulum.=20= In the example design this diamagnetic force is a decentering force, making=20= it very difficult to adjust the sensor to a state of stable long period equi= librium. I reduce this effect by essentially potting the coil in acrylic pla= stic, which is also diamagnetic, and having the boundaries of the plastic ex= tend well outside the edges of the magnetic field. Using a heavier pendulum=20= would be of great benefit, as well.


       Pure copper is diamagnetic, but some co= pper wire contains a tiny amount of iron, which is strongly paramagnetic. Th= e properties may vary in practice. This is even more of a pest and can resul= t in the coil being attracted by the strong field gradient at the edge of th= e magnets. With these high fields, you can get the situation where the coil=20= has two stable positions over the edges of the magnets, with an unstable reg= ion in between. You may need to check your reel, or your wound coil, or wind= a sample coil for a repulsion / attraction test. You may get an even strong= er effect when the winding is close to / over the central N/S magnet join.        You can reduce this type of problem by=20= increasing the separation between the coil and the edges of the magnets a bi= t, but this reduces the sensitivity; by limiting the travel of the arm so th= at the coil does not get too close to the edges of the magnets and by increa= sing the magnet area and hence the available coil travel, but this may requi= re a thicker backing plate and gives a higher coil resistance. The force on=20= the winding is proportional to H x dH/dr, which falls off very rapidly with=20= increasing r at the edges of the magnet.
       I appreciate the value of using a wider= plastic plate to reduce the change of susceptibility with position. I suspe= ct that it may be important to have a solid plastic core to the coil to redu= ce forces associated with the cental magnet join.
       Also, the less copper that is used, the= lower the force.

       Regards,

       Chris Chapman Subject: Re: Sensor magnet and coil design From: Bobhelenmcclure@....... Date: Sat, 7 Oct 2006 01:11:01 EDT On Fri, 6 Oct 2006 06:18:14 EDT, ChrisAtUpw@....... writes: > Now it is time to discuss what field strength you get, and what thickness > of steel is required. Suppose for my example using 6 mm thick magnets, I use > a gap of 6 mm. The resulting distance between plates is 18 mm, 12 mm filled > with magnet, and 6 mm with air. I call the ratio of total magnet thickness to > total plate separation the filling factor. To a first approximation, the gap > field the coercive force of the magnetic material multiplied by the filling > factor. In this example, the coercive force is 12 KOe and the filling factor > is 2/3, so the gap field is 8 KOe. The accuracy of this estimate depends on > the magnet width compared to the gap size. If the gap becomes appreciable > compared to the width, you will get more fringing field and less-than-expected > gap field. Can you run through the maths and assumptions of this please? Hi Chris, I am assuming that the Nd magnet material is very hard magnetically, and has an incremental permeability almost the same as air. It can be considered to be an empty volume whose pole faces are coated uniformly with magnetic charges. Charges on one face are connected by lines of force to opposite charges. First consider a stack of magnets with infinitesimal gaps between them. In this case, opposite charges are adjacent, so all the lines cross the gap to the next magnet, and none travel back through the magnet to the opposing poles at the other end, and we get at the gap the flux of the short circuit coercive force. As we widen the gaps, more and more flux returns to the opposing face of each magnet instead of crossing the gap to the next magnet. With this line of reasoning, we are down to a flux of 50% when the gap spacing equals the magnet thickness, and so on. The four pole magnet structure can be shown to be similar in field pattern to a repeating structure of magnets and gaps, so my conclusions rest on the validity of the assumption of a relative permeability of 1.0 for the magnets. If the incremental permeability is higher than 1, then the field will fall off faster with increasing gap spacing. The finite transverse dimensions of the magnets is another reason for more rapid falloff. --Bob
On Fri, 6 Oct 2006 06:18:14 EDT, ChrisAtUpw@.......=20 writes:
>   Now it is time to discuss what field strength yo= u=20 get, and what thickness
> of steel is required. Suppose for my exampl= e=20 using 6 mm thick magnets, I use
> a gap of 6 mm. The resulting distan= ce=20 between plates is 18 mm, 12 mm filled
> with magnet, and 6 mm with ai= r. I=20 call the ratio of total magnet thickness to
> total plate separation=20= the=20 filling factor. To a first approximation, the gap
> field the coerciv= e=20 force of the magnetic material multiplied by the filling
> factor. In= =20 this example, the coercive force is 12 KOe and the filling factor
> i= s=20 2/3, so the gap field is 8 KOe. The accuracy of this estimate depends on=20
> the magnet width compared to the gap size. If the gap becomes=20 appreciable
> compared to the width, you will get more fringing field= and=20 less-than-expected
> gap field.
 
       Can you run through the maths and=20 assumptions of this please?

Hi Chris,

  I am assuming that the Nd magnet material is very hard=20 magnetically, and has an incremental permeability almost the same as air. It= can=20 be considered to be an empty volume whose pole faces are coated uniform= ly=20 with magnetic charges. Charges on one face are connected by lines of force t= o=20 opposite charges. First consider a stack of magnets with infinitesimal gaps=20 between them. In this case, opposite charges are adjacent, so all the lines=20 cross the gap to the next magnet, and none travel back through the magnet to= the=20 opposing poles at the other end, and we get at the gap the flux of the short= =20 circuit coercive force. As we widen the gaps, more and more flux returns to=20= the=20 opposing face of each magnet instead of crossing the gap to the next magnet.= =20 With this line of reasoning, we are down to a flux of 50% when the gap spaci= ng=20 equals the magnet thickness, and so on.
 
  The four pole magnet structure can be shown to be similar in fie= ld=20 pattern to a repeating structure of magnets and gaps, so my conclusions rest= on=20 the validity of the assumption of a relative permeability of 1.0 for the=20 magnets. If the incremental permeability is higher than 1, then the field wi= ll=20 fall off faster with increasing gap spacing. The finite transverse dimension= s of=20 the magnets is another reason for more rapid falloff.
 
--Bob
 Subject: Korean nuclar test From: Bob Barns royb1@........... Date: Sat, 07 Oct 2006 10:35:19 -0400 Hi gang, N. Korea may test a nuclear bomb. I realize that is a complicated question but maybe someone can give a rough estimate of how big a seismic signal might be produced. Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Korean nuclar test From: jimo17@........ Date: Sat, 7 Oct 2006 10:07:18 -0700 Hi Bob- John Louie at UNR has a wonderful explanation of the Richter Mag scale at: http://www.seismo.unr.edu/ftp/pub/louie/class/100/magnitude.html It plots Mag vs Yields (bombs & explosions) Jim On Sat, 07 Oct 2006 10:35:19 -0400 Bob Barns writes: > Hi gang, > N. Korea may test a nuclear bomb. I realize that is a complicated > > question but maybe someone can give a rough estimate of how big a > seismic signal might be produced. > Bob > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Korean nuclar test From: apsn apsn@........... Date: Sat, 07 Oct 2006 09:17:03 -0800 http://earthquake.usgs.gov/learning/faq.php?categoryID=2&faqID=33 Bob Hammond Public Seismic Network - Alaska http://apsn.awcable.com At 04:39 AM 10/7/2006, you wrote: >Hi gang, > N. Korea may test a nuclear bomb. I realize that is a complicated > question but maybe someone can give a rough estimate of how big a > seismic signal might be produced. >Bob > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with the body >of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Korean nuclar test From: apsn apsn@........... Date: Sat, 07 Oct 2006 09:31:33 -0800 Here's another link: http://en.wikipedia.org/wiki/Moment_magnitude_scale Bob Hammond Public Seismic Network - Alaska http://apsn.awcable.com At 04:39 AM 10/7/2006, you wrote: >Hi gang, > N. Korea may test a nuclear bomb. I realize that is a complicated > question but maybe someone can give a rough estimate of how big a > seismic signal might be produced. >Bob > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with the body >of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Seismometer for Central Illinois From: "Armstrong" joe.armstrong@............. Date: Sun, 8 Oct 2006 00:03:54 -0500 I live in a subdivision in a city in Central Illinois. The geological = survey tells my that in my area, that bedrock is 10-30' feet below. I = have a basement, but also two active kids. I am interested in having a = seismometer that would be capable of detecting New Madrid activity. So far my attempts have involved the construction of a 8" coil using #34 = wire on a 3' - 3" pvc form using a pendulum of 6 magnetron magents. = Coil: Resistance of ~7.1kohm. =20 After I also have 3 - 4.5hz geophones. My questions follow: 1) Can you think of a project that I use the on-hand coil and magnets or = the geophones? Or should I just start over with another project? 2) Basement: Is it a suitable location? I have been told that that = gravel under the basement disperses most of the vibration. Would the = activity of the kids affect the readings? Should the seimometer be = physically secured to the concrete? 3) Can a home brew seismometer be effective in Central Illinois? Thanks for taking the time Joe
I live in a subdivision in a city in = Central=20 Illinois. The geological survey tells my that in my area, that bedrock = is 10-30'=20 feet below. I have a basement, but also two active kids. I am interested = in=20 having a seismometer that would be capable of detecting New Madrid=20 activity.
 
So far my attempts have involved the = construction=20 of a 8" coil using #34 wire on a 3' - 3" pvc form using a pendulum of 6=20 magnetron magents. Coil: Resistance of ~7.1kohm.  =
After I also have 3 - 4.5hz=20 geophones.
 
My questions follow:
1) Can you think of a project that I = use the=20 on-hand coil and magnets or the geophones? Or should I just start over = with=20 another project?
2) Basement: Is it a suitable = location? I have=20 been told that that gravel under the basement disperses most=20 of the vibration. Would the activity of the kids affect the = readings?=20 Should the seimometer be physically secured to the = concrete?
3) Can a home brew seismometer  be = effective=20 in Central Illinois?
 
Thanks for taking the time
Joe
Subject: ebay auction From: Bob Barns royb1@........... Date: Sun, 08 Oct 2006 10:26:46 -0400 Hi gang, Teledyne Geotech timing system TG-120 Seismometer Item number: 140039611592 ends Oct 13 Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Seismometer for Central Illinois From: jonfr500@......... Date: Sun, 8 Oct 2006 15:02:03 +0000 Hi A 4.5Hz geophone would work fine for you. Your local noise pickup would be = a bit hig (depending on car traffic and other things). I use 4.5Hz geophone and it works great for me. See the plot here http://ea= rthquakes.jonfr.com Regards. J=F3n Fr=EDmann. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Seismometer for Central Illinois From: "Thomas Dick" dickthomas01@............. Date: Sun, 8 Oct 2006 10:11:25 -0500 Hey Joe From Evansville, IN; I, too, have a basement. I sit on sediments much = deeper that yours. I have a 4 acre lake 25 ft from my back door. I have = a set of geophones outside and two lehmans and a homemade vertical in = the basement. It is just my wife and I at home. When the kids come back = for the holidays, detection is almost useless. I srongly suggest you put = your geophones in the ground outside. This will give you something to = compare house activities to. When things are quiet in the house, lehmans = will detect activity to your satisfaction well beyond the New Madrid = zone. Most New Madrid actiivty consists of earthquakes below two in = magnitude. I copy some of these quakes. This magnitude quake isn't as = satisfying (and probably will not interest you as you get more = operational/ get the bugs out of your system) as some of the regional = quakes in the 2.4 to 4 range. For instance, recently; the three quakes = in Maine, one in Oklahoma, the two in South Carolina were satisfying. = Plus, there is some quarry activity that you will see, and this activity = will hide/interfere with earthquake recording. When we are gone for a = week or so and the daughter-in-law or son come in to feed the cat, I can = tell the difference between her 120 lb walk in the hall upstairs to my = son's 210 lb walk. What I don't understand, is that the washing machine, = dryer and even the sump pump in the basement have not been a problem. = But you walk around down there! Or let the December sun fall the the = basement floor! There has been some very good discussions on the PSN = network in the last week or so. You will be wise and a penny saved to = heed them. Tom
Hey Joe
 
From Evansville, IN; I, too, have a = basement. I sit=20 on sediments much deeper that yours. I have a 4 acre lake 25 ft from my = back=20 door. I have a set of geophones outside and two lehmans and a homemade = vertical=20 in the basement. It is just my wife and I at home. When the kids come = back for=20 the holidays, detection is almost useless. I srongly suggest you put = your=20 geophones in the ground outside. This will give you something to = compare=20 house activities to. When things are quiet in the house, lehmans will = detect=20 activity to your satisfaction well beyond the New Madrid zone. Most = New=20 Madrid actiivty consists of earthquakes below two in magnitude. I copy = some of=20 these quakes. This magnitude quake isn't as satisfying (and probably = will not=20 interest you as you get more operational/ get the bugs out of your = system) as=20 some of the regional quakes in the 2.4 to 4 range. For instance, = recently; the=20 three quakes in Maine, one in Oklahoma, the two in South Carolina were=20 satisfying. Plus, there is some quarry activity that you will see, and = this=20 activity will hide/interfere with earthquake recording. When we are gone = for a=20 week or so and the daughter-in-law or son come in to feed the cat, I can = tell=20 the difference between her 120 lb walk in the hall upstairs to my son's = 210 lb=20 walk. What I don't understand, is that the washing machine, dryer and = even the=20 sump pump in the basement have not been a problem. But you walk around = down=20 there! Or let the December sun fall the the basement floor! There has = been some=20 very good discussions on the PSN network in the last week or so. You = will be=20 wise and a penny saved to heed them.
Tom
Subject: Re: Korean nuclar test From: "Connie and Jim Lehman" lehmancj@........... Date: Sun, 8 Oct 2006 12:57:41 -0400 Bob--Your interest in the Korean Nuclear Test is a nice challenge to consider. My only nuke tests copied here in VA years ago were the announced tests in Nevada----They were given a magnitude rating after the event (by the NEIS)--We probably received 10 to a dozen over 2 years -the mid l970's. Mag. 4 barely read--Mag. 5's much better, and several over 6.0 Mag--looked like a typical west coast/Calif. event in good detail. Travel time on the events was 6 minutes, 10 seconds for us The main signature difference was the obvious lack of a "S" wave, as the detonation was in a small spherical cavity a kilometer or two underground--and appeared as a point source. I understand some countries attempting tests during the banned times elongated their cavities to create a shear "S" componet in the signature.--and they appeared as a natural event. Perhaps this background note may be helpful. I am certain you will find more information on the web pages suggested. A Mag.5.5 or greater from Korea will be widely copied, no doubt by amateurs as well as professionals-- Have a good day-- Jim Lehman ----- Original Message ----- From: "Bob Barns" To: "psn mail" Sent: Saturday, October 07, 2006 10:35 AM Subject: Korean nuclar test > Hi gang, > N. Korea may test a nuclear bomb. I realize that is a complicated > question but maybe someone can give a rough estimate of how big a > seismic signal might be produced. > Bob > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Seismometer for Central Illinois From: ChrisAtUpw@....... Date: Sun, 8 Oct 2006 14:26:00 EDT In a message dated 2006/10/08, joe.armstrong@............. writes: > I live in a subdivision in a city in Central Illinois. The geological > survey tells my that in my area, that bedrock is 10-30' feet below. I have a > basement, but also two active kids. I am interested in having a seismometer that > would be capable of detecting New Madrid activity. > > So far my attempts have involved the construction of a 8" coil using #34 > wire on a 3' - 3" pvc form using a pendulum of 6 magnetron magents. Coil: > Resistance of ~7.1kohm. > After I also have 3 - 4.5hz geophones. Hi Joe, What are you calling 'Magnetron Magnets', please? What shape and size? Are they the donut type out of microwave cookers? Or the large horse shoe types, maybe up to 10" across the base from radar sets? See 3 & 4th photos from bottom at http://pages.prodigy.net/fxc/JC.html If you mount ANY magnets on the seismometer arm, you will likely find it very noisy. Seismometers may be capable of measuring movements down to a few 10s of nano metres. 1 thou of an inch = 25,400 nano metres. Magnets mounted on a seismometer arm are likely to pick up every large pulse on the house utility wiring, fridges turning on and off, washing machines, passing cars, trucks and trains, changes in the Earth's magnetic field...... This is definitely NOT a good idea. You should plan on putting the coil on the arm and on using a non magnetic mass. Brass is easy to machine. Lead and copper are also OK. If you use a horizontal copper plate(s) for the mass, you can damp it directly with magnets. I suggest that you stay clear of oil damping. It is temperature sensitive, relatively difficult to set up correctly and tends to be messy. My questions follow: > 1) Can you think of a project that I use the on-hand coil and magnets or > the geophones? Or should I just start over with another project? The coil is rather too large for ease of use. You may be able to buy 'spare coils' for sequence timers used on washing machines? The size depends on the dimension of the magnet poles and the layout. You usually use a hollow section / ring coil of about the same diameter. You might want to consider using NdFeB magnets? They give a much higher output and are 'affordable'. I use 1" square Neos in a quad arrangement with a rectangular coil about 1.25" long by 3/4" wide internal and 2,500 turns of finer wire. Resistance about 500 Ohm. See http://jclahr.com/science/psn/chapman/lehman/index.html Are the geophones the 4.5 Hz triaxial plastic cased ones that Larry sells? If so, I suggest that you get the geophones 'up and runnning' first to 'get some experience'. Larry at http://psn.quake.net/ sells amplifiers and an ADC for seismic work. Maybe try the geophones out at various locations to find out what other local and surface signals there are? > 2) Basement: Is it a suitable location? I have been told that that gravel > under the basement disperses most of the vibration. Would the activity of the > kids affect the readings? Should the seimometer be physically secured to the > concrete? The basement would likely be the best place to start with. Does it have a concrete floor? Alternatively, can you provide a shed or some protection in the garden, away from the house or nearby tall trees? You will likely find that the seismic signals will get through the gravel quite OK. You don't say anything about your kid's size, weight or activities! Your geophones should sit on concrete OK, but for long term use you should consider siting them maybe 20 ft or more from the house and underground, maybe 2 to 3 ft deep in a waterproof container? There is a lot of 'surface noise' about, which you probably don't want to see. If you are mounting a Lehman type seismometer on concrete, it is a good idea to provide three glazed tiles / glass squares / metal plates glued to the concrete with pool adhesive or similar to provde a hard even surface for the levelling screws. I use 2" squares of 1/8" stainless steel. You may be able to reduce local / house noise a lot by low pass filtering down to 5 or 3 Hz. How far down is the water table? I was wondering if you could cut a hole in the basement floor and cast a separate concrete pillar directly into the gravel underneath? This could 'isolate you' to some extent from the activities in the house. Try using the existing floor first though, away from outside walls or any support pillars. > 3) Can a home brew seismometer be effective in Central Illinois? I can see absolutely no reason why not!! But do expect to see local environmental and house associated noise. You need to train yourself to recognise what earthquake signals look like and to identify other noise types and patterns. You will likely see quite a few local quakes which do not get reported on a WW information database, but which may or may not get reported on USGS. You may also see blasts from quarrying. Regards, Chris Chapman In a me= ssage dated 2006/10/08, joe.armstrong@............. writes:

I live in a subdivision in a ci= ty in Central Illinois. The geological survey tells my that in my area, that= bedrock is 10-30' feet below. I have a basement, but also two active kids.=20= I am interested in having a seismometer that would be capable of detecting N= ew Madrid activity.

So far my attempts have involved the construction of a 8" coil using #34 wir= e on a 3' - 3" pvc form using a pendulum of 6 magnetron magents. Coil: Resis= tance of ~7.1kohm. 
After I also have 3 - 4.5hz geophones.


Hi Joe,

       What are you calling 'Magnetron Magnets= ', please? What shape and size? Are they the donut type out of microwave coo= kers? Or the large horse shoe types, maybe up to 10" across the base from ra= dar sets? See 3 & 4th  photos from bottom at http://pages.prodigy.n= et/fxc/JC.html

       If you mount ANY magnets on the seismom= eter arm, you will likely find it very noisy. Seismometers may be cap= able of measuring movements down to a few 10s of nano metres. 1 thou of an i= nch =3D 25,400 nano metres.
       Magnets mounted on a seismometer arm ar= e likely to pick up every large pulse on the house utility wiring, fridges t= urning on and off, washing machines, passing cars, trucks and trains, change= s in the Earth's magnetic field...... This is definitely NOT a good idea.
       You should plan on putting the coil on=20= the arm and on using a non magnetic mass. Brass is easy to machine. Lead and= copper are also OK. If you use a horizontal copper plate(s) for the mass, y= ou can damp it directly with magnets.
       I suggest that you stay clear of oil da= mping. It is temperature sensitive, relatively difficult to set up correctly= and tends to be messy.

My questions follow:
1) Can you think of a project=20= that I use the on-hand coil and magnets or the geophones? Or should I just s= tart over with another project?


           The coil is rat= her too large for ease of use. You may be able to buy 'spare coils' for sequ= ence timers used on washing machines?
    The size depends on the dimension of the magnet poles and= the layout. You usually use a hollow section  / ring coil of about the= same diameter.

    You might want to consider using NdFeB magnets? They give= a much higher output and are 'affordable'.
    I use 1" square Neos in a quad arrangement with a rectang= ular coil about 1.25" long by 3/4" wide internal and 2,500 turns of finer wi= re. Resistance about 500 Ohm.
     See http://jclahr.com/science/psn/chapman/lehman/in= dex.html

    Are the geophones the 4.5 Hz triaxial plastic cased ones=20= that Larry sells?

       If so, I suggest that you get the geoph= ones 'up and runnning' first to 'get some experience'. Larry at http://psn.q= uake.net/ sells amplifiers and an ADC for seismic work. Maybe try the geopho= nes out at various locations to find out what other local and surface signal= s there are?

2) Basement: Is it a suitable l= ocation? I have been told that that gravel under the basement disperses most= of the vibration. Would the activity of the kids affect the readings? Shoul= d the seimometer be physically secured to the concrete?


       The basement would likely be the best p= lace to start with. Does it have a concrete floor?
       Alternatively, can you provide a shed o= r some protection in the garden, away from the house or nearby tall trees?        You will likely find that the seismic s= ignals will get through the gravel quite OK.

       You don't say anything about your kid's= size, weight or activities!

       Your geophones should sit on concrete O= K, but for long term use you should consider siting them maybe 20 ft or more= from the house and underground, maybe 2 to 3 ft deep in a waterproof contai= ner? There is a lot of 'surface noise' about, which you probably don't want=20= to see.

       If you are mounting a Lehman type seism= ometer on concrete, it is a good idea to provide three glazed tiles / glass=20= squares / metal plates glued to the concrete with pool adhesive or similar t= o provde a hard even surface for the levelling screws. I use 2" squares of 1= /8" stainless steel.
       You may be able to reduce local / house= noise a lot by low pass filtering down to 5 or 3 Hz.

       How far down is the water table? I was=20= wondering if you could cut a hole in the basement floor and cast a separate=20= concrete pillar directly into the gravel underneath? This could 'isolate you= ' to some extent from the activities in the house. Try using the existing fl= oor first though, away from outside walls or any support pillars. 

3) Can a home brew seismometer=20= be effective in Central Illinois?


       I can see absolutely no reason why not!= !
       But do expect to see local environmenta= l and house associated noise. You need to train yourself to recognise what e= arthquake signals look like and to identify other noise types and patterns.<= BR>        You will likely see quite a few local q= uakes which do not get reported on a WW information database, but which may=20= or may not get reported on USGS. You may also see blasts from quarrying.
       Regards,

       Chris Chapman Subject: Re: Shunt damping From: ChrisAtUpw@....... Date: Sun, 8 Oct 2006 20:13:09 EDT In a message dated 2006/10/08, Bobhelenmcclure writes: > > A wire size of #38 or less will allow this number of turns to fit > > comfortably within the gap field cross-section. The coil will have a > resistance low > > enough to permit resistive shunt damping of a pendulum weighing up to a > > kilogram, in my opinion. My sensors have a pendulum mass of about 0.1Kg, > and > > critical damping is achieved at about 30 kOhms. Since the coil resistance > is only > > 340 Ohms, the shunt damping imposes negligible loss on output sensitivity. > > > Even a kilogram mass would require only about 10% loss of output using > shunt > > damping. > > The damping force required also depends on the set period. What > period are you using? > What effect does this damping current have on the input noise in > practice? Can it be significant? > > Hi Chris, > I bought cheap low temperature enameled magnet wire from Alltronics. I > have both #38 (3.97 thou OD) and #40 gauge (3.14 thou OD). I never tried to > use the #40 wire, as it is difficult for me to see, let alone handle. I strip > by burning off the enamel. My friend Victor frowns on that, and recommends > fine emery paper. Hi Bob, Magnet wire is available from Alltronics in 1/4 lb reels, but it is Kynar insulated http://www.alltronics.com/cgi-bin/category.cgi?&category=MW&start=0 If you buy the polyurethane insulated wire like Beldsol, you don't have to strip it. If you put a hot iron and solder on it, the insulation just melts - no problems - but I have only found this wire down to 36 AWG - 5 thou OD. With the Kynar insulated wire, you have to strip it first before you can solder it. I usually use the edge of a wax candle flame (or a match) to first burn off this insulation. (You have to be very careful with a butane lighter not to melt the wire) Then I pull it fairly gently several times through two small pads of the very fine wire wool. This both cleans it effectively and hardens it a bit. I once only wound two coils with 40,000 turns of 44 AWG copper wire with 1 thou paper interleaving to measure paramagnetic susceptability - it took me two whole days.... > My horizontal sensors are easily shunt damped. On one of them set to 12 > second period, I measured a Q of 1.1 with a shunt resistance (including the > amplifier) of 66 kOhms. My formula for Q is Q = K * R / P. The value for K is > therefore 0.2. The mass of the coil and solder weight is about 100 grams. The > coil resistance is 340 Ohms, the number of turns is 1100, the field strength > is ~0.8T, the field length per turn is 0.1m, and the sensor output is 85 > v-s/m. If you know your own sensor's output, pendulum mass, and period, you can > work out your own value for K from the above information, and determine what > shunt damping resistance you would need. However, remember that the coil > resistance, in series with the shunt resistance (in parallel with the amplifier > input resistance) is the damping resistance. What is P please? > Volts= B*L*(dx/dt) > Force=B*L*I > I= Volts/R = B*L*(dx/dt)/R > Force= B*L*B*L*(dx/dt)/R > Force / (dx/dt)= (B*L)^2 / R > > I have not checked yet to see if the above equation is consistent with my > observed damping versus resistance. In the force equation, isn't the force proportional to the number of turns, whereas the inductance is proportional to the square of the number of turns and depends on the magnetic return path? How does the length of the pendulum, the set period and the mass factor into these equations, please? > Shunt damping makes it easy for me to check my sensors. I measure their > natural period by disconnecting the shunt, and discharging a small capacitor > across the sensor-amplifier terminals. The decay of oscillation amplitude > lets me make sure that the partially undamped oscillation has the expected Q > value, and the time between zero crossings gives me the natural period. I would > abandon the sport of seismometry if I could not control damping this way. I prefer to have my damping and sensors on separate fittings and their setup independant, but I can see the attraction of variable resistive damping if you choose very powerful sensor magnets and a low to moderate seismic mass. I tend to use rather smaller / thinner magnets for sensing and they do not have a serious diamagnetic repulsion problem, although I have observed this type of effect. I use wide Cu plate for the damping, so that the arm hits the side stops before the outer edge of the damping plate gets close to the outside edge of a magnet. I try to 'design out' problems when possible. If you are using feedback sensors with electronically extended periods, Cu plate damping is a lot quieter than velocity feedback from a differentiated position signal. Have you any comparisons of the input noise due to shunt damping vs plate damping - or the noise when undamped and when damped? Won't the induced current generate additional noise directly? Regards, Chris Chapman In a me= ssage dated 2006/10/08, Bobhelenmcclure writes:

>   A wire size of= #38 or less will allow this number of turns to fit
> comfortably within the gap field cross-section. The coil will have a re= sistance low
> enough to permit resistive shunt damping of a pendulum weighing up to a=
> kilogram, in my opinion. My sensors have a pendulum mass of about 0.1Kg= , and
> critical damping is achieved at about 30 kOhms. Since the coil resistan= ce is only
> 340 Ohms, the shunt damping imposes negligible loss on output sensitivi= ty.
> Even a kilogram mass would require only about 10% loss of output using=20= shunt
> damping.

       The damping force required also depend= s on the set period. What period are you using?
       What effect does this damping current h= ave on the input noise in practice? Can it be significant?

Hi Chris,
    I bought cheap low temperature enameled magnet wire from=20= Alltronics. I have both #38 (3.97 thou OD) and #40 gauge (3.14 thou OD). I n= ever tried to use the #40 wire, as it is difficult for me to see, let alone=20= handle. I strip by burning off the enamel. My friend Victor frowns on that,=20= and recommends fine emery paper.


Hi Bob,

    Magnet wire is available from Alltronics in 1/4 lb reels,= but it is Kynar insulated
       http://www.alltronics.com/cgi-bin/categ= ory.cgi?&category=3DMW&start=3D0

       If you buy the polyurethane insulated w= ire like Beldsol, you don't have to strip it. If you put a hot iron and sold= er on it, the insulation just melts - no problems - but I have only found th= is wire down to 36 AWG - 5 thou OD.

       With the Kynar insulated wire, you have= to strip it first before you can solder it. I usually use the edge of a wax= candle flame (or a match) to first burn off this insulation. (You have to b= e very careful with a butane lighter not to melt the wire) Then I pull it fa= irly gently several times through two small pads of the very fine wire wool.= This both cleans it effectively and hardens it a bit.

       I once only wound two coils with 40,000= turns of 44 AWG copper wire with 1 thou paper interleaving to measure param= agnetic susceptability - it took me two whole days....

  My horizontal sensors ar= e easily shunt damped. On one of them set to 12 second period, I measured a=20= Q of 1.1 with a shunt resistance (including the amplifier) of 66 kOhms. My f= ormula for Q is Q =3D K * R / P. The value for K is therefore 0.2. The mass=20= of the coil and solder weight is about 100 grams. The coil resistance is 340= Ohms, the number of turns is 1100, the field strength is ~0.8T, the field l= ength per turn is 0.1m, and the sensor output is 85 v-s/m. If you know your=20= own sensor's output, pendulum mass, and period, you can work out your own va= lue for K from the above information, and determine what shunt damping resis= tance you would need. However, remember that the coil resistance, in series=20= with the shunt resistance (in parallel with the amplifier input resistance)=20= is the damping resistance.


       What is P please?

Volts=3D B*L*(dx/dt)
Force=3DB*L*I
I=3D Volts/R =3D B*L*(dx/dt)/R
Force=3D B*L*B*L*(dx/dt)/R
Force / (dx/dt)=3D (B*L)^2 / R

  I have not checked yet to see if the above equation is consist= ent with my observed damping versus resistance.


    In the force equation, isn't the force proportional to th= e number of turns, whereas the inductance is proportional to the square of t= he number of turns and depends on the magnetic return path?

       How does the length of the pendulum, th= e set period and the mass factor into these equations, please?

   Shunt damping make= s it easy for me to check my sensors. I measure their natural period by disc= onnecting the shunt, and discharging a small capacitor across the sensor-amp= lifier terminals. The decay of oscillation amplitude lets me make sure that=20= the partially undamped oscillation has the expected Q value, and the time be= tween zero crossings gives me the natural period. I would abandon the sport=20= of seismometry if I could not control damping this way.


       I prefer to have my damping and sensors= on separate fittings and their setup independant, but I can see the attract= ion of variable resistive damping if you choose very powerful sensor magnets= and a low to moderate seismic mass.

       I tend to use rather smaller / thinner=20= magnets for sensing and they do not have a serious diamagnetic repulsion pro= blem, although I have observed this type of effect.
       I use wide Cu plate for the damping, so= that the arm hits the side stops before the outer edge of the damping plate= gets close to the outside edge of a magnet. I try to 'design out' problems=20= when possible.

       If you are using feedback sensors with=20= electronically extended periods, Cu plate damping is a lot quieter than velo= city feedback from a differentiated position signal.
  
      Have you any comparisons of the input noise d= ue to shunt damping vs plate damping - or the noise when undamped and when d= amped? Won't the induced current generate additional noise directly?  <= BR>
       Regards,

       Chris Chapman Subject: Re: Korean nuclar test From: Canie canie@........... Date: Sun, 08 Oct 2006 22:00:01 -0700 It appears they have done the test -  (about 9:50pm 10/08/06 - PDT)
http://news.yahoo.com/s/ap/20061009/ap_on_re_as/koreas_nuclear_102

An official at South Korea's seismic monitoring center confirmed a magnitude-3.6 tremor felt at the time North Korea said it conducted the test was not a natural occurrence.

Australia also said there was seismic confirmation that North Korea conducted a nuclear test.

Canie

At 09:57 AM 10/8/2006, you wrote:
Bob--Your interest in the Korean Nuclear Test is a nice challenge to
consider.  My only nuke tests copied here in VA years ago were the announced
tests in Nevada----They were given a magnitude rating after the event (by
the NEIS)--We probably received 10 to a dozen over 2 years -the mid l970's.
Mag. 4 barely read--Mag. 5's much better, and several over 6.0 Mag--looked
like a typical west coast/Calif. event in good detail.   Travel time on the
events was 6 minutes, 10 seconds for us The main signature difference was
the obvious lack of a "S" wave, as the detonation was in a small spherical
cavity a kilometer or two underground--and appeared as a point source.
    I understand some countries attempting tests during the banned times
elongated their cavities to create a shear "S" componet in the
signature.--and they appeared as a natural event.
  Perhaps this background note may be helpful.  I am certain you will find
more information on the web pages suggested.  A Mag.5.5 or greater from
Korea will be widely copied, no doubt by amateurs as well as professionals--
   Have a good day-- Jim Lehman
Subject: Re: Korean nuclar test From: apsn apsn@........... Date: Sun, 08 Oct 2006 21:11:08 -0800 http://earthquake.usgs.gov/eqcenter/recenteqsww/Quakes/ustqab.php At 09:00 PM 10/8/2006, you wrote: >It appears they have done the test - (about 9:50pm 10/08/06 - PDT) >http://news.yahoo.com/s/ap/20061009/ap_on_re_as/koreas_nuclear_102 > >An official at >South >Korea's seismic monitoring center confirmed a magnitude-3.6 tremor >felt at the time North Korea said it conducted the test was not a >natural occurrence. > >Australia also said there was seismic confirmation that North Korea >conducted a nuclear test. > >Canie > >At 09:57 AM 10/8/2006, you wrote: >>Bob--Your interest in the Korean Nuclear Test is a nice challenge to >>consider. My only nuke tests copied here in VA years ago were the announced >>tests in Nevada----They were given a magnitude rating after the event (by >>the NEIS)--We probably received 10 to a dozen over 2 years -the mid l970's. >>Mag. 4 barely read--Mag. 5's much better, and several over 6.0 Mag--looked >>like a typical west coast/Calif. event in good detail. Travel time on the >>events was 6 minutes, 10 seconds for us The main signature difference was >>the obvious lack of a "S" wave, as the detonation was in a small spherical >>cavity a kilometer or two underground--and appeared as a point source. >> I understand some countries attempting tests during the banned times >>elongated their cavities to create a shear "S" componet in the >>signature.--and they appeared as a natural event. >> Perhaps this background note may be helpful. I am certain you will find >>more information on the web pages suggested. A Mag.5.5 or greater from >>Korea will be widely copied, no doubt by amateurs as well as professionals-- >> Have a good day-- Jim Lehman > >Bob Hammond >Public Seismic Network - Alaska >http://apsn.awcable.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Korean nuclar test From: Dave Nelson davenn@............... Date: Mon, 09 Oct 2006 15:57:12 +1000 well it looks like they have done the test and it registered a M4.2 on the NEIC listing cheers Dave > > Hi gang, > > N. Korea may test a nuclear bomb. I realize that is a complicated > > question but maybe someone can give a rough estimate of how big a > > seismic signal might be produced. > > Bob > > > > __________________________________________________________ > > > > Public Seismic Network Mailing List (PSN-L) > > > > To leave this list email PSN-L-REQUEST@.............. with > > the body of the message (first line only): unsubscribe > > See http://www.seismicnet.com/maillist.html for more information. > > > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > > > >-- >No virus found in this incoming message. >Checked by AVG Free Edition. >Version: 7.1.407 / Virus Database: 268.13.1/466 - Release Date: 7/10/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.407 / Virus Database: 268.13.1/466 - Release Date: 7/10/2006 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Korean nuclar test From: jonfr500@......... Date: Mon, 9 Oct 2006 09:19:18 +0000 Hi Did anyone here register this test ? Regards. J=F3n Fr=EDmann. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Shunt damping From: "Geoffrey" gmvoeth@........... Date: Mon, 9 Oct 2006 07:36:59 -0700 What is the possibility of using one turn of a heavy guage wire as a single loop and sharpening the ends to a point then sensing the voltages at the points I would think that changing the cross sectional area would increase the voltages by concentrating electrons or if you are faster in your thought holes sort of like having a resistor in the middle but no power loss. This is the way you change impedances in antennas or so i understand and what is a velocity sensor but an odd kind of antenna. ----- Original Message ----- From: To: Sent: Sunday, October 08, 2006 5:13 PM Subject: Re: Shunt damping > In a message dated 2006/10/08, Bobhelenmcclure writes: > >> > A wire size of #38 or less will allow this number of turns to fit >> > comfortably within the gap field cross-section. The coil will have a >> resistance low >> > enough to permit resistive shunt damping of a pendulum weighing up to a >> > kilogram, in my opinion. My sensors have a pendulum mass of about 0.1Kg, >> and >> > critical damping is achieved at about 30 kOhms. Since the coil resistance >> is only >> > 340 Ohms, the shunt damping imposes negligible loss on output sensitivity. >> >> > Even a kilogram mass would require only about 10% loss of output using >> shunt >> > damping. >> >> The damping force required also depends on the set period. What >> period are you using? >> What effect does this damping current have on the input noise in >> practice? Can it be significant? >> >> Hi Chris, >> I bought cheap low temperature enameled magnet wire from Alltronics. I >> have both #38 (3.97 thou OD) and #40 gauge (3.14 thou OD). I never tried to >> use the #40 wire, as it is difficult for me to see, let alone handle. I strip >> by burning off the enamel. My friend Victor frowns on that, and recommends >> fine emery paper. > > Hi Bob, > > Magnet wire is available from Alltronics in 1/4 lb reels, but it is Kynar > insulated > http://www.alltronics.com/cgi-bin/category.cgi?&category=MW&start=0 > > If you buy the polyurethane insulated wire like Beldsol, you don't > have to strip it. If you put a hot iron and solder on it, the insulation just > melts - no problems - but I have only found this wire down to 36 AWG - 5 thou OD. > > With the Kynar insulated wire, you have to strip it first before you > can solder it. I usually use the edge of a wax candle flame (or a match) to > first burn off this insulation. (You have to be very careful with a butane > lighter not to melt the wire) Then I pull it fairly gently several times through two > small pads of the very fine wire wool. This both cleans it effectively and > hardens it a bit. > > I once only wound two coils with 40,000 turns of 44 AWG copper wire > with 1 thou paper interleaving to measure paramagnetic susceptability - it took > me two whole days.... > >> My horizontal sensors are easily shunt damped. On one of them set to 12 >> second period, I measured a Q of 1.1 with a shunt resistance (including the >> amplifier) of 66 kOhms. My formula for Q is Q = K * R / P. The value for K is >> therefore 0.2. The mass of the coil and solder weight is about 100 grams. The >> coil resistance is 340 Ohms, the number of turns is 1100, the field strength >> is ~0.8T, the field length per turn is 0.1m, and the sensor output is 85 >> v-s/m. If you know your own sensor's output, pendulum mass, and period, you can >> work out your own value for K from the above information, and determine what >> shunt damping resistance you would need. However, remember that the coil >> resistance, in series with the shunt resistance (in parallel with the amplifier >> input resistance) is the damping resistance. > > What is P please? > >> Volts= B*L*(dx/dt) >> Force=B*L*I >> I= Volts/R = B*L*(dx/dt)/R >> Force= B*L*B*L*(dx/dt)/R >> Force / (dx/dt)= (B*L)^2 / R >> >> I have not checked yet to see if the above equation is consistent with my >> observed damping versus resistance. > > In the force equation, isn't the force proportional to the number of > turns, whereas the inductance is proportional to the square of the number of turns > and depends on the magnetic return path? > > How does the length of the pendulum, the set period and the mass > factor into these equations, please? > >> Shunt damping makes it easy for me to check my sensors. I measure their >> natural period by disconnecting the shunt, and discharging a small capacitor >> across the sensor-amplifier terminals. The decay of oscillation amplitude >> lets me make sure that the partially undamped oscillation has the expected Q >> value, and the time between zero crossings gives me the natural period. I would >> abandon the sport of seismometry if I could not control damping this way. > > I prefer to have my damping and sensors on separate fittings and their > setup independant, but I can see the attraction of variable resistive damping > if you choose very powerful sensor magnets and a low to moderate seismic > mass. > > I tend to use rather smaller / thinner magnets for sensing and they do > not have a serious diamagnetic repulsion problem, although I have observed > this type of effect. > I use wide Cu plate for the damping, so that the arm hits the side > stops before the outer edge of the damping plate gets close to the outside edge > of a magnet. I try to 'design out' problems when possible. > > If you are using feedback sensors with electronically extended > periods, Cu plate damping is a lot quieter than velocity feedback from a > differentiated position signal. > > Have you any comparisons of the input noise due to shunt damping vs > plate damping - or the noise when undamped and when damped? Won't the induced > current generate additional noise directly? > > Regards, > > Chris Chapman > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Shunt damping From: ChrisAtUpw@....... Date: Mon, 9 Oct 2006 10:48:08 EDT In a message dated 2006/10/09, gmvoeth@........... writes: > What is the possibility of using one turn of a heavy guage wire as a single > loop > and sharpening the ends to a point then sensing the voltages at the points > I would think that changing the cross sectional area would increase the > voltages by concentrating electrons or if you are faster in your thought holes > sort of like having a resistor in the middle but no power loss. Hi Geoff, Sorry, but you can't apply HF antenna theory to ~DC variations. You might be able to find the correct wire diameter for a single turn to provide critical damping. Regards, Chris Chapman In a me= ssage dated 2006/10/09, gmvoeth@........... writes:

What is the possibility of usin= g one turn of a heavy guage wire as a single loop
and sharpening the ends to a point then sensing the voltages at the points I would think that changing the cross sectional area would increase the volt= ages by concentrating electrons or if you are faster in your thought holes s= ort of like having a resistor in the middle but no power loss.
<= BR>
Hi Geoff,

       Sorry, but you can't apply HF antenna t= heory to ~DC variations.
       You might be able to find the correct w= ire diameter for a single turn to provide critical damping.

       Regards,

       Chris  Chapman Subject: Re: Seismometer for Central Illinois From: "Peter Laplante" laplantep@............... Date: Mon, 9 Oct 2006 08:54:34 -0700 Good morning Joe: I am just getting started with my equipment and do not have any = experience. I am afraid that I can not be of much help. I am using parts that I purchased from Larry Cockrine and hope to get my = station up and running in the next 6 months. Peter ----- Original Message -----=20 From: Armstrong=20 To: psn-l@................. Sent: Saturday, October 07, 2006 10:03 PM Subject: Seismometer for Central Illinois I live in a subdivision in a city in Central Illinois. The geological = survey tells my that in my area, that bedrock is 10-30' feet below. I = have a basement, but also two active kids. I am interested in having a = seismometer that would be capable of detecting New Madrid activity. So far my attempts have involved the construction of a 8" coil using = #34 wire on a 3' - 3" pvc form using a pendulum of 6 magnetron magents. = Coil: Resistance of ~7.1kohm. =20 After I also have 3 - 4.5hz geophones. My questions follow: 1) Can you think of a project that I use the on-hand coil and magnets = or the geophones? Or should I just start over with another project? 2) Basement: Is it a suitable location? I have been told that that = gravel under the basement disperses most of the vibration. Would the = activity of the kids affect the readings? Should the seimometer be = physically secured to the concrete? 3) Can a home brew seismometer be effective in Central Illinois? Thanks for taking the time Joe
Good morning Joe:
 
I am just getting started with my = equipment and do=20 not have any experience.  I am afraid that I can not be of much=20 help.
 
I am using parts that I purchased from = Larry=20 Cockrine and hope to get my station up and running in the next 6=20 months.
 
Peter
 
----- Original Message -----
From:=20 Armstrong
Sent: Saturday, October 07, = 2006 10:03=20 PM
Subject: Seismometer for = Central=20 Illinois

I live in a subdivision in a city in = Central=20 Illinois. The geological survey tells my that in my area, that bedrock = is=20 10-30' feet below. I have a basement, but also two active kids. I am=20 interested in having a seismometer that would be capable of detecting = New=20 Madrid activity.
 
So far my attempts have involved the = construction=20 of a 8" coil using #34 wire on a 3' - 3" pvc form using a pendulum of = 6=20 magnetron magents. Coil: Resistance of ~7.1kohm.  =
After I also have 3 - 4.5hz=20 geophones.
 
My questions follow:
1) Can you think of a project that I = use the=20 on-hand coil and magnets or the geophones? Or should I just start over = with=20 another project?
2) Basement: Is it a suitable = location? I=20 have been told that that gravel under the basement disperses most = of the vibration. Would the activity of the kids affect the=20 readings? Should the seimometer be physically secured to the=20 concrete?
3) Can a home brew seismometer =  be effective=20 in Central Illinois?
 
Thanks for taking the = time
Joe
Subject: RE: Korean nuclar test From: "Bob Hancock" carpediem1@......... Date: Mon, 9 Oct 2006 09:29:14 -0700 According to the news, the US has not confirmed that a nuclear device was exploded, only that the event was equivalent to a large amount of TNT, but below the kilo-ton level, a normal measurement for nuclear explosions. Does anyone in the PSN group have any thoughts about the different in seismic signatures between a chemical and nuclear explosion. I am wondering about the buildup of pressure that would generate the initial P-wave, and any differences in P-wave form that would be present between the chemical and nuclear explosions. Also, how does the rate of expansion on the shock wave compare between chemical and nuclear explosions. Bob Hancock __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Korean nuclar test From: apsn apsn@........... Date: Mon, 09 Oct 2006 08:58:43 -0800 Bob, how interesting that the very same question was a hot topic of debate in our house last night. Did the DPRK really set off a nuke or did they just set off a chemical explosion to fool everyone? I don't believe any but the closest seismometers would be able to discriminate between a nuke or a chemical explosion of M 4.2. The rise time of a nuke versus a chemical explosion would be different but to discriminate between the two at any distance from the hypocenter might be difficult. The modification of the initial P-wave by the country rock might make it even harder. This is something the CTBTO and USAF AFTAC and nuke-watching network operators WOULD know. :) Bob Hammond Public Seismic Network - Alaska http://apsn.awcable.com At 07:36 AM 10/9/2006, you wrote: >According to the news, the US has not confirmed that a nuclear device was >exploded, only that the event was equivalent to a large amount of TNT, but >below the kilo-ton level, a normal measurement for nuclear explosions. > >Does anyone in the PSN group have any thoughts about the different in >seismic signatures between a chemical and nuclear explosion. I am wondering >about the buildup of pressure that would generate the initial P-wave, and >any differences in P-wave form that would be present between the chemical >and nuclear explosions. Also, how does the rate of expansion on the shock >wave compare between chemical and nuclear explosions. > >Bob Hancock > > > > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. Bob Hammond Public Seismic Network - Alaska http://apsn.awcable.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Korean nuclar test From: jonfr500@......... Date: Mon, 9 Oct 2006 19:54:28 +0000 Hi Here is a explanation from BBC News about this test. http://news.bbc.co.uk/= 2/hi/asia-pacific/6033893.stm Regards. J=F3n Fr=EDmann. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Korean nuclar test From: jonfr500@......... Date: Mon, 9 Oct 2006 20:11:03 +0000 Hi I found a picture of the wave from the explosion in North Korea. It can be = found here, http://www.nordlys.no/nyheter/article2339116.ece The news is in norsk. Regards. J=F3n Fr=EDmann. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Korean nuclar test From: apsn apsn@........... Date: Mon, 09 Oct 2006 15:01:27 -0800 Hi all, Here's a great article on nuke detection and discrimination: http://www.ldeo.columbia.edu/res/pi/Monitoring/Doc/Srr_2005/PAPERS/03-22.pdf I went to graduate school with one of the authors (Dodge). Bob Hammond Public Seismic Network - Alaska http://apsn.awcable.com At 07:36 AM 10/9/2006, you wrote: >According to the news, the US has not confirmed that a nuclear device was >exploded, only that the event was equivalent to a large amount of TNT, but >below the kilo-ton level, a normal measurement for nuclear explosions. > >Does anyone in the PSN group have any thoughts about the different in >seismic signatures between a chemical and nuclear explosion. I am wondering >about the buildup of pressure that would generate the initial P-wave, and >any differences in P-wave form that would be present between the chemical >and nuclear explosions. Also, how does the rate of expansion on the shock >wave compare between chemical and nuclear explosions. > >Bob Hancock > > > > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. Bob Hammond Public Seismic Network - Alaska http://apsn.awcable.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Shunt damping From: Bobhelenmcclure@....... Date: Mon, 9 Oct 2006 21:17:07 EDT Hi Chris, For a damped pendulum, we are dealing with the equation F = m(d2x/dt2) + c(dx/dt) + kx, where F is some forcing function. m is mass, k is stiffness, and c is drag. Feynman defines k=m*Omega0^2, c=m*Gamma, and Q=Omega0/Gamma, where Omega0 is the natural frequency. In order to calculate the effect of a shunt load on the pickup coil for damping, recall that the sensor output sensitivity is given by S = B*L, where S is in units of volts per meter per second, B is field strength in Teslas, and L is active wire length in meters. If we pass current through the coil, the resultant motor force is f = S*I, where f is in newtons, and I is amperes. If we load the moving coil with the resistance of the coil in series with an external resistance, the generated voltage is E = S * v, and the current is I = E/R, so the resulting drag is c*v = S*I = S*E/R = S*(S*v)/R. So, c = S*S/R, where c is drag in newtons per meter per second. From the Feynman definitions, c = m * Gamma = m * Omega0 / Q. Since c from shunt damping is S^2 / R, we have the equality S *S / R = m * Omega0 / Q. Solving for Q, we obtain: Q = R * m * Omega0 / S^2 For a Q of unity, R = (Ps * S^2) / (2 * Pi * m), where Ps is sensor natural period in seconds. When I plug in my assumed values of Ps = 12 seconds, S = 85 v-s/m, and m = 0.1 kg, the value for R is 138 kOhms. In reality, the value I need to get a Q of 1.0 is less than half the above. I have no clue as to why. I calibrated the sensor output several ways, all yielding the same result. The mass was determined by weighing the solder wire mass and the coil assembly. To get better agreement, I would have to considerably decrease my value for S, which incidentally would also bring my calibrated seismic amplitudes into closer agreement with those recorded by station PAL. My present calibration gives me only 40% of the amplitude recorded at PAL. I hope someone out there can find a flaw in the mathematics. I am not happy with the apparent disagreement between theory and experiment. Cheers, Bob
Hi Chris,
 
  For a damped pendulum, we are dealing with the equation
 
  F =3D m(d2x/dt2) + c(dx/dt) + kx, where F is some forcing=20 function.
 
 m is mass, k is stiffness, and c is drag. Feynman defines=20 k=3Dm*Omega0^2, c=3Dm*Gamma, and Q=3DOmega0/Gamma, where Omega0 is the natur= al=20 frequency.
 
 In order to calculate the effect of a shunt load on the= =20 pickup coil for damping, recall that the sensor output sensitivity is given=20= by S=20 =3D B*L, where S is in units of volts per meter per second, B is field stren= gth in=20 Teslas, and L is active wire length in meters.
 
  If we pass current through the coil, the resultant motor force i= s f=20 =3D S*I, where f is in newtons, and I is amperes.
 
  If we load the moving coil with the resistance of the coil in se= ries=20 with an external resistance, the generated voltage is E =3D S * v, and the c= urrent=20 is I =3D E/R, so the resulting drag is c*v =3D S*I =3D S*E/R =3D S*(S*v)/R.<= /DIV>
 
  So, c =3D S*S/R, where c is drag in newtons per meter per second= .. From=20 the Feynman definitions, c =3D m * Gamma =3D m * Omega0 / Q. Since c from sh= unt=20 damping is S^2 / R, we have the equality S *S / R =3D m * Omega0 / Q.
 
  Solving for Q, we obtain:
 
Q =3D R * m * Omega0 / S^2
 
  For a Q of unity,
 
R =3D (Ps * S^2) / (2 * Pi * m), where Ps is sensor natural period in=20 seconds.
 
  When I plug in my assumed values of Ps =3D 12 seconds, S =3D 85=20= v-s/m,=20 and m =3D 0.1 kg, the value for R is 138 kOhms.
 
  In reality, the value I need to get a Q of 1.0 is less= =20 than half the above. I have no clue as to why. I calibrated the sensor outpu= t=20 several ways, all yielding the same result. The mass was determined by weigh= ing=20 the solder wire mass and the coil assembly. To get better agreement, I would= =20 have to considerably decrease my value for S, which incidentally would also=20 bring my calibrated seismic amplitudes into closer agreement with those reco= rded=20 by station PAL. My present calibration gives me only 40% of the amplitude=20 recorded at PAL.
 
  I hope someone out there can find a flaw in the mathematics. I a= m=20 not happy with the apparent disagreement between theory and experiment.
 
Cheers,
 
Bob
 
 
 Subject: Re: Korean nuclar test From: ChrisAtUpw@....... Date: Tue, 10 Oct 2006 00:04:40 EDT In a message dated 2006/10/09 , carpediem1@......... writes: > According to the news, the US has not confirmed that a nuclear device was > exploded, only that the event was equivalent to a large amount of TNT, but > below the kilo-ton level, a normal measurement for nuclear explosions. How far below a kilo ton? The Nagasaki bomb was about 20 kilo tons. Let's hope that it was a partial failure - or a chemical explosion !! Regards, Chris Chapman In a me= ssage dated 2006/10/09 , carpediem1@......... writes:

According to the news, the US h= as not confirmed that a nuclear device was
exploded, only that the event was equivalent to a large amount of TNT, but below the kilo-ton level, a normal measurement for nuclear explosions.

       How far below a kilo ton?

       The Nagasaki bomb was about 20 kilo ton= s.

       Let's hope that it was a partial failur= e - or a chemical explosion !!

       Regards,

       Chris Chapman Subject: Re: Building a lehman seismometer From: "tchannel" tchannel@.............. Date: Wed, 11 Oct 2006 08:57:28 -0600 Hi Chris, The sensor is coming along nicely. =20 Q. The coil is done, is it a good idea to coat the coil with glue or = something like that just to keep the wires from getting damaged, or is = it best just to leave it? Q. As the wires leave the coil and travel down the shaft to the lower = pivot, what is the best way to make the transition off the shaft to the = base? I have seen coiled wires to form a spring, to reduce drag on the = movement of the shaft. I have seen large loops and small coils. I = don't know if they should be hanging down or left and right. You must = have tried several different methods? Thanks, Ted ----- Original Message -----=20 From: ChrisAtUpw@.......... To: psn-l@................. Sent: Thursday, October 05, 2006 8:59 PM Subject: Re: Building a lehman seismometer In a message dated 2006/10/05, tchannel@.............. writes: I am in the process of building a sensor bases on your prototype, = and great drawings. I have most of the parts located, again with your = help and others on the mailing list. I will send pictures as I go along, = if you like, and if you tell me how to send them. Hi Ted, gif or jpg images would do fine to my EMail address. I regards to the angle between the bottom and top hinge, a fraction = of a degree, how do you measure for that? Or do you adjust and measure = the period, instead? I don't measure it, I calculate it. Then I make the structure = so that there is a small amount of adjustment. The axis is defined by = the centre of the ball and the edge of the top wire clamp. You vary the = slope of the long horizontal baseplate to set the period accurately, = using the end adjustment screw, but you keep the arm parallel to the = baseplate.=20 Chris, I see on your drawing you did not need to brace the vertical = arm of your device. Looks very strong. How did you attach that vertical = to the cross member? In my case the bottom of the vertical was milled flat and then = the centre sections were milled out ~15 thou so that there were four = longitudinal narrow strips about 1/16" wide x 3/4" long at the corners. = Then two bolts were put through the cross bar, the long base and = threaded into the vertical at the front and back ends. If you don't mill = out / file out the centre sections, the clamp force will be at the = centre, not at the edges where you want it and it will rock just enough = to give trouble. An alternative is to use a flat end and 3 or 4 shim = strips. You can also make three point suspensions, or you can glue the = vertical to the long base with two part modified acrylic glue. This is = strong and tough, unlike epoxy which is brittle. However you have to be = very quick as it has a gel time of about a couple of minutes in a warm = room.=20 An alternative construction might be to use a 3" dia tube for = the vertical? This can be held on either with a central vertical = threaded rod and a top plate, or by mounting a 3/4" circular rod = horizontally through two holes in the vertical tube, drilling and = tapping this and putting a vertical bolt up through the baseplate. You = would make three contact strip suspension flats at 120 deg. You can use an SS ball on a carbide flat lower hinge or crossed = cylinders. You can buy 1/8" solid tungsten carbide drills from = www.Smallparts.com or www.Digikey.com and cut the shanks to length with = a carbide disk. Glue one to the head of an SS bolt and the other to the = end of the arm with two part modified acrylic glue. I usually file a = shallow V first to locate the shank mechanically. Mount the vertical rod = or the ball on vertical support and the horizontal rod or the flat on = the arm, NOT the other way around! 8 thou Nickel plated piano wire is = available for mandolin strings at a music shop. See www.daddario.com Another method of construction which you might wish to consider? = In this I used Al alloy U channel, 3" wide x 1" high and three = triangular 3/16" to 1/4" thick corner plates at the end T / L joint. The = vertical is attached to the long horizontal base with two 5" corner = plates and four SS bolts per plate. I use two plain SS washers and a = spring washer per bolt to prevent it digging into the softer Al. The = open U is on the inside of the 90 deg joint. The cross bar is attached = to the outside of the vertical with four bolts and a 7" triangle. It = seems to work OK and makes quite a neat job. I bought it cut / chopped = to size, from a local metals supermarket. You maybe able to get 2" x 1" = U channel from building supplies / DIY. I tend to make things more = massive than absolutely necessary. The secret of the rigidity is mostly = in the three large triangular joint plates.=20 I tend to use 18" to 24" long tubular arms. 22" gives a 1.5 sec = basic pendulum which you can extend by x20 to 30 sec. 3 ft is a bit = bulky, but it gives maybe 40 sec or more? You can get compression = fittings for most tube. I use 1/2" SS water pipe and brass water = fittings, 15mm OD, but the tube may not be widely available? It is light = but rigid and non magnetic. Hard drawn Cu or brass are alternatives. You = can also buy general purpose brass compression 'engineering' fittings = for a wide range of standard pipe sizes, but these may only be available = through a few more specialist suppliers and they tend to be more = expensive than water fittings. Check on the availabilty of thin wall = welded SS water pipe?=20 Regards, Chris Chapman =20
Hi Chris,    The sensor = is coming=20 along nicely. 
Q.   The coil is done, is it = a good idea=20 to coat the coil with glue or something like that just to keep the wires = from=20 getting damaged, or is it best just to leave it?
Q.  As the wires leave the coil = and travel=20 down the shaft to the lower pivot, what is the best way to make the = transition=20 off the shaft to the base?  I have seen coiled wires to form a = spring, to=20 reduce drag on the movement of the shaft.  I have seen large loops = and=20 small coils.  I don't know if they should be hanging down or left = and=20 right.  You must have tried several different methods?
 
Thanks, Ted
 
 
 
----- Original Message -----
From:=20 ChrisAtUpw@.......
Sent: Thursday, October 05, = 2006 8:59=20 PM
Subject: Re: Building a lehman=20 seismometer

In a=20 message dated 2006/10/05, tchannel@..............=20 writes:

   I am in the process of building a sensor = bases on=20 your prototype, and great drawings. I have most of the parts = located, again=20 with your help and others on the mailing list. I will send pictures = as I go=20 along, if you like, and if you tell me how to send them.


Hi=20 Ted,

       gif or jpg images = would do=20 fine to my EMail address.

 I regards to the angle between the bottom and top hinge, = a=20 fraction of a degree, how do you measure for that? Or do you adjust = and=20 measure the period, instead?


       I don't=20 measure it, I calculate it. Then I make the structure so that there is = a small=20 amount of adjustment. The axis is defined by the centre of the ball = and the=20 edge of the top wire clamp. You vary the slope of the long horizontal=20 baseplate to set the period accurately, using the end adjustment = screw, but=20 you keep the arm parallel to the baseplate.

Chris, I see on your drawing you did not need to brace = the=20 vertical arm of your device. Looks very strong.  How did you = attach=20 that vertical to the cross member?


       In my=20 case the bottom of the vertical was milled flat and then the centre = sections=20 were milled out ~15 thou so that there were four longitudinal narrow = strips=20 about 1/16" wide x 3/4" long at the corners. Then two bolts were put = through=20 the cross bar, the long base and threaded into the vertical at the = front and=20 back ends. If you don't mill out / file out the centre sections, the = clamp=20 force will be at the centre, not at the edges where you want it and it = will=20 rock just enough to give trouble. An alternative is to use a flat end = and 3 or=20 4 shim strips.
       You can also = make three=20 point suspensions, or you can glue the vertical to the long base with = two part=20 modified acrylic glue. This is strong and tough, unlike epoxy which is = brittle. However you have to be very quick as it has a gel time of = about a=20 couple of minutes in a warm room. =
       An=20 alternative construction might be to use a 3" dia tube for the = vertical? This=20 can be held on either with a central vertical threaded rod and a top = plate, or=20 by mounting a 3/4" circular rod horizontally through two holes in the = vertical=20 tube, drilling and tapping this and putting a vertical bolt up through = the=20 baseplate. You would make three contact strip suspension flats at 120=20 deg.
       You can use an SS ball on = a=20 carbide flat lower hinge or crossed cylinders. You can buy 1/8" solid = tungsten=20 carbide drills from www.Smallparts.com or www.Digikey.com and cut the = shanks=20 to length with a carbide disk. Glue one to the head of an SS bolt and = the=20 other to the end of the arm with two part modified acrylic glue. I = usually=20 file a shallow V first to locate the shank mechanically. Mount the = vertical=20 rod or the ball on vertical support and the horizontal rod or the flat = on the=20 arm, NOT the other way around! 8 thou Nickel plated piano wire is = available=20 for mandolin strings at a music shop. See = www.daddario.com
    = Another method of = construction=20 which you might wish to consider? In this I used Al alloy U channel, = 3" wide x=20 1" high and three triangular 3/16" to 1/4" thick corner plates at the = end T /=20 L joint. The vertical is attached to the long horizontal base with two = 5"=20 corner plates and four SS bolts per plate. I use two plain SS washers = and a=20 spring washer per bolt to prevent it digging into the softer Al. The = open U is=20 on the inside of the 90 deg joint. The cross bar is attached to the = outside of=20 the vertical with four bolts and a 7" triangle. It seems to work OK = and makes=20 quite a neat job. I bought it cut / chopped to size, from a local = metals=20 supermarket. You maybe able to get 2" x 1" U channel from building = supplies /=20 DIY. I tend to make things more massive than absolutely necessary. The = secret=20 of the rigidity is mostly in the three large triangular joint plates.=20
    I tend to use 18" to 24" long tubular arms. 22" = gives a=20 1.5 sec basic pendulum which you can extend by x20 to 30 sec. 3 ft is = a bit=20 bulky, but it gives maybe 40 sec or more? You can get compression = fittings for=20 most tube. I use 1/2" SS water pipe and brass water fittings, 15mm OD, = but the=20 tube may not be widely available? It is light but rigid and non = magnetic. Hard=20 drawn Cu or brass are alternatives. You can also buy general purpose = brass=20 compression 'engineering' fittings for a wide range of standard pipe = sizes,=20 but these may only be available through a few more specialist = suppliers and=20 they tend to be more expensive than water fittings. Check on the = availabilty=20 of thin wall welded SS water pipe?

    = Regards,

    Chris=20 Chapman    =
Subject: Re: Building a lehman seismometer From: ChrisAtUpw@....... Date: Wed, 11 Oct 2006 14:52:43 EDT In a message dated 2006/10/11, tchannel@.............. writes: > Hi Chris, The sensor is coming along nicely. > Q. The coil is done, is it a good idea to coat the coil with glue or > something like that just to keep the wires from getting damaged, or is it best > just to leave it? Hi Ted, While it should be possible to varnish the coil, I have had nothing but trouble with this due to turns shorting out. I suggest that you leave it plain, but maybe wrap a length of 'self amalgamating' rubber tape around the outside. This rubber just sticks to itself, nothing else. Alternatively use paper or a cloth tape and a water based glue (no aromatic solvents). PVC tape tends to 'go sticky' and peel off after a few months. You may also be able to get large diameter heat shrink tube, but it tends to be expensive. > Q. As the wires leave the coil and travel down the shaft to the lower > pivot, what is the best way to make the transition off the shaft to the base? I > have seen coiled wires to form a spring, to reduce drag on the movement of > the shaft. I have seen large loops and small coils. I don't know if they > should be hanging down or left and right. You must have tried several different > methods? I mount a couple of solder pins on the coil former and then use thin shielded microphone cable from the coil to the hinge (and from the upright to the amplifier). Tie / tape it to the arm every 6" or so. Preferably look for the cable variety that has a black conducting plastic shield inside the braided copper screen. This gives the best performance / lowest noise - otherwise just use thin microphone cable. I use two bits of pinboard, each with 2 pins, one glued to the arm and one to the vertical. I use a V WIRE HAIRPINS about 2" long standing ~vertically of 36 / 38 gauge wire. I have not tried any thicker wire. You can use short coils, but you have to ensure that there are no turns touching. I use a polyurethane insulated magnet wire like Beldsol. I wrap a turn around the pin and then solder with a hot iron - or just solder the end 1/8" of wire, whichever is easier. The polyurethane insulation melts. It is easy to replace the wires. The apparatus / frame should be earthed. Regards, Chris Chapman In a me= ssage dated 2006/10/11, tchannel@.............. writes:

Hi Chris,    The= sensor is coming along nicely. 
Q.   The coil is done, is it a good idea to coat the coil with gl= ue or something like that just to keep the wires from getting damaged, or is= it best just to leave it?


 Hi Ted,

       While it should be possible to varnish=20= the coil, I have had nothing but trouble with this due to turns shorting out= .. I suggest that you leave it plain, but maybe wrap a length of 'self amalga= mating' rubber tape around the outside. This rubber just sticks to itself, n= othing else. Alternatively use paper or a cloth tape and a water based glue=20= (no aromatic solvents). PVC tape tends to 'go sticky' and peel off after a f= ew months. You may also be able to get large diameter heat shrink tube, but=20= it tends to be expensive.  

Q.  As the wires leave th= e coil and travel down the shaft to the lower pivot, what is the best way to= make the transition off the shaft to the base?  I have seen coiled wir= es to form a spring, to reduce drag on the movement of the shaft.  I ha= ve seen large loops and small coils.  I don't know if they should be ha= nging down or left and right. You must have tried several different methods?=


       I mount a couple of solder pins on the=20= coil former and then use thin shielded microphone cable from the coil to the= hinge (and from the upright to the amplifier). Tie / tape it to the arm eve= ry 6" or so. Preferably look for the cable variety that has a black conducti= ng plastic shield inside the braided copper screen. This gives the best perf= ormance / lowest noise - otherwise just use thin microphone cable.

       I use two bits of pinboard, each with 2= pins, one glued to the arm and one to the vertical. I use a V WIRE HAIRPINS= about 2" long standing ~vertically of 36 / 38 gauge wire. I have not tried=20= any thicker wire.
       You can use short coils, but you have t= o ensure that there are no turns touching.
       I use a polyurethane insulated magnet w= ire like Beldsol. I wrap a turn around the pin and then solder with a hot ir= on - or just solder the end 1/8" of wire, whichever is easier. The polyureth= ane insulation melts. It is easy to replace the wires.
       The apparatus / frame should be earthed= ..

       Regards,

       Chris Chapman Subject: Korean Nuclear test - Possible recording From: "Arie Verveer" greensky@.............. Date: Thu, 12 Oct 2006 20:18:25 +0800 Hi , I have posted some data that may show a recoding of the North Korean Nuclear event. The data values are very low and the recording may be noise. The calculated arrival times matches well. Alas the power failed on the arrival of the "S" wave. My system did record the Pakistan test a few years ago, though its signal to noise ratio was very low. Just a bump in a clear patch of data. Cheers Arie 061009.013926.au4.psn Mb4.2 8220km from Bickley, Western Australia __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Building a lehman seismometer From: "tchannel" tchannel@.............. Date: Thu, 12 Oct 2006 08:40:43 -0600 Hi Chris,=20 Q By V HAIRPINS, do you mean a piece of wire which forms a single "V" = shape? One for each wire, with no twist or turns? Q Just curious, about the magnet layout. Why are they arranged N,S on = the top and S,N on the bottom? If one used a horseshoe magnet it would be Just N,S Pictures tomorrow, I think. Thanks, Ted ----- Original Message -----=20 From: ChrisAtUpw@.......... To: psn-l@................. Sent: Wednesday, October 11, 2006 12:52 PM Subject: Re: Building a lehman seismometer In a message dated 2006/10/11, tchannel@.............. writes: Hi Chris, The sensor is coming along nicely. =20 Q. The coil is done, is it a good idea to coat the coil with glue = or something like that just to keep the wires from getting damaged, or = is it best just to leave it? Hi Ted, While it should be possible to varnish the coil, I have had = nothing but trouble with this due to turns shorting out. I suggest that = you leave it plain, but maybe wrap a length of 'self amalgamating' = rubber tape around the outside. This rubber just sticks to itself, = nothing else. Alternatively use paper or a cloth tape and a water based = glue (no aromatic solvents). PVC tape tends to 'go sticky' and peel off = after a few months. You may also be able to get large diameter heat = shrink tube, but it tends to be expensive. =20 Q. As the wires leave the coil and travel down the shaft to the = lower pivot, what is the best way to make the transition off the shaft = to the base? I have seen coiled wires to form a spring, to reduce drag = on the movement of the shaft. I have seen large loops and small coils. = I don't know if they should be hanging down or left and right. You must = have tried several different methods? I mount a couple of solder pins on the coil former and then use = thin shielded microphone cable from the coil to the hinge (and from the = upright to the amplifier). Tie / tape it to the arm every 6" or so. = Preferably look for the cable variety that has a black conducting = plastic shield inside the braided copper screen. This gives the best = performance / lowest noise - otherwise just use thin microphone cable.=20 I use two bits of pinboard, each with 2 pins, one glued to the = arm and one to the vertical. I use a V WIRE HAIRPINS about 2" long = standing ~vertically of 36 / 38 gauge wire. I have not tried any thicker = wire.=20 You can use short coils, but you have to ensure that there are = no turns touching. I use a polyurethane insulated magnet wire like Beldsol. I wrap = a turn around the pin and then solder with a hot iron - or just solder = the end 1/8" of wire, whichever is easier. The polyurethane insulation = melts. It is easy to replace the wires. The apparatus / frame should be earthed.=20 Regards, Chris Chapman
Hi Chris,
Q   By V HAIRPINS, do you = mean a piece of=20 wire which forms a single "V" shape?  One for each wire, with no = twist or=20 turns?
 
Q  Just curious, about the magnet=20 layout.  Why are they arranged N,S on the top and S,N on the=20 bottom?
If one used a horseshoe magnet it would = be Just=20 N,S
 
Pictures tomorrow, I think.   = Thanks,=20 Ted
----- Original Message -----
From:=20 ChrisAtUpw@.......
Sent: Wednesday, October 11, = 2006 12:52=20 PM
Subject: Re: Building a lehman=20 seismometer

In a=20 message dated 2006/10/11, tchannel@..............=20 writes:

Hi Chris,    The sensor is coming along=20 nicely. 
Q.   The coil is done, is it a good idea = to coat=20 the coil with glue or something like that just to keep the wires = from=20 getting damaged, or is it best just to leave it?

Hi=20 Ted,

       While it should be = possible=20 to varnish the coil, I have had nothing but trouble with this due to = turns=20 shorting out. I suggest that you leave it plain, but maybe wrap a = length of=20 'self amalgamating' rubber tape around the outside. This rubber just = sticks to=20 itself, nothing else. Alternatively use paper or a cloth tape and a = water=20 based glue (no aromatic solvents). PVC tape tends to 'go sticky' and = peel off=20 after a few months. You may also be able to get large diameter heat = shrink=20 tube, but it tends to be expensive.  

Q.  As the wires leave the coil and travel down the = shaft=20 to the lower pivot, what is the best way to make the transition off = the=20 shaft to the base?  I have seen coiled wires to form a spring, = to=20 reduce drag on the movement of the shaft.  I have seen large = loops and=20 small coils.  I don't know if they should be hanging down or = left and=20 right. You must have tried several different methods?

       I mount a = couple of=20 solder pins on the coil former and then use thin shielded microphone = cable=20 from the coil to the hinge (and from the upright to the amplifier). = Tie / tape=20 it to the arm every 6" or so. Preferably look for the cable variety = that has a=20 black conducting plastic shield inside the braided copper screen. This = gives=20 the best performance / lowest noise - otherwise just use thin = microphone=20 cable.

       I use two bits of=20 pinboard, each with 2 pins, one glued to the arm and one to the = vertical. I=20 use a V WIRE HAIRPINS about 2" long standing ~vertically of 36 / 38 = gauge=20 wire. I have not tried any thicker wire.=20
       You can use short coils, but = you have=20 to ensure that there are no turns=20 touching.
       I use a polyurethane = insulated magnet wire like Beldsol. I wrap a turn around the pin and = then=20 solder with a hot iron - or just solder the end 1/8" of wire, = whichever is=20 easier. The polyurethane insulation melts. It is easy to replace the=20 wires.
       The apparatus / frame = should be=20 earthed.

      =20 Regards,

       Chris = Chapman=20 Subject: Re: Building a lehman seismometer From: ChrisAtUpw@....... Date: Thu, 12 Oct 2006 15:23:50 EDT In a message dated 2006/10/12, tchannel@.............. writes: > Hi Chris, > Q By V HAIRPINS, do you mean a piece of wire which forms a single "V" > shape? One for each wire, with no twist or turns? Hi Ted, One ~straight piece of wire bent into a V / U shape with ~straight 2" sides and soldered to the pins at the ends, for each connection (like a hair pin). This works fine with the 36 AWG Cu wire that I use. > Q Just curious, about the magnet layout. Why are they arranged N,S on the > top and S,N on the bottom? > If one used a horseshoe magnet it would be Just N,S With a horse shoe magnet, you have to offset the position of the coil away from the poles, so that it experiences about 1/2 the maximum field. If the coil moves one way, the field increases, if it moves the other way the field decreases. But you are starting from the half field position and the field strength is ~S shaped - not very linear when the Lehman mass drifts in position! In my arrangement one winding of the coil moves in gap directly between a N pole on one face and a S pole on the other, carrying the full maximum field. You have opposite field directions for the two halves of the coil, so that the induced voltages add. This increases both the linearity and the output very considerably. The field strength is nearly constant anywhere over one pole. The return path from the back of the bar magnets is through the mild steel backing plates. Magnetically, this is a 'short circuit'. The N+S magnets only have to drive the external field across the central gap. You should get over 5x the field of an Alnico magnet. This allows the coil to be smaller while still giving an increased output. Another way of viewing the system is to consider the net field through the coil when it is centralised. You have two strong constant fields in opposite directions over the two halves, which balance out. Any movement applies a strong net field through the coil. Using the flat square NdFeB magnets makes this highly effective layout easy and inexpensive to achieve. Regards, Chris Chapman In a me= ssage dated 2006/10/12, tchannel@.............. writes:

Hi Chris,
Q   By V HAIRPINS, do you mean a piece of wire which forms a sing= le "V" shape?  One for each wire, with no twist or turns?

Hi Ted,

       One ~straight piece of wire bent into a= V / U shape with ~straight 2" sides and soldered to the pins at the ends, f= or each connection (like a hair pin). This works fine with the 36 AWG Cu wir= e that I use.

Q  Just curious, about th= e magnet layout. Why are they arranged N,S on the top and S,N on the bottom?=
If one used a horseshoe magnet it would be Just N,S


       With a horse shoe magnet, you have to o= ffset the position of the coil away from the poles, so that it experiences a= bout 1/2 the maximum field. If the coil moves one way, the field increases,=20= if it moves the other way the field decreases. But you are starting from the= half field position and the field strength is ~S shaped - not very linear w= hen the Lehman mass drifts in position!

       In my arrangement one winding of the co= il moves in gap directly between a N pole on one face and a S pole on the ot= her, carrying the full maximum field. You have opposite field directions for= the two halves of the coil, so that the induced voltages add. This increase= s both the linearity and the output very considerably. The field strength is= nearly constant anywhere over one pole.

       The return path from the back of the ba= r magnets is through the mild steel backing plates. Magnetically, this is a=20= 'short circuit'. The N+S magnets only have to drive the external field acros= s the central gap. You should get over 5x the field of an Alnico magnet. Thi= s allows the coil to be smaller while still giving an increased output.

       Another way of viewing the system is to= consider the net field through the coil when it is centralised. You have tw= o strong constant fields in opposite directions over the two halves, which b= alance out. Any movement applies a strong net field through the coil. Using=20= the flat square NdFeB magnets makes this highly effective layout easy and in= expensive to achieve.     

       Regards,

       Chris Chapman Subject: Sensor From: "tchannel" tchannel@.............. Date: Fri, 13 Oct 2006 15:12:11 -0600 Hi, I just wanted to let you all know I have finished my sensor. It = was patterned off the ideas and pictures from you folks. I have not tested it yet. I keep good records of the project, so If = anyone would like details or pictures just email me. Many thanks to Chris, and Bob for their ideas and help. And thanks to = all of you who took the time to answer so many of my questions. I let = you know how it works. Ted
Hi,  I just wanted to let you all = know I have=20 finished my sensor.  It was patterned off the ideas and pictures = from you=20 folks.
I have not tested it yet.   I = keep good=20 records of the project, so If anyone would like details or pictures just = email=20 me.
Many thanks to Chris, and Bob for their = ideas and=20 help.  And thanks to all of you who took the time to answer so many = of my=20 questions.   I let you know how it works.  =20 Ted
Subject: Intrest in Volcanos ? From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sat, 14 Oct 2006 04:57:01 +0000 Hi Is anyone here intrested in volcanos, along with earthquakes ? Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Intrest in Volcanos ? From: John Popelish jpopelish@........ Date: Sat, 14 Oct 2006 01:51:48 -0400 J=F3n Fr=EDmann wrote: > Hi >=20 > Is anyone here intrested in volcanos, along with earthquakes ?=20 I'm fascinated by them. Fortunately for me, there are many=20 web cams available so I can check in on many each day. i.e. http://www.nps.gov/archive/yell/oldfaithfulcam.htm http://hvo.wr.usgs.gov/cam/index.htm http://hvo.wr.usgs.gov/cam2/ http://www.fs.fed.us/gpnf/volcanocams/msh/images/mshvolcanocam.jpg http://www.geonet.org.nz/volcanocam.html http://www.avo.alaska.edu/webcam/a-spurr.jpg http://www.avo.alaska.edu/webcam/augtst.jpg http://www.avo.alaska.edu/webcam/veni.jpg __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Station Upgrde From: "Randy" rpratt@............. Date: Sat, 14 Oct 2006 08:41:11 -0500 Hi All, My lehmen has been inop for for some time after some power supply wires = shorted together and fried most everything including the computer ps and = motherboard. I have begun a rebuild with some changes and ideas = beginning with moving from EMON to Amaseis. I don't see instructions to = run multiple channels and I was wondering if this is possible? I tried = opening 2 copies in different directories and windows but the com port = conflicts. I have converted from the AD I constructed to a Dataq 154. =20 Randy
Hi All,
 
My lehmen has been inop for for = some time=20 after some power supply wires shorted together and fried most everything = including the computer ps and motherboard.  I have begun a = rebuild=20 with some changes and ideas beginning with moving from EMON to = Amaseis.  I=20 don't see instructions to run multiple channels and I was wondering if = this is=20 possible?  I tried opening 2 copies in different directories and = windows=20 but the com port conflicts.  I have converted from the AD I = constructed to=20 a Dataq 154. 
Randy
Subject: Re: Intrest in Volcanos ? From: Kim Barrow kimbarrow@....................... Date: Sat, 14 Oct 2006 08:03:35 -0700 (PDT) Hi Jon, Yes we are. I am the owner and founder of Earthquake Epi-Center located in the San Francisco Bay area (California.) I read yours and the other updates everyday on psn. We have a number of scientists on our boards at www.earthquakeepi-center.com Please feel free to post your thoughts, questions, comments on our website anytime. We are interested in all sorts of seismic & volcanic news. Sincerely Yours, Kim Barrow Jón Frímann wrote: Hi Is anyone here intrested in volcanos, along with earthquakes ? Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L)
Hi Jon,
 
Yes we are. I am the owner and founder of Earthquake Epi-Center located in the San Francisco Bay area (California.)
 
I read yours and the other updates everyday on psn. We have a number of scientists on our boards at www.earthquakeepi-center.com
 
Please feel free to post your thoughts, questions, comments on our website anytime. We are interested in all sorts of seismic & volcanic news.
 
Sincerely Yours,
Kim Barrow


Jón Frímann <jonfr500@simnet.is> wrote:
Hi

Is anyone here intrested in volcanos, along with earthquakes ?

Regards.
--
Jón Frímann
http://www.jonfr.com
http://www.simnet.is/jonfr500/earthquake/

__________________________________________________________

Public Seismic Network Mailing List (PSN-L)

To leave this list email PSN-L-REQUEST@SEISMICNET.COM with
the body of the message (first line only): unsubscribe
See http://www.seismicnet.com/maillist.html for more information.

Subject: RE: Intrest in Volcanos ? From: "Bob Hancock" carpediem1@......... Date: Sat, 14 Oct 2006 08:19:23 -0700 Jon - Arizona State University (ASU) maintains a Volcano information log where they send out weekly updates on volcano activity world wide. They also = have other postings of interest. Here is the link to join the list: http://lists.asu.edu/cgi-bin/wa?SUBED1=3Dvolcano&A=3D1 Bob Hancock Three Points, AZ -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of J=F3n Fr=EDmann Sent: Friday, October 13, 2006 21:57 To: PSN-Postlist Subject: Intrest in Volcanos ? Hi Is anyone here intrested in volcanos, along with earthquakes ?=20 Regards. --=20 J=F3n Fr=EDmann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Intrest in Volcanos ? From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sat, 14 Oct 2006 19:25:25 +0000 Hi It is good to know that I am not alone in haveing intrest in volcanos here. I regulary record earthquakes from volcanos here in Iceland. But there are also four volcanos that are less then 100 km away from me and a dozen volcanos in less then 200 km away from me. Since I got my geophone there hasn't been a eruption. But I am sure that I won't have to wait long time until it does. I don't know if many of you are close to active volcanos. It would be intresting to get info on that. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Station Upgrde From: ChrisAtUpw@....... Date: Sat, 14 Oct 2006 17:19:16 EDT In a message dated 2006/10/14, rpratt@............. writes: > I don't see instructions to run multiple channels and I was wondering if > this is possible? I tried opening 2 copies in different directories and > windows but the com port conflicts. I have converted from the AD I constructed to > a Dataq 154. Hi Randy, Amaseis is single channel only. However, you can run two copies under Windows, but you would need two ADCs on different ports.... Maybe Alan will add a multi channel option sometime....? Regards, Chris Chapman In a me= ssage dated 2006/10/14, rpratt@............. writes:

I don't see instructions to ru= n multiple channels and I was wondering if this is possible?  I tried o= pening 2 copies in different directories and windows but the com port confli= cts.  I have converted from the AD I constructed to a Dataq 154.=

Hi Randy,

       Amaseis is single channel only. However= , you can run two copies under Windows, but you would need two ADCs on diffe= rent ports.... Maybe Alan will add a multi channel option sometime....?

       Regards,

       Chris Chapman Subject: Re: Interest in Volcanos ? From: Dave Nelson davenn@............... Date: Sun, 15 Oct 2006 10:58:54 +1000 Hi Jon, I have a great love of volcanoes, preferably up close and=20 personal. the list of volcanoes I have visited around the world, both active and=20 dormant, is slowly growing :) not to mention the dozens of extinct ones=20 specifically visited for samples and onsite study. where possible collecting rock/ash samples for study . Volcanoes ... location .......... active/dormant ..... yr/s= =20 visited Mt St Helens, Washington State, USA .... active... 1999 / 2006 Mt Ruapehu, Nth Island, New Zealand ..... active .... 1983 Mt Tongariro, Nth Island, New Zealand ..... active .... 1983 Mt Ngarahoe, Nth Island, New Zealand ..... active .... 1983 Mauna Kea, Hawai'i ........... acitve .... 1999 Ta'al Volcano, Luzon, Philippines ....... active .... 2000 / 2005 some longer term dormant ones but by no means extinct Mt Hood, Washington State, USA Mt Shasta, Oregon State, USA Mt Taranaki (Egmont), Nth Is, New Zealand, and a few photographed from a distance several others in the Philippines Lassen Peak', USA Mt Ranier, USA Truely extinct volcanoes ... The Dunedin Volcano and the others of the SE coast of the South Is.of= NZ. extensive study during my BSc studies The ones around Flagstaff, Arizona, USA Wishlist for visits ..... Vanuatu's active volcanoes other active ones in Philippines Indonesian volcanoes including Merapi and Anak Krakatoa Indonesia is paradise for volcano touring :) and ohhhhh if it wasnt for the hi cost ..... Japan... 3 main ones there would be Sakura jima. Fuji, and Unzen At 04:57 AM 14/10/2006 +0000, you wrote: >Hi >Is anyone here intrested in volcanos, along with earthquakes ? >Regards. >-- >J=F3n Fr=EDmann -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.408 / Virus Database: 268.13.4/476 - Release Date: 14/10/2006 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Interest in Volcanos ? From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sun, 15 Oct 2006 01:13:23 +0000 Hi I've been to Hekla volcano here in Iceland. It was intresting and I got pictures from that trip. I also got few ask rocks from that mountin, really new one, problay not older then 10 or 20 years old. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Interest in Volcanos ? EDITED ! From: Dave Nelson davenn@............... Date: Sun, 15 Oct 2006 11:13:49 +1000 just an edit to correct a couple of serious mistakes in the last posting Hi Jon, I have a great love of volcanoes, preferably up close and=20 personal. the list of volcanoes I have visited around the world, both active and=20 dormant, is slowly growing :) not to mention the dozens of extinct ones=20 specifically visited for samples and onsite study. where possible collecting rock/ash samples for study . Volcanoes ... location .......... ..... yr/s visited Mt St Helens, Washington State, USA .... active... 1999 / 2006 Mt Ruapehu, Nth Island, New Zealand ..... active .... 1983 Mt Tongariro, Nth Island, New Zealand ..... active .... 1983 Mt Ngarahoe, Nth Island, New Zealand ..... active .... 1983 Kilauea Volcano, Hawai'i ........... active .... 1999 Ta'al Volcano, Luzon, Philippines ....... active .... 2000 / 2005 some longer term dormant ones but by no means extinct Mauna Kea, Hawai'i Mauna Loa, Hawai'i Mt Hood, Washington State, USA Mt Shasta, California State, USA Mt Taranaki (Egmont), Nth Is, New Zealand, and a few photographed from a distance several others in the Philippines Lassen Peak', USA Mt Ranier, USA Truely extinct volcanoes ... The Dunedin Volcano and the others of the SE coast of the South Is.of= NZ. extensive study during my BSc studies The ones around Flagstaff, Arizona, USA Wishlist for visits ..... Vanuatu's active volcanoes other active ones in Philippines Indonesian volcanoes including Merapi and Anak Krakatoa Indonesia is paradise for volcano touring :) and ohhhhh if it wasnt for the hi cost ..... Japan... 3 main ones there would be Sakura jima. Fuji, and Unzen Lifetime highlight ..... "playing" in the lava flows from Kilauea in 1999 scooping up 800 -1000 deg lava in soup ladels and other impliments Thanks to Tony, from the Big Island ... also a member of the PSN cheers Dave Nelson Sydney At 04:57 AM 14/10/2006 +0000, you wrote: >Hi >Is anyone here intrested in volcanos, along with earthquakes ? >Regards. >-- >J=F3n Fr=EDmann -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.408 / Virus Database: 268.13.4/476 - Release Date: 14/10/2006 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Station Upgrade From: Bobhelenmcclure@....... Date: Sat, 14 Oct 2006 21:29:03 EDT On Sat, 14 Oct 2006 08:41:11 -0500, "Randy" writes, My lehmen has been inop for for some time after some power supply wires shorted together and fried most everything including the computer ps and motherboard. I have begun a rebuild with some changes and ideas beginning with moving from EMON to Amaseis. I don't see instructions to run multiple channels and I was wondering if this is possible? I tried opening 2 copies in different directories and windows but the com port conflicts. I have converted from the AD I constructed to a Dataq 154. Hi Randy, If you are using a Dataq device, you can log, filter, and heliplot display up to four channels, using my suite of software. You can also convert the WDQ files to Winquake PSN Type 4 files. See _http://www.jclahr.com/science/psn/mcclure/_ (http://www.jclahr.com/science/psn/mcclure/) and download "seismic_dataq.zip" Cheers, Bob
On Sat, 14 Oct 2006 08:41:11 -0500, "Randy" writes,
My lehmen has be= en=20 inop for for some time after some power supply wires
shorted together an= d=20 fried most everything including the computer ps and
motherboard.  I= =20 have begun a rebuild with some changes and ideas
beginning with moving f= rom=20 EMON to Amaseis.  I don't see instructions to
run multiple channels= and=20 I was wondering if this is possible?  I tried
opening 2 copies in=20 different directories and windows but the com port
conflicts.  I ha= ve=20 converted from the AD I constructed to a Dataq 154.
 
Hi Randy,
 
  If you are using a Dataq device, you can log, filter, and helipl= ot=20 display up to
four channels, using my suite of software. You can also con= vert=20 the WDQ
files to Winquake PSN Type 4 files.
 
  See http://www.jclahr.com/sc= ience/psn/mcclure/=20 and download "seismic_dataq.zip"
 
Cheers,
 
Bob
Subject: Large earthquake at hawaii island From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sun, 15 Oct 2006 17:51:23 +0000 Hi According to this there was just now a mag 6.3 earthquake at Hawaii Islands. See there, http://www.emsc-csem.org/index.php?page=current&sub=detail&id=35164 Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Large earthquake at hawaii island From: ian ian@........... Date: Sun, 15 Oct 2006 21:08:05 +0100 looks like Tony (quakekona - psn member) is sitting right on top of it in Kona. Hope he's okay! Ian Jón Frímann wrote: >Hi > >According to this there was just now a mag 6.3 earthquake at Hawaii >Islands. See there, >http://www.emsc-csem.org/index.php?page=current&sub=detail&id=35164 > >Regards. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Large earthquake at hawaii island From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sun, 15 Oct 2006 20:48:01 +0000 Hi USGS now says the earthquake was mag 6.6 Mcd, while emsc-csem says it is Mw 6.5. According to new towns nearby the epicenter of this earthquake lost power and some mudslides have happened. I have been monitoring aftershocks on USGS webpage and based on that I am expecting at least one larger earthquake in the range of mag 5.5 - 6.5, based on that data. I might offcorse be wrong. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Large earthquake at hawaii island From: Dave Nelson davenn@............... Date: Mon, 16 Oct 2006 07:01:21 +1000 a double whammy M6.6 mainshock and a M58 maj aftershock Dave N At 08:48 PM 15/10/2006 +0000, you wrote: >Hi > >USGS now says the earthquake was mag 6.6 Mcd, while emsc-csem says it is >Mw 6.5. According to new towns nearby the epicenter of this earthquake >lost power and some mudslides have happened. I have been monitoring >aftershocks on USGS webpage and based on that I am expecting at least >one larger earthquake in the range of mag 5.5 - 6.5, based on that data. >I might offcorse be wrong. > >Regards. >-- >J=F3n Fr=EDmann >http://www.jonfr.com >http://www.simnet.is/jonfr500/earthquake/ > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > > > >-- >No virus found in this incoming message. >Checked by AVG Free Edition. >Version: 7.1.408 / Virus Database: 268.13.4/476 - Release Date: 14/10/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.408 / Virus Database: 268.13.4/476 - Release Date: 14/10/2006 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Large earthquake at hawaii island From: "Jerry Payton" gpayton880@....... Date: Sun, 15 Oct 2006 16:06:52 -0500 Here is FOX NEWS report on it: http://www.foxnews.com/story/0,2933,220977,00.html Jerry Payton ----- Original Message ----- From: Jón Frímann To: psn-l@.............. Sent: Sunday, October 15, 2006 3:48 PM Subject: Re: Large earthquake at hawaii island Hi USGS now says the earthquake was mag 6.6 Mcd, while emsc-csem says it is Mw 6.5. According to new towns nearby the epicenter of this earthquake lost power and some mudslides have happened. I have been monitoring aftershocks on USGS webpage and based on that I am expecting at least one larger earthquake in the range of mag 5.5 - 6.5, based on that data. I might offcorse be wrong. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) To leave this list email PSN-L-REQUEST@.............. with the body of the message (first line only): unsubscribe See http://www.seismicnet.com/maillist.html for more information.
Here is FOX NEWS report on it:
http://www.fo= xnews.com/story/0,2933,220977,00.html
 
Jerry Payton
----- Original Message -----
From:=20 J=F3n = Fr=EDmann=20
Sent: Sunday, October 15, 2006 = 3:48=20 PM
Subject: Re: Large earthquake = at hawaii=20 island

Hi

USGS now says the earthquake was mag 6.6 Mcd, = while=20 emsc-csem says it is
Mw 6.5. According to new towns nearby the = epicenter of=20 this earthquake
lost power and some mudslides have happened. I have = been=20 monitoring
aftershocks on USGS webpage and based on that I am = expecting at=20 least
one larger earthquake in the range of mag 5.5 - 6.5, based on = that=20 data.
I might offcorse be wrong.

Regards.
--
J=F3n=20 Fr=EDmann
http://www.jonfr.com
http://www.simnet.is/j= onfr500/earthquake/

__________________________________________= ________________

Public=20 Seismic Network Mailing List (PSN-L)

To leave this list email = PSN-L-REQUEST@............... =20 with
the body of the message (first line only): unsubscribe
See = http://www.seismicnet.co= m/maillist.html=20 for more information.
Subject: Re: Large earthquake at hawaii island From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sun, 15 Oct 2006 21:12:05 +0000 Hi Here is a news about this earthquake from BBC News. http://news.bbc.co.uk/1/hi/world/americas/6053796.stm Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Large earthquake at hawaii island From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sun, 15 Oct 2006 22:29:00 +0000 Hi I also hope that Tony is ok. According to news there are alot of power outrage in Hawaii at the moment becose of the earthquake. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Large earthquake at hawaii island From: peaches@............ Date: Sun, 15 Oct 2006 14:43:58 -1000 (HST) Hi all. Im ok. Thanks for your concern. Just a few minor injuries reported on the island so far. Ive just posed my data for the main shock and the main aftershock. Both are hopelessly clipped to give an accurate WQ magnitude. There have been rock slides here and there on the island along with some homes and structures being damaged. There has been a state-wide power outage, incl Honolulu. Our power just came back on about an hour ago so things are starting to get back to normal. We had lots of breakage mostly in the kitchen from dishes, glasses etc being thrown from the cabinets. My 19" tv was thrown from the shelf and smashed. It was truly frightning I must say. It felt like a 7. or better from here, only 9 miles away. It was hard to stand. Most of the energy was in an E-W direction as things facing that direction were thrown the most. Anyway, once again, thank you all for your concern. Aloha Tony Potenzo Hawaii Psn > Hi > > I also hope that Tony is ok. According to news there are alot of power > outrage in Hawaii at the moment becose of the earthquake. > > Regards. > -- > Jón Frímann > http://www.jonfr.com > http://www.simnet.is/jonfr500/earthquake/ > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Large earthquake at hawaii island From: Kim Barrow kimbarrow@....................... Date: Sun, 15 Oct 2006 17:56:34 -0700 (PDT) Hi Peaches, I wanted to say I'm glad to hear you're okay too! We have family vacationing on the Island of Hawaii...what timing huh. This is a copy of my message I posted earlier at EARTHQUAKE EPI-CENTER . Take care, Kim ____________________________________________________ From: http://www.websitetoolbox.com/tool/post/earthquake/vpost?id=1448264&trail=15#1 KimLosGatosCA Today at 04:28 PM --------------------------------- Hi Everyone, Family members visiting Hawaii called to say they had no power and widespread damage. Magnitude 6.6 ISLAND OF HAWAII, HAWAII October 15, 2006 http://quake.wr.usgs.gov/ Possible pre shocks? 2005 07 17-Hawaii region, Hawaii- M5.2 2005 07 15-Hawaii region,Hawaii- M5.3 Information obtained at: http://earthquake.usgs.gov/regional/world/historical.php Please be prepared to evacuate away from low lying areas near coastal waters in the event a stronger quake occurs and a tsunami warning is issued. We want to extend our best wishes to everyone involved in this mornings major quake a speedy recovery. NOTE: There is a likely hood of sizable west coast quake is possible if history repeats itself...more on this probability to follow. Take care, Kim peaches@............ wrote: Hi all. Im ok. Thanks for your concern. Just a few minor injuries reported on the island so far. Ive just posed my data for the main shock and the main aftershock. Both are hopelessly clipped to give an accurate WQ magnitude. There have been rock slides here and there on the island along with some homes and structures being damaged. There has been a state-wide power outage, incl Honolulu. Our power just came back on about an hour ago so things are starting to get back to normal. We had lots of breakage mostly in the kitchen from dishes, glasses etc being thrown from the cabinets. My 19" tv was thrown from the shelf and smashed. It was truly frightning I must say. It felt like a 7. or better from here, only 9 miles away. It was hard to stand. Most of the energy was in an E-W direction as things facing that direction were thrown the most. Anyway, once again, thank you all for your concern. Aloha Tony Potenzo Hawaii Psn > Hi > > I also hope that Tony is ok. According to news there are alot of power > outrage in Hawaii at the moment becose of the earthquake. > > Regards. > -- > Jón Frímann > http://www.jonfr.com > http://www.simnet.is/jonfr500/earthquake/ > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L)
Hi Peaches,
 
I wanted to say I'm glad to hear you're okay too!
 
We have family vacationing on the Island of Hawaii...what timing huh.
 
This is a copy of my message I posted earlier at EARTHQUAKE EPI-CENTER .
 
Take care,
Kim
____________________________________________________
 
 
KimLosGatosCA

 

 
Unread post Today at 04:28 PM     
Hi Everyone,
Family members visiting Hawaii called to say they had no power and widespread damage.
 
Magnitude 6.6 ISLAND OF HAWAII, HAWAII October 15, 2006
http://quake.wr.usgs.gov/ 
 
Possible pre shocks? 2005 07 17-Hawaii region, Hawaii- M5.2 2005 07 15-Hawaii region,Hawaii- M5.3
Information obtained at:
 
Please be prepared to evacuate away from low lying areas near coastal waters in the event a stronger quake occurs and a tsunami warning is issued.
 
We want to extend our best wishes to everyone involved in this mornings major quake a speedy recovery.
 
NOTE: There is a likely hood of sizable west coast quake is possible if history repeats itself...more on this probability to follow.
 
Take care,
Kim


peaches@............ wrote:
Hi all.

Im ok. Thanks for your concern. Just a few minor injuries reported
on the island so far.
Ive just posed my data for the main shock and the main aftershock.
Both are hopelessly clipped to give an accurate WQ magnitude.
There have been rock slides here and there on the island along with
some homes and structures being damaged. There has been a state-wide
power outage, incl Honolulu. Our power just came back on about an hour
ago so things are starting to get back to normal. We had lots of breakage
mostly in the kitchen from dishes, glasses etc being thrown from the
cabinets. My 19" tv was thrown from the shelf and smashed.
It was truly frightning I must say. It felt like a 7. or better from here,
only 9 miles away. It was hard to stand. Most of the energy was in an E-W
direction as things facing that direction were thrown the most.
Anyway, once again, thank you all for your concern.

Aloha
Tony Potenzo
Hawaii Psn

> Hi
>
> I also hope that Tony is ok. According to news there are alot of power
> outrage in Hawaii at the moment becose of the earthquake.
>
> Regards.
> --
> Jón Frímann
> http://www.jonfr.com
> http://www.simnet.is/jonfr500/earthquake/
>
> __________________________________________________________
>
> Public Seismic Network Mailing List (PSN-L)
>
> To leave this list email PSN-L-REQUEST@.............. with
> the body of the message (first line only): unsubscribe
> See http://www.seismicnet.com/maillist.html for more information.
>


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Subject: Re: Digest from 10/14/2006 00:00:34 From: "Randy" rpratt@............. Date: Sun, 15 Oct 2006 20:47:43 -0500 Thanks Bob, It looks like you have proven the feasability of running multichannels from one AD in 2 or more windows. Couldn't the same logic go into Amaseis quite easily? Now I need some things to plug into more channels. Randy ----- Original Message ----- From: To: Sent: Sunday, October 15, 2006 2:01 AM Subject: Digest from 10/14/2006 00:00:34 > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 1 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: Station Upgrde > From: "Randy" > Date: Sat, 14 Oct 2006 08:41:11 -0500 > > This is a multi-part message in MIME format. > > ------=_NextPart_000_0008_01C6EF6C.807B2BA0 > Content-Type: text/plain; > charset="iso-8859-1" > Content-Transfer-Encoding: quoted-printable > > Hi All, > > My lehmen has been inop for for some time after some power supply wires = > shorted together and fried most everything including the computer ps and = > motherboard. I have begun a rebuild with some changes and ideas = > beginning with moving from EMON to Amaseis. I don't see instructions to = > run multiple channels and I was wondering if this is possible? I tried = > opening 2 copies in different directories and windows but the com port = > conflicts. I have converted from the AD I constructed to a Dataq 154. =20 > Randy > ------=_NextPart_000_0008_01C6EF6C.807B2BA0 > Content-Type: text/html; > charset="iso-8859-1" > Content-Transfer-Encoding: quoted-printable > > > > charset=3Diso-8859-1"> > > > > >
Hi All,
>
 
>
My lehmen has been inop for for = > some time=20 > after some power supply wires shorted together and fried most everything = > > including the computer ps and motherboard.  I have begun a = > rebuild=20 > with some changes and ideas beginning with moving from EMON to = > Amaseis.  I=20 > don't see instructions to run multiple channels and I was wondering if = > this is=20 > possible?  I tried opening 2 copies in different directories and = > windows=20 > but the com port conflicts.  I have converted from the AD I = > constructed to=20 > a Dataq 154. 
>
Randy
> > ------=_NextPart_000_0008_01C6EF6C.807B2BA0-- > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 2 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: Re: Intrest in Volcanos ? > From: Kim Barrow > Date: Sat, 14 Oct 2006 08:03:35 -0700 (PDT) > > --0-5202789-1160838215=:91705 > Content-Type: text/plain; charset=iso-8859-1 > Content-Transfer-Encoding: 8bit > > Hi Jon, > > Yes we are. I am the owner and founder of Earthquake Epi-Center located in the San Francisco Bay area (California.) > > I read yours and the other updates everyday on psn. We have a number of scientists on our boards at www.earthquakeepi-center.com > > Please feel free to post your thoughts, questions, comments on our website anytime. We are interested in all sorts of seismic & volcanic news. > > Sincerely Yours, > Kim Barrow > > > Jón Frímann wrote: > Hi > > Is anyone here intrested in volcanos, along with earthquakes ? > > Regards. > -- > Jón Frímann > http://www.jonfr.com > http://www.simnet.is/jonfr500/earthquake/ > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > > --0-5202789-1160838215=:91705 > Content-Type: text/html; charset=iso-8859-1 > Content-Transfer-Encoding: 8bit > >
Hi Jon,
 
Yes we are. I am the owner and founder of Earthquake Epi-Center located in the San Francisco Bay area (California.)
 
I read yours and the other updates everyday on psn. We have a number of scientists on our boards at www.earthquakeepi-center.com
 
Please feel free to post your thoughts, questions, comments on our website anytime. We are interested in all sorts of seismic & volcanic news.
 
>
Sincerely Yours,
Kim Barrow


Jón Frímann <jonfr500@.........> wrote:
Hi

Is anyone here intrested in volcanos, along with earthquakes ?

Regards.
--
Jón Frímann
http://www.jonfr.com
http://www.simnet.is/jonfr500/earthquake/

__________________________________________________________

Pu blic Seismic Network Mailing List (PSN-L)

To leave this list email PSN-L-REQUEST@.............. with
the body of the message (first line only): unsubscribe
See http://www.seismicnet.com/maillist.html for more information.

> --0-5202789-1160838215=:91705-- > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 3 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: RE: Intrest in Volcanos ? > From: "Bob Hancock" > Date: Sat, 14 Oct 2006 08:19:23 -0700 > > Jon - > > Arizona State University (ASU) maintains a Volcano information log where > they send out weekly updates on volcano activity world wide. They also = > have > other postings of interest. > > Here is the link to join the list: > > http://lists.asu.edu/cgi-bin/wa?SUBED1=3Dvolcano&A=3D1 > > Bob Hancock > Three Points, AZ > > -----Original Message----- > From: psn-l-request@.............. [mailto:psn-l-request@............... = > On > Behalf Of J=F3n Fr=EDmann > Sent: Friday, October 13, 2006 21:57 > To: PSN-Postlist > Subject: Intrest in Volcanos ? > > Hi > > Is anyone here intrested in volcanos, along with earthquakes ?=20 > > Regards. > --=20 > J=F3n Fr=EDmann > http://www.jonfr.com > http://www.simnet.is/jonfr500/earthquake/ > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with=20 > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 4 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: Re: Intrest in Volcanos ? > From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= > Date: Sat, 14 Oct 2006 19:25:25 +0000 > > Hi > > It is good to know that I am not alone in haveing intrest in volcanos > here. I regulary record earthquakes from volcanos here in Iceland. But > there are also four volcanos that are less then 100 km away from me and > a dozen volcanos in less then 200 km away from me. Since I got my > geophone there hasn't been a eruption. But I am sure that I won't have > to wait long time until it does. > > I don't know if many of you are close to active volcanos. It would be > intresting to get info on that. > > Regards. > -- > Jón Frímann > http://www.jonfr.com > http://www.simnet.is/jonfr500/earthquake/ > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 5 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: Re: Station Upgrde > From: ChrisAtUpw@....... > Date: Sat, 14 Oct 2006 17:19:16 EDT > > > --part1_c72.25e6ab7.3262ae54_boundary > Content-Type: text/plain; charset="US-ASCII" > Content-Transfer-Encoding: 7bit > > In a message dated 2006/10/14, rpratt@............. writes: > > > I don't see instructions to run multiple channels and I was wondering if > > this is possible? I tried opening 2 copies in different directories and > > windows but the com port conflicts. I have converted from the AD I constructed to > > a Dataq 154. > > Hi Randy, > > Amaseis is single channel only. However, you can run two copies under > Windows, but you would need two ADCs on different ports.... Maybe Alan will > add a multi channel option sometime....? > > Regards, > > Chris Chapman > > --part1_c72.25e6ab7.3262ae54_boundary > Content-Type: text/html; charset="US-ASCII" > Content-Transfer-Encoding: quoted-printable > > In a me= > ssage dated 2006/10/14, rpratt@............. writes:
>
>
: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px"> I don't see instructions to ru= > n multiple channels and I was wondering if this is possible?  I tried o= > pening 2 copies in different directories and windows but the com port confli= > cts.  I have converted from the AD I constructed to a Dataq 154.= > " SIZE=3D3 PTSIZE=3D12 FAMILY=3D"SANSSERIF" FACE=3D"Arial" LANG=3D"0"> KQUOTE>
> #ffffff" SIZE=3D2 PTSIZE=3D10 FAMILY=3D"SANSSERIF" FACE=3D"Arial" LANG=3D"0"= > >
> Hi Randy,
>
>        Amaseis is single channel only. However= > , you can run two copies under Windows, but you would need two ADCs on diffe= > rent ports.... Maybe Alan will add a multi channel option sometime....?
>
>        Regards,
>
>        Chris Chapman > > --part1_c72.25e6ab7.3262ae54_boundary-- > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 6 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: Re: Interest in Volcanos ? > From: Dave Nelson > Date: Sun, 15 Oct 2006 10:58:54 +1000 > > > Hi Jon, > I have a great love of volcanoes, preferably up close and=20 > personal. > the list of volcanoes I have visited around the world, both active and=20 > dormant, > is slowly growing :) not to mention the dozens of extinct ones=20 > specifically visited > for samples and onsite study. > where possible collecting rock/ash samples for study . > > Volcanoes ... location .......... active/dormant ..... yr/s= > =20 > visited > Mt St Helens, Washington State, USA .... active... 1999 / 2006 > Mt Ruapehu, Nth Island, New Zealand ..... active .... 1983 > Mt Tongariro, Nth Island, New Zealand ..... active .... 1983 > Mt Ngarahoe, Nth Island, New Zealand ..... active .... 1983 > Mauna Kea, Hawai'i ........... acitve .... 1999 > Ta'al Volcano, Luzon, Philippines ....... active .... 2000 / 2005 > > some longer term dormant ones but by no means extinct > > Mt Hood, Washington State, USA > Mt Shasta, Oregon State, USA > Mt Taranaki (Egmont), Nth Is, New Zealand, > > and a few photographed from a distance > several others in the Philippines > Lassen Peak', USA > Mt Ranier, USA > > Truely extinct volcanoes ... > > The Dunedin Volcano and the others of the SE coast of the South Is.of= > NZ. > extensive study during my BSc studies > The ones around Flagstaff, Arizona, USA > > Wishlist for visits ..... > > Vanuatu's active volcanoes > other active ones in Philippines > Indonesian volcanoes including Merapi and Anak Krakatoa > Indonesia is paradise for volcano touring :) > and ohhhhh if it wasnt for the hi cost ..... Japan... > 3 main ones there would be Sakura jima. Fuji, and Unzen > > > > > At 04:57 AM 14/10/2006 +0000, you wrote: > >Hi > >Is anyone here intrested in volcanos, along with earthquakes ? > >Regards. > >-- > >J=F3n Fr=EDmann > > > > -- > No virus found in this outgoing message. > Checked by AVG Free Edition. > Version: 7.1.408 / Virus Database: 268.13.4/476 - Release Date: 14/10/2006 > > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 7 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: Re: Interest in Volcanos ? > From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= > Date: Sun, 15 Oct 2006 01:13:23 +0000 > > Hi > > I've been to Hekla volcano here in Iceland. It was intresting and I got > pictures from that trip. I also got few ask rocks from that mountin, > really new one, problay not older then 10 or 20 years old. > > Regards. > -- > Jón Frímann > http://www.jonfr.com > http://www.simnet.is/jonfr500/earthquake/ > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 8 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: Re: Interest in Volcanos ? EDITED ! > From: Dave Nelson > Date: Sun, 15 Oct 2006 11:13:49 +1000 > > > just an edit to correct a couple of serious mistakes in the last posting > > Hi Jon, > I have a great love of volcanoes, preferably up close and=20 > personal. > the list of volcanoes I have visited around the world, both active and=20 > dormant, > is slowly growing :) not to mention the dozens of extinct ones=20 > specifically visited > for samples and onsite study. > where possible collecting rock/ash samples for study . > > Volcanoes ... location .......... ..... yr/s visited > Mt St Helens, Washington State, USA .... active... 1999 / 2006 > Mt Ruapehu, Nth Island, New Zealand ..... active .... 1983 > Mt Tongariro, Nth Island, New Zealand ..... active .... 1983 > Mt Ngarahoe, Nth Island, New Zealand ..... active .... 1983 > Kilauea Volcano, Hawai'i ........... active .... 1999 > Ta'al Volcano, Luzon, Philippines ....... active .... 2000 / 2005 > > some longer term dormant ones but by no means extinct > Mauna Kea, Hawai'i > Mauna Loa, Hawai'i > Mt Hood, Washington State, USA > Mt Shasta, California State, USA > Mt Taranaki (Egmont), Nth Is, New Zealand, > > and a few photographed from a distance > several others in the Philippines > Lassen Peak', USA > Mt Ranier, USA > > Truely extinct volcanoes ... > > The Dunedin Volcano and the others of the SE coast of the South Is.of= > NZ. > extensive study during my BSc studies > The ones around Flagstaff, Arizona, USA > > Wishlist for visits ..... > > Vanuatu's active volcanoes > other active ones in Philippines > Indonesian volcanoes including Merapi and Anak Krakatoa > Indonesia is paradise for volcano touring :) > and ohhhhh if it wasnt for the hi cost ..... Japan... > 3 main ones there would be Sakura jima. Fuji, and Unzen > > > > Lifetime highlight ..... "playing" in the lava flows from Kilauea in 1999 > scooping up 800 -1000 deg lava in soup ladels and other impliments > > Thanks to Tony, from the Big Island ... also a member of the PSN > > cheers > Dave Nelson > Sydney > > > At 04:57 AM 14/10/2006 +0000, you wrote: > >Hi > >Is anyone here intrested in volcanos, along with earthquakes ? > >Regards. > >-- > >J=F3n Fr=EDmann > > > > -- > No virus found in this outgoing message. > Checked by AVG Free Edition. > Version: 7.1.408 / Virus Database: 268.13.4/476 - Release Date: 14/10/2006 > > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 9 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: Re: Station Upgrade > From: Bobhelenmcclure@....... > Date: Sat, 14 Oct 2006 21:29:03 EDT > > > -------------------------------1160875743 > Content-Type: text/plain; charset="US-ASCII" > Content-Transfer-Encoding: 7bit > > On Sat, 14 Oct 2006 08:41:11 -0500, "Randy" writes, > My lehmen has been inop for for some time after some power supply wires > shorted together and fried most everything including the computer ps and > motherboard. I have begun a rebuild with some changes and ideas > beginning with moving from EMON to Amaseis. I don't see instructions to > run multiple channels and I was wondering if this is possible? I tried > opening 2 copies in different directories and windows but the com port > conflicts. I have converted from the AD I constructed to a Dataq 154. > > Hi Randy, > > If you are using a Dataq device, you can log, filter, and heliplot display > up to > four channels, using my suite of software. You can also convert the WDQ > files to Winquake PSN Type 4 files. > > See _http://www.jclahr.com/science/psn/mcclure/_ > (http://www.jclahr.com/science/psn/mcclure/) and download "seismic_dataq.zip" > > Cheers, > > Bob > > -------------------------------1160875743 > Content-Type: text/html; charset="US-ASCII" > Content-Transfer-Encoding: quoted-printable > > > > > > Arial"=20 > bottomMargin=3D7 leftMargin=3D7 topMargin=3D7 rightMargin=3D7> e_document=20 > face=3DArial color=3D#000000 size=3D2> >
On Sat, 14 Oct 2006 08:41:11 -0500, "Randy" writes,
My lehmen has be= > en=20 > inop for for some time after some power supply wires
shorted together an= > d=20 > fried most everything including the computer ps and
motherboard.  I= > =20 > have begun a rebuild with some changes and ideas
beginning with moving f= > rom=20 > EMON to Amaseis.  I don't see instructions to
run multiple channels= > and=20 > I was wondering if this is possible?  I tried
opening 2 copies in=20 > different directories and windows but the com port
conflicts.  I ha= > ve=20 > converted from the AD I constructed to a Dataq 154.
>
 
>
Hi Randy,
>
 
>
  If you are using a Dataq device, you can log, filter, and helipl= > ot=20 > display up to
four channels, using my suite of software. You can also con= > vert=20 > the WDQ
files to Winquake PSN Type 4 files.
>
 
>
  See href=3D"http://www.jclahr.com/science/psn/mcclure/">http://www.jclahr.com/sc = > ience/psn/mcclure/=20 > and download "seismic_dataq.zip"
>
 
>
Cheers,
>
 
>
Bob
> > -------------------------------1160875743-- > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-DIGEST-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Large earthquake at hawaii island From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Mon, 16 Oct 2006 02:06:46 +0000 Hi It is good to hear that you are ok Tony and your family. The damage can be repared. What is worring for me is when I am looking at the aftershock pattern, it appears to be slow and few smaller aftershocks that I was expecting. I find that rater strange, The earthquake that did follow straigt after the main quake is something that I have seen before, but the same thing did happen in Iceland, when a Ms 6.5 earthquake did hit SIZS (south Iceland) in Iceland. I am still exspecting at least one mag 5.5 aftershock, based on the ideas I have on how this large type of earthquakes changes the crust around the epicenter. I am also bit intrested if there has been any changes in volcano activite, since this earthquake is large enugh to change volcano activite. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Station Upgrde From: John or Jan Lahr JohnJan@........ Date: Sun, 15 Oct 2006 21:34:27 -0700 At 06:41 AM 10/14/2006, you wrote: >Hi All, > >My lehmen has been inop for for some time after some power supply >wires shorted together and fried most everything including the >computer ps and motherboard. I have begun a rebuild with some >changes and ideas beginning with moving from EMON to Amaseis. I >don't see instructions to run multiple channels and I was wondering >if this is possible? I tried opening 2 copies in different >directories and windows but the com port conflicts. I have >converted from the AD I constructed to a Dataq 154. >Randy Hi Randy, I think you should be able to run two copies of AmaSeis, each out of its own directory, and each looking at a different com port. Is that what you tried to do? John Lahr __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Large earthquake at hawaii island From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Mon, 16 Oct 2006 18:54:35 +0000 Hi I saw today that USGS has upgraded the size of this earthquake to Mw6.7. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: What happened at 17:40 to 17:50 UT on Oct 15th? From: George Bush ke6pxp@....... Date: Mon, 16 Oct 2006 12:59:36 -0700 Hello- I was wondering if anyone else detected a strong signal in the background to the M6.7 Hawaii Is. quake? It is visible on the N-S and E-W signals, and is strongest on my vertical detector, but the frequency is higher and different than the event at 17:07:48??? You can go to the PSN web and see my signal at 061015.170749.srz \quakes\0610\061015.170019.srz.psn. I was not able to find any event in the above time frame that could have caused this (the M5.4 at 17:14 happened too soon to be what I saw)??? It could have been something local, but it was much stronger than any normal road traffic noise I detect from a nearby road. I would appreciate any ideas or thoughts as to what I detected. George Bush Sea Ranch, CA, USA 38.73775N, 123.48882W __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: What happened at 17:40 to 17:50 UT on Oct 15th? From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Mon, 16 Oct 2006 20:07:02 +0000 Hi I did take a look at the signal. It appears to be local noise, on E-W and N-S it wanish when I lowpassfilter the signal to 1Hz, on Z the signal shows when I lowpass it to 1Hz. But it cuts into the surfise waves that you are recording. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: What happened at 17:40 to 17:50 UT on Oct 15th? From: George Bush ke6pxp@....... Date: Mon, 16 Oct 2006 13:33:38 -0700 Thank you J=F3n,=20 You are probably right, but I was hoping it was a nearby quake. At 08:07 PM 10/16/2006 +0000, you wrote: >Hi > >I did take a look at the signal. It appears to be local noise, on E-W >and N-S it wanish when I lowpassfilter the signal to 1Hz, on Z the >signal shows when I lowpass it to 1Hz. But it cuts into the surfise >waves that you are recording. > >Regards. >--=20 >J=F3n Fr=EDmann >http://www.jonfr.com >http://www.simnet.is/jonfr500/earthquake/ > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with=20 >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > George __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Large earthquake at hawaii island From: peaches@............ Date: Mon, 16 Oct 2006 16:16:12 -1000 (HST) Hi Jon To answer your question about the volcano, the HVO reports are saying that there is no change in eruptive activity so far. However large quakes have been known to alter the "plumbing" and change eruptive patterns. We are pretty much back to normal here. Also, no appreciable aftershocks today so far. We did have a couple tiny ones in the wee morning hours tho. Anyway, check out http://hvo.wr.usgs.gov/kilauea/update/main.html for the latest updates and deformation charts of our volcanoes. Im just finishing recording the surface waves from the New Britian event. Will be posting it soon. Thanks for writing and take care. Aloha Tony > Hi > > It is good to hear that you are ok Tony and your family. The damage can > be repared. What is worring for me is when I am looking at the > aftershock pattern, it appears to be slow and few smaller aftershocks > that I was expecting. I find that rater strange, The earthquake that did > follow straigt after the main quake is something that I have seen > before, but the same thing did happen in Iceland, when a Ms 6.5 > earthquake did hit SIZS (south Iceland) in Iceland. I am still > exspecting at least one mag 5.5 aftershock, based on the ideas I have on > how this large type of earthquakes changes the crust around the > epicenter. > > I am also bit intrested if there has been any changes in volcano > activite, since this earthquake is large enugh to change volcano > activite. > > Regards. > -- > Jón Frímann > http://www.jonfr.com > http://www.simnet.is/jonfr500/earthquake/ > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Unusual signal on Northern Cal. Seismometers From: kpayea@........... Date: Mon, 16 Oct 2006 20:04:16 -0700 Hello All, especially those of you in Northern California. The alarm went off on my system a few minutes ago, and the signal on the screen was very unusual. It was a decent sized sine wave, about 20 second period. I thought it might be local, caused by heavy construction on 101 nearby, but most of the Berkeley network instruments at http://www.ncedc.org/bdsn/quicklook.html show the same thing. To my eye, this doesn't look like a normal EQ signal. Or is it just me? The signal is still ringing down, after a good 25 minutes. What do you all think? Cheers, Keith Keith Payea Bryant Labs kpayea@.............. www.bryantlabs.net (707) 566-8935
Hello = All,=20 especially those of you in Northern California.  The alarm went off = on my=20 system a few minutes ago, and the signal on the screen was very = unusual. =20 It was a decent sized sine wave, about 20 second period.  I thought = it=20 might be local, caused by heavy construction on 101 nearby, but most of = the=20 Berkeley network instruments at http://www.nce= dc.org/bdsn/quicklook.html =20 show the same thing.  To my eye, this doesn't look like a normal EQ = signal.  Or is it just me?
 
The = signal is still=20 ringing down, after a good 25 minutes.
 
What = do you all=20 think?
 
Cheers,
 
 
    Keith
 
Keith=20 Payea
Bryant Labs
kpayea@..............
www.bryantlabs.net
(707)=20 566-8935
 
Subject: Re: Unusual signal on Northern Cal. Seismometers From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Tue, 17 Oct 2006 03:09:36 +0000 Hi Based on raw data from emsc-csem, there appears to have been earthquake near cost of Japan. There was a mag 6.6 near New Britain earliar this night. See here, http://www.emsc-csem.org/index.php?page=current&sub=detail&id=35211 Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Unusual signal on Northern Cal. Seismometers From: Stephen & Kathy skmort@............ Date: Mon, 16 Oct 2006 20:22:44 -0700 FYI,, your seeing the surface waves from the New Britain quake! On my system, east of Sacramento, they are approx. 18 seconds,,, my system started recording the surface waves at approx. 02:08:22 UTC = 19:08:22 PDT ! Stephen PSN Station #55 kpayea@........... wrote: > Hello All, especially those of you in Northern California. The alarm > went off on my system a few minutes ago, and the signal on the screen > was very unusual. It was a decent sized sine wave, about 20 second > period. I thought it might be local, caused by heavy construction on > 101 nearby, but most of the Berkeley network instruments at > http://www.ncedc.org/bdsn/quicklook.html > show the same > thing. To my eye, this doesn't look like a normal EQ signal. Or is > it just me? > > The signal is still ringing down, after a good 25 minutes. > > What do you all think? > > Cheers, > > > /Keith/ > > Keith Payea > Bryant Labs > kpayea@.............. > www.bryantlabs.net > (707) 566-8935 > FYI,,   your seeing the surface waves from the New Britain quake!
On my system, east of Sacramento, they are approx. 18 seconds,,,  my system started recording the surface waves at approx. 02:08:22 UTC = 19:08:22 PDT !
  Stephen
  PSN Station #55

kpayea@........... wrote:
Hello All, especially those of you in Northern California.  The alarm went off on my system a few minutes ago, and the signal on the screen was very unusual.  It was a decent sized sine wave, about 20 second period.  I thought it might be local, caused by heavy construction on 101 nearby, but most of the Berkeley network instruments at http://www.ncedc.org/bdsn/quicklook.html  show the same thing.  To my eye, this doesn't look like a normal EQ signal.  Or is it just me?
 
The signal is still ringing down, after a good 25 minutes.
 
What do you all think?
 
Cheers,
 
 
    Keith
 
Keith Payea
Bryant Labs
(707) 566-8935
 
Subject: Re: Unusual signal on Northern Cal. Seismometers From: Pete Rowe ptrowe@......... Date: Mon, 16 Oct 2006 20:39:27 -0700 (PDT) I recorded the signal here in San Jose but my alarm didn't go off. I don't think I have the trigger paramenters set correctly. Any suggestions for setting the trigger level? Pete --- Stephen & Kathy wrote: > FYI,, your seeing the surface waves from the New > Britain quake! > On my system, east of Sacramento, they are approx. > 18 seconds,,, my > system started recording the surface waves at > approx. 02:08:22 UTC = > 19:08:22 PDT ! > Stephen > PSN Station #55 > > kpayea@........... wrote: > > Hello All, especially those of you in Northern > California. The alarm > > went off on my system a few minutes ago, and the > signal on the screen > > was very unusual. It was a decent sized sine > wave, about 20 second > > period. I thought it might be local, caused by > heavy construction on > > 101 nearby, but most of the Berkeley network > instruments at > > http://www.ncedc.org/bdsn/quicklook.html > > > > show the same > > thing. To my eye, this doesn't look like a normal > EQ signal. Or is > > it just me? > > > > The signal is still ringing down, after a good 25 > minutes. > > > > What do you all think? > > > > Cheers, > > > > > > /Keith/ > > > > Keith Payea > > Bryant Labs > > kpayea@.............. > > > www.bryantlabs.net > > (707) 566-8935 > > > __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Long period sensor plan From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Tue, 17 Oct 2006 03:45:41 +0000 Hi Here is my first long period sensor plan. This sensor is simple and I hope that this idea is workable. Here is a raw drawing of the sensor, this is just a draft. The picture is quite large. http://www.simnet.is/jonfr500/sensor/long.period.sensor.v1.0.jpg Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Unusual signal on Northern Cal. Seismometers From: Stephen & Kathy skmort@............ Date: Mon, 16 Oct 2006 21:05:52 -0700 If you have a software alarm, others will have to help,,, I have a hardware alarm which monitors the input to the A/D and is adjusted right at the largest of the storm wave energy we get along the N. Cal coast! Stephen PSN Station #55 Pete Rowe wrote: > I recorded the signal here in San Jose but my alarm > didn't go off. I don't think I have the trigger > paramenters set correctly. Any suggestions for setting > the trigger level? > Pete > > --- Stephen & Kathy wrote: > > >> FYI,, your seeing the surface waves from the New >> Britain quake! >> On my system, east of Sacramento, they are approx. >> 18 seconds,,, my >> system started recording the surface waves at >> approx. 02:08:22 UTC = >> 19:08:22 PDT ! >> Stephen >> PSN Station #55 >> >> kpayea@........... wrote: >> >>> Hello All, especially those of you in Northern >>> >> California. The alarm >> >>> went off on my system a few minutes ago, and the >>> >> signal on the screen >> >>> was very unusual. It was a decent sized sine >>> >> wave, about 20 second >> >>> period. I thought it might be local, caused by >>> >> heavy construction on >> >>> 101 nearby, but most of the Berkeley network >>> >> instruments at >> >>> http://www.ncedc.org/bdsn/quicklook.html >>> >>> >> >> show the same >> >>> thing. To my eye, this doesn't look like a normal >>> >> EQ signal. Or is >> >>> it just me? >>> >>> The signal is still ringing down, after a good 25 >>> >> minutes. >> >>> >>> What do you all think? >>> >>> Cheers, >>> >>> >>> /Keith/ >>> >>> Keith Payea >>> Bryant Labs >>> kpayea@.............. >>> >> >> >>> www.bryantlabs.net >>> (707) 566-8935 >>> >>> > > > __________________________________________________ > Do You Yahoo!? > Tired of spam? Yahoo! Mail has the best spam protection around > http://mail.yahoo.com > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > > If you have a software alarm, others will have to help,,,   I have a hardware alarm which monitors the input to the A/D and is adjusted right at the largest of the storm wave energy we get along the N. Cal coast!
  Stephen
  PSN Station #55

Pete Rowe wrote: 
I recorded the signal here in San Jose but my alarm
didn't go off. I don't think I have the trigger
paramenters set correctly. Any suggestions for setting
the trigger level?
Pete

--- Stephen & Kathy <skmort@............> wrote:

  
FYI,,   your seeing the surface waves from the New
Britain quake!
On my system, east of Sacramento, they are approx.
18 seconds,,,  my 
system started recording the surface waves at
approx. 02:08:22 UTC = 
19:08:22 PDT !
  Stephen
  PSN Station #55

kpayea@........... wrote:
    
Hello All, especially those of you in Northern
      
California.  The alarm 
    
went off on my system a few minutes ago, and the
      
signal on the screen 
    
was very unusual.  It was a decent sized sine
      
wave, about 20 second 
    
period.  I thought it might be local, caused by
      
heavy construction on 
    
101 nearby, but most of the Berkeley network
      
instruments at 
    
http://www.ncedc.org/bdsn/quicklook.html 

      
<BLOCKED::http://www.ncedc.org/bdsn/quicklook.html> 
show the same 
    
thing.  To my eye, this doesn't look like a normal
      
EQ signal.  Or is 
    
it just me?
 
The signal is still ringing down, after a good 25
      
minutes.
    
 
What do you all think?
 
Cheers,
 
 
    /Keith/
 
Keith Payea
Bryant Labs
kpayea@..............
      
<mailto:kpayea@..............>
    
www.bryantlabs.net <http://www.bryantlabs.net/>
(707) 566-8935
 
      


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Subject: Questions From: "tchannel" tchannel@.............. Date: Tue, 17 Oct 2006 12:30:51 -0600 I have finished my sensor, and have had it running for three days. 1. During the night hours, 11pm to 6am, the tract goes from normal to = noisy, getting worse each hour. The sensor sits in the garage on a = concrete slab. No draft and no heat. As soon as I go into the garage = in the AM and the room gets warmer, because the sun warms the room to = about 60 f. The trace returns to normal. Is this temperature effect? I = also turn off the monitor and turn it back on in the AM. Could the CTR = or the computer create noise? They set about three feet from the sensor. = Again no heat, no draft and nothing running out there in the night. 2. I think I am getting a good recording, I have see the last two = quakes and to me they look normal. I am in Boise Idaho and have tried to compare my .PSN with any others = close by. However our local one in Boise is down and the next, nearest = one is in Washington State. Now here is a hard question to ask: I = created my expanded trace, using the same time plotted on the .PSN in = Washington (061017.013725.ebgz.psn M6.5 10356km from Ellensburg, Wa.,) = This was around one hour of trace. I did this so I could compare the = two side by side. I was a little surprised to see the Wa. psn to show a = large spike on the P and a short spike on the S. My trace looks very = similar, but I show a large spike on the S and a smaller spike on the P. = From the description of the Ellensburg Wa file it has a Z in it, is = that a Vertical sensor? and since my sensor is a Horz pointing N/S, = would that explain the different. These events came from the East, and I = have my beam pointing North. Anyone who would like me to send both .PSN's to them for a critique, = please email me. I would appreciate someone looking at them and = voicing an opinion as to my level of gain, not sure if it is correct, = and some advise as to how to best filter this event to enhance the P and = S. I am just using trial and error. 3. Presently I am building a Plexiglas box. But would it help to = reduce noise if I built a second box wrapped with alum foil? Or other = ideas on building a box which would make a positive different? 4. I know weather can alter the way the trace looks, I thought my = situation was weather, but it was clear today. What is there in a front moving thru that creates the noise? Lets say = a front with little wind and no lightening. Many thanks, Ted
I have finished my sensor, and have had = it running=20 for three days.
 
1.  During the night hours, 11pm = to 6am, the=20 tract goes from normal to noisy, getting worse each hour.  The = sensor sits=20 in the garage on a concrete slab.  No draft and no heat.  As = soon as I=20 go into the garage in the AM and the room gets warmer, because the = sun=20 warms the room to about 60 f. The trace returns to normal.  Is this = temperature effect?  I also turn off the monitor and turn it back = on in the=20 AM.  Could the CTR or the computer create noise? They set about = three feet=20 from the sensor. Again no heat, no draft and nothing running out there = in the=20 night.
 
2.   I think I am getting a = good=20 recording, I have see the last two quakes and to me they look=20 normal.
I am in Boise Idaho and have tried to = compare my=20 ..PSN with any others close by.  However our local one in Boise is = down and=20 the next, nearest one is in Washington State.   Now here is a = hard=20 question to ask:  I created my expanded trace, using the same time = plotted=20 on the .PSN in Washington (061017.013725.ebgz.psn M6.5 10356km from Ellensburg, Wa.,) = This was=20 around one hour of trace.  I did this so I could compare the two = side by=20 side.  I was a little surprised to see the Wa. psn to show a large = spike on=20 the P and a short spike on the S.  My trace looks very similar, but = I show=20 a large spike on the S and a smaller spike on the P.   From = the=20 description of the Ellensburg Wa file it has a Z in it, is that a = Vertical=20 sensor? and since my sensor is a Horz pointing N/S, would that explain = the=20 different. These events came from the East, and I have my beam pointing=20 North.
Anyone who would like me to send both .PSN's to them for a = critique, please=20 email me.   I would appreciate someone looking at them and = voicing an=20 opinion as to my level of gain, not sure if it is correct, and some = advise as to=20 how to best filter this event to enhance the P and S. I am just using = trial and=20 error.
 
3.  Presently I am building a = Plexiglas=20 box.  But would it help to reduce noise if I built a second box = wrapped=20 with alum foil?   Or other ideas on building a box which would = make a=20 positive different?
 
4.   I know weather can alter = the way the=20 trace looks, I thought my situation was weather, but it was clear=20 today.
What is there in a front moving thru = that creates=20 the noise?   Lets say a front with little wind and no=20 lightening.
 
Many thanks, = Ted
Subject: Re: Questions From: John Popelish jpopelish@........ Date: Tue, 17 Oct 2006 17:17:41 -0400 tchannel wrote: (snip) > 3. Presently I am building a Plexiglas box. > But would it help to reduce noise if I built > a second box wrapped with alum foil? > Or other ideas on building a box which would make a positive different? Though it is nice to look through a Plexiglass box, it is not a very good thermal performer. you can buy a 4 by 8 foot sheet of foam insulation form any builder's supply, including possibly one that has a foil surface. This can be cut into rectangles and fit together into a very light weight and thermally insulating box for a fraction of the cost of a Plexiglass one. Add a night light or other small heat source to the top, inside, to stratify the temperature inside the box, to suppress convection currents at night, when the floor is warmer than the air. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Questions From: ChrisAtUpw@....... Date: Tue, 17 Oct 2006 17:28:20 EDT In a message dated 2006/10/17, tchannel@.............. writes: > I have finished my sensor, and have had it running for three days. Hi Ted, Sorry, but you haven't finished your sensor until you have evaluated and proved it!! > 1. During the night hours, 11pm to 6am, the tract goes from normal to > noisy, getting worse each hour. The sensor sits in the garage on a concrete slab. > No draft and no heat. This is the evening cooling problem due to air convection. You need to house the seismometer in a thermally insulated case and place a heater giving about 10 Watts inside the top. I use two Al cased power resistors bolted to a sheet of Al. This maintains a positive vertical internal temperature gradient at all times and suppresses convection. Make the enclosure out of 2" Celotex. This has fibre glass skins and Al foil top coats. Tape the joins with 3" gaffer tape and glue the joints with foam grouting. You can make double windows with either photocopy film or cellulose sheet. See http://pages.prodigy.net/fxc/seiscoverslg.jpg More work, but 100% essential! > 2. I think I am getting a good recording, I have see the last two quakes > and to me they look normal. > I am in Boise Idaho and have tried to compare my .PSN with any others close > by. However our local one in Boise is down and the next, nearest one is in > Washington State. Now here is a hard question to ask: I created my expanded > trace, using the same time plotted on the .PSN in Washington ( > 061017.013725.ebgz.psn M6.5 10356km from Ellensburg, Wa.,) This was around one hour of trace. > I did this so I could compare the two side by side. I was a little > surprised to see the Wa. psn to show a large spike on the P and a short spike on the > S. My trace looks very similar, but I show a large spike on the S and a > smaller spike on the P. From the description of the Ellensburg Wa file it has a > Z in it, is that a Vertical sensor? and since my sensor is a Horz pointing > N/S, would that explain the different. Z signifies a vertical sensor. The two other designations are E east and N north, both true, not magnetic. The P and Rayleigh waves are predominantly vertical, so a Lehman, which is a horizontal sensor, will have a low sensitivity to them. The S and Love waves are horizontal and you should see relatively large signals. The amplitude of the signals also depends both on the type and on the angular range. > I would appreciate someone looking at them and voicing an opinion as to my > level of gain, not sure if it is correct, and some advise as to how to best > filter this event to enhance the P and S. I suggest that you set the lowpass filter at 2 Hz and the highpass filter at 0.4 Hz, both at least 4 pole. > 3. Presently I am building a Plexiglas box. See my previous EMail and the advice above. You need a thermally insulated enclosure with sealed joints and a top heater, probably not a perspex box. > 4. I know weather can alter the way the trace looks, I thought my situation > was weather, but it was clear today. > What is there in a front moving thru that creates the noise? Lets say a > front with little wind and no lightning. Cold fronts tend to give more seismic noise that warm fronts. All fronts have wind and turbulence / pressure variations associated with them, at altitude, if not so much at ground level. Broad band wind noise is a common seismic problem. Regards, Chris Chapman In a message dated 2006/10/17, tcha= nnel@.............. writes:

I have finished my sensor, and=20= have had it running for three days.


Hi Ted,

       Sorry, but you haven't finished your se= nsor until you have evaluated and proved it!!

1.  During the night hour= s, 11pm to 6am, the tract goes from normal to noisy, getting worse each hour= .. The sensor sits in the garage on a concrete slab. No draft and no heat.&nb= sp;


       This is the evening cooling problem du= e to air convection. You need to house the seismometer in a thermally insula= ted case and place a heater giving about 10 Watts inside the top. I use two=20= Al cased power resistors bolted to a sheet of Al. This maintains a positive=20= vertical internal temperature gradient at all times and suppresses convectio= n. Make the enclosure out of 2" Celotex. This has fibre glass skins and Al f= oil top coats. Tape the joins with 3" gaffer tape and glue the joints with f= oam grouting. You can make double windows with either photocopy film or cell= ulose sheet. See http://pages.prodigy.net/fxc/seiscoverslg.jpg More work, bu= t 100% essential!

2.   I think I am get= ting a good recording, I have see the last two quakes and to me they look no= rmal.
I am in Boise Idaho and have tried to compare my .PSN with any others close= by.  However our local one in Boise is down and the next, nearest one=20= is in Washington State.  Now here is a hard question to ask: I created=20= my expanded trace, using the same time plotted on the .PSN in Washington (061017.013725.ebgz.psn M6.5 10356km from Ellensburg, Wa.,) This was=20= around one hour of trace.  I did this so I could compare the two side b= y side.  I was a little surprised to see the Wa. psn to show a large sp= ike on the P and a short spike on the S.  My trace looks very similar,=20= but I show a large spike on the S and a smaller spike on the P. From the des= cription of the Ellensburg Wa file it has a Z in it, is that a Vertical sens= or? and since my sensor is a Horz pointing N/S, would that explain the diffe= rent.


       Z signifies a vertical sensor. The two= other designations are E east and N north, both true, not magnetic. The P a= nd Rayleigh waves are predominantly vertical, so a Lehman, which is a horizo= ntal sensor, will have a low sensitivity to them. The S and Love waves are h= orizontal and you should see relatively large signals. The amplitude of the=20= signals also depends both on the type and on the angular range.
  
I would appreciate some= one looking at them and voicing an opinion as to my level of gain, not sure=20= if it is correct, and some advise as to how to best filter this event to enh= ance the P and S.


       I suggest that you set the lowpass fil= ter at 2 Hz and the highpass filter at 0.4 Hz, both at least 4 pole.<= FONT COLOR=3D"#000000" BACK=3D"#ffffff" style=3D"BACKGROUND-COLOR: #ffffff"= SIZE=3D3 PTSIZE=3D12 FAMILY=3D"SERIF" FACE=3D"Times New Roman" LANG=3D"0"><= BR>
3.  Presently I am buildi= ng a Plexiglas box.


       See my previous EMail and the advice a= bove. You need a thermally insulated enclosure with sealed joints and a top=20= heater, probably not a perspex box.

4. I know weather can alter the= way the trace looks, I thought my situation was weather, but it was clear t= oday.
What is there in a front moving thru that creates the noise?  Lets say= a front with little wind and no lightning.


       Cold fronts tend to give more seismic n= oise that warm fronts. All fronts have wind and turbulence / pressure variat= ions associated with them, at altitude, if not so much at ground level. Broa= d band wind noise is a common seismic problem.

       Regards,

       Chris Chapman Subject: Re: Long period sensor plan From: ChrisAtUpw@....... Date: Tue, 17 Oct 2006 20:48:16 EDT In a message dated 2006/10/17, jonfr500@......... writes: > Here is my first long period sensor plan. This sensor is simple and I > hope that this idea is workable. Here is a raw drawing of the sensor, > this is just a draft. The picture is quite large. > http://www.simnet.is/jonfr500/sensor/long.period.sensor.v1.0.jpg Hi Jon, I'm sorry, but I don't understand your drawing. What are the component parts and how is it supposed to work? Regards, Chris Chapman In a me= ssage dated 2006/10/17, jonfr500@......... writes:

Here is my first long period se= nsor plan. This sensor is simple and I
hope that this idea is workable. Here is a raw drawing of the sensor,
this is just a draft. The picture is quite large.
http://www.simnet.is/jonfr500/sensor/long.period.sensor.v1.0.jpg

Hi Jon,

       I'm sorry, but I don't understand your=20= drawing. What are the component parts and how is it supposed to work?

       Regards,

       Chris Chapman Subject: Re: Long period sensor plan From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Wed, 18 Oct 2006 01:53:10 +0000 Hi This is just a first draw of the sensor. The basic idea comes from the lehman type of seismometer. I have already moved the dapming to the front of the coil and the magnets. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Questions From: "Geoffrey" gmvoeth@........... Date: Wed, 18 Oct 2006 04:52:24 -0700 Hello Ted; The file 061017.013725.ebgz.psn is way too noisy. The gain should be reduced to the point where noise is only +/- a few counts. This signal reminds me of the Hawaii quake I received but instead of getting any S wave I just got two "P" waves (Main event/aftershock) and what seemed to be followed by surface waves. note: I have found that Winquake does not want me to start my converted files on a decimal point I must start my files on an exact second start point to get correct times. If I start my files in the middle of a second it will offset all the measured times with an error by the decimal amount. Winquake seems to ignore fractional values smaller than the whole second at the start of a data set. Dont know if I am clear here. Regards; geoff ----- Original Message ----- From: "tchannel" To: Sent: Tuesday, October 17, 2006 11:30 AM Subject: Questions I have finished my sensor, and have had it running for three days. 1. During the night hours, 11pm to 6am, the tract goes from normal to noisy, getting worse each hour. The sensor sits in the garage on a concrete slab. No draft and no heat. As soon as I go into the garage in the AM and the room gets warmer, because the sun warms the room to about 60 f. The trace returns to normal. Is this temperature effect? I also turn off the monitor and turn it back on in the AM. Could the CTR or the computer create noise? They set about three feet from the sensor. Again no heat, no draft and nothing running out there in the night. 2. I think I am getting a good recording, I have see the last two quakes and to me they look normal. I am in Boise Idaho and have tried to compare my .PSN with any others close by. However our local one in Boise is down and the next, nearest one is in Washington State. Now here is a hard question to ask: I created my expanded trace, using the same time plotted on the .PSN in Washington (061017.013725.ebgz.psn M6.5 10356km from Ellensburg, Wa.,) This was around one hour of trace. I did this so I could compare the two side by side. I was a little surprised to see the Wa. psn to show a large spike on the P and a short spike on the S. My trace looks very similar, but I show a large spike on the S and a smaller spike on the P. From the description of the Ellensburg Wa file it has a Z in it, is that a Vertical sensor? and since my sensor is a Horz pointing N/S, would that explain the different. These events came from the East, and I have my beam pointing North. Anyone who would like me to send both .PSN's to them for a critique, please email me. I would appreciate someone looking at them and voicing an opinion as to my level of gain, not sure if it is correct, and some advise as to how to best filter this event to enhance the P and S. I am just using trial and error. 3. Presently I am building a Plexiglas box. But would it help to reduce noise if I built a second box wrapped with alum foil? Or other ideas on building a box which would make a positive different? 4. I know weather can alter the way the trace looks, I thought my situation was weather, but it was clear today. What is there in a front moving thru that creates the noise? Lets say a front with little wind and no lightening. Many thanks, Ted __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Questions From: ChrisAtUpw@....... Date: Wed, 18 Oct 2006 09:41:45 EDT In a message dated 2006/10/18, gmvoeth@........... writes: > Hello Ted; > The file 061017.013725.ebgz.psn is way too noisy. The gain should be reduced > to the point where noise is only +/- a few counts. > > This signal reminds me of the Hawaii quake I received but instead of getting > any S wave I just got two "P" waves (Main event/aftershock) and what seemed > to be followed by surface waves. Hi Geoff, Ted, This advice is not correct. Ted has a Lehman which senses the microseismic background of 0.5 to 15 microns amplitude as well as quake signals. Ted will want to sense longer period quakes which are a small fraction of this amplitude and to filter them out, so he needs the background to be at least 100 counts. Regards, Chris Chapman In a me= ssage dated 2006/10/18, gmvoeth@........... writes:

Hello Ted;
The file 061017.013725.ebgz.psn is way too noisy. The gain should be reduced=
to the point where noise is only +/- a few counts.

This signal reminds me of the Hawaii quake I received but instead of getting= any S wave I just got two "P" waves (Main event/aftershock) and what seemed=
to be followed by surface waves.


Hi Geoff, Ted,

       This advice is not correct. Ted has a L= ehman which senses the microseismic background of 0.5 to 15 microns amplitud= e as well as quake signals. Ted will want to sense longer period quakes whic= h are a small fraction of this amplitude and to filter them out, so he needs= the background to be at least 100 counts. 

       Regards,

       Chris Chapman Subject: Re: Questions From: "tchannel" tchannel@.............. Date: Wed, 18 Oct 2006 09:15:58 -0600 Hi Folks, For those who are new to these subjects, here is my case = study on a specific problem, and the group's advise which fixed it. = With my new station setup and running, the trace would get progressively = noisier, starting at 11:00pm until 8:00am. This noise was huge, the trace started out, looking like a pencil line = and then,would progress to something like the teeth of a saw, so large = it would almost touch the line above and below. As the room went back to = day time temp, so did the trace quite down. The garage, where it sat, has no heat and no drafts. The temp in the = garage, at night, would get to 40-50 and during the day 60's. Because I had not finished my cover/box the sensor sat on the floor open = to the air. I was advised to build a box which would protect the sensor = from air currents and thermos. So last night, temporarily, I covered = the sensor using two sawhorses and two blankets. The trace remained = perfectly still all night As a newcomer to these issues, I had no idea the importance of these = enclosures. I noticed if I waved my hand or made any movements, which = created air movement I would see a spike. I did not realize that = invisible air currents in the room, caused by the different in floor vs. = air temperature, would cause huge noise. Thanks for the guidance. Q 1. I understand that some people orient their sensor N/S others E/W, = Are the sensors ever oriented at a 45 degree angle between the two? Q 2. What are the expectations of a Lehman sensor? I know that depends = on many factors, and not the lease of which is the quality of the = sensor, and its environment, as well as the type and location of the = events. But just in general terms. The AS1, which is not a Lehman = suggest one should be able to see 6.0m from several thousand mile away, = or something like that. The reason I ask, I do hear statements, both over and under my = expectations. Time will tell, but I wanted your opinions. Cheers, Ted ----- Original Message -----=20 From: ChrisAtUpw@.......... To: psn-l@................. Sent: Wednesday, October 18, 2006 7:41 AM Subject: Re: Questions In a message dated 2006/10/18, gmvoeth@........... writes: Hello Ted; The file 061017.013725.ebgz.psn is way too noisy. The gain should be = reduced to the point where noise is only +/- a few counts. This signal reminds me of the Hawaii quake I received but instead of = getting any S wave I just got two "P" waves (Main event/aftershock) and = what seemed to be followed by surface waves. Hi Geoff, Ted, This advice is not correct. Ted has a Lehman which senses the = microseismic background of 0.5 to 15 microns amplitude as well as quake = signals. Ted will want to sense longer period quakes which are a small = fraction of this amplitude and to filter them out, so he needs the = background to be at least 100 counts. =20 Regards, Chris Chapman
Hi Folks,    For = those who are=20 new to these subjects, here is my case study on a specific problem, and = the=20 group's advise which fixed it.  With my new station setup and = running, the=20 trace would get progressively noisier, starting at 11:00pm until=20 8:00am.
This noise was huge, the trace started = out, looking=20 like a pencil line and then,would progress to something like the teeth = of a saw,=20 so large it would almost touch the line above and below. As the room = went back=20 to day time temp, so did the trace quite down.
The garage, where it sat, has no heat = and no=20 drafts.  The temp in the garage, at night, would get to 40-50 and = during=20 the day 60's.
 
Because I had not finished my cover/box = the sensor=20 sat on the floor open to the air.  I was advised to build a box = which would=20 protect the sensor from air currents and thermos. So last night,=20 temporarily, I  covered the sensor using two sawhorses and two = blankets. The trace remained perfectly still all night
 
As a newcomer to these issues, I had no = idea the=20 importance of these enclosures.  I noticed if I waved my hand or = made=20 any  movements, which created air movement I would see a = spike.  I did=20 not realize that invisible air currents in the room, caused by the = different in=20 floor vs. air temperature, would cause huge noise.
 
Thanks for the guidance.
 
Q 1.  I understand that some = people=20 orient their sensor N/S others E/W,  Are the sensors ever oriented = at a 45=20 degree angle between the two?
 
Q 2. What are the expectations of a = Lehman=20 sensor?  I know that depends on many factors, and not the lease of = which is=20 the quality of the sensor, and its environment, as well as the type and = location=20 of the events.  But just in general terms. The AS1, which is not a = Lehman=20 suggest one should be able to see 6.0m from several thousand mile away, = or=20 something like that.
The reason I ask, I do hear statements, = both over=20 and under my expectations.  Time will tell, but I wanted your=20 opinions.
 
Cheers, Ted
 
 
 
 
----- Original Message -----
From:=20 ChrisAtUpw@.......
Sent: Wednesday, October 18, = 2006 7:41=20 AM
Subject: Re: Questions

In a=20 message dated 2006/10/18, gmvoeth@........... = writes:

Hello Ted;
The file 061017.013725.ebgz.psn is way too = noisy.=20 The gain should be reduced
to the point where noise is only +/- a = few=20 counts.

This signal reminds me of the Hawaii quake I received = but=20 instead of getting any S wave I just got two "P" waves (Main=20 event/aftershock) and what seemed
to be followed by surface=20 waves.


Hi Geoff,=20 Ted,

       This advice is not = correct.=20 Ted has a Lehman which senses the microseismic background of 0.5 to 15 = microns=20 amplitude as well as quake signals. Ted will want to sense longer = period=20 quakes which are a small fraction of this amplitude and to filter them = out, so=20 he needs the background to be at least 100 counts. =20

      =20 Regards,

       Chris = Chapman=20
Subject: Questions From: Roger Sparks rsparks@.......... Date: Wed, 18 Oct 2006 08:30:43 -0700 Hi Ted, Congratulations on making your new seismometer operational. Welcome to the hobby. psn-l-digest-request@.............. wrote: > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 1 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: Questions > From: "tchannel" > Date: Tue, 17 Oct 2006 12:30:51 -0600 > > This is a multi-part message in MIME format. > > ------=_NextPart_000_0003_01C6F1E8.14FC65F0 > Content-Type: text/plain; > charset="iso-8859-1" > Content-Transfer-Encoding: quoted-printable > > I have finished my sensor, and have had it running for three days. > > 1. During the night hours, 11pm to 6am, the tract goes from normal to = > noisy, getting worse each hour. The sensor sits in the garage on a = > concrete slab. No draft and no heat. As soon as I go into the garage = > in the AM and the room gets warmer, because the sun warms the room to = > about 60 f. The trace returns to normal. Is this temperature effect? I = > also turn off the monitor and turn it back on in the AM. Could the CTR = > or the computer create noise? They set about three feet from the sensor. = > Again no heat, no draft and nothing running out there in the night. > You do not mention a cover over the seismometer. A garage provides a cover which is much too large to prevent internal heat driven air currents which a seismometer will easily detect. Try a much smaller cover over the seismometer. The Plexiglas cover you are considering should be adequate, but you may also need some heating as suggested by Chris. The heating should be less to control air currents, but would work more to stabilize heat related dimensional changes to the seismometer components. > 2. I think I am getting a good recording, I have see the last two = > quakes and to me they look normal. > I am in Boise Idaho and have tried to compare my .PSN with any others = > close by. However our local one in Boise is down and the next, nearest = > one is in Washington State. Now here is a hard question to ask: I = > created my expanded trace, using the same time plotted on the .PSN in = > Washington (061017.013725.ebgz.psn M6.5 10356km from Ellensburg, Wa.,) = > This was around one hour of trace. I did this so I could compare the = > two side by side. I was a little surprised to see the Wa. psn to show a = > large spike on the P and a short spike on the S. My trace looks very = > similar, but I show a large spike on the S and a smaller spike on the P. = > From the description of the Ellensburg Wa file it has a Z in it, is = > that a Vertical sensor? and since my sensor is a Horz pointing N/S, = > would that explain the different. These events came from the East, and I = > have my beam pointing North. > Anyone who would like me to send both .PSN's to them for a critique, = > please email me. I would appreciate someone looking at them and = > voicing an opinion as to my level of gain, not sure if it is correct, = > and some advise as to how to best filter this event to enhance the P and = > S. I am just using trial and error. > Please post your files to the PSN web site. The seismometer at ebgz is mostly vertical but has a tilt of about 20 degrees above horizontal and runs north/south. The best filter to use depends upon the quake so trial and error is the rule. You will see quakes originating in Idaho or Montana much better if you use a high pass filter, passing frequencies of about 0.5 Hz and higher. These local quakes will have frequencies present up to about 10 Hz. Station ebgz http://www.seismicnet.com/quakes/0610/061014.153020.ebgzx.psn demonstrates the effectiveness of a high pass filter on local quake data. > 3. Presently I am building a Plexiglas box. But would it help to = > reduce noise if I built a second box wrapped with alum foil? Or other = > ideas on building a box which would make a positive different? > > 4. I know weather can alter the way the trace looks, I thought my = > situation was weather, but it was clear today. > What is there in a front moving thru that creates the noise? Lets say = > a front with little wind and no lightening. > > Many thanks, Ted > Best wishes, Roger __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Questions From: "Benji Johnson" Benji.Johnson@.................. Date: Wed, 18 Oct 2006 12:56:55 -0700 Hi Ted, I don't know how much practical difference this makes, but in addition to placing an insulated cover over the sensor, I also place 1/4" of the rigid foam insulation on the concrete floor, in order to further insulate it from temperature changes. This extends 6 - 8" beyond the outer edge of the box. If you place your sensor onto this foam, the feet will leave an imprint, which you then need to cut out slightly oversized with a knife so that there is contact with the floor. If the legs on your sensor are longer, you could go with thicker insulation, but you don't want there to be any contact with this insulation. Lastlly, I attach a soft "garage door" insulation strip onto the floor insulation, which the box then sits upon. This seems to provide a nice seal against air leaks between the two hard insulation surfaces. In the past, others have mentioned filling some of the empty space within the cover with light foam, so as to displace air which might otherwise cause problems if it becomes convective. On the other hand, I could see this being a problem if all that you end up doing is focusing the remaining air movement onto the coil. Again, I'm not sure that either of these additional steps make a real difference, but thought I'd throw them out as food for thought. Benji __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Questions From: "Jack Ivey" ivey@.......... Date: Wed, 18 Oct 2006 16:29:24 -0400 Also, even with the cover, you might end up with convection currents within the box, due to the concrete staying warm while the air above cools at night. Some people put a small (10 watt?) heater or light bulb inside the top of the box, causing the air at in the box to stratify. The idea is to make sure each layer=20 of air is warmer than the one below it to eliminate convection currents. Jack -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Benji Johnson Sent: Wednesday, October 18, 2006 3:57 PM To: PSN-L@.............. Subject: Re: Questions Hi Ted, I don't know how much practical difference this makes, but in addition to placing an insulated cover over the sensor, I also place 1/4" of the rigid foam insulation on the concrete floor, in order to further insulate it from temperature changes. This extends 6 - 8" beyond the outer edge of the box. If you place your sensor onto this foam, the feet will leave an imprint, which you then need to cut out slightly oversized with a knife so that there is contact with the floor. If the legs on your sensor are longer, you could go with thicker insulation, but you don't want there to be any contact with this insulation.=20 Lastlly, I attach a soft "garage door" insulation strip onto the floor insulation, which the box then sits upon. This seems to provide a nice seal against air leaks between the two hard insulation surfaces. In the past, others have mentioned filling some of the empty space within the cover with light foam, so as to displace air which might otherwise cause problems if it becomes convective. On the other hand, I could see this being a problem if all that you end up doing is focusing the remaining air movement onto the coil. Again, I'm not sure that either of these additional steps make a real difference, but thought I'd throw them out as food for thought. Benji __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Question about expected performance From: Larry Conklin lconklin@............ Date: Wed, 18 Oct 2006 16:40:17 -0400 Hi Ted, I have been running a Shakelford-Gunderson sensor since mid 2000, and in that time have collected a little over 500 events. I made up a couple of Excel spreadsheets to keep track of them. The spreadsheets automatically plot the events on a magnitude - distance scatter plot along with a color coded (and very subjective) measure of "quality" of the detection. At my location in central NY my plots show a lot of detections from about Mag 5.5 and up at ranges of 3000 mi and greater. Closer in than 3000 mi, I see a lot of stuff at lower magnitudes. I think the noise performance of my set-up leaves a lot to be desired but that otherwise, it seems to do about as well as people are reporting for their Lehmans. I could send you copies of my data if you're interested. I think this listserve strips off attachments, but I will send the info directly to anyone who is curious. Larry Conklin lconklin@............ tchannel wrote: > > Q 2. What are the expectations of a Lehman sensor? I know that depends > on many factors, and not the lease of which is the quality of the > sensor, and its environment, as well as the type and location of the > events. But just in general terms. The AS1, which is not a Lehman > suggest one should be able to see 6.0m from several thousand mile away, > or something like that. > The reason I ask, I do hear statements, both over and under my > expectations. Time will tell, but I wanted your opinions. > > Cheers, Ted __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Questions From: ChrisAtUpw@....... Date: Wed, 18 Oct 2006 16:48:38 EDT In a message dated 2006/10/18, tchannel@.............. writes: > As a newcomer to these issues, I had no idea the importance of these > enclosures. I did not realize that invisible air currents in the room, caused by > the different in floor vs. air temperature, would cause huge noise. Hi Ted, With Larry's low noise amplifier and a Neo magnet sensor, your amplifier noise level is likely as a rough guess to be less than 20 nano metres. That is 20 millionths of 1 mm. My Lehman LVDT sensor has a noise level of about 7 nano metres, but the environmental noise is well over 10x this. These sensors are extremely sensitive. > Q 1. I understand that some people orient their sensor N/S others E/W, Are > the sensors ever oriented at a 45 degree angle between the two? It is entirely up to you, but if you want to compare your results with others, or with USGS sites, you need the same orientation. Remember that if the axis of the Lehman is N/S, the detection sensitivity is E/W. > Q 2. What are the expectations of a Lehman sensor? I know that depends on > many factors, and not the lease of which is the quality of the sensor, and its > environment, as well as the type and location of the events. But just in > general terms. The AS1, which is not a Lehman suggest one should be able to see > 6.0m from several thousand mile away, or something like that. You should be able to get significantly better results than an AS-1, but what you see is likely to depend almost entirely on the local man made and natural environmental noise. With say a 25 to 30 sec period, good bearings and a rigid frame, I would expect you to be able to detect mag 6 quakes world wide. Mag 3 quakes from 200 to maybe 500 km. You need to learn how best to set your display filters. The professionals can get better results since they choose low noise sites and may also bury their seismometers ~100 m deep to reduce surface noise. See http://jclahr.com/science/psn/magnitude.html Note the small control buttons at the bottom of the screen. Regards, Chris Chapman In a me= ssage dated 2006/10/18, tchannel@.............. writes:

As a newcomer to these issues,=20= I had no idea the importance of these enclosures.   I did not real= ize that invisible air currents in the room, caused by the different in floo= r vs. air temperature, would cause huge noise.


Hi Ted,
      
       With Larry's low noise amplifier and a=20= Neo magnet sensor, your amplifier noise level is likely as a rough guess to=20= be less than 20 nano metres. That is 20 millionths of 1 mm. My Lehman LVDT s= ensor has a noise level of about 7 nano metres, but the environmental noise=20= is well over 10x this. These sensors are extremely sensitive.

Q 1. I understand that some pe= ople orient their sensor N/S others E/W,  Are the sensors ever oriented= at a 45 degree angle between the two?


       It is entirely up to you, but if you w= ant to compare your results with others, or with USGS sites, you need the sa= me orientation. Remember that if the axis of the Lehman is N/S, the detectio= n sensitivity is E/W.

Q 2. What are the expectations= of a Lehman sensor? I know that depends on many factors, and not the lease=20= of which is the quality of the sensor, and its environment, as well as the t= ype and location of the events. But just in general terms. The AS1, which is= not a Lehman suggest one should be able to see 6.0m from several thousand m= ile away, or something like that. 


       You should be able to get significantly= better results than an AS-1, but what you see is likely to depend almost en= tirely on the local man made and natural environmental noise. With say a 25=20= to 30 sec period, good bearings and a rigid frame, I would expect you to be=20= able to detect mag 6 quakes world wide. Mag 3 quakes from 200 to maybe 500 k= m. You need to learn how best to set your display filters. The professionals= can get better results since they choose low noise sites and may also bury=20= their seismometers ~100 m deep to reduce surface noise.

       See http://jclahr.com/science/psn/magni= tude.html Note the small control buttons at the bottom of the screen.

       Regards,

       Chris Chapman Subject: Re: Long period sensor plan From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Wed, 18 Oct 2006 23:44:18 +0000 Hi Here is a updated drawing of the sensor, http://www.simnet.is/jonfr500/sensor/long.period.sensor.v1.0.1.jpg This sensor is based on mass. It won't have any springs in it. But a damping system on the end and a magnets and coils in front of it. I am also going to use a resistance to get the signal as close to 1Hz as I can. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Questions From: Barry Lotz barry_lotz@............. Date: Wed, 18 Oct 2006 20:07:26 -0700 (PDT) Hi Ted It seems that we all have the issue of how sensitive to make the system. More sensitive and you can pick up more distant events but if it is too sensitive one gets clipped signals during stronger events. Larry's circuits and others have two recording gain levels which is probably the best but one could set the gain lower and use a higher bit A/D converter like 24 bit. I have plotted magnitude vs distance vs count for my systems and have selected some level which is ok with me for the time being but like any hobby, there is always a desire to improve. Regards Barry snip- Q 2. What are the expectations of a Lehman sensor? I know that depends on many factors, and not the lease of which is the quality of the sensor, and its environment, as well as the type and location of the events. But just in general terms. The AS1, which is not a Lehman suggest one should be able to see 6.0m from several thousand mile away, or something like that. The reason I ask, I do hear statements, both over and under my expectations. Time will tell, but I wanted your opinions. Cheers, Ted
Hi Ted
  It seems that we all have the issue of how sensitive to make the system. More sensitive and you can pick up more distant events but if it is too sensitive one gets clipped signals during stronger events. Larry's circuits and others have two recording gain levels which is probably the best but one could set the gain lower and use a higher bit A/D converter like 24 bit. I have plotted magnitude vs distance vs count for my systems and have selected some level which is ok with me for the time being but like any hobby, there is always a desire to improve.
Regards
Barry
 

snip-
 
Q 2. What are the expectations of a Lehman sensor?  I know that depends on many factors, and not the lease of which is the quality of the sensor, and its environment, as well as the type and location of the events.  But just in general terms. The AS1, which is not a Lehman suggest one should be able to see 6.0m from several thousand mile away, or something like that.
The reason I ask, I do hear statements, both over and under my expectations.  Time will tell, but I wanted your opinions.
 
Cheers, Ted
 
Subject: Re: Questions From: ian ian@........... Date: Thu, 19 Oct 2006 06:47:47 +0100 I connect my sensor to 3 channels of my 16 bit A/D, each of which are set to differrent gains/maximum input voltage. In realtime, the software uses the highest gain channel that isn't saturated for each sample. This, in some respects, gets about 21 bits of resolution out of my 16 bit A/D. Obviously the voltage resolution of the signal deminishes as it moves up the channels but it avoids saturation and you don't need the highest voltage resolution as the signal increases in magnitude. Ian Barry Lotz wrote: > Hi Ted > It seems that we all have the issue of how sensitive to make the > system. More sensitive and you can pick up more distant events but if > it is too sensitive one gets clipped signals during stronger events. > Larry's circuits and others have two recording gain levels which is > probably the best but one could set the gain lower and use a higher > bit A/D converter like 24 bit. I have plotted magnitude vs distance vs > count for my systems and have selected some level which is ok with me > for the time being but like any hobby, there is always a desire to > improve. > Regards > Barry > > > snip- > > Q 2. What are the expectations of a Lehman sensor? I know that > depends on many factors, and not the lease of which is the quality > of the sensor, and its environment, as well as the type and > location of the events. But just in general terms. The AS1, which > is not a Lehman suggest one should be able to see 6.0m from > several thousand mile away, or something like that. > The reason I ask, I do hear statements, both over and under my > expectations. Time will tell, but I wanted your opinions. > > Cheers, Ted > > I connect my sensor to 3 channels of my 16 bit A/D, each of which are set to differrent gains/maximum input voltage.  In realtime, the software uses the highest gain channel that isn't saturated for each sample.  This, in some respects, gets about 21 bits of resolution out of my 16 bit A/D.  Obviously the voltage resolution of the signal deminishes as it moves up the channels but it avoids saturation and you don't need the highest voltage resolution as the signal increases in magnitude.

Ian

Barry Lotz wrote:
Hi Ted
  It seems that we all have the issue of how sensitive to make the system. More sensitive and you can pick up more distant events but if it is too sensitive one gets clipped signals during stronger events. Larry's circuits and others have two recording gain levels which is probably the best but one could set the gain lower and use a higher bit A/D converter like 24 bit. I have plotted magnitude vs distance vs count for my systems and have selected some level which is ok with me for the time being but like any hobby, there is always a desire to improve.
Regards
Barry
 

snip-
 
Q 2. What are the expectations of a Lehman sensor?  I know that depends on many factors, and not the lease of which is the quality of the sensor, and its environment, as well as the type and location of the events.  But just in general terms. The AS1, which is not a Lehman suggest one should be able to see 6.0m from several thousand mile away, or something like that.
The reason I ask, I do hear statements, both over and under my expectations.  Time will tell, but I wanted your opinions.
 
Cheers, Ted
 

Subject: Redwood City PSN Website Is Down From: Larry Cochrane lcochrane@.............. Date: Thu, 19 Oct 2006 22:14:36 -0700 Hi Tony and other PSNers, I'm having a DSL outage. Luckily I have two DSL line just for this type of problem, so I'm not totally off-line. Hopefully www.seismicnet.com will be back on the air in a few days. My web site can be accessed using this domain name psn.seismicnet.com or psn.quake.net. Email should be working just fine. Regards, Larry Cochrane Redwood City, PSN quakekona wrote: > Hi Larry. > > I just wanted you to know, if you didn't already, that your www.seismicnet.com > website is down. It wont open for me, however psn.quake.net is working. > Just to remind you, I will be shutting down SDR on saturday for 2 weeks. > I hope you have enjoyed all the aftershocks, I just posted 3 more today, but > there won't be anymore postings after saturday until I get back...sorry. > Until I talk to you again... > > Aloha > > Tony > > > > > __________________________________________________ > Do You Yahoo!? > Tired of spam? Yahoo! Mail has the best spam protection around > http://mail.yahoo.com > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Two Ca. Events From: "tchannel" tchannel@.............. Date: Fri, 20 Oct 2006 14:31:07 -0600 Hi Folks, I just recorded the 4.5m from Northern Cal. When I placed = the p and s there was a strong single 4 mins in front of it. I when back to the maps and found a 1.5m in the same general area. Both = singles were clear and pronounced. The time seems exactly correct for = the 1.5 as well as the 4.5. Could I have seen a 1.5m 472miles away, = here in Boise? Happy to send the .psn if that would help. Thanks Ted
Hi Folks,   I just recorded = the 4.5m from=20 Northern Cal.  When I placed the p and s there was a strong single = 4 mins=20 in front of it.
I when back to the maps and found a = 1.5m in the=20 same general area.  Both singles were clear and pronounced.  = The time=20 seems exactly correct for the 1.5 as well as the 4.5.  Could I have = seen a=20 1.5m 472miles away, here in Boise?
Happy to send the .psn if that would=20 help.
Thanks Ted
Subject: Re: Two Ca. Events From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 20 Oct 2006 21:09:31 +0000 Hi Don't expect to see mag 1.5 at ~700 km distance, I can see them up to ~150 km away from me. But send me the psn file so I can take a look. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Two Ca. Events From: ChrisAtUpw@....... Date: Fri, 20 Oct 2006 22:46:48 EDT In a message dated 2006/10/20, tchannel@.............. writes: > Hi Folks, I just recorded the 4.5m from Northern Cal. When I placed the > p and s there was a strong single 4 mins in front of it. > I when back to the maps and found a 1.5m in the same general area. Hi Ted, First check your filtering. You won't see a M1.5 from 472 m. I suggest that you check the lists again later today / tomorrow. www.iris.edu/seismon is now showing a M4.5 at 17:00:06 in N CA Regards, Chris Chapman In a me= ssage dated 2006/10/20, tchannel@.............. writes:

Hi Folks,   I just re= corded the 4.5m from Northern Cal.  When I placed the p and s there was= a strong single 4 mins in front of it.
I when back to the maps and found a 1.5m in the same general area. <= FONT COLOR=3D"#000000" BACK=3D"#ffffff" style=3D"BACKGROUND-COLOR: #ffffff"= SIZE=3D3 PTSIZE=3D12 FAMILY=3D"SANSSERIF" FACE=3D"Arial" LANG=3D"0">

Hi Ted,

       First check your filtering. You won't s= ee a M1.5 from 472 m.
       I suggest that you check the lists agai= n later today / tomorrow. 

       www.iris.edu/seismon is now showing a M= 4.5 at 17:00:06 in N CA

       Regards,

       Chris Chapman Subject: Local vs distance events From: "tchannel" tchannel@.............. Date: Mon, 23 Oct 2006 08:48:37 -0600 Hi, I was asked to explain the different between Sensors developed for = local events vs those developed for long distance events. Is there a summary posted that explains this in terms easy to = understand? This is for a group of children and adults. Thanks, Ted
Hi,  I was asked to explain the = different=20 between Sensors  developed for local events vs those developed = for=20 long distance events.
Is there a summary posted that explains = this in=20 terms easy to understand?   This is for a group of children = and=20 adults.
Thanks, Ted
Subject: Re: Local vs distance events From: John or Jan Lahr JohnJan@........ Date: Mon, 23 Oct 2006 08:45:28 -0700 At 07:48 AM 10/23/2006, you wrote: >Hi, I was asked to explain the different between Sensors developed >for local events vs those developed for long distance events. >Is there a summary posted that explains this in terms easy to >understand? This is for a group of children and adults. >Thanks, Ted Hi Ted, Local earthquakes are rich in all frequencies. The best frequencies for picking sharp arrival times for P, S and other phases are the high frequencies, above 1 Hz. As the waves from an earthquake travel away from the source, the higher frequencies are attenuated more quickly than the low frequencies. At a great distance most of the energy is at frequencies lower than 1 Hz. In particular, surface waves with frequencies of 1/20 Hz (20 second period) usually are the most prominent signal for very distant events (call teleseisms). The other factor for consideration is the frequency of the "noise" in the earth. There is a peak in this noise at a period of 4 to 5 seconds. This is due to what are called higher-mode surface waves from non-earthquake sources such as wind and ocean storms. Look a the graph on this site to see a plot of the background noise: http://dmc.iris.washington.edu/stations/seisWorkshop04/iris_sensor_ws_9.19.05.pdf In the days of paper seismograms, two different systems were generally used: a short-period system for frequencies higher than 1 Hz and a long period system with peak response near 1/15 Hz (15 second period). See: . With the advent of digital recording, many new systems are "broad band," meaning that they are sensitive to a wide range of frequencies. In order to view data from one of these systems it is often best to use a digital filter to create either a short period or a long period seismogram. This graph shows the growth of broad-band stations and the decline of the older worldwide photograph-paper systems from the WWSSN ( World-Wide Standard Seismograph Network). The response of the broad-band station at Corvallis, Oregon (COR) is shown on this page: . On this page one can toggle between the broad-band seismogram and one that is filtered to become either a short period or a long period seismogram. Very distant events are usually not even visible on the short-period seismogram, where as a local or regional event will be seen best on the short-period record. Hope this helps! I've included a lot of details so that you will have to background necessary to develop a simpler explanation. Cheers, John __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Local vs distance events From: ChrisAtUpw@....... Date: Mon, 23 Oct 2006 11:56:40 EDT In a message dated 2006/10/23, tchannel@.............. writes: > Hi, I was asked to explain the different between Sensors developed for > local events vs those developed for long distance events. > Is there a summary posted that explains this in terms easy to understand? > This is for a group of children and adults. Hi Ted, ????? Are these amateur or professional sensors? There are a variety of sensors available professionally. 4.5 Hz and more particularly 1 Hz geophones may be used for local quakes / volcanoes and may record from 60 Hz down to the corner frequency. Then you have a variety of broad band medium to high sensitivity seismic sensors which record from 50 / 40 Hz all the way to 40, 60, 120 or even 360 seconds. Then there are 'strong motion' sensors, more often used close to faults or for civil engineering. These record accelerations up to about 2 g but may only go down to a milli g and are usually broad band. Local events may have motion components from maybe 40 Hz down to 30 seconds. As quake waves travel through / over the surface of the Earth, the higher frequencies are selectively absorbed. Teleseismic quakes tend to have P waves of 1 to 2 Hz, S waves about 0.45 the frequency of the P waves and Love / Rayleigh long surface waves with periods less than 60 seconds, often about 15 to 30 seconds. However, those from 'great' quakes may have waves of much greater periods. Regards, Chris Chapman In a me= ssage dated 2006/10/23, tchannel@.............. writes:

Hi,  I was asked to explai= n the different between Sensors developed for local events vs those develope= d for long distance events.
Is there a summary posted that explains this in terms easy to understand? T= his is for a group of children and adults.


Hi Ted,

       ?????

       Are these amateur or professional senso= rs?

       There are a variety of sensors availabl= e professionally.
       4.5 Hz and more particularly 1 Hz geoph= ones may be used for local quakes / volcanoes and may record from 60 Hz down= to the corner frequency.
       Then you have a variety of broad band m= edium to high sensitivity seismic sensors which record from 50 / 40 Hz all t= he way to 40, 60, 120 or even 360 seconds.
       Then there are 'strong motion' sensors,= more often used close to faults or for civil engineering. These record acce= lerations up to about 2 g but may only go down to a milli g and are usually=20= broad band.

       Local events may have motion components= from maybe 40 Hz down to 30 seconds.

       As quake waves travel through / over th= e surface of the Earth, the higher frequencies are selectively absorbed.

       Teleseismic quakes tend to have P waves= of 1 to 2 Hz, S waves about 0.45 the frequency of the P waves and Love / Ra= yleigh long surface waves with periods less than 60 seconds, often about 15=20= to 30 seconds. However, those from 'great' quakes may have waves of much gre= ater periods.

       Regards,

       Chris Chapman Subject: Re: Local vs distance events From: "tchannel" tchannel@.............. Date: Mon, 23 Oct 2006 16:07:18 -0600 Thanks for this information. Chris, These are amateur sensors, and = students. Ted ----- Original Message -----=20 From: ChrisAtUpw@.......... To: psn-l@................. Sent: Monday, October 23, 2006 9:56 AM Subject: Re: Local vs distance events In a message dated 2006/10/23, tchannel@.............. writes: Hi, I was asked to explain the different between Sensors developed = for local events vs those developed for long distance events. Is there a summary posted that explains this in terms easy to = understand? This is for a group of children and adults. Hi Ted,=20 ????? Are these amateur or professional sensors? There are a variety of sensors available professionally.=20 4.5 Hz and more particularly 1 Hz geophones may be used for = local quakes / volcanoes and may record from 60 Hz down to the corner = frequency. Then you have a variety of broad band medium to high = sensitivity seismic sensors which record from 50 / 40 Hz all the way to = 40, 60, 120 or even 360 seconds. Then there are 'strong motion' sensors, more often used close = to faults or for civil engineering. These record accelerations up to = about 2 g but may only go down to a milli g and are usually broad band. Local events may have motion components from maybe 40 Hz down = to 30 seconds. As quake waves travel through / over the surface of the Earth, = the higher frequencies are selectively absorbed. Teleseismic quakes tend to have P waves of 1 to 2 Hz, S waves = about 0.45 the frequency of the P waves and Love / Rayleigh long surface = waves with periods less than 60 seconds, often about 15 to 30 seconds. = However, those from 'great' quakes may have waves of much greater = periods. Regards, Chris Chapman
Thanks for this = information.  =20 Chris, These are  amateur sensors, and students.  =20 Ted
----- Original Message -----
From:=20 ChrisAtUpw@.......
Sent: Monday, October 23, 2006 = 9:56=20 AM
Subject: Re: Local vs distance=20 events

In a=20 message dated 2006/10/23, tchannel@..............=20 writes:

Hi,  I was asked to explain the different between = Sensors=20 developed for local events vs those developed for long distance=20 events.
Is there a summary posted that explains this in = terms easy to=20 understand? This is for a group of children and = adults.


Hi=20 Ted,

      =20 ?????

       Are these amateur or = professional sensors?

       = There are a=20 variety of sensors available professionally.=20
       4.5 Hz and more particularly = 1 Hz=20 geophones may be used for local quakes / volcanoes and may record from = 60 Hz=20 down to the corner frequency.
       = Then you=20 have a variety of broad band medium to high sensitivity seismic = sensors which=20 record from 50 / 40 Hz all the way to 40, 60, 120 or even 360=20 seconds.
       Then there are = 'strong=20 motion' sensors, more often used close to faults or for civil = engineering.=20 These record accelerations up to about 2 g but may only go down to a = milli g=20 and are usually broad = band.

       Local=20 events may have motion components from maybe 40 Hz down to 30=20 seconds.

       As quake waves = travel=20 through / over the surface of the Earth, the higher frequencies are=20 selectively absorbed.

       = Teleseismic=20 quakes tend to have P waves of 1 to 2 Hz, S waves about 0.45 the = frequency of=20 the P waves and Love / Rayleigh long surface waves with periods less = than 60=20 seconds, often about 15 to 30 seconds. However, those from 'great' = quakes may=20 have waves of much greater=20 periods.

      =20 Regards,

       Chris = Chapman=20
Subject: Unkown teleseimic signal From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Mon, 23 Oct 2006 23:03:34 +0000 Hi all I did notice a unkown teleseismic singal on few of the helcorders that I montior. None of the known earthquakes fit within the the appearance of that signal, the latest big earthquake was at 21:17 UTC and that was a mag 6.1 earthquake in Japan reagion. So far nothing has appeard on emsc-csem or usgs that explains the timeing of that signal. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Unkown teleseimic signal From: "Geoffrey" gmvoeth@........... Date: Mon, 23 Oct 2006 16:43:10 -0700 Mr. Jón Frímann; When you talk about any unknown signals, can you please tell the UTC date and time and position at which the unknown signal was received. Most unknown I have received have turned out to be mining operations. These will usually be within 150 Statute miles from me. They will normally happen during daylight weekdays and between the hours of 1400 and 1700 locally. They look like small regional quakes between 2 and 3.5 in Richter magnitude. Or so I am led to believe. I have two (L or S)-P times that are dead givaways they are like 7 seconds or 25 seconds. Regards; geoff ----- Original Message ----- From: "Jón Frímann" To: "PSN-Postlist" Sent: Monday, October 23, 2006 4:03 PM Subject: Unkown teleseimic signal > Hi all > > I did notice a unkown teleseismic singal on few of the helcorders that I > montior. None of the known earthquakes fit within the the appearance of > that signal, the latest big earthquake was at 21:17 UTC and that was a > mag 6.1 earthquake in Japan reagion. So far nothing has appeard on > emsc-csem or usgs that explains the timeing of that signal. > > Regards. > -- > Jón Frímann > http://www.jonfr.com > http://www.simnet.is/jonfr500/earthquake/ > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Unkown teleseimic signal From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Tue, 24 Oct 2006 00:17:23 +0000 Hi This signal did appear on few of the helcorders in monitor on my own webpage. It didn't appear on my sensor (far as I know). The signal appears around 22:07 UTC, on the 23rd October, 2006. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Dissipation of Seismic Waves From: "Bob Hancock" carpediem1@......... Date: Mon, 23 Oct 2006 18:14:40 -0700 Hi All - I believe that the intensity of light drops by the square of the distance i.e., double the distance and the new value is the square root of the distance. How does this apply to seismic waves which are basically sound waves? In addition, how does this affect the amplitude and radiated seismic energy of the waves? Bob Hancock

Hi All -

 

I believe that the intensity of light drops by the square of the distance = i.e., double the distance and the new value is the square root of the = distance.  How does this apply to seismic waves which are basically sound = waves?  In addition, how does this affect the amplitude and radiated seismic energy = of the waves? 

 

Bob Hancock

Subject: Earthtides From: Bill S wls@......... Date: Tue, 24 Oct 2006 12:38:54 -0400 Hi, Does anyone know of a site showing live earthtide measurements? Bill S __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Earthtides From: ian ian@........... Date: Tue, 24 Oct 2006 17:44:18 +0100 Hi, I'm not sure if you mean ocean waves. If so: https://www.fnmoc.navy.mil/PUBLIC/WAM/all_glbl.html Bill S wrote: > Hi, > Does anyone know of a site showing live earthtide measurements? > Bill S > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with the body of > the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Earthtides From: Bill S wls@......... Date: Tue, 24 Oct 2006 13:15:38 -0400 No, not ocean waves. I mean the deformation of the earth as affected by the gravity of the sun and moon. >Hi, > >I'm not sure if you mean ocean waves. If so: >https://www.fnmoc.navy.mil/PUBLIC/WAM/all_glbl.html > >Bill S wrote: > >>Hi, >>Does anyone know of a site showing live earthtide measurements? >>Bill S >> >> >>__________________________________________________________ >> >>Public Seismic Network Mailing List (PSN-L) >> >>To leave this list email PSN-L-REQUEST@.............. with the body of >>the message (first line only): unsubscribe >>See http://www.seismicnet.com/maillist.html for more information. >> > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with the body of the >message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Earthtides From: ChrisAtUpw@....... Date: Tue, 24 Oct 2006 13:23:09 EDT In a message dated 2006/10/24, wls@......... writes: Does anyone know of a site showing live earthtide measurements? > Bill S Hi Bill, They are measured by the ECGS at Walferdange in Belgium, but I don't know what is 'on-line'. See http://www.ecgs.lu/index.php?Itemid=1 Nicolas d'Oreye is very helpful. There are biaxial tiltmeters near Seattle in Washington State. See http://cires.colorado.edu/~bilham/ They say that data from the Long Caldera Valley is available subject to power outages.... Regards, Chris Chapman In a me= ssage dated 2006/10/24, wls@......... writes:

Does anyone know of a site showing live earthtide measurements?
Bill S



Hi Bill,

       They are measured by the ECGS at Walfer= dange in Belgium, but I don't know what is 'on-line'.
       See http://www.ecgs.lu/index.php?Itemid= =3D1
       Nicolas d'Oreye is very helpful.

       There are biaxial tiltmeters near Seatt= le in Washington State. See http://cires.colorado.edu/~bilham/
       They say that data from the Long Calder= a Valley is available subject to power outages....

       Regards,

       Chris Chapman Subject: Re: Earthtides From: Stephen & Kathy skmort@............ Date: Tue, 24 Oct 2006 10:54:54 -0700 I think this is what your looking for: http://aiuas3.unibe.ch/dpgm/zm_graph_tide.html Stephen PSN Station #55 Bill S wrote: > Hi, > Does anyone know of a site showing live earthtide measurements? > Bill S > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with the body of > the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > I think this is what your looking for:

http://aiuas3.unibe.ch/dpgm/zm_graph_tide.html

  Stephen
  PSN Station #55

Bill S wrote:
Hi,
Does anyone know of a site showing live earthtide measurements?
Bill S


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Subject: Re: Dissipation of Seismic Waves From: "Geoffrey" gmvoeth@........... Date: Tue, 24 Oct 2006 12:37:00 -0700 Spreading losses are the square of the distance so long as the spreading is 3D. There are other losses also. Several in fact. But it boils down to the generation of heat which is lost to entropy forever. It was so long ago that I studied this in SONAR and can no longer remember everything. Regards; geoff ----- Original Message ----- From: "Bob Hancock" To: "'PSN'" Sent: Monday, October 23, 2006 6:14 PM Subject: Dissipation of Seismic Waves > Hi All - > > > > I believe that the intensity of light drops by the square of the distance > i.e., double the distance and the new value is the square root of the > distance. How does this apply to seismic waves which are basically sound > waves? In addition, how does this affect the amplitude and radiated seismic > energy of the waves? > > > > Bob Hancock > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: My seismometer vault solution From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Wed, 25 Oct 2006 00:30:38 +0000 Hi all I have finally figured out a good way to put my geophone underground, into relative quite and noise free envroment (as can be done here). I am going to have put it in a plast bucket with a waterproof top. That is the only cheap way for me to do it, I have looked at other options and they are exspensive for me and hard to impliment, since this solution has to be waterproof and that is the most important factor in all of this. I plan to put my geophone underground soon as possible, problay next week. Becose I have to do it before the ground completie freezes over. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: My seismometer vault solution From: ian ian@........... Date: Wed, 25 Oct 2006 07:23:03 +0100 Hi, you can also use plastic soil pipe (the piping used for toilets and is about 5" in diameter). You'll find lots of different parts to put together in the plumbing shops. You can glue them together and drill a hole for the geophone metal spike to stick out of. Cheers Ian Jón Frímann wrote: >Hi all > >I have finally figured out a good way to put my geophone underground, >into relative quite and noise free envroment (as can be done here). I am >going to have put it in a plast bucket with a waterproof top. That is >the only cheap way for me to do it, I have looked at other options and >they are exspensive for me and hard to impliment, since this solution >has to be waterproof and that is the most important factor in all of >this. I plan to put my geophone underground soon as possible, problay >next week. Becose I have to do it before the ground completie freezes >over. > >Regards. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Dissipation of Seismic Waves From: John or Jan Lahr JohnJan@........ Date: Tue, 24 Oct 2006 23:49:40 -0700 At 06:14 PM 10/23/2006, you wrote: >Hi All - > >I believe that the intensity of light drops by the square of the >distance i.e., double the distance and the new value is the square >root of the distance. How does this apply to seismic waves which >are basically sound waves? In addition, how does this affect the >amplitude and radiated seismic energy of the waves? > >Bob Hancock Hi Bob, The graphs on the page below of amplitude versus distance show how seismic waves decay with distance. Ground motion amplitude and velocity as a function of distance, magnitude, and depth. (Only works well with MSIE -- Not Firefox.) Keep in mind that bacteria range from about 1 to 10 microns in diameter, while a human hair may be from 50 to 100 microns in diameter. For waves that expand in three dimensions, ignoring conversion to heat, the total energy flux through a sphere at any radius will be constant. The surface area of the sphere is 4 pi r^2, so the energy per unit area must be proportional to 1/r^2. The energy carried by the wave is proportional to the amplitude squared (A^2), so A^2 is proportional to 1/r^2, or A is proportional to 1/r. I'm not sure how to relate this to the amplitude at the surface versus geocentric distance for body waves in a spherical earth with velocity that varies with depth! For surface waves that are constrained to the surface of the earth, ignoring conversion to heat or leaking of some energy into the interior, the total energy flux through a circular zone or any radius will be constant. The area of the outer edge of a circular zone of a given thickness is proportional to the radius of the zone, so the energy per unit area must be proportional to 1/r. Then, since the energy is proportional to A^2, A^2 is proportional to 1/r, or A is proportional to 1/sqrt(r). From the formula for surface wave magnitude, Ms = log (A/T) + 1.66 log D + 3.3, one can show that the Amplitude is proportional to 1/ (D^1.66) This is much faster decay than 1/(D^.5), due, I suppose, to attenuation (conversion of energy to heat) and leaking of energy into the interior of the Earth. Actually the amplitude increases again near the opposite side of the earth as the surface waves converge from all directions. See: http://jclahr.com/science/software/magnitude/ms/msmag.html Don't know if this helps much! Cheers, John __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: My seismometer vault solution From: "Geoffrey" gmvoeth@........... Date: Wed, 25 Oct 2006 00:26:16 -0700 The air must be kept absolutely dry if you have a closed system. You need something included inside the container to absorb any free moisture. In the military they pump dry nitrogen into closed cavities. What is the coldest temp ? The airs dew point must be kept below that temp. I would use a pyrex like glass container specially built to keep a vacuum. Provide electrical isolation from the ground. It seems everything I want to do simply costs too much monies. I would need to be at a university working on a government funded project to try out all my ideas. Regards; geoff ----- Original Message ----- From: "Jón Frímann" To: "PSN-Postlist" Sent: Tuesday, October 24, 2006 5:30 PM Subject: My seismometer vault solution > Hi all > > I have finally figured out a good way to put my geophone underground, > into relative quite and noise free envroment (as can be done here). I am > going to have put it in a plast bucket with a waterproof top. That is > the only cheap way for me to do it, I have looked at other options and > they are exspensive for me and hard to impliment, since this solution > has to be waterproof and that is the most important factor in all of > this. I plan to put my geophone underground soon as possible, problay > next week. Becose I have to do it before the ground completie freezes > over. > > Regards. > -- > Jón Frímann > http://www.jonfr.com > http://www.simnet.is/jonfr500/earthquake/ > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: My seismometer vault solution From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Wed, 25 Oct 2006 12:07:47 +0000 Hi I am going to close the system inside, so the air is going to be resanable dry. However the sand I got might not be so dry, since I got it from outside and it is coverd in snow. I am going to let it dry (inside) for few days, at least until I have the weather to put my geophone underground. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: My seismometer vault solution From: "Jerry Payton" gpayton880@....... Date: Wed, 25 Oct 2006 07:17:24 -0500 Jon, The air inside your system WILL contain some amount of moisture. This moisture will "sweat" or condense with changes in outside tempratures. Unless the air is evacuated or nitrogen inserted into a sealed container, I think you may still have problems. Best Wishes, Jerry Payton ----- Original Message ----- From: Jón Frímann To: psn-l@.............. Sent: Wednesday, October 25, 2006 7:07 AM Subject: Re: My seismometer vault solution Hi I am going to close the system inside, so the air is going to be resanable dry. However the sand I got might not be so dry, since I got it from outside and it is coverd in snow. I am going to let it dry (inside) for few days, at least until I have the weather to put my geophone underground. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) To leave this list email PSN-L-REQUEST@.............. with the body of the message (first line only): unsubscribe See http://www.seismicnet.com/maillist.html for more information.
Jon,
 
The air inside your system WILL contain some amount of = moisture.  This=20 moisture will "sweat" or condense with changes in outside = tempratures. =20 Unless the air is evacuated or nitrogen inserted into a sealed = container, I=20 think you may still have problems.
 
Best Wishes,
Jerry Payton
----- Original Message -----
From:=20 J=F3n = Fr=EDmann=20
Sent: Wednesday, October 25, = 2006 7:07=20 AM
Subject: Re: My seismometer = vault=20 solution

Hi

I am going to close the system inside, so the = air is=20 going to be
resanable dry. However the sand I got might not be so = dry,=20 since I got
it from outside and it is coverd in snow. I am going to = let it=20 dry
(inside) for few days, at least until I have the weather to put = my
geophone underground.

Regards.
--
J=F3n = Fr=EDmann
http://www.jonfr.com
http://www.simnet.is/j= onfr500/earthquake/

__________________________________________= ________________

Public=20 Seismic Network Mailing List (PSN-L)

To leave this list email = PSN-L-REQUEST@............... =20 with
the body of the message (first line only): unsubscribe
See = http://www.seismicnet.co= m/maillist.html=20 for more information.
Subject: Re: My seismometer vault solution From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Wed, 25 Oct 2006 12:42:36 +0000 Hi I plan to use a woll (that they use in walls here in Iceland) to minizie that, at least I hope it is going to do that. But the geophone is going to be on at least 80 cm depth, I don't know about tempature changes on that depth. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: My seismometer vault solution From: "Jack Ivey" ivey@.......... Date: Wed, 25 Oct 2006 08:44:53 -0400 Jon, You can get dessicant packs to put in your container. They contain = silica gel, absorbent clay, or alumina, or some combination. Sand isn't going to get dry soon by sitting around = your house, and you will get=20 condensation or frost if you don't put something in to soak up the = humidity. =20 =20 You can also take some wallboard (gypsum construction material used for = inside walls in houses),=20 get rid of the paper coating, and bake the inside stuff (mostly calcium = sulphate). It takes a lot of this=20 compared to other materials. =20 =20 If you are brave, quicklime (not slaked lime) also works, but unlike the = other options, it is=20 not practical to bake the water out for reuse. =20 Jack =20 ________________________________ From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of Jerry Payton Sent: Wednesday, October 25, 2006 8:17 AM To: psn-l@.............. Subject: Re: My seismometer vault solution =20 Jon, =20 The air inside your system WILL contain some amount of moisture. This = moisture will "sweat" or condense with changes in outside tempratures. = Unless the air is evacuated or nitrogen inserted into a sealed = container, I think you may still have problems. =20 Best Wishes, Jerry Payton ----- Original Message -----=20 From: J=F3n Fr=EDmann =20 To: psn-l@................. Sent: Wednesday, October 25, 2006 7:07 AM Subject: Re: My seismometer vault solution =20 Hi =09 I am going to close the system inside, so the air is going to be resanable dry. However the sand I got might not be so dry, since I got it from outside and it is coverd in snow. I am going to let it dry (inside) for few days, at least until I have the weather to put my geophone underground. =09 Regards. --=20 J=F3n Fr=EDmann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ =09 __________________________________________________________ =09 Public Seismic Network Mailing List (PSN-L) =09 To leave this list email PSN-L-REQUEST@.............. with=20 the body of the message (first line only): unsubscribe See http://www.seismicnet.com/maillist.html for more information.

Jon,

You can get dessicant packs to put = in your container.=A0 They contain silica gel, absorbent clay, or alumina, = or

some combination.=A0 Sand = isn’t going to get dry soon by sitting around your house, and you will get =

condensation or frost if you = don’t put something in to soak up the humidity.=A0 =

 

You can also take some wallboard = (gypsum construction material used for inside walls in houses), =

get rid of the paper coating, and = bake the inside stuff (mostly calcium sulphate).=A0 It takes a lot of this =

compared to other materials.=A0 =

 

If you are brave, quicklime (not = slaked lime) also works, but unlike the other options, it is =

not practical to bake the water out = for reuse.

 

Jack

 

From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of Jerry Payton
Sent: Wednesday, October = 25, 2006 8:17 AM
To: psn-l@..............
Subject: Re: My = seismometer vault solution

 

Jon,

 

The air inside your system WILL contain some amount of = moisture.  This moisture will "sweat" or condense with changes in outside tempratures.  Unless the air is evacuated or nitrogen inserted into = a sealed container, I think you may still have = problems.

 

Best Wishes,

Jerry Payton

----- Original Message ----- =

Sent: = Wednesday, October 25, 2006 7:07 AM

Subject: Re: My = seismometer vault solution

 

Hi

I am going to close the system inside, so the air is going to be
resanable dry. However the sand I got might not be so dry, since I = got
it from outside and it is coverd in snow. I am going to let it dry
(inside) for few days, at least until I have the weather to put my
geophone underground.

Regards.
--
J=F3n Fr=EDmann
http://www.jonfr.com
http://www.simnet.is/j= onfr500/earthquake/

__________________________________________________________

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To leave this list email PSN-L-REQUEST@............... with
the body of the message (first line only): unsubscribe
See http://www.seismicnet.co= m/maillist.html for more information.

Subject: weather From: "tchannel" tchannel@.............. Date: Wed, 25 Oct 2006 10:16:53 -0600 Hi All, I was so happy with my sensor, over the last few day. I had a = major problem with thermos, which disappeared with my insulated box. = This question has to do with weather changes, and why that effects = noise. A day ago the tract was quiet at night and a little bit of noise during = the day time and city activities. Many hours ago a cold front came thru, arriving at 8:00 pm with winds. = The trace went from quite to noisy several hour ahead of the front. You = could look at the trace and see the change as the front got closer. = This weather should move out in the next 24 hours. So I expect things = will go back to normal. I don't understand, what is stimulating the sensor. 1. Does it respond to barometric pressure changes? 2. When wind is part of the storm, and the wind moves the trees, is = this transferred thru the ground to the sensors as earth movements? 3. Would a bolt of lightening be displayed on the trace? As a front approaches it is like the atmosphere starts to fill with = electromagnet noise. I'm just trying to understand what creates it. Inside the garage and inside the box it seem so isolated, no wind, no = air current, no vibrations or physical movements. Yet the sensor can see = a front hours before it arrives. Thanks, Ted
Hi All,   I was so happy with = my sensor,=20 over the last few day.  I had a major problem with thermos, which=20 disappeared with my insulated box.   This question has to do = with=20 weather changes, and why that effects noise.
A day ago the tract was quiet at night = and a little=20 bit of noise during the day time and city activities.
Many hours ago a cold front came = thru,=20 arriving at 8:00 pm with winds.   The trace went from quite to = noisy=20 several hour ahead of the front.  You could look at the trace and = see the=20 change as the front got closer.   This weather should move out = in the=20 next 24 hours.  So I expect things will go back to = normal.
 
I don't understand, what is stimulating = the=20 sensor.
1.  Does it respond to barometric = pressure=20 changes?
2.  When wind is part of the = storm, and the=20 wind moves the trees, is this transferred thru the ground to the sensors = as=20 earth movements?
3.  Would a bolt of lightening be = displayed on=20 the trace?
 
As a front approaches it is like the = atmosphere=20 starts to fill with electromagnet noise.  I'm just trying to = understand=20 what creates it.
Inside the garage and inside the box it = seem so=20 isolated, no wind, no air current, no vibrations or physical movements. = Yet the=20 sensor can see a front hours before it arrives.
Thanks, Ted
Subject: Re: My seismometer vault solution From: "Erich Kern" efkern@............. Date: Wed, 25 Oct 2006 09:28:43 -0700 Hi, The method I've used to dry sand is spread it on a couple of cookie tin sheets and bake in the kitchen oven at 250 F. or 120 C. for at least an hour. Let it cool on the tins before pouring into a container. Sand in a bucket will take forever to dry because the air can't get to the lower portion. There's an enormous surface area in sand that holds moisture. Erich ----- Original Message ----- From: "Jón Frímann" To: Sent: Wednesday, October 25, 2006 5:07 AM Subject: Re: My seismometer vault solution Hi I am going to close the system inside, so the air is going to be resanable dry. However the sand I got might not be so dry, since I got it from outside and it is coverd in snow. I am going to let it dry (inside) for few days, at least until I have the weather to put my geophone underground. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Dissipation of Seismic Waves From: "Bob Hancock" carpediem1@......... Date: Wed, 25 Oct 2006 10:19:58 -0700 Hi John - Very Interesting.......I plotted out the data using the two formulas 1/r^2 and 1/sqrt r for distances up to 15000 km. This helps explain the prominence of the Love and Rayleigh waves on teleseismic events, and why I am loosing the P and S waves in the background on some events. You have given me a lot to study so it take a while to absorb all of it, but then again, that's the challenge of life.....learning new things. Thanks Again - your help is SINCERELY APPRECIATED !!! Bob -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of John or Jan Lahr Sent: Tuesday, October 24, 2006 23:50 To: psn-l@.............. Subject: Re: Dissipation of Seismic Waves __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Katla volcano webcam From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Wed, 25 Oct 2006 17:25:49 +0000 Hi all I just found out that they are now monitoring Katla volcano with a webcam. You can see the current view here, http://www.ruv.is/katla/ The page is in Icelandic and requires java to work. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: My seismometer vault solution From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Wed, 25 Oct 2006 17:44:39 +0000 Hi I am dealing with a lot of sand. Problay around 3 - 5 kg. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: My seismometer vault solution From: "Erich Kern" efkern@............. Date: Wed, 25 Oct 2006 11:10:33 -0700 All the more reason to get rid of as much moisture as possible. 5 kg is not what I would call a lot of sand. It can easily be dried in the kitchen oven. Once the sand is sealed in a bucket all the dessicant packs you can fit in it will not get rid of the moisture. Better do it before it's sealed. Erich ----- Original Message ----- From: "Jón Frímann" To: Sent: Wednesday, October 25, 2006 10:44 AM Subject: Re: My seismometer vault solution Hi I am dealing with a lot of sand. Problay around 3 - 5 kg. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: My seismometer vault solution From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Wed, 25 Oct 2006 18:50:33 +0000 Hi I will figure out how to dry the sand. The soil type where I am placing my geophone is intresting, appears to be mostly sand and rocks. At least my shuffle didn't go deep into the ground when I was testing it this moment. I am going to start diggin the hole tomorrow if the weather allows. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Earthtides From: Bill S wls@......... Date: Wed, 25 Oct 2006 15:17:30 -0400 Stephen, Thanks, it was just what I was looking for. Bill S At 01:54 PM 10/24/2006, you wrote: >I think this is what your looking for: > >http://aiuas3.unibe.ch/dpgm/zm_graph_tide.html > > Stephen > PSN Station #55 > >Bill S wrote: >>Hi, >>Does anyone know of a site showing live earthtide measurements? >>Bill S >> >> >>__________________________________________________________ >> >>Public Seismic Network Mailing List (PSN-L) >> >>To leave this list email >>PSN-L-REQUEST@.............. with >>the body of the message (first line only): unsubscribe >>See >>http://www.seismicnet.com/maillist.html >>for more information. >> Stephen,
Thanks, it was just what I was looking for.
Bill S


At 01:54 PM 10/24/2006, you wrote:

I think this is what your looking for:

http://aiuas3.unibe.ch/dpgm/zm_graph_tide.html

  Stephen
  PSN Station #55

Bill S wrote:
Hi,
Does anyone know of a site showing live earthtide measurements?
Bill S


__________________________________________________________

Public Seismic Network Mailing List (PSN-L)

To leave this list email PSN-L-REQUEST@.............. with the body of the message (first line only): unsubscribe
See http://www.seismicnet.com/maillist.html for more information.

Subject: Re: weather From: Richard Webb dwebb002@............. Date: Wed, 25 Oct 2006 16:20:38 -0400 Ted, Could be something as simple as wind in the trees disturbing the ground. I see the same problem because my vault, although 6 feet below ground level is in a wooded area and roots go quite deep. Dick tchannel wrote: > Hi All, I was so happy with my sensor, over the last few day. I had > a major problem with thermos, which disappeared with my insulated > box. This question has to do with weather changes, and why that > effects noise. > A day ago the tract was quiet at night and a little bit of noise > during the day time and city activities. > Many hours ago a cold front came thru, arriving at 8:00 pm with > winds. The trace went from quite to noisy several hour ahead of the > front. You could look at the trace and see the change as the front > got closer. This weather should move out in the next 24 hours. So I > expect things will go back to normal. > > I don't understand, what is stimulating the sensor. > 1. Does it respond to barometric pressure changes? > 2. When wind is part of the storm, and the wind moves the trees, is > this transferred thru the ground to the sensors as earth movements? > 3. Would a bolt of lightening be displayed on the trace? > > As a front approaches it is like the atmosphere starts to fill with > electromagnet noise. I'm just trying to understand what creates it. > Inside the garage and inside the box it seem so isolated, no wind, no > air current, no vibrations or physical movements. Yet the sensor can > see a front hours before it arrives. > Thanks, Ted __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: weather From: ChrisAtUpw@....... Date: Wed, 25 Oct 2006 20:11:10 EDT In a message dated 2006/10/25, tchannel@.............. writes: > Subj:weather > Hi All, I was so happy with my sensor, over the last few day. I had a > major problem with thermos, which disappeared with my insulated box. This > question has to do with weather changes, and why that effects noise. > A day ago the trace was quiet at night and a little bit of noise during the > day time and city activities. > Many hours ago a cold front came thru, arriving at 8:00 pm with winds. The > trace went from quiet to noisy several hour ahead of the front. You could look > at the trace and see the change as the front got closer. > I don't understand, what is stimulating the sensor. > 1. Does it respond to barometric pressure changes? Hi Ted, Horizontal seismometers have a relatively low sensitivity to baromatric pressure changes. Vertical sensors are effected directly and may show x100 the noise. > 2. When wind is part of the storm, and the wind moves the trees, is this > transferred thru the ground to the sensors as earth movements? A front / storm has quite violent local turbulence. The quite small absolute pressure changes effect large ground areas. The wind noise is right across the spectrum and it effects everything from the phone wires to whole mountains. Tall isolated trees pick up wind noise very well. So do tall buildings. The frequency of the noise is proportional to the wind velocity, but inversely proportional to the effective width of the tree, building etc. > 3. Would a bolt of lightening be displayed on the trace? This is likely to be a sharp transient - you may also see a second sound signal. > As a front approaches it is like the atmosphere starts to fill with > electromagnet noise. I'm just trying to understand what creates it. > Inside the garage and inside the box it seem so isolated, no wind, no air > current, no vibrations or physical movements. Yet the sensor can see a front > hours before it arrives. A sheet of writing paper may be 0.1 mm thick. You seismometer can sense movements which are less than 1/1000 of this over many seconds. If your garage was not dead quiet, your seismometer would be way off scale. A storm front has huge eddies of air weighing hundreds to thousands of tons churning about. Air is quite heavy stuff. Regards, Chris Chapman In a me= ssage dated 2006/10/25, tchannel@.............. writes:

Subj:weather
Hi All,   I was so happy with my sensor, over the last few day. I=20= had a major problem with thermos, which disappeared with my insulated box. T= his question has to do with weather changes, and why that effects noise. A day ago the trace was quiet at night and a little bit of noise during the= day time and city activities.
Many hours ago a cold front came thru, arriving at 8:00 pm with winds. The=20= trace went from quiet to noisy several hour ahead of the front. You could lo= ok at the trace and see the change as the front got closer. 
I don't understand, what is stimulating the sensor.
1.  Does it respond to barometric pressure changes?


Hi Ted,

       Horizontal seismometers have a relative= ly low sensitivity to baromatric pressure changes. Vertical sensors are effe= cted directly and may show x100 the noise.

2.  When wind is part of=20= the storm, and the wind moves the trees, is this transferred thru the ground= to the sensors as earth movements?


       A front / storm has quite violent loca= l turbulence. The quite small absolute pressure changes effect large ground=20= areas.
       The wind noise is right across the spec= trum and it effects everything from the phone wires to whole mountains. Tall= isolated trees pick up wind noise very well. So do tall buildings. The freq= uency of the noise is proportional to the wind velocity, but inversely propo= rtional to the effective width of the tree, building etc.

3.  Would a bolt of light= ening be displayed on the trace?


       This is likely to be a sharp transient= - you may also see a second sound signal.

As a front approaches it is li= ke the atmosphere starts to fill with electromagnet noise.  I'm just tr= ying to understand what creates it.
Inside the garage and inside the box it seem so isolated, no wind, no air c= urrent, no vibrations or physical movements. Yet the sensor can see a front=20= hours before it arrives.


       A sheet of writing paper may be 0.1 mm=20= thick. You seismometer can sense movements which are less than 1/1000 of thi= s over many seconds. If your garage was not dead quiet, your seismometer wou= ld be way off scale. 
       A storm front has huge eddies of air we= ighing hundreds to thousands of tons churning about. Air is quite heavy stuf= f.

       Regards,

       Chris Chapman Subject: Re: My seismometer vault solution From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Thu, 26 Oct 2006 10:53:34 +0000 Hi I have started makeing the seismometer vault, I did start to dig the hole this morning. Unfortunaly it started to rain so I had to stop digging. I have dryed up the sand, that did go farly well. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: My seismometer vault solution From: Mark Robinson mark.robinson@............... Date: Fri, 27 Oct 2006 00:13:16 +1300 Jón Frímann wrote: > Hi > > I have started makeing the seismometer vault, I did start to dig the > hole this morning. Unfortunaly it started to rain so I had to stop > digging. I have dryed up the sand, that did go farly well. > > Regards. I'd be tempted to pot the geophone in neutral cure silicon rubber. There are special formulations available which are quite friable (crumbly) when set in case you ever need to remove it. Other useful materials include self-amalgamating Poly-Iso-Butylene tape (3M '23' tape, available from electrical wholesalers) and a favourite among New Zealand antenna engineers, lanoline grease from sheep's wool (Lanocote). Cheers Mark -- 27 Oct 1728 James Cook born. 27 Oct 1782 Niccolo Paganini born in Genoa. 27 Oct 1854 Mormon missionaries first visit New Zealand for 3 weeks preaching 27 Oct 1959 Soviet Lunik III spacecraft takes photographs of the dark side of the moon. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Dissipation of Seismic Waves From: ChrisAtUpw@....... Date: Thu, 26 Oct 2006 10:39:10 EDT In a message dated 2006/10/24, carpediem1@......... writes: > I believe that the intensity of light drops by the square of the distance > i.e., double the distance and the new value is the square root of the > distance. How does this apply to seismic waves which are basically sound waves? In > addition, how does this affect the amplitude and radiated seismic energy of the > waves? Hi Bob, The transmission can get quite complicated. I suggest that you visit Larry Braile's website and download 'seismic waves' and other introductory programs. Some of the programs are quite large. See http://web.ics.purdue.edu/~braile/ The initial Pressure and Shear waves are generated asymmetrically at the quake site, but travel outwards in all directions. They will experience square law effects and the higher frequency waves tend to be absorbed selectively with increasing distance. Since the density of rocks tends to increase with depth, the ray paths are curved, not straight lines, due to changes in the refractive index. Add on the fact that we are considering a solid sphere and you get ring shaped areas where some signals are weak or non existant. See http://neic.usgs.gov/neis/travel_times/index.html and http://neic.usgs.gov/neis/travel_times/ttgraph.html There are several layers at which signals can be reflected, or refracted to a different angle, mostly both. In general, a single signal like a P wave will give a mixture of P and S waves at these boundaries. Only the P waves can travel through the Earth's core. S waves cannot travel through a liquid. So, inside the Earth you get quite a complicated dynamic wave pattern building up with continuous absorption, some focusing, some refraction and also increased spreading. When the initial P and S waves travel upwards, they are partially reflected from the Earth's surface, but they also interact to generate Rayleigh vertical surface waves and Love shear surface waves, which then propagate outwards, roughly in a circle. Because they are surface waves, the fall off of intensity with distance is two dimensional and hence slower. Again, the higher initial frequencies tend to be absorbed more. Surface waves travel with decreasing amplitude out to about 140 degrees. For the next 20 degrees the amplitude in nearly constant, since while there is still absorption, the periphery of the wave circle around the globe is now shrinking significantly. Then they increase in amplitude as they approach 180 degrees, due to the rapidly decreasing perimeter. The intensity of the initial surface waves depends on the depth of the rupture below the surface, with deeper quakes tending to give less energetic surface waves. The earthquake intensity also depends on the length and the width (total area) of the rupture. The great quakes tend to occur at subduction zones when huge areas of land with diagonal faulting to considerable depths may be involved, not just a short near vertical surface crack. With great quakes, like the 2004 one in Indonesia, the various signals can travel several times through and around the Earth, being reflected and refracted all along the way. They also make the whole Earth oscillate in several 'natural eigen modes', a bit like a jelly, for several days. Regards, Chris Chapman In a me= ssage dated 2006/10/24, carpediem1@......... writes:

I believe that the intensity of= light drops by the square of the distance i.e., double the distance and the= new value is the square root of the distance. How does this apply to seismi= c waves which are basically sound waves? In addition, how does this affect t= he amplitude and radiated seismic energy of the waves?


Hi Bob,

       The transmission can get quite complica= ted. I suggest that you visit Larry Braile's website and download 'seismic w= aves' and other introductory programs. Some of the programs are quite large.= See http://web.ics.purdue.edu/~braile/

       The initial Pressure and Shear waves ar= e generated asymmetrically at the quake site, but travel outwards in all dir= ections. They will experience square law effects and the higher frequency wa= ves tend to be absorbed selectively with increasing distance.
       Since the density of rocks tends to inc= rease with depth, the ray paths are curved, not straight lines, due to chang= es in the refractive index. Add on the fact that we are considering a solid=20= sphere and you get ring shaped areas where some signals are weak or non exis= tant.
       See http://neic.usgs.gov/neis/travel_ti= mes/index.html
       and  http://neic.usgs.gov/neis/tra= vel_times/ttgraph.html  
       There are several layers at which signa= ls can be reflected, or refracted to a different angle, mostly both. In gene= ral, a single signal like a P wave will give a mixture of P and S waves at t= hese boundaries.
       Only the P waves can travel through the= Earth's core. S waves cannot travel through a liquid.
       So, inside the Earth you get quite a co= mplicated dynamic wave pattern building up with continuous absorption, some=20= focusing, some refraction and also increased spreading.

       When the initial P and S waves travel u= pwards, they are partially reflected from the Earth's surface, but they also= interact to generate Rayleigh vertical surface waves and Love shear surface= waves, which then propagate outwards, roughly in a circle. Because they are= surface waves, the fall off of intensity with distance is two dimensional a= nd hence slower. Again, the higher initial frequencies tend to be absorbed m= ore.
       Surface waves travel with decreasing am= plitude out to about 140 degrees. For the next 20 degrees the amplitude in n= early constant, since while there is still absorption, the periphery of the=20= wave circle around the globe is now shrinking significantly. Then they incre= ase in amplitude as they approach 180 degrees, due to the rapidly decreasing= perimeter.

       The intensity of the initial surface wa= ves depends on the depth of the rupture below the surface, with deeper quake= s tending to give less energetic surface waves. The earthquake intensity als= o depends on the length and the width (total area) of the rupture. The great= quakes tend to occur at subduction zones when huge areas of land with diago= nal faulting to considerable depths may be involved, not just a short near v= ertical surface crack.

       With great quakes, like the 2004 one in= Indonesia, the various signals can travel several times through and around=20= the Earth, being reflected and refracted all along the way. They also make t= he whole Earth oscillate in several 'natural eigen modes', a bit like a jell= y, for several days. 

       Regards,

       Chris Chapman

       Subject: RE: Dissipation of Seismic Waves From: "Bob Hancock" carpediem1@......... Date: Thu, 26 Oct 2006 09:44:21 -0700 Hi Chris - Great information - thanks for taking the time to respond..Yes as both you and John Lahr have pointed out there are no simple answers, and the background required to understand some of these answers is not always at hand, but that makes it all the more interesting to learn. Larry Braile's website has some excellent information and I have bookmarked it. It's interesting looking at the different dissipation rates of surface and body waves and the science behind the differences. Thanks Again Bob _____ From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of ChrisAtUpw@....... Sent: Thursday, October 26, 2006 07:39 To: psn-l@.............. Subject: Re: Dissipation of Seismic Waves Hi Bob, The transmission can get quite complicated. I suggest that you visit Larry Braile's website and download 'seismic waves' and other introductory programs. Some of the programs are quite large. See http://web.ics.purdue.edu/~braile/

Hi Chris = –

 

Great information = – thanks for taking the time to respond……Yes as both you and = John Lahr have pointed out there are no simple answers, and the background = required to understand some of these answers is not always at hand, but that = makes it all the more interesting to learn.

 

Larry = Braile’s website has some excellent information and I have bookmarked = it.

 

It’s = interesting looking at the different dissipation rates of surface and body waves and = the science behind the differences.

 

Thanks = Again

 

Bob

 

 

From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of = ChrisAtUpw@.......
Sent: Thursday, October = 26, 2006 07:39
To: psn-l@..............
Subject: Re: Dissipation = of Seismic Waves

 

Hi Bob,

       The transmission can get quite complicated. I suggest that you visit Larry Braile's website and = download 'seismic waves' and other introductory programs. Some of the programs = are quite large. See http://web.ics.purdue.edu/~braile/


Subject: Re: My seismometer vault solution From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Thu, 26 Oct 2006 18:24:34 +0000 Hi all My geophone is now outside, in the hole, inside the bucket, filled with sand and wool type of materal to isolate the cultural noise. Unfortunal I didn't find anything to seal the hole in the bucket for the plastic pipe that I use, but the hole and the pipe are both exacly 20 mm and it is on the side. So I don't expect water to be able to go inside the bucket that way. If it does, well, then I have to do some repairs (and upgrades). For any suggestions, send them now becose I am going to finish up soon. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: My seismometer vault solution From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Thu, 26 Oct 2006 18:49:30 +0000 Hi all (agen) I have setup a picture gallery here, with some pictures from this installation. http://www.jonfr.com/myndir/v/eq/geophone/ Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: My seismometer vault solution From: John Popelish jpopelish@........ Date: Thu, 26 Oct 2006 17:57:04 -0400 J=F3n Fr=EDmann wrote: > Hi all >=20 > My geophone is now outside, in the hole, inside the bucket, filled with= > sand and wool type of materal to isolate the cultural noise. Unfortunal= > I didn't find anything to seal the hole in the bucket for the plastic > pipe that I use, but the hole and the pipe are both exacly 20 mm and it= > is on the side. So I don't expect water to be able to go inside the > bucket that way. If it does, well, then I have to do some repairs (and > upgrades). >=20 > For any suggestions, send them now becose I am going to finish up soon.= I think I would try to seal any joints with bathroom or=20 siding type silicone caulk. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: My seismometer vault solution From: ChrisAtUpw@....... Date: Thu, 26 Oct 2006 21:04:58 EDT In a message dated 2006/10/26, jonfr500@......... writes: > My geophone is now outside, in the hole, inside the bucket, filled with > sand and wool type of material to isolate the cultural noise. Unfortunately > I didn't find anything to seal the hole in the bucket for the plastic > pipe that I use, but the hole and the pipe are both exactly 20 mm and it > is on the side. So I don't expect water to be able to go inside the > bucket that way. If it does, well, then I have to do some repairs (and > upgrades). > > For any suggestions, send them now because I am going to finish up soon. Hi Jon, If you use plastic water pipe you can buy a 'tank' fitting with a rubber / plastic seal. You bore a hole in the lid and it bolts into place and onto the tube. Simple! Alternatively, you can use a 'cable gland' which will seal just the cable into the bucket lid. This would be my choice. Do you have a tight fitting lid for the bucket? If you go to a house painter / decorator, they will likely have old plastic containers with waterproof lids available free. The water / emulsion decorating paints come in them. It might be a good idea to use silicone rubber to seal the lid in place? You should use the variety which does NOT smell of acetic acid / vinegar. Alternatively, use either self amalgamating rubber tape or good quality PVC tape. You do have one of Larry's 3 axis geophones in a plastic case, don't you? http://psn.quake.net/geophone/index.html#L15B (12.6 cm OD by 7.3 cm high with 3 cm connectors on opposite sides) You may need to seal the lid on and seal the cable into the cable gland on the side. You may also need to plug the second cable lead in on the other side. It would be a good idea to put a packet of either silica gel crystals or of zeolite pellets inside the geophone case to absorb any moisture. Don't use any of the other dessicants - they may be corrosive (eg CaO, CaCl2) Regards, Chris Chapman In a me= ssage dated 2006/10/26, jonfr500@......... writes:

My geophone is now outside, in=20= the hole, inside the bucket, filled with
sand and wool type of material to isolate the cultural noise. Unfortunately<= BR> I didn't find anything to seal the hole in the bucket for the plastic
pipe that I use, but the hole and the pipe are both exactly 20 mm and it
is on the side. So I don't expect water to be able to go inside the
bucket that way. If it does, well, then I have to do some repairs (and
upgrades).

For any suggestions, send them now because I am going to finish up soon.

Hi Jon,

       If you use plastic water pipe you can b= uy a 'tank' fitting with a rubber / plastic seal. You bore a hole in the lid= and it bolts into place and onto the tube. Simple!
       Alternatively, you can use a 'cable gla= nd' which will seal just the cable into the bucket lid. This would be my cho= ice.
       Do you have a tight fitting lid for the= bucket? If you go to a house painter / decorator, they will likely have old= plastic containers with waterproof lids available free. The water / emulsio= n decorating paints come in them. It might be a good idea to use silicone ru= bber to seal the lid in place? You should use the variety which does NOT sme= ll of acetic acid / vinegar. Alternatively, use either self amalgamating rub= ber tape or good quality PVC tape.
       You do have one of Larry's 3 axis geoph= ones in a plastic case, don't you?  http://psn.quake.net/geophone/index= ..html#L15B (12.6 cm OD by 7.3 cm high with 3 cm connectors on opposite sides= ) You may need to seal the lid on and seal the cable into the cable gland on= the side. You may also need to plug the second cable lead in on the other s= ide. It would be a good idea to put a packet of either silica gel crystals o= r of zeolite pellets inside the geophone case to absorb any moisture. Don't=20= use any of the other dessicants - they may be corrosive (eg CaO, CaCl2)

       Regards,

       Chris Chapman Subject: Re: My seismometer vault solution From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 27 Oct 2006 12:30:15 +0000 Hi I got a silicon material that is waterproof and is intended to be used in bathrooms. I am using 4.5Hz geophone from Larry. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Channel strangeness From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 27 Oct 2006 15:07:42 +0000 Hi all I have noticed that the channels on the geophone downt show the same level of noise as I am execting. For instance, now is the North-south channel showing normal noise leve, also the vertical channel, but the east-west channel is relative quiet. Just before that the north-south channel was the quieter one. Far as I can tell, the cable is fine and properly connected. I did check the connection to the geophone (I use rc connection type of connect to the geophone, prior to that there is ~1m long cable from the geophone, that is also in good condision.) and it appears to be fine. Before I started to seal the seismomter vault better, all channels where showing simular level of noise. But now the east-west channel is completly flat. What might be the issue ? Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Dissipation of Seismic Waves From: Kim Barrow kimbarrow@....................... Date: Fri, 27 Oct 2006 08:39:53 -0700 (PDT) Bob Hancock wrote: v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} st1\:*{behavior:url(#default#ieooui) } Hi Chris – Great information – thanks for taking the time to respond……Yes as both you and John Lahr have pointed out there are no simple answers, and the background required to understand some of these answers is not always at hand, but that makes it all the more interesting to learn. Larry Braile’s website has some excellent information and I have bookmarked it. It’s interesting looking at the different dissipation rates of surface and body waves and the science behind the differences. Thanks Again Bob --------------------------------- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of ChrisAtUpw@....... Sent: Thursday, October 26, 2006 07:39 To: psn-l@.............. Subject: Re: Dissipation of Seismic Waves Hi Bob, The transmission can get quite complicated. I suggest that you visit Larry Braile's website and download 'seismic waves' and other introductory programs. Some of the programs are quite large. See http://web.ics.purdue.edu/~braile/

Bob Hancock <carpediem1@.........> wrote:
Hi Chris –
 
Great information – thanks for taking the time to respond……Yes as both you and John Lahr have pointed out there are no simple answers, and the background required to understand some of these answers is not always at hand, but that makes it all the more interesting to learn.
 
Larry Braile’s website has some excellent information and I have bookmarked it.
 
It’s interesting looking at the different dissipation rates of surface and body waves and the science behind the differences.
 
Thanks Again
 
Bob
 
 
From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of ChrisAtUpw@.......
Sent: Thursday, October 26, 2006 07:39
To: psn-l@webtronics.com
Subject: Re: Dissipation of Seismic Waves
 
Hi Bob,

       The transmission can get quite complicated. I suggest that you visit Larry Braile's website and download 'seismic waves' and other introductory programs. Some of the programs are quite large. See http://web.ics.purdue.edu/~braile/



Subject: Re: My seismometer vault solution From: ChrisAtUpw@....... Date: Fri, 27 Oct 2006 11:49:54 EDT In a message dated 2006/10/27, jonfr500@......... writes: > I got a silicon material that is waterproof and is intended to be used > in bathrooms Hi Jon, Please smell it. If it smells of acetic acid / vinegar, do you use it on your electronics. Acetic acid is likely to corrode it. There is another sort which has no small at all and is quite safe. Regards, Chric Chapman In a me= ssage dated 2006/10/27, jonfr500@......... writes:

I got a silicon material that i= s waterproof and is intended to be used
in bathrooms


Hi Jon,

       Please smell it. If it smells of acetic= acid / vinegar, do you use it on your electronics. Acetic acid is likely to= corrode it. There is another sort which has no small at all and is quite sa= fe.

       Regards,

       Chric Chapman Subject: Re: Channel strangeness From: geodynamics@....... Date: Fri, 27 Oct 2006 16:50:47 +0000 Jon, Get out the specifications for the geophones and look-up the coil and shunt (if installed) resistance. The coil should be 150, 240 or 380 ohms and the shunt may be 0, 4133, 2739, or 1992 ohms (per Larry Cochrane's posted specs). Remember, the resistances are in parallel so you'll have to do some number crunching to compute the theoretical resistance. Now disconnect the wires at the terminal board and, using a multimeter, check the resistance of the three geophones. If the resistance on the east-west sensor is zero then you've got a broken connection. If the resistance is substantially different from the specifications (your calculations and the other two geophones) then you've probably got a bad connection or a short. If the resistance is proper, then the east-west geophone is probably tilted off-axis (unlikely if the others are functioning properly). If you didn't solder your connections, you must do so or you will have recurring problems. Jon, what ever happened with the ground movement (landslide) that started to show-up at your folk's farm? Regards, -Tim- -------------- Original message from Jón Frímann : -------------- > Hi all > > I have noticed that the channels on the geophone downt show the same > level of noise as I am execting. For instance, now is the North-south > channel showing normal noise leve, also the vertical channel, but the > east-west channel is relative quiet. Just before that the north-south > channel was the quieter one. > > Far as I can tell, the cable is fine and properly connected. I did check > the connection to the geophone (I use rc connection type of connect to > the geophone, prior to that there is ~1m long cable from the geophone, > that is also in good condision.) and it appears to be fine. > > Before I started to seal the seismomter vault better, all channels where > showing simular level of noise. But now the east-west channel is > completly flat. > > What might be the issue ? > > Regards. > -- > Jón Frímann > http://www.jonfr.com > http://www.simnet.is/jonfr500/earthquake/ > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information.

Jon,

Get out the specifications for the geophones and look-up the coil and shunt (if installed) resistance. The coil should be 150, 240 or 380 ohms and the shunt may be 0, 4133, 2739, or 1992 ohms (per Larry Cochrane's posted specs). Remember, the resistances are in parallel so you'll have to do some number crunching to compute the theoretical resistance.

 

Now disconnect the wires at the terminal board and, using a multimeter, check the resistance of the three geophones. If the resistance on the east-west sensor is zero then you've got a broken connection. If the resistance is substantially different from the specifications (your calculations and the other two geophones) then you've probably got a bad connection or a short. If the resistance is proper, then the east-west geophone is probably tilted off-axis (unlikely if the others are functioning properly). If you didn't solder your connections, you must do so or you will have recurring problems.

 

Jon, what ever happened with the ground movement (landslide) that started to show-up at your folk's farm?

 

Regards,

-Tim-

-------------- Original message from Jón Frímann <jonfr500@.........>: --------------


> Hi all
>
> I have noticed that the channels on the geophone downt show the same
> level of noise as I am execting. For instance, now is the North-south
> channel showing normal noise leve, also the vertical channel, but the
> east-west channel is relative quiet. Just before that the north-south
> channel was the quieter one.
>
> Far as I can tell, the cable is fine and properly connected. I did check
> the connection to the geophone (I use rc connection type of connect to
> the geophone, prior to that there is ~1m long cable from the geophone,
> that is also in good condision.) and it appears to be fine.
>
> Before I started to seal the seismomter vault better, all channels where
> showing si mular level of noise. But now the east-west channel is
> completly flat.
>
> What might be the issue ?
>
> Regards.
> --
> Jón Frímann
> http://www.jonfr.com
> http://www.simnet.is/jonfr500/earthquake/
>
> __________________________________________________________
>
> Public Seismic Network Mailing List (PSN-L)
>
> To leave this list email PSN-L-REQUEST@.............. with
> the body of the message (first line only): unsubscribe
> See http://www.seismicnet.com/maillist.html for more information.
Subject: Re: Channel strangeness From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 27 Oct 2006 17:11:12 +0000 Hi I got the channel back to normal. I did just fill the hole and the east-west channel appears to have gone silent agen (sight). But there is a chanse that the channel is just saturated becose of the noise created when I did fill the hole. If not, then I am defently haveing some new issue that I need to short out. The channel appears to be correcting it self, according to my plot online. At least I think so. I do now belive that this problem lies in the rc plug that I use, I need to figure out a better way to connect the geophone to the main cable. The ground movement at my mom and dads farm doesn't appears to have moved anything since this summer. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Channel strangeness From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 27 Oct 2006 17:42:37 +0000 Hi all There is defently something wrong. :-( The east-west channel signal is weaker then the north-south channel signal or the vertical channel signal. It there, but it is weak. Is there any reason for this to happen, this started after I did put the geophone underground. I did test to jump near the sensor, in order to test the sensitivite, the files from that test can be found here. http://157.157.215.56/~jonfr/psn.file/ I really want to know what this is, so I can correct this issue. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Channel strangeness From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 27 Oct 2006 19:21:01 +0000 Hi all How does sensor failure appear in the 4.5Hz geophone ? Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Channel strangeness From: ChrisAtUpw@....... Date: Fri, 27 Oct 2006 16:58:19 EDT In a message dated 2006/10/27, jonfr500@......... writes: > How does sensor failure appear in the 4.5Hz geophone ? > Hi Jon, The most likely problem is the failure of a soldered joint giving an open circuit, a cable break giving an open circuit, or a melted cable insulation giving a short circuit. The L15B geophones that I bought from Larry were 380 Ohms. I needed to solder a 2.7 K Ohm resistors across them to give optimal damping. 1/380 + 1/2700 = 1/R = 1/333, hence putting a resistance meter on the end of the cable should read about 333 Ohms. When you bought the geophones, were they wired up with connecting cable, or did you have to fit one? I seem to remember you were using CAT5 cable? The main reason why I don't use this for geophones is that the wires are solid copper which can simply break when bent repeatedly. I use screened multicore which may have 7 or more small wires twisted together as the conductor. I use six core with a braided copper screen enclosing the bundle of wires. Were the damping resistors soldered across the geophone terminals in the plastic case, or did you have to do it? Use the resistance range on your meter to measure the resistances where the cables connect to your amplifier board. What are the readings? Remember that the 380 Ohm geophones have +/-5% tolerence ---> 361 to 399 Ohms. Regards, Chris Chapman In a me= ssage dated 2006/10/27, jonfr500@......... writes:

How does sensor failure appear=20= in the 4.5Hz geophone ?

Hi Jon,

       The most likely problem is the failure=20= of a soldered joint giving an open circuit, a cable break giving an open cir= cuit, or a melted cable insulation giving a short circuit.

       The L15B geophones that I bought from L= arry were 380 Ohms. I needed to solder a 2.7 K Ohm resistors across them to=20= give optimal damping.
       1/380 + 1/2700 =3D 1/R =3D 1/333, hence= putting a resistance meter on the end of the cable should read about 333 Oh= ms.

       When you bought the geophones, were the= y wired up with connecting cable, or did you have to fit one? I seem to reme= mber you were using CAT5 cable? The main reason why I don't use this for geo= phones is that the wires are solid copper which can simply break when bent r= epeatedly.
       I use screened multicore which may have= 7 or more small wires twisted together as the conductor. I use six core wit= h a braided copper screen enclosing the bundle of wires.

       Were the damping resistors soldered acr= oss the geophone terminals in the plastic case, or did you have to do it?
       Use the resistance range on your meter=20= to measure the resistances where the cables connect to your amplifier board.= What are the readings? Remember that the 380 Ohm geophones have +/-5% toler= ence ---> 361 to 399 Ohms.

       Regards,

       Chris Chapman Subject: Re: Channel strangeness From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 27 Oct 2006 21:11:19 +0000 Hi The problem appears to have been a simple one. The geophone got tilterd the wrong way. When I did test it inside it worked without a problem. So what did happen was that east-west channel got titled too far, same appalyes to the north-south channel. I was unaware of how tilt sensitive the geophones really are. I am going to start now to finish up and put the geophone back underground agen. But this time in such manner that it works properly. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: My seismometer vault solution From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 27 Oct 2006 21:14:25 +0000 Hi It smells, this I was able to get here is called, everbuild everflex premium+ 500, bath & sanitary silicon. The main problem with this is that it doesn't stick to a plastic, it comes right off it appears. It also needs 24 hours to dry. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: My seismometer vault solution From: ChrisAtUpw@....... Date: Fri, 27 Oct 2006 17:40:00 EDT In a message dated 2006/10/27, jonfr500@......... writes: > It smells, this I was able to get here is called, everbuild everflex > premium+ 500, bath & sanitary silicon. Hi Jon, You don't want this type. See if you can get Everbuild Everflex Premium Builders Silicone 450 (Product # Everbuild Everflex Premium Builders Silicone 450 Product #50101 Regards, Chris Chapman In a me= ssage dated 2006/10/27, jonfr500@......... writes:

It smells, this I was able to g= et here is called, everbuild everflex
premium+ 500, bath & sanitary silicon.


Hi Jon,

       You don't want this type.

       See if you can get Everbuild Everfle= x Premium Builders Silicone 450    (Product #
       Everbuild Everflex Premium Builders= Silicone 450 Product #50101

       Regards,

       Chris Chapman Subject: Re: My seismometer vault solution From: geodynamics@....... Date: Fri, 27 Oct 2006 22:21:57 +0000 Jon, I looked at your posted photos. There's a few things you should consider changing. 1. Eliminate the spliced connection (rc connectors?) and wire the cable directly to the geophones. 2. Completely seal the geophone housing. [For a sealant, look for GE Contractor Bath/Plumbing products, GE6040 (clear) and GE6070 (white). They are specifically formulated to be non-corrosive to metals.] 3. With the housing for the geophones sealed, the plastic bucket becomes far less important for keeping water out. In fact, because of the way you have the hose connected, I'd suggest that you dump the sand out of the bucket then drill or punch a series of 1-cm holes in the bottom. Install a piece of window screen on the bottom then add about 2 or 3-inches of coarse gravel (1 to 2-cm dia) then place another piece of screen. Now fill the bucket the rest of the way with your sand and install the geophone housing. Over a long period of time, particularly in your climate, you'll get condensate forming on the inside of the hose and it will eventually make its way to the plastic bucket. By poking holes in the bottom, excess moisture can excape. The gravel layer will break the capillary tension and minimize the amount of moisture held in the sand. After looking at some of your recent traces, it appears that you do not always turn off your acquisition system when you're moving or otherwise working on the geophones. As a matter of standard practice, you should always turn off the system (or at least disconnect the geophone cables) when moving things around. Even slight jostling of the geophones can generate a pretty strong signal -- well in excess of 10-volts -- that can over-saturate or even damage some DAC boards. Regards, -Tim- -------------- Original message from Jón Frímann : -------------- > Hi > > It smells, this I was able to get here is called, everbuild everflex > premium+ 500, bath & sanitary silicon. The main problem with this is > that it doesn't stick to a plastic, it comes right off it appears. It > also needs 24 hours to dry. > > Regards. > -- > Jón Frímann > http://www.jonfr.com > http://www.simnet.is/jonfr500/earthquake/ > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information.

Jon,

I looked at your posted photos. There's a few things you should consider changing.

 

1. Eliminate the spliced connection (rc connectors?) and wire the cable directly to the geophones.

 

2. Completely seal the geophone housing. [For a sealant, look for GE Contractor Bath/Plumbing products, GE6040 (clear) and GE6070 (white). They are specifically formulated to be non-corrosive to metals.]

 

3. With the housing for the geophones sealed, the plastic bucket becomes far less important for keeping water out. In fact, because of the way you have the hose connected, I'd suggest that you dump the sand out of the bucket then drill or punch a series of 1-cm holes in the bottom. Install a piece of window screen on the bottom then add about 2 or 3-inches of coarse gravel (1 to 2-cm dia) then place another piece of screen. Now fill the bucket the rest of the way with your sand and install the geophone housing.

 

Over a long period of time, particularly in your climate, you'll get condensate forming on the inside of the hose and it will eventually make its way to the plastic bucket. By poking holes in the bottom, excess moisture can excape. The gravel layer will break the capillary tension and minimize the amount of moisture held in the sand.

 

 

After looking at some of your recent traces, it appears that you do not always turn off your acquisition system when you're moving or otherwise working on the geophones. As a matter of standard practice, you should always turn off the system (or at least disconnect the geophone cables) when moving things around. Even slight jostling of the geophones can generate a pretty strong signal -- well in excess of 10-volts -- that can over-saturate or even damage some DAC boards.

 

Regards,

-Tim-

 

-------------- Original message from Jón Frímann <jonfr500@.........>: --------------


> Hi
>
> It smells, this I was able to get here is called, everbuild everflex
> premium+ 500, bath & sanitary silicon. The main problem with this is
> that it doesn't stick to a plastic, it comes right off it appears. It
> also needs 24 hours to dry.
>
> Regards.
> --
> Jón Frímann
> http://www.jonfr.com
> http://www.simnet.is/jonfr500/earthquake/
>
> __________________________________________________________
>
> Public Seismic Network Mailing List (PSN-L)
>
> To leave this list email PSN-L-REQUEST@.............. with
> the body of the message (first line only): unsubscribe
> See http://www.seismicnet.com/maillist.html for more information.
Subject: Re: My seismometer vault solution From: geodynamics@....... Date: Fri, 27 Oct 2006 22:27:40 +0000 Oops, make that ADC not DAC. -Tim-
Oops, make that ADC not DAC.
-Tim-
Subject: Re: My seismometer vault solution From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 27 Oct 2006 23:00:31 +0000 Hi Tim and everybody else. 1. I have removed the rca connections (I forgot a "a"), the geophone is now directly connected to my Amplifer board. The signal that I am getting at the moment is alot clearer then before (appears to be so). There is a wind now, and for some reasons it appears really clear on my plot at the moment. The noise level is quite hig at the moment. 2. The bucket is water proof, the only issue is the connection point between the pip and the bucket, I don't think it is going to be a problem. At least I hope so. I have sealed the end of the pip, hopefully both of them. 3. I can't do that at the moment, this setup is finised. But I will keep this in mind when I need to do a maintance. Thanks for the point about the voltage and the adc boards. I didn't know about this. I do not think that my adc board has sufferd any damage becose of too strong signal. At least everything appears to be displaying at normal levels at the moment. There is strong wind at the moment and the noise level appears to be hig. I even think that I see the ocen wave at 0.1Hz, at least there is a signal spike when I check the frequance chart in winquake. I did switch geophones, I had a other one around (was going to a second station, remote one). In order to check for bugs or possible failurs in the hardware I did switch the geophones from the one I have been using for the past 11 months. I did also change the wireing inside the box, I removed the rca plugs that I had been using. It takes me a little time to see if there is any change in signal and sensitivite of my system becose of this changes. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: My seismometer vault solution From: ChrisAtUpw@....... Date: Fri, 27 Oct 2006 19:16:05 EDT In a message dated 2006/10/27, geodynamics@....... writes: > Even slight jostling of the geophones can generate a pretty strong signal > -- well in excess of 10-volts -- that can over-saturate or even damage some > ADC boards. Hi Tim, Jon is using one of Larry's amplifiers. It has 12 V rails. If Jon does as you suggest and the whole area floods with snow melt water, melts and re freezes a few times, won't it likely damage the geophones? The climate in Iceland is chilly in winter. I would enclose them in a sealed container under dry sand. It is not difficult to seal cable into plastic water pipe. You can easily buy tank fittings for plastic water pipe to seal to a container. Can you check this message and see if there is a HTML attachment, please? Regards, Chris Chapman In a me= ssage dated 2006/10/27, geodynamics@....... writes:

Even slight jostling of the geo= phones can generate a pretty strong signal -- well in excess of 10-volts --=20= that can over-saturate or even damage some ADC boards.


Hi Tim,

       Jon is using one of Larry's amplifiers.= It has 12 V rails.

       If Jon does as you suggest and the whol= e area floods with snow melt water, melts and re freezes a few times, won't=20= it likely damage the geophones? The climate in Iceland is chilly in winter.=20= I would enclose them in a sealed container under dry sand. It is not difficu= lt to seal cable into plastic water pipe. You can easily buy tank fittings f= or plastic water pipe to seal to a container.

       Can you check this message and see if t= here is a HTML attachment, please?

       Regards,

       Chris Chapman Subject: Re: My seismometer vault solution From: geodynamics@....... Date: Sat, 28 Oct 2006 03:47:19 +0000 Chris, The meltwater and rain percolation are just the things I'm concerned about. It is much more efficient to seal the small housing of the geophones than it is to seal a plastic bucket lid and the access hole. As long as Jon gets rid of the external splices (1-meter pigtail coming out from the geophone case) the geophone case should be sufficiently sealed to easily withstand the local climate and long-term burial. If he chooses to leave the splices then all bets are off because he's probably left a channel for moistrue migration into the geophone case. Frankly, if it was mine, I wouldn't even bother with the plastic bucket. However, for Jon's installation the bucket does afford some additional protection, particularly when it comes time to dig it up again. I've had contless installations, both surface and subsurface for monitioring of both ground and structural vibrations. Many were in-place over a period of years using geophone cases very similar to the one Jon is using. The only problems we've had have occured when a subcontractor neglected to connect shield wires and, on the same job, just twisted wire splices instead of soldering them. We've never had a problem with moisture migration but we've always been careful to seal the cases with non-corrosive silicon sealant. One installation had triaxial sets about 20-feet below the groundwater level for over two years and they are still being used on other jobs, some 10-years later. Here in Michigan, we don't have the extremes that Iceland does but I'd suspect that we have more free ze-thaw cycles -- and that's what typically causes the greatest problems. Regards, -Tim- -------------- Original message from ChrisAtUpw@........ -------------- In a message dated 2006/10/27, geodynamics@....... writes: Even slight jostling of the geophones can generate a pretty strong signal -- well in excess of 10-volts -- that can over-saturate or even damage some ADC boards. Hi Tim, Jon is using one of Larry's amplifiers. It has 12 V rails. If Jon does as you suggest and the whole area floods with snow melt water, melts and re freezes a few times, won't it likely damage the geophones? The climate in Iceland is chilly in winter. I would enclose them in a sealed container under dry sand. It is not difficult to seal cable into plastic water pipe. You can easily buy tank fittings for plastic water pipe to seal to a container. Can you check this message and see if there is a HTML attachment, please? Regards, Chris Chapman

Chris,

The meltwater and rain percolation are just the things I'm concerned about. It is much more efficient to seal the small housing of the geophones than it is to seal a plastic bucket lid and the access hole. As long as Jon gets rid of the external splices (1-meter pigtail coming out from the geophone case) the geophone case should be sufficiently sealed to easily withstand the local climate and long-term burial. If he chooses to leave the splices then all bets are off because he's probably left a channel for moistrue migration into the geophone case.

 

Frankly, if it was mine, I wouldn't even bother with the plastic bucket. However, for Jon's installation the bucket does afford some additional protection, particularly when it comes time to dig it up again. I've had contless installations, both surface and subsurface for monitioring of both ground and structural vibrations. Many were in-place over a period of years using geophone cases very similar to the one Jon is using. The only problems we've had have occured when a subcontractor neglected to connect shield wires and, on the same job, just twisted wire splices instead of soldering them. We've never had a problem with moisture migration but we've always been careful to seal the cases with non-corrosive silicon sealant. One installation had triaxial sets about 20-feet below the groundwater level for over two years and they are still being used on other jobs, some 10-years later. Here in Michigan, we don't have the extremes that Iceland does but I 'd suspect that we have more freeze-thaw cycles -- and that's what typically causes the greatest problems.

Regards,

-Tim-
-------------- Original message from ChrisAtUpw@........ --------------

In a message dated 2006/10/27, geodynamics@....... writes:

Even slight jostling of the geophones can generate a pretty strong signal -- well in excess of 10-volts -- that can over-saturate or even damage some ADC boards.



Hi Tim,

       Jon is using one of Larry's amplifiers. It has 12 V rails.

       If Jon does as you suggest and the whole area floods with snow melt water, melts and re freezes a few times, won't it likely damage the geophones? The climate in Iceland is chilly in winter. I would enclose them in a sealed container under dry sand. It is not difficult to seal cable into plastic water pipe. You can easily buy tank fittings for plastic water pipe to seal to a container.

       Can you check this message and see if there is a HTML attachment, please?

       Regards,

       Chris Chapman
Subject: New sensor in use From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sat, 28 Oct 2006 09:04:38 +0000 Hi all Yesterday I did switch geophones and I did start to use a diffrent geophone that I did buy last summer. Based on the data so far, it appears that the geophone picks up the wind even if he is underground. I do not understand the reason why this happens. The geophone also picks up limited amount of noise from my block, but the distance from the house is ~8 meters. The depth down to the sensor is ~80 cm, that is why I am surpriced of seeing wind noise. I also did change the connections from the geophone and into the main cable, I now simply wire the wires together and I add a simple wire skrew with a plastic shield to make sure that the connection doesn't loosen up. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: My seismometer vault solution From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sat, 28 Oct 2006 13:45:11 +0000 Hi all Today there has been a lot of rain in my area. So far everything looks normal. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: New sensor in use From: "Bob Hancock" carpediem1@......... Date: Sat, 28 Oct 2006 07:30:05 -0700 Jon - You could be picking up ground movement initiated by movement of = buildings, trees, or anything else the wind strikes even though that object is = located at some distance from the sensor. I have the same problem in Arizona. = My sensor is over 25 m from my house, over 60 cm deep, and I see ground movement when the wind blows. It's very difficult to get away from = unless you go much deeper with your installation. Bob Hancock -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of J=F3n Fr=EDmann Sent: Saturday, October 28, 2006 02:05 To: PSN-Postlist Subject: New sensor in use Hi all Yesterday I did switch geophones and I did start to use a diffrent geophone that I did buy last summer. Based on the data so far, it appears that the geophone picks up the wind even if he is underground. I do not understand the reason why this happens. The geophone also picks up limited amount of noise from my block, but the distance from the house is ~8 meters. The depth down to the sensor is ~80 cm, that is why I am surpriced of seeing wind noise. I also did change the connections from the geophone and into the main cable, I now simply wire the wires together and I add a simple wire skrew with a plastic shield to make sure that the connection doesn't loosen up. Regards. --=20 J=F3n Fr=EDmann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: =?iso-8859-1?Q?J=F3n's_helicorder_web_site.?= From: John or Jan Lahr JohnJan@........ Date: Sat, 28 Oct 2006 09:31:16 -0700 J=F3n, You web page showing many PSN seismic records is=20 quite nice. You might want to add a link to this=20 page:=20 http://jclahr.com/science/psn/as1/heli/allas1.php=20 which shows the educational AS-1 records from stations run by teachers. Also, if any PSN member lives near one of the=20 schools that is running a seismic station, check=20 with the teacher about giving them a hand with=20 their instrument, helping with interpretation of=20 their seismograms, or giving a talk to their=20 class. I'm sure that they would appreciate=20 knowing someone else in the community who is interested in seismology. Cheers, John At 06:45 AM 10/28/2006, you wrote: >Hi all > >Today there has been a lot of rain in my area. So far everything looks >normal. > >Regards. >-- >J=F3n Fr=EDmann >http://www.jonfr.com >http://www.simnet.is/jonfr500/earthquake/ > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: New sensor in use From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sat, 28 Oct 2006 17:00:26 +0000 Hi There aren't many trees around me. But the noise is diffrent when the geophone is outside and underground then inside. But I don't think it is higer then from inside the house. However, I get rid of the indoor noise that was a problem for me. The wind has always been a problem and that isn't going away any time soon. Also car traffic. What might be a new noise source is when pepole pass by it. Since the block garden doesn't have any fense or trees etc. Besides that, everything looks fine. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: =?ISO-8859-1?Q?J=F3n's?= helicorder web site. From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sat, 28 Oct 2006 18:33:26 +0000 Hi John I will add this link to the webpage next time I update it. Thanks. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: My seismometer vault solution From: ChrisAtUpw@....... Date: Sat, 28 Oct 2006 19:14:32 EDT In a message dated 2006/10/28, geodynamics@....... writes: > The meltwater and rain percolation are just the things I'm concerned about. > It is much more efficient to seal the small housing of the geophones than it > is to seal a plastic bucket lid and the access hole. Hi Tim, I tend to use a belt + braces policy - two barriers are better than one. Also, you may need something for the geophone housing to sit on and dry sand is just fine. It is not too difficult to make a good seal to a plastic bucket with a clip on lid. You can easily buy tank connectors and plastic water pipe. Alternatively, waterproof cable gland seals are readily available. As long as Jon gets rid of the external splices (1-meter pigtail coming out from the > geophone case) the geophone case should be sufficiently sealed to easily > withstand the local climate and long-term burial. If he chooses to leave the > splices then all bets are off because he's probably left a channel for moisture > migration into the geophone case. The way that I deal with splices is to fit adhesive heatshrink to both the wires and to the main cable. You slide heatshrink over one end, solder the two wires, slide the heatshrink over the joint and shrink it onto both wire insulations. Then you join the other wires etc, slide the outer heatshrink over the bundle of joins and shrink it. This gives a waterproof seal. Adhesive heatshrink is a bit more expensive, but you don't need much of it - and it works fine! If you want added rigidity, you can use two overlapping heatshrink layers on the main cable. I prefer the alternative of replacing a short length of cable when possible. I strongly suggest using multicore cable with a woven copper screen. I don't like the CAT5 cable very much for this job - it has a single copper wire cores and usually no screen. It doesn't take many repeat bends for a wire to break - the copper is hard drawn. > Frankly, if it was mine, I wouldn't even bother with the plastic bucket. > However, for Jon's installation the bucket does afford some additional > protection, particularly when it comes time to dig it up again. I've had countless > installations, both surface and subsurface for monitoring of both ground and > structural vibrations. Many were in-place over a period of years using geophone > cases very similar to the one Jon is using. We've never had a problem with > moisture migration but we've always been careful to seal the cases with > non-corrosive silicon sealant. One installation had triaxial sets about 20-feet > below the groundwater level for over two years and they are still being used on > other jobs, some 10-years later. Here in Michigan, we don't have the extremes > that Iceland does but I 'd suspect that we have more freeze-thaw cycles -- > and that's what typically causes the greatest problems. For sealing the case, I use an adhesive mastic called BluTack or WhiteTack. I don't know if you can get an equivalent product. It is like a non drying slightly tacky putty and is sold in stationery shops etc for mounting posters to notice boards, to wallpaper.... any temporary job. It sticks well enough, but you can peel it off and it does not leave a mark. A rolled ring of this makes an excellent waterproof seal for a geophone case. You can demount the join, re roll the ring and use it again - unlike silicone rubber. If you use silicone rubber, it must be the variety which sets with no smell. The type which smells strongly of acetic acid / vinegar should NOT be used - it corrodes copper wire like fun. You can buy porous paper sachets containing silica gel in a range of sizes. Some may have a color indicator to tell you when they need to be baked to remove absorbed moisture. Placing a drying sachet inside the geophone case should prevent condensation problems. DON'T use lime or calcium chloride. An alternative method if you have a chest type of Deep Freezer, is to separately lower the lid and the case of the geophones slowly over a few minutes to the bottom of the freezer and assemble them there. So long as you don't 'stir it up', the air inside a chest freezer is cold and very dry - in spite of any ice on the sides. You have to be careful not to brush off any ice crystals into the geophone case during assembly. The temperature 20 feet below ground will be above freezing and nearly constant, summer and winter. Jon lives quite close to the shore in northern Iceland. I would expect the ground to freeze, to maybe over two feet down, but the surface temperature changes to be quite variable around zero - due to the ocean and the wind direction. The results of likely surface freeze / thaw cycles was concerning me. A sealed plastic drum part filled with dry sand should be OK. See climate links in http://www.vedur.is/english/ Regards, Chris Chapman In a me= ssage dated 2006/10/28, geodynamics@....... writes:

The meltwater and rain percolat= ion are just the things I'm concerned about. It is much more efficient to se= al the small housing of the geophones than it is to seal a plastic bucket li= d and the access hole.


Hi Tim,

       I tend to use a belt + braces policy -=20= two barriers are better than one. Also, you may need something for the geoph= one housing to sit on and dry sand is just fine.
       It is not too difficult to make a good=20= seal to a plastic bucket with a clip on lid. You can easily buy tank connect= ors and plastic water pipe. Alternatively, waterproof cable gland seals are=20= readily available.

As long as Jon gets rid of the external splices (1-meter pigtail coming out=20= from the
geophone case) the geophone ca= se should be sufficiently sealed to easily withstand the local climate and l= ong-term burial. If he chooses to leave the splices then all bets are off be= cause he's probably left a channel for moisture migration into the geophone=20= case.


       The way that I deal with splices is to= fit adhesive heatshrink to both the wires and to the main cable. You slide=20= heatshrink over one end, solder the two wires, slide the heatshrink over the= joint and shrink it onto both wire insulations. Then you join the other wir= es etc, slide the outer heatshrink over the bundle of joins and shrink it. T= his gives a waterproof seal. Adhesive heatshrink is a bit more expensive, bu= t you don't need much of it - and it works fine!  If you want added rig= idity, you can use two overlapping heatshrink layers on the main cable.
       I prefer the alternative of replacing a= short length of cable when possible. I strongly suggest using multicore cab= le with a woven copper screen. I don't like the CAT5 cable very much for thi= s job - it has a single copper wire cores and usually no screen. It doesn't=20= take many repeat bends for a wire to break - the copper is hard drawn. =

Frankly, if it was mine, I wou= ldn't even bother with the plastic bucket. However, for Jon's installation t= he bucket does afford some additional protection, particularly when it comes= time to dig it up again. I've had countless installations, both surface and= subsurface for monitoring of both ground and structural vibrations. Many we= re in-place over a period of years using geophone cases very similar to the=20= one Jon is using. We've never had a problem with moisture migration but we'v= e always been careful to seal the cases with non-corrosive silicon sealant.=20= One installation had triaxial sets about 20-feet below the groundwater level= for over two years and they are still being used on other jobs, some 10-yea= rs later. Here in Michigan, we don't have the extremes that Iceland does but= I 'd suspect that we have more freeze-thaw cycles -- and that's what typica= lly causes the greatest problems.


       For sealing the case, I use an adhesive= mastic called BluTack or WhiteTack. I don't know if you can get an equivale= nt product. It is like a non drying slightly tacky putty and is sold in stat= ionery shops etc for mounting posters to notice boards, to wallpaper.... any= temporary job. It sticks well enough, but you can peel it off and it does n= ot leave a mark. A rolled ring of this makes an excellent waterproof seal fo= r a geophone case. You can demount the join, re roll the ring and use it aga= in - unlike silicone rubber. If you use silicone rubber, it must be the vari= ety which sets with no smell. The type which smells strongly of acetic acid=20= / vinegar should NOT be used - it corrodes copper wire like fun.
       You can buy porous paper sachets contai= ning silica gel in a range of sizes. Some may have a color indicator to tell= you when they need to be baked to remove absorbed moisture. Placing a dryin= g sachet inside the geophone case should prevent condensation problems. = ; DON'T use lime or calcium chloride. An alternative method if you have a ch= est type of Deep Freezer, is to separately lower the lid and the case of the= geophones slowly over a few minutes to the bottom of the freezer and assemb= le them there. So long as you don't 'stir it up', the air inside a chest fre= ezer is cold and very dry - in spite of any ice on the sides. You have to be= careful not to brush off any ice crystals into the geophone case during ass= embly.
       The temperature 20 feet below ground wi= ll be above freezing and nearly constant, summer and winter. Jon lives quite= close to the shore in northern Iceland. I would expect the ground to freeze= , to maybe over two feet down, but the surface temperature changes to be qui= te variable around zero - due to the ocean and the wind direction. The resul= ts of likely surface freeze / thaw cycles was concerning me. A sealed plasti= c drum part filled with dry sand should be OK.
       See climate links in http://www.vedur.i= s/english/

       Regards,

       Chris Chapman Subject: Re: My seismometer vault solution From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sun, 29 Oct 2006 19:20:06 +0000 Hi all Yesterday it was raining a quite lot. But everything looks fine at this moment. I don't see anything pointing to that the bucket is leaking. The ground titls a little bit down where the geophone is, so the flow of the water is down. The real test comes when the snow arrives and leaves. Noise levels are good, better then I did expect, but I haven't seen everything yet. So I don't know how this looks in the long term. Sensitivite appears to be good, if I can use the local noise a guide. There hasn't been a earthquake that I can use to check, yet anyway. It has started to freeze agen, so I might see frostearthquakes soon, small spikes that happen when the ground freezes, the geologist at Icelandic Met office told me about them, I am going to look out for them when freezing happens. I didn't seal the geophone where the cable comes out, if water gets in I don't think that anything is going to stop it anyway from reaching the internals of the geophone. I also expect to see it farly quickly if that happens. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: First earthquakes detected From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Mon, 30 Oct 2006 15:47:33 +0000 Hi all My first earthquakes since I did move my geophone outside have been detected. Check the psn file list for the trace. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Amaseis From: "Randy" rpratt@............. Date: Tue, 31 Oct 2006 17:25:49 -0600 Hi, I finally have my instrument up and running again to an extent. I have = converted to the Dataq 154RS and Amaseis. I have some questions on = Amaseis and my results. First is I expected and set a zero level of = 2048 from the 12 bits. On my display the data value shows as 30800 = approximately. In Windaq the trace runs very close to zero voltage and = is not offset significantly. Next, on the helicorder display I get = large spikes and about 2 minutes of missing data on each hour. If I = extract an event across the hour the event does not show the spikes. It = seems to be only the helicorder view. A screen shot can be seen at = http://mit.midco.net/rpratt/. The helicorder image is the only relevant = content on the page. =20 Randy
Hi,
 
I finally have my instrument up and = running=20 again to an extent.  I have converted to the Dataq 154RS and=20 Amaseis.  I have some questions on Amaseis and my results.  = First is I=20 expected and set a zero level of 2048 from the 12 bits.  On my = display=20 the data value shows as 30800 approximately.  In Windaq the trace = runs very=20 close to zero voltage and is not offset significantly.  Next, on = the=20 helicorder display I get large spikes and about 2 minutes of missing = data on=20 each hour.  If I extract an event across the hour the event does = not show=20 the spikes.  It seems to be only the helicorder view.  A = screen shot=20 can be seen at http://mit.midco.net/rpratt/.&n= bsp; The=20 helicorder image is the only relevant content on the page.  =
 
Randy
Subject: Re: Amaseis From: ChrisAtUpw@....... Date: Tue, 31 Oct 2006 19:08:16 EST In a message dated 2006/10/31, rpratt@............. writes: > finally have my instrument up and running again to an extent. I have > converted to the Dataq 154RS and Amaseis. I have some questions on Amaseis and > my results. First is I expected and set a zero level of 2048 from the 12 > bits. On my display the data value shows as 30800 approximately. Hi Randy, Sounds like it is reading a 16 bit value? Is AmaSeis selected for the DI-154? Try inputting a zero of 32768? Regards, Chris Chapman In a me= ssage dated 2006/10/31, rpratt@............. writes:

finally have my instrument up=20= and running again to an extent.  I have converted to the Dataq 154RS an= d Amaseis.  I have some questions on Amaseis and my results.  Firs= t is I expected and set a zero level of 2048 from the 12 bits.  On my d= isplay the data value shows as 30800 approximately.


Hi Randy,

       Sounds like it is reading a 16 bit valu= e? Is AmaSeis selected for the DI-154? Try inputting a zero of  32768?=20=

       Regards,

       Chris Chapman Subject: Re: My seismometer vault solution From: "Geoffrey" gmvoeth@........... Date: Tue, 31 Oct 2006 21:12:18 -0700 Hello; What about the calibration of the instrument itself ? Will the instrument/sensor be adjusted properly in the temp range it will operate ? Regards; geoff ----- Original Message ----- From: To: Sent: Friday, October 27, 2006 4:16 PM Subject: Re: My seismometer vault solution > In a message dated 2006/10/27, geodynamics@....... writes: > >> Even slight jostling of the geophones can generate a pretty strong signal >> -- well in excess of 10-volts -- that can over-saturate or even damage some >> ADC boards. > > Hi Tim, > > Jon is using one of Larry's amplifiers. It has 12 V rails. > > If Jon does as you suggest and the whole area floods with snow melt > water, melts and re freezes a few times, won't it likely damage the geophones? > The climate in Iceland is chilly in winter. I would enclose them in a sealed > container under dry sand. It is not difficult to seal cable into plastic water > pipe. You can easily buy tank fittings for plastic water pipe to seal to a > container. > > Can you check this message and see if there is a HTML attachment, > please? > > Regards, > > Chris Chapman > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: My seismometer vault solution From: ChrisAtUpw@....... Date: Wed, 1 Nov 2006 00:10:58 EST In a message dated 2006/11/01, gmvoeth@........... writes: > What about the calibration of the instrument itself ? > > Will the instrument/sensor be adjusted properly > in the temp range it will operate ? Hi Geoff, I would not expect the sensitivity to change more than a few % with temperature. I do not have to operating range for a L15B, but typcial operation of geophones may be from -20 F to 160F. If you dig a nice cosy hole for it, you won't see any temperature extremes. Regards, Chris Chapman In a me= ssage dated 2006/11/01, gmvoeth@........... writes:

What about the calibration of t= he instrument itself ?

Will the instrument/sensor be adjusted properly
in the temp range it will operate ?


Hi Geoff,

       I would not expect the sensitivity to c= hange more than a few % with temperature.

       I do not have to operating range for a=20= L15B, but typcial operation of geophones may be from -20 F to 160F. If you d= ig a nice cosy hole for it, you won't see any temperature extremes.

       Regards,

       Chris Chapman Subject: Re: Amaseis From: John or Jan Lahr JohnJan@........ Date: Tue, 31 Oct 2006 22:00:46 -0800 I believe AmaSeis does some averaging when used with a Dataq 154RS ADC, so the precision is greater than 12 bits. 2^15 is 32768, so that's half way to the maximum for a 16-bit number. Cheers, John At 04:08 PM 10/31/2006, you wrote: >In a message dated 2006/10/31, rpratt@............. writes: > >>finally have my instrument up and running again to an extent. I >>have converted to the Dataq 154RS and Amaseis. I have some >>questions on Amaseis and my results. First is I expected and set a >>zero level of 2048 from the 12 bits. On my display the data value >>shows as 30800 approximately. > > >Hi Randy, > > Sounds like it is reading a 16 bit value? Is AmaSeis > selected for the DI-154? Try inputting a zero of 32768? > > Regards, > > Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Amaseis From: ChrisAtUpw@....... Date: Wed, 1 Nov 2006 01:17:50 EST In a message dated 2006/10/31, rpratt@............. writes: > I finally have my instrument up and running again to an extent. I have > converted to the Dataq 154RS and Amaseis. I have some questions on Amaseis and > my results. First is I expected and set a zero level of 2048 from the 12 > bits. On my display the data value shows as 30800 approximately Hi Randy, After starting the computer and the AmaSeis program, click on Settings at the top left hand corner, click on Com Port and reset it if necessary. Click on Settings, click on Device, select the DATQ154 option and click OK. Click on Settings, short circuit the input to the DI-154RS (CH1 and Gnd), disconnecting / switching off your amplifier if necessary, click on Read Data Value and note the number. You do need to short circuit the ADC input terminals - it draws / gives out current. Click on Settings, click on Set zero level, delete the figure displayed (2048?), enter this figure and then click OK. My DI-154RS gives a zero at 32640 instead of 32768 - 2^15 - but for $39, who cares? Go to the other options in settings and enter any relevant data. Hope that this helps, Chris Chapman In a me= ssage dated 2006/10/31, rpratt@............. writes:

I finally have my instrument up= and running again to an extent.  I have converted to the Dataq 154RS a= nd Amaseis.  I have some questions on Amaseis and my results.  Fir= st is I expected and set a zero level of 2048 from the 12 bits.  On my=20= display the data value shows as 30800 approximately


Hi Randy,

       After starting the computer and the Ama= Seis program, click on Settings at the top left hand corner, click on Com Po= rt and reset it if necessary.

       Click on Settings, click on Device, sel= ect the DATQ154 option and click OK.

       Click on Settings, short circuit the in= put to the DI-154RS (CH1 and Gnd), disconnecting / switching off your amplif= ier if necessary, click on Read Data Value and note the number. You do need=20= to short circuit the ADC input terminals - it draws / gives out current.

       Click on Settings, click on Set zero le= vel, delete the figure displayed (2048?), enter this figure and then click O= K.

       My DI-154RS gives a zero at 32640 inste= ad of 32768 - 2^15 - but for $39, who cares?

       Go to the other options in settings and= enter any relevant data.

       Hope that this helps,

       Chris Chapman Subject: Re: My seismometer vault solution From: "Geoffrey" gmvoeth@........... Date: Wed, 1 Nov 2006 01:13:42 -0700 Hi Chris; There is this cave in tucson and i think it is always 65F all year round but do not know how deep it is. Regards; geoff ----- Original Message ----- From: To: Sent: Tuesday, October 31, 2006 10:10 PM Subject: Re: My seismometer vault solution > In a message dated 2006/11/01, gmvoeth@........... writes: > >> What about the calibration of the instrument itself ? >> >> Will the instrument/sensor be adjusted properly >> in the temp range it will operate ? > > Hi Geoff, > > I would not expect the sensitivity to change more than a few % with > temperature. > > I do not have to operating range for a L15B, but typcial operation of > geophones may be from -20 F to 160F. If you dig a nice cosy hole for it, you > won't see any temperature extremes. > > Regards, > > Chris Chapman > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: My seismometer vault solution From: "Geoffrey" gmvoeth@........... Date: Wed, 1 Nov 2006 05:06:24 -0700 Hello All; These are some speculations into making a good geophone installation. I looked further into the clossal caves of Tucson Arizona USA and this is what i found: "Today visitors take a fifty-minute, one-half mile guided tour down six stories into Colossal Cave to see the beautiful formations." It seems that to get a stable temp of 70F at 90% to 100% RH you need to be about 6 stories underground. I am not sure what a story is but if it is 15 feet then thats about 100Feet underground. I was there for a visit many years ago and got very ill after vacationing there I think those caves when they are full of people are little more then vectors for diseases. If I could i would bore a 6inch hole 50 feet to 100 feet deep then somehow place my geophone there. Otherwise I would isolate the geophone with very good insulation and moisture protection on a tripod of metal stakes driven into the base of the hole with a ceramic tile glued with liquid nails or something. Try to vibrationally isolate the body of the geophone from the sides of the hole. It seems to me a proper installation is not really possible for the average person. It is too expensive. Have you ever seen a geophone that is resistant to higher freq vibrations by being placed on a foam like material instead of hard ground ??? Such a thing might if it can be adjusted right might reduce higher freq noise without affecting the range we desire to look at ?? Sort of like the submarine makers isolating moving machinery from the hull etc... The sound radiation is reduced but the item/machinery still travels with the sub whose motions are relatively slower then the vibrations. Regards; geoff __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: My seismometer vault solution From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Wed, 01 Nov 2006 13:55:19 +0000 Hi all My solution appears to be working good. I have recorded earthquakes already and the sensitvitie appears to be really good. I am even able to detect small earthquakes at the distance of ~220 km. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Mag 5 earthquake in Iceland From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Wed, 01 Nov 2006 14:16:21 +0000 Hi all At 13:55 there was a earthquake with size 5.0ML near a small island called Flatey. It problay was a larger then plemary resaults show. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: My seismometer vault solution From: "Timothy Carpenter" geodynamics@....... Date: Wed, 1 Nov 2006 11:01:49 -0500 Chris, There was no HTML attachment associated with you message. What did we = miss? -Tim- =20 -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of ChrisAtUpw@....... Sent: Friday, October 27, 2006 7:16 PM To: psn-l@.............. Subject: Re: My seismometer vault solution =20 In a message dated 2006/10/27, geodynamics@....... writes: Even slight jostling of the geophones can generate a pretty strong = signal -- well in excess of 10-volts -- that can over-saturate or even damage some = ADC boards. Hi Tim, Jon is using one of Larry's amplifiers. It has 12 V rails. If Jon does as you suggest and the whole area floods with snow = melt water, melts and re freezes a few times, won't it likely damage the geophones? The climate in Iceland is chilly in winter. I would enclose = them in a sealed container under dry sand. It is not difficult to seal cable = into plastic water pipe. You can easily buy tank fittings for plastic water = pipe to seal to a container.=20 Can you check this message and see if there is a HTML attachment, please? Regards, Chris Chapman

Chris,

There was no HTML attachment = associated with you message. What did we miss?

-Tim-

 

-----Original = Message-----
From: = psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of ChrisAtUpw@.......
Sent: Friday, October 27, = 2006 7:16 PM
To: psn-l@..............=
Subject: Re: My = seismometer vault solution

 

In a message dated = 2006/10/27, geodynamics@....... writes:


Even slight jostling of the geophones can generate a pretty strong signal -- well in excess of = 10-volts -- that can over-saturate or even damage some ADC boards.



Hi Tim,

       Jon is using one of Larry's = amplifiers. It has 12 V rails.

       If Jon does as you suggest and the = whole area floods with snow melt water, melts and re freezes a few times, = won't it likely damage the geophones? The climate in Iceland is chilly in winter. = I would enclose them in a sealed container under dry sand. It is not = difficult to seal cable into plastic water pipe. You can easily buy tank fittings for plastic water pipe to seal to a container.

       Can you check this message and see = if there is a HTML attachment, please?

       Regards,

       Chris Chapman

Subject: Calculating magnitude correction for winsdr / winquake ? From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Wed, 01 Nov 2006 23:36:55 +0000 Hi Is there any good howto on how I can calculate magcorrection for winsdr and winquake ? Thanks. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Calculating magnitude correction for winsdr / winquake ? From: ChrisAtUpw@....... Date: Wed, 1 Nov 2006 21:44:54 EST In a message dated 2006/11/01, jonfr500@......... writes: > Is there any good how to on how I can calculate mag correction for winsdr > and winquake? Hi Jon, You at least need the amplitudes of the P or S waves. Sorry, but your 4.5 Hz geophones are unlikely to give you a good estimate of this. Regards, Chris Chapman In a me= ssage dated 2006/11/01, jonfr500@......... writes:

Is there any good how to on how= I can calculate mag correction for winsdr
and winquake?


Hi Jon,

       You at least need the amplitudes of the= P or S waves. Sorry, but your 4.5 Hz geophones are unlikely to give you a g= ood estimate of this.

       Regards,

       Chris Chapman Subject: Re: Calculating magnitude correction for winsdr / winquake ? From: Larry Cochrane lcochrane@.............. Date: Wed, 01 Nov 2006 23:44:29 -0800 Hi Jón, I have some information here http://www.seismicnet.com/wqdocs/calcmag.html on how WinQuake calculates magnitude. WinSDR does not calculate magnitude, it just supplies information about the sensor in the event file so programs like WinQuake can calculate the magnitude of the event. Regards, Larry Cochrane Redwood City, PSN Jón Frímann wrote: > Hi > > Is there any good howto on how I can calculate magcorrection for winsdr > and winquake ? > > Thanks. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: My seismometer vault solution From: ChrisAtUpw@....... Date: Thu, 2 Nov 2006 03:11:27 EST In a message dated 2006/11/01, gmvoeth@........... writes: > These are some speculations into making a good geophone installation. > I looked further into the clossal caves of > Tucson Arizona USA and this is what i found: > "Today visitors take a fifty-minute, one-half mile guided tour down six > stories into Colossal Cave to see the beautiful formations." > > It seems that to get a stable temp of 70F at 90% to 100% RH you need to be > about 6 stories underground. I am not sure what a story is but if it is 15 > feet then thats about 100 Feet underground. > If I could i would bore a 6inch hole 50 feet to 100 feet deep then somehow > place my geophone there. > > Otherwise I would isolate the geophone with very good insulation and > moisture protection on a tripod of metal stakes driven into the base of the hole > with a ceramic tile glued with liquid nails or something. Try to vibrationally > isolate the body of the geophone from the sides of the hole. You want the geophone to be in very good contact with the ground. > It seems to me a proper installation is not really possible for the average > person. > It is too expensive. Do some 'vertical thinking'? Hire an auger, preferably motorised, to dig a hole maybe 6ft or a bit more deep, install a plastic drain pipe already containing the seismometer with sealed ends. Then backfill with slurry around the pipe? This won't get you away from surface vibrations entirely, but it should help reduce the wind noise? Looking at published noise data, you may need to get to over 100 m to really get away from surface noise. That is a long way down. > Have you ever seen a geophone that is resistant to higher freq > vibrations by being placed on a foam like material instead of hard ground ? No. You don't usually bother. You rely on a fairly linear axial sensor response, a low cross response and electronic low pass filters. I suspect that you would have problems getting full vertical sensitivity just over the range that you want. And it would need to be fairly independant of temperature effects. > Such a thing might if it can be adjusted right might reduce higher freq > noise without affecting the range we desire to look at ? I don't know when / where this has been a problem? Have you had problems of this sort? > Sort of like the submarine makers isolating moving machinery from the > hull etc... > The sound radiation is reduced but the item / machinery still travels with > the sub whose motions are relatively slower then the vibrations. But in a submarine you want to isolate all vibrations, not just selectively the high frequency ones. Building high performance mechanical low pass filters might not be too easy? Regards, Chris Chapman In a me= ssage dated 2006/11/01, gmvoeth@........... writes:

These are some speculations int= o making a good geophone installation.
I looked further into the clossal caves of
Tucson Arizona USA and this is what i found:
"Today visitors take a fifty-minute, one-half mile guided tour down six stor= ies into Colossal Cave to see the beautiful formations."

It seems that to get a stable temp of 70F at 90% to 100% RH you need to be a= bout 6 stories underground. I am not sure what a story is but if it is 15 fe= et then thats about 100 Feet underground.
If I could i would bore a 6inch hole 50 feet to 100 feet deep then somehow p= lace my geophone there.

Otherwise I would isolate the geophone with very good insulation and moistur= e protection on a tripod of metal stakes driven into the base of the hole wi= th a ceramic tile glued with liquid nails or something. Try to vibrationally= isolate the body of the geophone from the sides of the hole.

       You want the geophone to be in very go= od contact with the ground.

It seems to me a proper install= ation is not really possible for the average person.
It is too expensive.


       Do some 'vertical thinking'? Hire an a= uger, preferably motorised, to dig a hole maybe 6ft or a bit more deep, inst= all a plastic drain pipe already containing the seismometer with sealed ends= .. Then backfill with slurry around the pipe? This won't get you away from su= rface vibrations entirely, but it should help reduce the wind noise? Looking= at published noise data, you may need to get to over 100 m to really get aw= ay from surface noise. That is a long way down.

    Have you eve= r seen a geophone that is resistant to higher freq vibrations by being place= d on a foam like material instead of hard ground ?


       No. You don't usually bother. You rely= on a fairly linear axial sensor response, a low cross response and electron= ic low pass filters. I suspect that you would have problems getting full ver= tical sensitivity just over the range that you want. And it would need to be= fairly independant of temperature effects.

    Such a thing= might if it can be adjusted right might reduce higher freq noise without af= fecting the range we desire to look at ?


    I don't know when / where this has been a problem? Have=20= you had problems of this sort?

    Sort of lik= e the submarine makers isolating moving machinery from the hull etc...
The sound radiation is reduced but the item / machinery still travels with t= he sub whose motions are relatively slower then the vibrations.
=

       But in a submarine you want to isolate=20= all vibrations, not just selectively the high frequency ones. Building high=20= performance mechanical low pass filters might not be too easy?

       Regards,

       Chris Chapman Subject: Re: My seismometer vault solution From: ChrisAtUpw@....... Date: Thu, 2 Nov 2006 03:11:27 EST In a message dated 2006/11/01, gmvoeth@........... writes: > These are some speculations into making a good geophone installation. > I looked further into the clossal caves of > Tucson Arizona USA and this is what i found: > "Today visitors take a fifty-minute, one-half mile guided tour down six > stories into Colossal Cave to see the beautiful formations." > > It seems that to get a stable temp of 70F at 90% to 100% RH you need to be > about 6 stories underground. I am not sure what a story is but if it is 15 > feet then thats about 100 Feet underground. > If I could i would bore a 6inch hole 50 feet to 100 feet deep then somehow > place my geophone there. > > Otherwise I would isolate the geophone with very good insulation and > moisture protection on a tripod of metal stakes driven into the base of the hole > with a ceramic tile glued with liquid nails or something. Try to vibrationally > isolate the body of the geophone from the sides of the hole. You want the geophone to be in very good contact with the ground. > It seems to me a proper installation is not really possible for the average > person. > It is too expensive. Do some 'vertical thinking'? Hire an auger, preferably motorised, to dig a hole maybe 6ft or a bit more deep, install a plastic drain pipe already containing the seismometer with sealed ends. Then backfill with slurry around the pipe? This won't get you away from surface vibrations entirely, but it should help reduce the wind noise? Looking at published noise data, you may need to get to over 100 m to really get away from surface noise. That is a long way down. > Have you ever seen a geophone that is resistant to higher freq > vibrations by being placed on a foam like material instead of hard ground ? No. You don't usually bother. You rely on a fairly linear axial sensor response, a low cross response and electronic low pass filters. I suspect that you would have problems getting full vertical sensitivity just over the range that you want. And it would need to be fairly independant of temperature effects. > Such a thing might if it can be adjusted right might reduce higher freq > noise without affecting the range we desire to look at ? I don't know when / where this has been a problem? Have you had problems of this sort? > Sort of like the submarine makers isolating moving machinery from the > hull etc... > The sound radiation is reduced but the item / machinery still travels with > the sub whose motions are relatively slower then the vibrations. But in a submarine you want to isolate all vibrations, not just selectively the high frequency ones. Building high performance mechanical low pass filters might not be too easy? Regards, Chris Chapman In a me= ssage dated 2006/11/01, gmvoeth@........... writes:

These are some speculations int= o making a good geophone installation.
I looked further into the clossal caves of
Tucson Arizona USA and this is what i found:
"Today visitors take a fifty-minute, one-half mile guided tour down six stor= ies into Colossal Cave to see the beautiful formations."

It seems that to get a stable temp of 70F at 90% to 100% RH you need to be a= bout 6 stories underground. I am not sure what a story is but if it is 15 fe= et then thats about 100 Feet underground.
If I could i would bore a 6inch hole 50 feet to 100 feet deep then somehow p= lace my geophone there.

Otherwise I would isolate the geophone with very good insulation and moistur= e protection on a tripod of metal stakes driven into the base of the hole wi= th a ceramic tile glued with liquid nails or something. Try to vibrationally= isolate the body of the geophone from the sides of the hole.

       You want the geophone to be in very go= od contact with the ground.

It seems to me a proper install= ation is not really possible for the average person.
It is too expensive.


       Do some 'vertical thinking'? Hire an a= uger, preferably motorised, to dig a hole maybe 6ft or a bit more deep, inst= all a plastic drain pipe already containing the seismometer with sealed ends= .. Then backfill with slurry around the pipe? This won't get you away from su= rface vibrations entirely, but it should help reduce the wind noise? Looking= at published noise data, you may need to get to over 100 m to really get aw= ay from surface noise. That is a long way down.

    Have you eve= r seen a geophone that is resistant to higher freq vibrations by being place= d on a foam like material instead of hard ground ?


       No. You don't usually bother. You rely= on a fairly linear axial sensor response, a low cross response and electron= ic low pass filters. I suspect that you would have problems getting full ver= tical sensitivity just over the range that you want. And it would need to be= fairly independant of temperature effects.

    Such a thing= might if it can be adjusted right might reduce higher freq noise without af= fecting the range we desire to look at ?


    I don't know when / where this has been a problem? Have=20= you had problems of this sort?

    Sort of lik= e the submarine makers isolating moving machinery from the hull etc...
The sound radiation is reduced but the item / machinery still travels with t= he sub whose motions are relatively slower then the vibrations.
=

       But in a submarine you want to isolate=20= all vibrations, not just selectively the high frequency ones. Building high=20= performance mechanical low pass filters might not be too easy?

       Regards,

       Chris Chapman Subject: Re: Calculating magnitude correction for winsdr / winquake ? From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Thu, 02 Nov 2006 15:54:03 +0000 Hi I do think this has worked. I used the M 4.17 event yesterday to calculate the mag corrention. For that event it did show ML 4.2, for other events it was either about the correct size or alot smaller. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Calculating magnitude correction for winsdr / winquake ? From: "Stephen Hammond" shammon1@............. Date: Thu, 2 Nov 2006 11:41:54 -0800 HI, I've come to the realization that this value will never be 100% for each event. I suggest that you try building a table and collect ML values which can be compared to the three dimensions N/S/Z in your system. Each domain will be different. In Winquake under the Display/modify sensor information enter a value that causes your computed ML value to equal the reported then record this for future reference. For example, the Aptos, CA Z HS10 geophone is set to .0004, the N is .0007 and the E is .0005. Continue gathering data until you find a value the provides the best average yielding the best result. Once you have developed a meaningful correction value, move to SDR and update the MAG correction value so that it is appended to the event file. Keep in mind, if you change the gain in your amps, you need to tweak the value in the sensor information. Regards, Steve Hammond PSN San Jose, Aptos CA -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of Jón Frímann Sent: Thursday, November 02, 2006 7:54 AM To: psn-l@.............. Subject: Re: Calculating magnitude correction for winsdr / winquake ? Hi I do think this has worked. I used the M 4.17 event yesterday to calculate the mag corrention. For that event it did show ML 4.2, for other events it was either about the correct size or alot smaller. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Geophone source From: "Jack Ivey" ivey@.......... Date: Thu, 2 Nov 2006 15:19:32 -0500 Hi all, Anyone know of a source of cheap 10 Hz or better geophones or geophone=20 cartridges? There's a guy selling kits including a cartridge and=20 display board on Ebay for $26+$8, but I was holding out for even less. =20 I was interested in 8 or so. I think All Electronics used to have some but they're not in their catalog anymore. Thanks, Jack __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Geophone source From: "Jerry Payton" gpayton880@....... Date: Thu, 2 Nov 2006 14:24:27 -0600 You might check out http://www.rtclark.com/ . Regards, Jerry Payton ----- Original Message ----- From: Jack Ivey To: psn-l@.............. Sent: Thursday, November 02, 2006 2:19 PM Subject: Geophone source Hi all, Anyone know of a source of cheap 10 Hz or better geophones or geophone cartridges? There's a guy selling kits including a cartridge and display board on Ebay for $26+$8, but I was holding out for even less. I was interested in 8 or so. I think All Electronics used to have some but they're not in their catalog anymore. Thanks, Jack __________________________________________________________ Public Seismic Network Mailing List (PSN-L) To leave this list email PSN-L-REQUEST@.............. with the body of the message (first line only): unsubscribe See http://www.seismicnet.com/maillist.html for more information.
You might check out  http://www.rtclark.com/  = ..
 
Regards,
Jerry Payton
----- Original Message -----
From:=20 Jack = Ivey
Sent: Thursday, November 02, = 2006 2:19=20 PM
Subject: Geophone source

Hi all,
Anyone know of a source of cheap 10 Hz or = better=20 geophones or geophone
cartridges?  There's a guy selling kits = including a cartridge and
display board on Ebay for $26+$8, but I = was=20 holding out for even less. 
I was interested in 8 or = so.  I=20 think All Electronics used to have
some but they're not in their = catalog=20 = anymore.
Thanks,
Jack
__________________________________________= ________________

Public=20 Seismic Network Mailing List (PSN-L)

To leave this list email = PSN-L-REQUEST@............... =20 with
the body of the message (first line only): unsubscribe
See = http://www.seismicnet.co= m/maillist.html=20 for more information.
Subject: Re: Geophone source From: Pete Rowe ptrowe@......... Date: Thu, 2 Nov 2006 13:32:39 -0800 (PST) Jack I bought some used geophone strings from RT Clark several years ago. They were really cheap! Each string has 10 to 20 geophones on it. Beware that these are WELL used and some may not work. I was pleased with mine. At the time they didn't take anything but checks for payment. The very nice lady there sent them to me and I then I sent her a personal check. Pete --- Jerry Payton wrote: > You might check out http://www.rtclark.com/ . > > Regards, > Jerry Payton > ----- Original Message ----- > From: Jack Ivey > To: psn-l@.............. > Sent: Thursday, November 02, 2006 2:19 PM > Subject: Geophone source > > > Hi all, > Anyone know of a source of cheap 10 Hz or better > geophones or geophone > cartridges? There's a guy selling kits including > a cartridge and > display board on Ebay for $26+$8, but I was > holding out for even less. > I was interested in 8 or so. I think All > Electronics used to have > some but they're not in their catalog anymore. > Thanks, > Jack > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email > PSN-L-REQUEST@.............. with > the body of the message (first line only): > unsubscribe > See http://www.seismicnet.com/maillist.html for > more information. > ____________________________________________________________________________________ We have the perfect Group for you. Check out the handy changes to Yahoo! Groups (http://groups.yahoo.com) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Geophone source From: "Timothy Carpenter" geodynamics@....... Date: Thu, 2 Nov 2006 17:42:56 -0500 Jack, A fellow using the handle "sazequip" has been selling geophones on ebay = for many months. His supply consists of 28-Hz vert and 4.5-Hz horiz. He's = been selling in lots of three, strings of 6 or 12 and multiple strings (just recently he unsuccessfully tried to sell 10-strings of 12-sensors each). = You should consider dropping him a note from within ebay. Also if you do a search on his name for "completed items" you can see what he has been offering. Unfortunately the 28-Hz vert units are probably too high a frequency to be useful in EQ monitoring. Regards, -Tim- Timothy Carpenter, P.E., Pres. GeoDynamics Consultants, Inc. 5043 Whitlow Court Commerce Township, Michigan 48382 248-363-4529 (Voice & Fax) 248-766-1629 (Cell) geodynamics@........... (primary) geodynamics@....... (secondary) -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of Jack Ivey Sent: Thursday, November 02, 2006 3:20 PM To: psn-l@.............. Subject: Geophone source Hi all, Anyone know of a source of cheap 10 Hz or better geophones or geophone=20 cartridges? There's a guy selling kits including a cartridge and=20 display board on Ebay for $26+$8, but I was holding out for even less. =20 I was interested in 8 or so. I think All Electronics used to have some but they're not in their catalog anymore. Thanks, Jack __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Norwegian sea seismic events From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Thu, 02 Nov 2006 23:14:40 +0000 Hi all There are currently ongoing a seismetic events in the Norwegian sea, see http://www.emsc-csem.org/index.php?page=current&sub=list for more details. The largest earthquake so far is mb4.6. There is a new earthquake at 22:52, but size is unkown. Time frame is 2nd November, 2006. 22:47 and 22:52. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: What sensor to build From: Sophie Talbot sophie@.................. Date: Thu, 02 Nov 2006 23:44:57 +0000 Hello, My name is Sophie, I am 11 years old and I want to build a seismometer system to investigate earthquakes. I live in England so most big earthquakes I would like to detect are a long way away but I would also like to detect the blasting in the quarry about a mile away if I can. I have read lots of interesting things on the web page but am not sure what sort of sensor would be best for me and dad to make. Can you help me decide which sort to build Thanks Sophie __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Unsung Heroines: Ruth B. Simon From: John or Jan Lahr JohnJan@........ Date: Fri, 03 Nov 2006 21:15:46 -0800 An article on Ruth Simon is in the November/December 2006 issue of the Seismological Research Letters, a publication of the Seismological Society of America. Unsung Heroines: Ruth B. Simon Ruth was working at Lamont Observatory during my first year in graduate school. It reminded me of the manual that she wrote: Earthquake interpretations : a manual for reading seismograms, which I haven't thought about since my graduate schoold days. My professional seismology work only involved local and regional seismograms, mostly from southern Alaska, so I think I'll look up her manual to help with interpreting the seismograms that I typically record on my AS-1 system. The article also included a useful link to a web site for finding library materials. That's a useful site of which I was unaware. Use this link to see if there is a copy of her manual in a library near you: http://www.worldcatlibraries.org/wcpa/top3mset/f421589db9985f18.html Cheers, John #################################/ John C. Lahr ################################/ Emeritus Seismologist ###############################/ U.S. Geological Survey ==========================/ Central Region Geologic Hazards Team #############################//################################# ############################//################################## PO Box 548 /################################### Corvallis, Oregon 97339 /=============================== Phone: (541) 758-2699 /#################################### Cell: (541) 740-4844 /##################################### Fax: (413) 658-2699 /###################################### jjpub@........ /####################################### http://jclahr.com/science/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Unsung Heroines: Ruth B. Simon From: "Thomas Dick" dickthomas01@............. Date: Sat, 4 Nov 2006 08:44:02 -0600 About two years ago, I got a hold of a copy of her book from the University of Southern Illinois library through my son who was teaching there. I don't think it was being loaned out but faculty have priveleges. Good book. From your comments, I take it she has died. Paul Simon died rather suddenly too several years ago. I met him in a restaurant at Carbondale. His hobby was Lincoln history to which I have an interest. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Unsung Heroines: Ruth B. Simon From: apsn apsn@........... Date: Sat, 04 Nov 2006 09:39:14 -0900 I was given a copy of Ruth's book as a guide to interpreting seismograms when I first began working in seismology at the World-Wide Seismograph Station Network station MSO in Missoula, Montana. That was about 30 years ago. I still have her book and it's still a gem. Bob Hammond Public Seismic Network - Alaska http://apsn.awcable.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: unknown events From: "tchannel" tchannel@.............. Date: Sat, 4 Nov 2006 12:36:04 -0700 Hi, The last week, in Idaho, has been rather quiet. Some weather = changes is about all there is to watch on the helicorder. This is a general question which only quiet times would allow for. = During the day time hours I receive a spike about once an hour to = several times an hour. No pattern. They all have something's in = common. They are short in duration less than one minute. Things are = quiet and then another hit. Sometimes these hits cover ten mins, on and off. I live in the city, = next to the mountains, no blasting or construction that I know of. I don't think they are weather, They don't repeat at the same time each = day. They are short but strong. Kind of like someone is dropping a = large weight. Sometime three or four of different shape, in a row. Any ideas as to their origin? Thanks, Ted
Hi,  The last week, in Idaho, has = been rather=20 quiet.  Some weather changes is about all there is to watch on the=20 helicorder.
This is a general question which only = quiet times=20 would allow for.   During the day time hours I receive a spike = about=20 once an hour to several times an hour.  No pattern.   = They all=20 have something's in common.  They are short in duration less=20 than one minute. Things are quiet and then another = hit.
Sometimes these hits cover ten mins, on = and=20 off.   I live in the city, next to the mountains, no blasting = or=20 construction that I know of.
 
 
I don't think they are weather, They = don't repeat=20 at the same time each day. They are short but strong.  Kind of like = someone=20 is dropping  a large weight.    Sometime three or = four of=20 different shape, in a row.
 
 
Any ideas as to their = origin?   =20 Thanks, Ted
Subject: Re: unknown events From: ChrisAtUpw@....... Date: Sat, 4 Nov 2006 20:13:03 EST In a message dated 2006/11/04, tchannel@.............. writes: > This is a general question which only quiet times would allow for. During > the day time hours I receive a spike about once an hour to several times an > hour. No pattern. They all have something's in common. They are short in > duration less than one minute. Things are quiet and then another hit. > Sometimes these hits cover ten mins, on and off. I live in the city, next to > the mountains, no blasting or construction that I know of. > > I don't think they are weather, They don't repeat at the same time each day. > They are short but strong. Kind of like someone is dropping a large weight. > Sometime three or four of different shape, in a row. > > Any ideas as to their origin? Hi Ted, I suggest that you use a battery portable radio. Tune in to the long wave end of the MW AM band, but in between stations. Then listen for any RFI signals which correspond to the pulse noise? Can you use the directional aerial properties to ~locate the signal? How about your fridges / central heating system? Is anyone doing any electric welding / construction locally? Do the signals only occur during 'working' hours? Regards, Chris Chapman In a me= ssage dated 2006/11/04, tchannel@.............. writes:

This is a general question whic= h only quiet times would allow for. During the day time hours I receive a sp= ike about once an hour to several times an hour. No pattern. They all have s= omething's in common. They are short in duration less than one minute. Thing= s are quiet and then another hit.
Sometimes these hits cover ten mins, on and off. I live in the city, next t= o the mountains, no blasting or construction that I know of.
 
I don't think they are weather, They don't repeat at the same time each day= .. They are short but strong.  Kind of like someone is dropping a large=20= weight.  Sometime three or four of different shape, in a row.

Any ideas as to their origin?


Hi Ted,

       I suggest that you use a battery portab= le radio. Tune in to the long wave end of the MW AM band, but in between sta= tions. Then listen for any RFI signals which correspond to the pulse noise?=20= Can you use the directional aerial properties to ~locate the signal?

       How about your fridges / central heatin= g system? Is anyone doing any electric welding / construction locally? Do th= e signals only occur during 'working' hours? 

       Regards,

       Chris Chapman Subject: Re: unknown events From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sun, 05 Nov 2006 01:18:43 +0000 Hi Can you send me a trace (psn format) of one or two of thease events. Thanks. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: unknown events From: "Bob Hancock" carpediem1@......... Date: Sat, 4 Nov 2006 21:48:50 -0700 Hi Ted - Just one question - these unknown events - what is the initial P wave direction - are they consistent in one direction or are do they show both compression and dilation. If the initial P waves are different, do they show any pattern? Bob Hancock _____ From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of tchannel Sent: Saturday, November 04, 2006 12:36 To: psn-l@.............. Subject: unknown events Hi, The last week, in Idaho, has been rather quiet. Some weather changes is about all there is to watch on the helicorder. This is a general question which only quiet times would allow for. During the day time hours I receive a spike about once an hour to several times an hour. No pattern. They all have something's in common. They are short in duration less than one minute. Things are quiet and then another hit. Sometimes these hits cover ten mins, on and off. I live in the city, next to the mountains, no blasting or construction that I know of. I don't think they are weather, They don't repeat at the same time each day. They are short but strong. Kind of like someone is dropping a large weight. Sometime three or four of different shape, in a row. Any ideas as to their origin? Thanks, Ted

Hi Ted = –

 

Just one question – these = unknown events – what is the initial P wave direction – are they = consistent in one direction or are do they show both compression and = dilation.  If the initial P waves are different, do they show any = pattern?

 

Bob = Hancock

 

 

From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of tchannel
Sent: Saturday, November = 04, 2006 12:36
To: psn-l@..............
Subject: unknown = events

 

Hi,  The last week, in Idaho, has been rather quiet.  = Some weather changes is about all there is to watch on the = helicorder.

This is a general question which only quiet times = would allow for.   During the day time hours I receive a spike about = once an hour to several times an hour.  No pattern.   They all = have something's in common.  They are short in duration less = than one minute. Things are quiet and then another = hit.

Sometimes these hits cover ten mins, on and = off.   I live in the city, next to the mountains, no blasting or construction = that I know of.

 

 

I don't think they are weather, They don't repeat at = the same time each day. They are short but strong.  Kind of like = someone is dropping  a large weight.    Sometime three or four = of different shape, in a row.

 

 

Any ideas as to their origin?    = Thanks, Ted

Subject: Re: unknown events From: "tchannel" tchannel@.............. Date: Sun, 5 Nov 2006 09:17:12 -0700 Hi, When I enlarge the unknown events, the initial single is generally = just a spike, a little like a "M" or "W" in shape. It has some length = but short in duration, it has no dilation or compression that I can see. = Just that shape followed by nothing and one mins later another signal = different in shape, but about the same size. These events only occur during day time hours. When I get a series of = them they last about 10 mins, maybe 5 events each lasting 1 to 1.5 mins = each. All the shapes are different. No pattern that I can see. So they = sometimes look like earthquakes, but I check other Idaho State stations = and they don't show them. Other times it is just one "M" shaped signal. = I am not near any major highways, but there is a busy intersection 1/2 = mile away, and at one point the timing seemed to be that of rush hour = evening traffic. And that maybe part of it. I also am about 10 miles = from the mountains. I did as Chris suggested with the AM radio but I could not hear anything = of the radio which coincided. I have eliminated wind or weather, at least any weather I can observe. No road construction that I am aware of. About the only thing I can say for sure is they don't happen at night. The sensor is now in my basement and does not pickup any street traffic. = I don't see it picking up any of our household appliances. It does = respond if you approach the sensor, as it flexes the concrete floor. Thanks, Ted ----- Original Message -----=20 From: Bob Hancock=20 To: psn-l@................. Sent: Saturday, November 04, 2006 9:48 PM Subject: RE: unknown events Hi Ted - =20 Just one question - these unknown events - what is the initial P wave = direction - are they consistent in one direction or are do they show = both compression and dilation. If the initial P waves are different, do = they show any pattern? =20 Bob Hancock =20 =20 -------------------------------------------------------------------------= ----- From: psn-l-request@.............. = [mailto:psn-l-request@............... On Behalf Of tchannel Sent: Saturday, November 04, 2006 12:36 To: psn-l@.............. Subject: unknown events =20 Hi, The last week, in Idaho, has been rather quiet. Some weather = changes is about all there is to watch on the helicorder. This is a general question which only quiet times would allow for. = During the day time hours I receive a spike about once an hour to = several times an hour. No pattern. They all have something's in = common. They are short in duration less than one minute. Things are = quiet and then another hit. Sometimes these hits cover ten mins, on and off. I live in the city, = next to the mountains, no blasting or construction that I know of. =20 =20 I don't think they are weather, They don't repeat at the same time = each day. They are short but strong. Kind of like someone is dropping = a large weight. Sometime three or four of different shape, in a row. =20 =20 Any ideas as to their origin? Thanks, Ted
Hi,  When I enlarge the unknown = events, the=20 initial single is generally just a spike, a little like a "M" or = "W" in=20 shape.   It has some length but short in duration, it has = no=20 dilation or compression that I can see. Just that shape followed by = nothing and=20 one mins later another signal different in shape, but about the same=20 size.
 
These events only occur during day time = hours.  When I get a series of them they last about 10 mins, maybe = 5 events=20 each lasting 1 to 1.5 mins each. All the shapes are different.  No = pattern=20 that I can see.  So they sometimes look like earthquakes, but I = check other=20 Idaho State stations and they don't show them.  Other times it is = just one=20 "M" shaped signal.   I am not near any major highways, but = there is a=20 busy intersection 1/2 mile away,  and at one point the timing = seemed to be=20 that of rush hour evening traffic. And that maybe part of = it.   I also=20 am about 10 miles from the mountains.
 
I did as Chris suggested with the AM = radio but I=20 could not hear anything of the radio which coincided.
I have eliminated wind or weather, at = least any=20 weather I can observe.
No road construction that I am aware = of.
 
About the only thing I can say for sure = is they=20 don't happen at night.
The sensor is now in my basement and = does not=20 pickup any street traffic.  I don't see it picking up any of our = household=20 appliances. It does respond if you approach the sensor, as it flexes the = concrete floor.
 
Thanks, Ted
 
 
----- Original Message -----
From:=20 Bob=20 Hancock
Sent: Saturday, November 04, = 2006 9:48=20 PM
Subject: RE: unknown = events

Hi Ted=20 =96

 

Just one = question =96=20 these unknown events =96 what is the initial P wave direction =96 are = they=20 consistent in one direction or are do they show both compression and=20 dilation.  If the initial P waves are different, do they show any = pattern?

 

Bob=20 Hancock

 

 

From: psn-l-request@............... =20 [mailto:psn-l-request@............... On=20 Behalf Of tchannel
Sent: Saturday, November 04, = 2006=20 12:36
To: = psn-l@..............
Subject: unknown=20 events

 

Hi,  The last week, = in=20 Idaho, has=20 been rather quiet.  Some weather changes is about all there is to = watch=20 on the helicorder.

This is a general = question which=20 only quiet times would allow for.   During the day time = hours I=20 receive a spike about once an hour to several times an hour.  No=20 pattern.   They all have something's in common.  They = are short=20 in duration less than one minute. Things are quiet and then = another=20 hit.

Sometimes these hits = cover ten=20 mins, on and off.   I live in the city, next to the = mountains, no=20 blasting or construction that I know = of.

 

 

I don't think they are = weather,=20 They don't repeat at the same time each day. They are short but = strong. =20 Kind of like someone is dropping  a large = weight.   =20 Sometime three or four of different shape, in a=20 row.

 

 

Any ideas as to their=20 origin?    Thanks,=20 Ted

Subject: Re: What sensor to build From: "Connie and Jim Lehman" lehmancj@........... Date: Sun, 5 Nov 2006 11:42:24 -0500 Sophie---It is always good to hear from young people interested in seismic related topics. Sensors generally are in three categories----Geophones, the AS-l Educational Design, and the "Lehman" long period type design. Each of these designs have their own strengths in terms of simplicity and performance. Information and plans on any of these sensors are available on the Public Seismic Network, or sources suggested. Don't hesitate to ask questions--there is a lot of good help on the Public Seismic Network-- Jim ----- Original Message ----- From: "Sophie Talbot" To: Sophie Sent: Thursday, November 02, 2006 6:44 PM Subject: What sensor to build > Hello, > My name is Sophie, I am 11 years old and I want to build a seismometer > system to investigate earthquakes. I live in England so most big > earthquakes I would like to detect are a long way away but I would also > like to detect the blasting in the quarry about a mile away if I can. > I have read lots of interesting things on the web page but am not sure > what sort of sensor would be best for me and dad to make. Can you help > me decide which sort to build > Thanks > Sophie > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Test Only From: "Steve Shufflebotham" Cellectronic@............. Date: Sun, 5 Nov 2006 16:38:49 -0000 Test only, do not reply Thankyou
Test only, do not reply
Thankyou
Subject: Re: What sensor to build From: ChrisAtUpw@....... Date: Sun, 5 Nov 2006 15:26:36 EST In a message dated 2006/11/02, sophie@.................. writes: > Hello, > My name is Sophie, I am 11 years old and I want to build a seismometer > system to investigate earthquakes. I live in England so most big > earthquakes I would like to detect are a long way away but I would also > like to detect the blasting in the quarry about a mile away if I can. > I have read lots of interesting things on the web page but am not sure > what sort of sensor would be best for me and dad to make. Can you help > me decide which sort to build Hi Sophie + Dad, You will likely only be picking up quite distant earthquakes. The UK gets maybe 40 very small local quakes each year. See http://www.earthquakes.bgs.ac.uk/ You will only pick one of these up if they are within about 100 miles of you. Earthquakes often start with a P wave at about 1 to 2 cycles per second, later an S wave at about 0.5 to 1 cycle per second and these are followed by much larger surface waves which take 10 to 30 seconds each. For quakes from the other side of the world, you may only pick up the surface waves. We get a fair number of regional quakes from the Mediterranean area. A "garden gate" type of pendulum sensor will pick these up. It is not too difficult to make one of these. See http://jclahr.com/science/psn/chapman/lehman/index.html You can buy 'long period' geophones of about 1 second, but they are quite expensive. See www.geophone.com type LF-24. An alternative is to buy 4.5Hz used geophones from psn.quake.net and use an extra SEQUA10 extension amplifier from Sara, but neither of these will pick up the slow surface waves. You will also need a seismic type amplifier, an analogue to digital converter and a 'spare' computer to record and display the traces. Your dad could likely make an amplifier, but you will probably need to buy an ADC. Have a look at www.sara.pg.it for electronics and Mauro's website at http://mariottim.interfree.it/index_e.htm Mauro also provides a free seismic recording and analysis program called Seismowin which you can download onto your computer. The software timing clocks on computers are not accurate enough for recording seismic signals and may drift by 30 seconds a day. However Sara sell an inexpensive DCF77 radio clock module which connects to their ADC. This is a lot cheaper than GPS clock modules and it covers all of the UK. A complete long period system from Sara would be a SPOW10 power supply, a SAMP20 amplifier, a SADC10 a to d converter and a DCF77 clock module. These are the electronics boards. You can buy an Al box from Maplin to house them. I suggest that you buy the connecting cables from Sara. There is carriage and VAT at 20% to add to the Sara prices. All this is likely to make quite a large hole in your pocket money. Ask your dad to EMail me if he wants any further help or advice? There are other choices possible. Best Wishes, Chris Chapman In a me= ssage dated 2006/11/02, sophie@.................. writes:

Hello,
My name is Sophie, I am 11 years old and I want to build a seismometer
system to investigate earthquakes. I live in England so most big
earthquakes I would like to detect are a long way away but I would also
like to detect the blasting in the quarry about a mile away if I can.
I have read lots of interesting things on the web page but am not sure
what sort of sensor would be best for me and dad to make. Can you help
me decide which sort to build


Hi Sophie + Dad,

       You will likely only be picking up quit= e distant earthquakes. The UK gets maybe 40 very small local quakes each yea= r. See http://www.earthquakes.bgs.ac.uk/ You will only pick one of these up=20= if they are within about 100 miles of you. Earthquakes often start with a P=20= wave at about 1 to 2 cycles per second, later an S wave at about 0.5 to 1 cy= cle per second and these are followed by much larger surface waves which tak= e 10 to 30 seconds each. For quakes from the other side of the world, you ma= y only pick up the surface waves. We get a fair number of regional quakes fr= om the Mediterranean area.
       A "garden gate" type of pendulum sensor= will pick these up. It is not too difficult to make one of these. See http:= //jclahr.com/science/psn/chapman/lehman/index.html
       You can buy 'long period' geophones of=20= about 1 second, but they are quite expensive. See www.geophone.com type LF-2= 4.
       An alternative is to buy 4.5Hz used geo= phones from psn.quake.net and use an extra SEQUA10 extension amplifier from=20= Sara, but neither of these will pick up the slow surface waves.
       You will also need a seismic type ampli= fier, an analogue to digital converter and a 'spare' computer to record and=20= display the traces. Your dad could likely make an amplifier, but you will pr= obably need to buy an ADC. Have a look at www.sara.pg.it for electronics and= Mauro's website at http://mariottim.interfree.it/index_e.htm Mauro also pro= vides a free seismic recording and analysis program called Seismowin which y= ou can download onto your computer.
       The software timing clocks on computers= are not accurate enough for recording seismic signals and may drift by 30 s= econds a day. However Sara sell an inexpensive DCF77 radio clock module whic= h connects to their ADC. This is a lot cheaper than GPS clock modules and it= covers all of the UK.
       A complete long period system from Sara= would be a SPOW10 power supply, a SAMP20 amplifier, a SADC10 a to d convert= er and a DCF77 clock module. These are the electronics boards. You can buy a= n Al box from Maplin to house them. I suggest that you buy the connecting ca= bles from Sara. There is carriage and VAT at 20% to add to the Sara prices.=20=
       All this is likely to make quite a larg= e hole in your pocket money. Ask your dad to EMail me if he wants any furthe= r help or advice? There are other choices possible.

       Best Wishes,

       Chris Chapman
      
       Subject: Thank you and another question from Sophie From: Sophie Talbot sophie@.................. Date: Mon, 06 Nov 2006 21:45:38 +0000 Sophie here again, Thank you for all the replies to my last question, I've had an interesting weekend looking at loads of information. I know all about the BGS as dad works there and his best friend runs the Monserrat Volcano Observatory where I got interesed in seismology. I think I have decided on this sensor: http://www.fairpoint.net/~sparksite/CSpring%20Seismometer.html as dad says he has all the bits to make it and most of the BGS sites seem to use vertical component sensors. Also these electronics: http://www.infiltec.com/seismo/inf-qm10.htm , dad says he is out of practice at making electronic things so we better buy some! We have an old pentium 3 laptop that will collect the data and dad says he knows ways of using our home network and internet time services to keep the time on it correct to within a few hundreths of a second. Does this look an OK way to start a seismology hobby station? I can see lots more I can do later but that looks a quick, easy way to get going. Thanks Sophie __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Thank you and another question from Sophie From: ChrisAtUpw@....... Date: Mon, 6 Nov 2006 18:23:14 EST In a message dated 2006/11/06, sophie@.................. writes: > Sophie here again, > Thank you for all the replies to my last question, I've had an > interesting weekend looking at loads of information. I know all about > the BGS as dad works there and his best friend runs the Monserrat > Volcano Observatory where I got interesed in seismology. > I think I have decided on this sensor: > http://www.fairpoint.net/~sparksite/CSpring%20Seismometer.html as dad > says he has all the bits to make it and most of the BGS sites seem to > use vertical component sensors. Hi Sophie, This older version uses oil damping and does not have a hinge mec hanism to prevent side to side oscillations. You won't get much sensitivity for the very long period Rayleigh waves. Send an EMail to Roger asking for updates? I think that Roger now uses Magnet + Plate damping. If not, I can provide your dad with suggestions for doing this. You will find oil damping difficult to set up correctly, very temperature sensitive and seriously messy. You need to damp this sort of sensor both vertically and horizontally. It is not as easy / simple as it looks. Buy fully hard hacksaw blades (NOT the ordinary ones) and get your dad to grind the teeth and bends right off. Otherwise the blades will be noisy and crack in service. A rather better spring system still uses two blades, but set at a V angle to stiffen it for side to side motion. Also these electronics: > http://www.infiltec.com/seismo/inf-qm10.htm , dad > says he is out of practice at making electronic things so we better buy some! > We have an > old pentium 3 laptop that will collect the data and dad says he knows > ways of using our home network and internet time services to keep the > time on it correct to within a few hundreths of a second. > Does this look an OK way to start a seismology hobby station? I can see > lots more I can do later but that looks a quick, easy way to get going. There is a reference to time servers on the John Lahr's website. Many commercial ones suffer from digital transmission delays, which can be seconds at peak periods. Chris Chapman (in the UK) In a me= ssage dated 2006/11/06, sophie@.................. writes:

Sophie here again,
Thank you for all the replies to my last question, I've had an
interesting weekend looking at loads of information. I know all about
the BGS as dad works there and his best friend runs the Monserrat
Volcano Observatory where I got interesed in seismology.
I think I have decided on this sensor:
http://www.fairpoint.net/~sparksite/CSpring%20Seismometer.html as dad
says he has all the bits to make it and most of the BGS sites seem to
use vertical component sensors.


Hi Sophie,

       This older version uses oil damping and= does not have a hinge mechanism to prevent side to side oscillations. You w= on't get much sensitivity for the very long period Rayleigh waves. Send an E= Mail to Roger asking for updates? I think that Roger now uses Magnet + Plate= damping. If not, I can provide your dad with suggestions for doing this. Yo= u will find oil damping difficult to set up correctly, very temperature sens= itive and seriously messy. You need to damp this sort of sensor both vertica= lly and horizontally. It is not as easy / simple as it looks. Buy fully hard= hacksaw blades (NOT the ordinary ones) and get your dad to grind the teeth=20= and bends right off. Otherwise the blades will be noisy and crack in service= .. A rather better spring system still uses two blades, but set at a V angle=20= to stiffen it for side to side motion.
 
Also these electronics:
http://= www.infiltec.com/seismo/inf-qm10.htm , dad says he is out of practice at mak= ing electronic things so we better buy some! We have an
old pentium 3 laptop that will collect the data and dad says he knows
ways of using our home network and internet time services to keep the
time on it correct to within a few hundreths of a second.
Does this look an OK way to start a seismology hobby station? I can see
lots more I can do later but that looks a quick, easy way to get going.

       There is a reference to time servers on= the John Lahr's website. Many commercial ones suffer from digital transmiss= ion delays, which can be seconds at peak periods.

       Chris Chapman (in the UK) Subject: Re: Thank you and another question from Sophie From: shammon1@............. Date: Mon, 6 Nov 2006 19:09:36 -0800 (GMT-08:00) Hi Sophie, the saw design looks interesting however it may take some special tools to build at home. If you are looking for a very simple vertical design, you might also look at http://pw2.netcom.com/~shammon1/compressed/VERTICAL.GIF This design is very simple to construct using common hand tools. All of the materials can be purchased at a local hardware store. Regards, Steve Hammond PSN San Jose -=- Aptos, California -----Original Message----- >From: Sophie Talbot >Sent: Nov 6, 2006 1:45 PM >To: PSN-L@.............. >Subject: Thank you and another question from Sophie > >Sophie here again, >Thank you for all the replies to my last question, I've had an >interesting weekend looking at loads of information. I know all about >the BGS as dad works there and his best friend runs the Monserrat >Volcano Observatory where I got interesed in seismology. >I think I have decided on this sensor: >http://www.fairpoint.net/~sparksite/CSpring%20Seismometer.html as dad >says he has all the bits to make it and most of the BGS sites seem to >use vertical component sensors. Also these electronics: >http://www.infiltec.com/seismo/inf-qm10.htm , dad says he is out of >practice at making electronic things so we better buy some! We have an >old pentium 3 laptop that will collect the data and dad says he knows >ways of using our home network and internet time services to keep the >time on it correct to within a few hundreths of a second. >Does this look an OK way to start a seismology hobby station? I can see >lots more I can do later but that looks a quick, easy way to get going. > >Thanks >Sophie > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Thank you and another question from Sophie From: John or Jan Lahr JohnJan@........ Date: Mon, 06 Nov 2006 22:16:29 -0800 Hi Sophie, I haven't built a system using the saw blades, but it looks a bit dangerous to me, as the blades would spring up if the weight was removed. I built a simple system that is pictured here: http://jclahr.com/science/psn/wooden/index.html It uses a door spring and is made of wood. Not the best material for a seismic system, but this might be a good design to start with. Cheers, John At 07:09 PM 11/6/2006, you wrote: >Hi Sophie, the saw design looks interesting however it may take some >special tools to build at home. If you are looking for a very simple >vertical design, you might also look at >http://pw2.netcom.com/~shammon1/compressed/VERTICAL.GIF >This design is very simple to construct using common hand tools. All >of the materials can be purchased at a local hardware store. > >Regards, Steve Hammond PSN San Jose -=- Aptos, California #################################/ John C. Lahr ################################/ Emeritus Seismologist ###############################/ U.S. Geological Survey ==========================/ Central Region Geologic Hazards Team #############################//################################# ############################//################################## PO Box 548 /################################### Corvallis, Oregon 97339 /=============================== Phone: (541) 758-2699 /#################################### Cell: (541) 740-4844 /##################################### Fax: (413) 658-2699 /###################################### jjpub@........ /####################################### http://jclahr.com/science/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Unsung Heroines: Ruth B. Simon From: "meredith lamb" paleoartifact@......... Date: Tue, 7 Nov 2006 12:01:23 -0700 I actually met Ruth Simon at the Colorado School of Mines in Golden, Colorado in 1968; during a brief initial interest foray there. Very unusual individual in that from my inquiries I was "ushered" into her work area. She was extremely busy, but still took quite some time to show me afew things....and ended up giving me a free autographed copy of her first 1968 issue book "Earthquake Interpretations". I was quite impressed with her; her patience, time and the book material donation to say the least! Mentally Looking back now with all their mechanical, expensive servo ink and optical photography seismo setups; it was for the time about impossible to get much of anything "up and running", as little to nothing was remotely afordable for a individual to acquire. We're lucky to have what we have now to setup a seismogrph recording system.....and a BUNCH of wiling helpful experienced individuals!!! On 11/3/06, John or Jan Lahr wrote: > An article on Ruth Simon is in the November/December 2006 issue of > the Seismological Research Letters, a publication of the > Seismological Society of > America. > Unsung > Heroines: Ruth B. Simon Ruth was working at Lamont Observatory > during my first year in graduate school. > > It reminded me of the manual that she wrote: Earthquake > interpretations : a manual for reading seismograms, which I haven't > thought about since my graduate schoold days. My professional > seismology work only involved local and regional seismograms, mostly > from southern Alaska, so I think I'll look up her manual to help with > interpreting the seismograms that I typically record on my AS-1 system. > > The article also included a useful link to a web site for finding > library materials. That's a useful site of which I was unaware. Use > this link to see if there is a copy of her manual in a library near > you: > http://www.worldcatlibraries.org/wcpa/top3mset/f421589db9985f18.html > > Cheers, > John > > > > #################################/ John C. Lahr >
I actually met Ruth Simon at the Colorado School of Mines in Golden, Colorado
in 1968; during a brief initial interest foray there.  Very unusual individual in that
from my inquiries I was "ushered" into her work area.  She was extremely busy,
but still took quite some time to show me afew things....and ended up giving me a free
autographed copy of her first 1968 issue book "Earthquake Interpretations".  I was
quite impressed with her; her patience, time and the book material donation to say
the least!
 
Mentally Looking back now with all their mechanical, expensive servo ink and optical
photography seismo setups; it was for the time about impossible to get much of
anything "up and running", as little to nothing was remotely afordable for a individual
to acquire.  We're lucky to have what we have now to setup a seismogrph recording
system.....and a BUNCH of wiling helpful experienced individuals!!!
 
   
 
On 11/3/06, John or Jan Lahr <JohnJan@........ > wrote:
An article on Ruth Simon is in the November/December 2006 issue of
the Seismological Research Letters, a publication of the
Seismological Society of
America.
<http://www.seismosoc.org/publications/SRL/SRL_77/srl_77-6_uh.html >Unsung
Heroines: Ruth B. Simon   Ruth was working at Lamont Observatory
during my first year in graduate school.

It reminded me of the manual that she wrote:   Earthquake
interpretations : a manual for reading seismograms, which I haven't
thought about since my graduate schoold days.  My professional
seismology work only involved local and regional seismograms, mostly
from southern Alaska, so I think I'll look up her manual to help with
interpreting the seismograms that I typically record on my AS-1 system.

The article also included a useful link to a web site for finding
library materials.  That's a useful site of which I was unaware. Use
this link to see if there is a copy of her manual in a library near
you:   http://www.worldcatlibraries.org/wcpa/top3mset/f421589db9985f18.html

Cheers,
John



#################################/ John C. Lahr
Subject: "C" Spring Seismometer From: "Geoffrey" gmvoeth@........... Date: Wed, 8 Nov 2006 13:10:29 -0700 I know for a fact that spring companies will build you a custom spring but you must pay setup charges that are quite steep making the very first spring the most expensive of all. Possibly we could somehow combine our resources to have a proper custom spring made to build that machine Sophie likes because i like it too, If you put limits in its ability to move loss of the mass will cause little damage. Since the magnet/coil arrangement does not induce voltages with horizontal motion that weakeness will not keep you Maybe we could all chip in $10 apiece or so to collect enough to have a custom leaf spring built. I can not handle the monies due to legal complications but maybe someone at PSN would be willing to do so ? Chris would probably be the best one to send in the design ?? from getting a first time of arrival. I have never seen such a device before but the lack of a hinge and the 4 second eigen frequency makes it a very desirable design for myself. Is anyone interested in somehow getting a spring company like "Century" to build a custon spring ??? The setup charges are like maybe $200 or so I think. Not sure it was quite awhile ago i looked into this. Isnt that hack saw blade a kind of leaf spring and a similar idea would be a torque-tube spring. I made a simple seismometer using an antenna element as a torque-tube spring but circumstances beyond my control destroyed my ability to test the idea fully. I have not been getting any new PSN mail since MSIE updated itself to version 7. Is there something wrong at PSN ?? Regards, geoff __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: "C" Spring Seismometer From: ChrisAtUpw@....... Date: Wed, 8 Nov 2006 20:23:14 EST In a message dated 2006/11/08, gmvoeth@........... writes: http://www.fairpoint.net/~sparksite/CSpring%20Seismometer.html > Isn't that hack saw blade a kind of leaf spring and a similar idea would be > a torque-tube spring. Hi Geoff, I think that this is one of Roger's older designs. A newer version is shown at http://mariottim.interfree.it/doc02v_e.htm but I think that Roger now uses magnetic damping. You do need to buy hacksaw blades which are hardened right through. The ordinary ones only have the edge strip with the teeth on it hardened. You also need to grind the teeth and the wavy backing off. If you don't, the blade will be noisy and will eventually crack at one or more of the teeth / waves. PSN seems to be OK. Can you revert to an older tested version of MSIE? Regards, Chris Chapman In a me= ssage dated 2006/11/08, gmvoeth@........... writes:

http://www.fairpoint.net/~sparksite/CSpring%20Seismometer.html

Isn't that hack saw blade a kin= d of leaf spring and a similar idea would be a torque-tube spring.

Hi Geoff,

       I think that this is one of Roger's old= er designs. A newer version is shown at http://mariottim.interfree.it/doc02v= _e.htm but I think that Roger now uses magnetic damping.

       You do need to buy hacksaw blades which= are hardened right through. The ordinary ones only have the edge strip with= the teeth on it hardened. You also need to grind the teeth and the wavy bac= king off. If you don't, the blade will be noisy and will eventually crack at= one or more of the teeth / waves. 

       PSN seems to be OK. Can you revert to a= n older tested version of MSIE?

       Regards,

       Chris Chapman Subject: Re: "C" Spring Seismometer From: Barry Lotz barry_lotz@............. Date: Wed, 8 Nov 2006 18:18:03 -0800 (PST) Hi The Late Sean Thomas Morrissey has used a tapeing blade commonly found in hardware stores in his vertical design. I have used it in two verticals with success. It does require respect since it requires a moderate amount of force to bend it to 180 degrees. Once there, the force is quite constant and lower. There is some relaxation which occurs for a period of time after being bent. It is not as good for compact designs as hack saw blades since the bend diameter is larger than a bent hack saw blade.see documents @ http://www.eas.slu.edu/People/STMorrissey/index.html Regards Barry Geoffrey wrote: I know for a fact that spring companies will build you a custom spring but you must pay setup charges that are quite steep making the very first spring the most expensive of all. Possibly we could somehow combine our resources to have a proper custom spring made to build that machine Sophie likes because i like it too, If you put limits in its ability to move loss of the mass will cause little damage. Since the magnet/coil arrangement does not induce voltages with horizontal motion that weakeness will not keep you Maybe we could all chip in $10 apiece or so to collect enough to have a custom leaf spring built. I can not handle the monies due to legal complications but maybe someone at PSN would be willing to do so ? Chris would probably be the best one to send in the design ?? from getting a first time of arrival. I have never seen such a device before but the lack of a hinge and the 4 second eigen frequency makes it a very desirable design for myself. Is anyone interested in somehow getting a spring company like "Century" to build a custon spring ??? The setup charges are like maybe $200 or so I think. Not sure it was quite awhile ago i looked into this. Isnt that hack saw blade a kind of leaf spring and a similar idea would be a torque-tube spring. I made a simple seismometer using an antenna element as a torque-tube spring but circumstances beyond my control destroyed my ability to test the idea fully. I have not been getting any new PSN mail since MSIE updated itself to version 7. Is there something wrong at PSN ?? Regards, geoff
Hi
  The Late Sean Thomas Morrissey has used a tapeing blade commonly found in hardware stores in his vertical design. I have used it in two verticals with success. It does require respect since it requires a moderate amount of force to bend it to 180 degrees. Once there, the force is quite constant and lower. There is some relaxation which occurs for a period of time after being bent. It is not as good for compact designs as hack saw blades since the bend diameter is larger than a bent hack saw blade.see documents @
Regards
Barry
 
Geoffrey <gmvoeth@...........> wrote:
I know for a fact that spring companies will build you a custom spring but you must pay setup charges that are quite steep making
the very first spring the most expensive of all. Possibly we could somehow combine our resources to have a proper custom spring made
to build that machine Sophie likes because i like it too, If you put limits in its ability to move loss of the mass will cause
little damage. Since the magnet/coil arrangement does not induce voltages with horizontal motion that weakeness will not keep you
Maybe we could all chip in $10 apiece or so
to collect enough to have a custom leaf spring built.
I can not handle the monies due to legal complications
but maybe someone at PSN would be willing
to do so ? Chris would probably be the best one
to send in the design ??

from getting a first time of arrival. I have never seen such a device before but the lack of a hinge and the 4 second eigen
frequency makes it a very desirable design for myself. Is anyone interested in somehow getting a spring company like "Century" to
build a custon spring ???

The setup charges are like maybe $200 or so I think.
Not sure it was quite awhile ago i looked into this.

Isnt that hack saw blade a kind of leaf spring and a similar idea would be a torque-tube spring.
I made a simple seismometer using an antenna element as a torque-tube spring but circumstances beyond my control destroyed my
ability to test the idea fully.

I have not been getting any new PSN mail since
MSIE updated itself to version 7.
Is there something wrong at PSN ??


Regards,
geoff

Subject: Geophone Questions From: Dave Willey davewilley@............. Date: Thu, 9 Nov 2006 01:28:37 -0800 (PST) I’ve got one of Larry’s geophone systems for detection just local activity. Maybe I’ll build a SG sensor later on. But for now, I’m now moving my geophone away from the house to out back in an area that is relatively isolated... I am trying to come up with a container of some sort to house one of Larry’s 3 axis geophone, and some way to develop the new site for the geophone. Several questions come to mind: I’ve seen talk on controlling the temp in SG type sensors. But nothing specific to 4.5 Hz geophones. I’ve also heard talk on the list of folks burying the geophones in the ground. So it would seem to me that I would not need to temp stabilize the geophone if they are down 4 – 6 feet in the ground So temperature stabilization of a geophone would be major overkill? Just for background. I have 180 feet between the top of the ground and bedrock (bummer!), so I can’t place the geophone on bedrock. As much as I like to. 8” dia thick walled PVC water pipe and end caps are relatively easy to obtain locally. Any reason not to bury 4 – 6 feet of vertical pipe in the ground and place the geophone glued in the bottom of the cap? The geophone case itself is cracked and no longer waterproof. So I am planning to make the PVC pipe waterproof Will barometric pressure changes affect the geophone? Should I allow air pressure to equalize by placing a small breath hole in the PVC at the top where the wires are located?? Or does anyone have a better idea / suggestion as a way to develop a new site for a geophone? (Other than moving to a site with exposed bedrock.) Thanks, Dave Willey
I’ve got one of Larry’s geophone systems for detection just local activity.
Maybe I’ll build a SG sensor later on.

But for now, I’m now moving my geophone away from the house to out back in an area that is relatively isolated...

I am trying to come up with a container of some sort to house one of Larry’s 3 axis geophone, and some way to develop the  new site for the geophone.

Several questions come to mind:

I’ve seen talk on controlling the temp in SG type sensors.  But nothing specific to 4.5 Hz geophones.  I’ve also heard talk on the list of folks burying the geophones in the ground.  So it would seem to me that I would not need to temp stabilize the geophone  if they are down 4 – 6 feet in the ground  So temperature stabilization of a geophone would be major overkill?

Just for background.  I have 180 feet between the top of the ground and bedrock (bummer!), so I can’t place the geophone on bedrock.  As much as I like to.

8” dia thick walled PVC water pipe and end caps are relatively easy to obtain locally.  Any reason not to bury 4 – 6 feet of vertical pipe in the ground and place the geophone glued in the bottom of the cap?

The geophone case itself is cracked and no longer waterproof.  So I am planning to make the PVC pipe waterproof   Will barometric pressure changes affect the geophone? Should I allow air pressure to equalize by placing a small breath hole in the PVC at the top where the wires are located??

Or does anyone have a better idea / suggestion as a way to develop a new site for a geophone?  (Other than moving to a site with exposed bedrock.)


Thanks,


Dave Willey

Subject: Re: Geophone Questions From: Henry Bland henry@............ Date: Thu, 09 Nov 2006 10:03:56 -0700 Dave, The main reasons for burying geophones are - keeping them away from the wind - keeping them away from raindrops (which are very noisy) - reducing air-borne environmental noise - providing a firm planting base - avoiding the slow weathering layer Temperature is not much of a factor for geophones -- neither is barometric pressure. Before planting the geophone be sure to fully understand which of the three axes are doing what. Also, test the polarity in advance. Don't plant the geophone until you are 100% sure. Take lots of pictures and label all the electrical outputs ahead of time. In oscilloscope is very helpful in figuring out the polarities. The important thing is making sure the geophone doesn't leak. Apply exterior grade (typically black) silicone over all the cracks, openings, and cable-entry. Allow it to dry fully -- this usually takes a couple of days. I would recommend digging down at least a foot or two, preferably stopping when you hit something more solid than sand or topsoil. Plant the geophone making sure to note the orientation (align the big arrow to true north) and level. Then, back-fill the hole, ensuring that the geophone's orientation and level is unchanged. I would personally stay away from PVC pipe as it has the chance of acting as a conduit for surface noise. PVC is good for retrieving deeply-buried geophones (10m), but for something that is a 3-4 feet deep, I wouldn't worry about it. The geophone cable is usually very durable so long as it doesn't get tripped over. After years of getting sunlight, it will start to weaken and crack. For industrial installations, I usually run geophone cable through rubber-coated liquid-tight conduit. If it were my back yard, I wouldn't bother, but I would probably dig a shallow trench to avoid having the kids trip on it. Regards, Henry Bland __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Geophone Questions From: ChrisAtUpw@....... Date: Thu, 9 Nov 2006 16:21:25 EST In a message dated 2006/11/09, davewilley@............. writes: > Subj:Geophone Questions=20 > Date:2006/11/09 09:28:50 GMT Standard Time > From:davewilley@............. > I=E2=80=99ve got one of Larry=E2=80=99s geophone systems for detection jus= t local activity.=20 >=20 > Maybe I=E2=80=99ll build a SG sensor later on. Hi Dave, Unfortunately, Larry has stopped producing the SG boards, although th= e=20 circuits are available. > But for now, I=E2=80=99m now moving my geophone away from the house to out= back in=20 > an area that is relatively isolated... > I am trying to come up with a container of some sort to house one of Larry= =E2=80=99s=20 > 3 axis geophone, and some way to develop the new site for the geophone. >=20 > I=E2=80=99ve seen talk on controlling the temp in SG type sensors. But no= thing=20 > specific to 4.5 Hz geophones. =20 You don't have to control the temperature of geophones. The SG=20 seismometer used diode detectors which drifted with temperature. I=E2=80=99ve also heard talk on the list of folks burying the geophones in t= he=20 ground. So it=20 > would seem to me that I would not need to temp stabilize the geophone if=20 > they are down 4 =E2=80=93 6 feet in the ground So temperature stabilizati= on of a=20 > geophone would be major overkill? Definitley NOT neccessary to control the temperature! Burying the=20 geophones can get ythem away from quite a bit of surface noise and it also s= creens=20 for RFI. > 8=E2=80=9D dia thick walled PVC water pipe and end caps are relatively eas= y to=20 > obtain locally. Any reason not to bury 4 =E2=80=93 6 feet of vertical pip= e in the ground=20 > and place the geophone glued in the bottom of the cap?=20 The tube needs to be completely sealed and a waterproof gland used fo= r=20 the cable. Also seal the ends of the cable.=20 =20 Note that you have to mount the vertical geophone with the pins=20 DOWNWARD. The plastic geophone cases are about 5" OD by 3" high, but the wires=20 come out sideways. This can add an extra couple of inches or more. It is usu= al=20 to seal the geophone case after filling with dry N2. You might consider mounting the geophone case inside a plastic tube=20 with both ends sealed, say about 1 ft long? Make alignment marks on the outs= ide=20 of the tube corresponding to N and E. Then dig a hole with an auger over 3 f= t=20 deep, put in the tube, align it and backfill with soil. You need a loop of=20 nylon rope attached around the tube so that you can retrieve it if necessary= .. =20 > The geophone case itself is cracked and no longer waterproof. So I am=20 > planning to make the PVC pipe waterproof Will barometric pressure change= s=20 > affect the geophone?=20 Air pressure changes should not effect the geophones themselves -=20 their cases are hermetically sealed. Should I allow air pressure to equalize by placing a small breath hole in th= e=20 PVC at=20 > the top where the wires are located? NO. Seal it completely! Otherwise you will get condensation problems=20 and the chamber will quite slowly fill with water. Can you fill the sealed=20 chamber with dry gas / add a bag of silica gel crystals?=20 If the seismometer is outside the house, you should add some=20 protection diodes to guard against lightning surges. > Or does anyone have a better idea / suggestion as a way to develop a new=20 > site for a geophone?=20 You can hire motor driven augers and extension arms for digging holes= ?=20 Regards, Chris Chapman In a me= ssage dated 2006/11/09, davewilley@............. writes:

Subj:Geophone Questions =
Date:2006/11/09 09:28:50 GMT Standard Time
From:davewilley@.............
I=E2=80=99ve got one of Larry=E2=80=99s geophone systems for detection just=20= local activity.
Maybe I=E2=80=99ll build a SG sensor later on.


Hi Dave,

       Unfortunately, Larry has stopped produc= ing the SG boards, although the circuits are available.

But for now, I=E2=80=99m now mo= ving my geophone away from the house to out back in an area that is relative= ly isolated...
I am trying to come up with a container of some sort to house one of Larry= =E2=80=99s 3 axis geophone, and some way to develop the  new site for t= he geophone.

I=E2=80=99ve seen talk on controlling the temp in SG type sensors.  But= nothing specific to 4.5 Hz geophones. 


       You don't have to control the temperat= ure of geophones. The SG seismometer used diode detectors which drifted with= temperature.

I=E2=80=99ve also heard talk on the list of folks burying the geophones in t= he ground.  So it
would seem to me that I would=20= not need to temp stabilize the geophone  if they are down 4 =E2=80=93 6= feet in the ground  So temperature stabilization of a geophone would b= e major overkill?


       Definitley NOT neccessary to control t= he temperature! Burying the geophones can get ythem away from quite a bit of= surface noise and it also screens for RFI.

8=E2=80=9D dia thick walled PVC= water pipe and end caps are relatively easy to obtain locally.  Any re= ason not to bury 4 =E2=80=93 6 feet of vertical pipe in the ground and place= the geophone glued in the bottom of the cap?


       The tube needs to be completely sealed= and a waterproof gland used for the cable. Also seal the ends of the cable.=
      
       Note that you have to mount the vertica= l geophone with the pins DOWNWARD.

       The plastic geophone cases are about 5"= OD by 3" high, but the wires come out sideways. This can add an extra coupl= e of inches or more. It is usual to seal the geophone case after filling wit= h dry N2.

       You might consider mounting the geophon= e case inside a plastic tube with both ends sealed, say about 1 ft long? Mak= e alignment marks on the outside of the tube corresponding to N and E. Then=20= dig a hole with an auger over 3 ft deep, put in the tube, align it and backf= ill with soil. You need a loop of nylon rope attached around the tube so tha= t you can retrieve it if necessary. 

The geophone case itself is cra= cked and no longer waterproof.  So I am planning to make the PVC pipe w= aterproof   Will barometric pressure changes affect the geophone?=20=


       Air pressure changes should not effect= the geophones themselves - their cases are hermetically sealed.

Should I allow air pressure to equalize by placing a small breath hole in th= e PVC at
the top where the wires are lo= cated?


       NO. Seal it completely! Otherwise you=20= will get condensation problems and the chamber will quite slowly fill with w= ater. Can you fill the sealed chamber with dry gas / add a bag of silica gel= crystals?

       If the seismometer is outside the house= , you should add some protection diodes to guard against lightning surges.
Or does anyone have a better i= dea / suggestion as a way to develop a new site for a geophone?

       You can hire motor driven augers and ex= tension arms for digging holes?

       Regards,

       Chris Chapman Subject: Re: Geophone Questions From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 10 Nov 2006 01:47:01 +0000 Hi Dave. I did recently did put my geophone underground, so far everything is working well. You cannot get rid of the wind noise, since the ground vibrates as the wind goes over it. You can see pictures of how I put my geophone underground here, http://www.jonfr.com/myndir/v/eq/geophone/ My geophone is ~80 cm underground and in a waterproof bucket (far as I can tell, the waterproof appears to work, until proved otherwise). I did just use a 20 mm plastic pipe and I did seal the other end, I did use 8 meters of the pipe. Since I was not able to put my geophone at more distance from my apartment. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Reducing Sensor Background Noise With Sand From: "Bob Hancock" carpediem1@......... Date: Thu, 9 Nov 2006 20:48:23 -0700 Hi All - I found an interesting article on the Albuquerque Seismological Laboratory web site about reducing background noise with sand. The link to article is: http://earthquake.usgs.gov/regional/asl/pubs/PDF_Files/sand_installation.pdf While the article addresses the work that ASL performed with borehole sensors, the use of sand appears to be applicable to any sensor that is placed in the ground. Bob Hancock

Hi All –

 

I found an interesting article on the Albuquerque Seismological Laboratory = web site about reducing background noise with sand.  The link to = article is:

 

       &nbs= p;    http://earthquake.usgs.gov/regional/asl/pubs/PDF_Files/sand_= installation.pdf

 

While the article addresses the work that ASL performed with borehole sensors, = the use of sand appears to be applicable to any sensor that is placed in the = ground.

 

Bob Hancock

Subject: Magnetic Damping From: "Jerry Payton" gpayton880@....... Date: Sat, 11 Nov 2006 08:29:25 -0600 Where may I find details for constructing magnetic damping for a Lehman sensor, please. Thank you, Jerry Payton
Where may I find details for constructing magnetic damping for a = Lehman=20 sensor, please.
 
Thank you,
Jerry Payton
Subject: Re: Magnetic Damping From: "tchannel" tchannel@.............. Date: Sat, 11 Nov 2006 08:46:30 -0700 Hi Jerry, I am sure others will post the various sites showing magnetic = damping, but I just wanted to share my experiences with both types of = damping, oil vs magnetic. I used Chris's magnetic design and it worked perfectly, very effective, = very simple and easy to adjust. But before that, I tried the oil in a cup design. It too was simple = and easy to adjust. When I filled the cup, one of my wife's Tupperware = containers I spilled a little oil on the floor, After adjusting it I = spilled a little more, then I bumped it and spilled alot. I needed to = move things around and in doing so I spilled the entire cup, = Fortunately it was on a concrete floor, but I had to use solvents and = lots of paper towels, to get the oil off of the concrete. THINGS HAPPEN! The oil, seems to be a good damp, but compared to the = magnetic there is no contest. Thanks, Ted ps if you email me I can send you a close-up of the = magnetic damper on my Lehman. ----- Original Message -----=20 From: Jerry Payton=20 To: PSN-L=20 Sent: Saturday, November 11, 2006 7:29 AM Subject: Magnetic Damping Where may I find details for constructing magnetic damping for a = Lehman sensor, please. Thank you, Jerry Payton
Hi Jerry,  I am sure others will = post the=20 various sites showing magnetic damping, but I just wanted to share my=20 experiences with both types of damping, oil vs magnetic.
I used Chris's magnetic design and it = worked=20 perfectly, very effective, very simple and easy to adjust.
But before that, I tried the oil in a = cup=20 design.   It too was simple and easy to adjust.  = When I=20 filled the cup, one of my wife's Tupperware containers I spilled a = little oil on=20 the floor,  After adjusting it I spilled a little more, then I = bumped it=20 and spilled alot.  I needed to move things around and in doing so I = spilled=20 the entire cup,  Fortunately it was on a concrete floor, but I had = to use=20 solvents and lots of paper towels, to get the oil off of the=20 concrete.
THINGS HAPPEN!   The oil, = seems to be a=20 good damp, but compared to the magnetic there is no = contest.
Thanks, Ted   ps if you email = me I can=20 send you a close-up of the magnetic damper on my Lehman.
----- Original Message -----
From:=20 Jerry = Payton=20
To: PSN-L
Sent: Saturday, November 11, = 2006 7:29=20 AM
Subject: Magnetic Damping

Where may I find details for constructing magnetic damping for a = Lehman=20 sensor, please.
 
Thank you,
Jerry Payton
Subject: Re: Magnetic Damping From: ChrisAtUpw@....... Date: Sat, 11 Nov 2006 11:02:53 EST In a message dated 2006/11/11, gpayton880@....... writes: > Where may I find details for constructing magnetic damping for a Lehman > sensor, please. > Thank you, > Jerry Payton Hi Jerry, Have a look at http://jclahr.com/science/psn/chapman/lehman/index.html and for magnets at http://jclahr.com/science/psn/chapman/as1%20damping/index.html I use 20mm x 10 mm x 5mm NdFeB bar magnets with a 1 Kg mass. You may need the 1" x 1/2" x 1/4" magnets with a larger mass. Another source is www.amazingmagnets.com Try using a horizontal tongue of 1/16" copper. This is a bit of overkill, but you can then increase the central magnet gap to make adjustment easier. I suggest using a tongue about 2" wide - this allows a movement of about +/-10mm with the construction shown. You want the tongue to totally cover the magnet block at maximum travel, to avoid any edge effects. Cu hasn't given me any problems but AlSi is paramagnetic with 5x the susceptibility. There are quite high fields at the edges of the magnet block. I suggest that you place the damping blade vertically level with the centre of mass of the arm. This ensures that there is no tendency for the arm to rotate about it's long axis if you are using a single wire suspension. Regards, Chris Chapman In a me= ssage dated 2006/11/11, gpayton880@....... writes:

Where may I find details for co= nstructing magnetic damping for a Lehman sensor, please.
Thank you,
Jerry Payton


Hi Jerry,

       Have a look at http://jclahr.com/scienc= e/psn/chapman/lehman/index.html
       and for magnets at  
       http://jclahr.com/science/psn/chapman/a= s1%20damping/index.html
       I use 20mm x 10 mm x 5mm NdFeB bar magn= ets with a 1 Kg mass. You may need the 1" x 1/2" x 1/4" magnets with a large= r mass.
       Another source is www.amazingmagnets.co= m

       Try using a horizontal tongue of 1/16"=20= copper. This is a bit of overkill, but you can then increase the central mag= net gap to make adjustment easier. I suggest using a tongue about 2" wide -=20= this allows a movement of about +/-10mm with the construction shown. You wan= t the tongue to totally cover the magnet block at maximum travel, to avoid a= ny edge effects. Cu hasn't given me any problems but AlSi is paramagnetic wi= th 5x the susceptibility. There are quite high fields at the edges of the ma= gnet block.  

       I suggest that you place the damping bl= ade vertically level with the centre of mass of the arm. This ensures that t= here is no tendency for the arm to rotate about it's long axis if you are us= ing a single wire suspension.

       Regards,

       Chris Chapman Subject: Re: Magnetic Damping From: "Jerry Payton" gpayton880@....... Date: Sat, 11 Nov 2006 10:42:52 -0600 Thanks Chris, Would you please identify the part number your use from the www.amazingmagnets.com website? Correct me if I am wrong, but I believe that you are in the UK. Cu plate or sheets "might" be a challenge finding. Any sources for that to suggest? Thank you. Jerry
Thanks Chris,
 
Would you please identify the part number your use from the www.amazingmagnets.com=20 website?
 
Correct me if I am wrong, but I believe = that you=20 are in the UK.  Cu plate or sheets "might" be a challenge = finding. =20 Any sources for that to suggest?
 
Thank you.
Jerry
Subject: Re: Magnetic Damping From: Sophie Talbot sophie@.................. Date: Sat, 11 Nov 2006 17:52:26 +0000 Dad found some very cheap 16swg copper plate on ebay from to do the damper in the C spring seismometer we are working on from ebay seller maccmodels
He also might have found somewhere to make the springs properly as I know some other people were interested. He will know next week if it is possible and what it would cost.
Sophie
Jerry Payton wrote:
Thanks Chris,
 
Would you please identify the part number your use from the www.amazingmagnets.com website?
 
Correct me if I am wrong, but I believe that you are in the UK.  Cu plate or sheets "might" be a challenge finding.  Any sources for that to suggest?
 
Thank you.
Jerry

Subject: Re: Magnetic Damping From: "Jerry Payton" gpayton880@....... Date: Sat, 11 Nov 2006 12:00:43 -0600 Thank you so much Sophie. Good luck on your construction project. However, I live in the US and I'm afraid the shipping from this UK supplier would not be cost effective. Thank you anyway. I'm sure there are UK & European people that might be interested. Best wishes, Jerry ----- Original Message ----- From: Sophie Talbot To: psn-l@.............. Sent: Saturday, November 11, 2006 11:52 AM Subject: Re: Magnetic Damping Dad found some very cheap 16swg copper plate on ebay from to do the damper in the C spring seismometer we are working on from ebay seller maccmodels He also might have found somewhere to make the springs properly as I know some other people were interested. He will know next week if it is possible and what it would cost. Sophie Jerry Payton wrote: Thanks Chris, Would you please identify the part number your use from the www.amazingmagnets.com website? Correct me if I am wrong, but I believe that you are in the UK. Cu plate or sheets "might" be a challenge finding. Any sources for that to suggest? Thank you. Jerry
Thank you so much Sophie.  Good luck on your construction=20 project.
 
However, I live in the US and I'm afraid the shipping from this UK = supplier=20 would not be cost effective. 
 
Thank you anyway.  I'm sure there are UK & European people = that=20 might be interested.
 
Best wishes,
Jerry
 
----- Original Message -----
From:=20 Sophie Talbot
Sent: Saturday, November 11, = 2006 11:52=20 AM
Subject: Re: Magnetic = Damping

Dad found some very cheap 16swg copper plate on ebay = from to do=20 the damper in the C spring seismometer we are working on from ebay = seller=20 maccmodels=
He=20 also might have found somewhere to make the springs properly as I know = some=20 other people were interested. He will know next week if it is possible = and=20 what it would cost.
Sophie
Jerry Payton wrote:=20
Thanks Chris,
 
Would you please identify the part number your use from the = www.amazingmagnets.com=20 website?
 
Correct me if I am wrong, but I = believe that=20 you are in the UK.  Cu plate or sheets "might" be a challenge=20 finding.  Any sources for that to suggest?
 
Thank you.
Jerry

Subject: RE: Magnetic Damping From: "Stephen Hammond" shammon1@............. Date: Sat, 11 Nov 2006 10:22:09 -0800 Hi Jerry, here are the pictures of my Lehman's in Aptos CA. http://pw2.netcom.com/~shammon1/AptosStn.htm look for the red magnets. I mounted two aluminum "L" brackets on aluminum plate using brass machine screws. Regards, Steve Hammond PSN San Jose, Aptos CA -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of Jerry Payton Sent: Saturday, November 11, 2006 6:29 AM To: PSN-L Subject: Magnetic Damping Where may I find details for constructing magnetic damping for a Lehman sensor, please. Thank you, Jerry Payton
Hi=20 Jerry, here are the pictures of my Lehman's in Aptos CA. http://pw2.netcom.c= om/~shammon1/AptosStn.htm look=20 for the red magnets. I mounted two aluminum "L" brackets on = aluminum plate=20 using brass machine screws.
Regards, Steve Hammond PSN San Jose, Aptos = CA
-----Original Message-----
From: = psn-l-request@................. [mailto:psn-l-request@...............On Behalf Of Jerry=20 Payton
Sent: Saturday, November 11, 2006 6:29 = AM
To:=20 PSN-L
Subject: Magnetic Damping

Where may I find details for constructing magnetic damping for a = Lehman=20 sensor, please.
 
Thank you,
Jerry Payton
Subject: Re: Magnetic Damping From: ChrisAtUpw@....... Date: Sat, 11 Nov 2006 14:41:06 EST In a message dated 2006/11/11, gpayton880@....... writes: > Would you please identify the part number your use from the > www.amazingmagnets.com website? > > Correct me if I am wrong, but I believe that you are in the UK. Cu plate or > sheets "might" be a challenge finding. Any sources for that to suggest? Hi Jerry, I use the P250DH size 1" x 1/2" x 1/4" which is more than adequate with a 1 kg mass. What mass are you using? You will find that Alnico U magnets are quite expensive as well as having a much lower field. Yes, I am in the UK. I have a Metals Supermarket about 5 m away! www.ksmetals.com stock 1/16" Al and 1/32" Cu. Model shops carry their products. They are not cheap, but you don't need much Can you use your phone directory to look for non ferrous metal stockists? How about Home Depot and similar places which sell hardware / plumbing / building supplies? They stock the bright mild steel strip and zinc plated mild steel set screws. You do have a huge online hardware supplier, but I can't remember the name. Steve Hammond might remember? Sean Morrissey used them a lot. I think that it began with M? Sorry, but my other computer is 'down'. Check http://www.webstersonline.com/ ? Regards, Chris Chapman In a me= ssage dated 2006/11/11, gpayton880@....... writes:

Would you please identify the p= art number your use from the www.= amazingmagnets.com website?

Correct me if I am wrong, but I believe that you are in the UK.  Cu pl= ate or sheets "might" be a challenge finding.  Any sources for that to=20= suggest?


Hi Jerry,

       I use the P250DH size 1" x 1/2" x 1/4"=20= which is more than adequate with a 1 kg mass.

       What mass are you using? 

       You will find that Alnico U magnets are= quite expensive as well as having a much lower field.

       Yes, I am in the UK. I have a Metals Su= permarket about 5 m away!   

       www.ksmetals.com stock 1/16" Al and 1/3= 2" Cu. Model shops carry their products. They are not cheap, but you don't n= eed much
       Can you use your phone directory to loo= k for non ferrous metal stockists? How about Home Depot and similar places w= hich sell hardware / plumbing / building supplies? They stock the bright mil= d steel strip and zinc plated mild steel set screws.
       You do have a huge online hardware supp= lier, but I can't remember the name. Steve Hammond might remember? Sean Morr= issey used them a lot. I think that it began with M? Sorry, but my other com= puter is 'down'. Check http://www.webstersonline.com/ ?

       Regards,

       Chris Chapman Subject: Re: Magnetic Damping From: =?ISO-8859-1?Q?Ra=FAl_Alvarez?= ralvarez@........ Date: Sat, 11 Nov 2006 12:54:12 -0700 Hello fellow builders, If I can be of any service to you in obtaining hardware and or electronic parts, please feel free to check my ebay store. http://stores.ebay.com/Alvarez-Electronic-and-Hardware Thanks very much. Hope this did not appear too much as a plug for my store. I really am serious about helping with any special parts needs. Raul www.LaEstrellitaObservatory.org ChrisAtUpw@....... wrote: > In a message dated 2006/11/11, gpayton880@....... writes: > >> Would you please identify the part number your use from the >> www.amazingmagnets.com website? >> >> Correct me if I am wrong, but I believe that you are in the UK. Cu >> plate or sheets "might" be a challenge finding. Any sources for that >> to suggest? > > > > Hi Jerry, > > I use the P250DH size 1" x 1/2" x 1/4" which is more than > adequate with a 1 kg mass. > > What mass are you using? > > You will find that Alnico U magnets are quite expensive as well > as having a much lower field. > > Yes, I am in the UK. I have a Metals Supermarket about 5 m > away! > > www.ksmetals.com stock 1/16" Al and 1/32" Cu. Model shops carry > their products. They are not cheap, but you don't need much > Can you use your phone directory to look for non ferrous metal > stockists? How about Home Depot and similar places which sell hardware > / plumbing / building supplies? They stock the bright mild steel strip > and zinc plated mild steel set screws. > You do have a huge online hardware supplier, but I can't > remember the name. Steve Hammond might remember? Sean Morrissey used > them a lot. I think that it began with M? Sorry, but my other computer > is 'down'. Check http://www.webstersonline.com/ ? > > Regards, > > Chris Chapman Hello fellow builders,

If I can be of any service to you in obtaining hardware and or electronic parts, please feel free to check my ebay store.

http://stores.ebay.com/Alvarez-Electronic-and-Hardware

Thanks very much. Hope this did not appear too much as a plug for my store. I really am serious about helping with any special parts needs.

Raul

www.LaEstrellitaObservatory.org


ChrisAtUpw@....... wrote:
In a message dated 2006/11/11, gpayton880@....... writes:
Would you please identify the part number your use from the www.amazingmagnets.com website?

Correct me if I am wrong, but I believe that you are in the UK.  Cu plate or sheets "might" be a challenge finding.  Any sources for that to suggest?


Hi Jerry,

       I use the P250DH size 1" x 1/2" x 1/4" which is more than adequate with a 1 kg mass.

       What mass are you using? 

       You will find that Alnico U magnets are quite expensive as well as having a much lower field.

       Yes, I am in the UK. I have a Metals Supermarket about 5 m away!   

       www.ksmetals.com stock 1/16" Al and 1/32" Cu. Model shops carry their products. They are not cheap, but you don't need much
       Can you use your phone directory to look for non ferrous metal stockists? How about Home Depot and similar places which sell hardware / plumbing / building supplies? They stock the bright mild steel strip and zinc plated mild steel set screws.
       You do have a huge online hardware supplier, but I can't remember the name. Steve Hammond might remember? Sean Morrissey used them a lot. I think that it began with M? Sorry, but my other computer is 'down'. Check http://www.webstersonline.com/ ?

       Regards,

       Chris Chapman
Subject: Re: Magnetic Damping From: Bobhelenmcclure@....... Date: Sat, 11 Nov 2006 23:38:42 EST You might want to take a look at _http://www.smallparts.com_ (http://www.smallparts.com) when you need material that is otherwise hard to find locally. They are not cheap, however. For copper sheet suitable for damping, see page _http://www.smallparts.com/products/descriptions/smc%2Ecfm_ (http://www.smallparts.com/products/descriptions/smc.cfm) For steel rectangular stock, see page _http://www.smallparts.com/products/descriptions/zrts%2Ecfm_ (http://www.smallparts.com/products/descriptions/zrts.cfm) If you need spring steel strips more suitable than hacksaw blades, see page _http://www.smallparts.com/products/descriptions/fss%2Ecfm_ (http://www.smallparts.com/products/descriptions/fss.cfm) My favorite source for Nd block magnets is _http://www.gaussboys.com/_ (http://www.gaussboys.com/) I buy magnet wire from Alltronics. See page _http://www.alltronics.com/cgi-bin/category.cgi?&category=MW&start=20_ (http://www.alltronics.com/cgi-bin/category.cgi?&category=MW&start=20) Cheers, Bob McClure
You might want to take a look at
 
  http://www.smallparts.com
 
when you need material that is otherwise hard to find locally. They are= not=20 cheap, however.
 
  For copper sheet suitable for damping, see page
 
  http://ww= w.smallparts.com/products/descriptions/smc%2Ecfm
 
  For steel rectangular stock, see page
 
  http://w= ww.smallparts.com/products/descriptions/zrts%2Ecfm
 
  If you need spring steel strips more suitable than hacksaw blade= s,=20 see page
 
  http://ww= w.smallparts.com/products/descriptions/fss%2Ecfm
 
  My favorite source for Nd block magnets is
 
  http://www.gaussboys.com/
 
  I buy magnet wire from Alltronics. See page
 
  http://www.alltronics.com/cgi-bin/category.cgi?&category= =3DMW&start=3D20
 
Cheers,
 
Bob McClure
 Subject: Re: Magnetic Damping From: ChrisAtUpw@....... Date: Sun, 12 Nov 2006 07:08:59 EST In a message dated 2006/11/11, ralvarez@........ writes: > Hello fellow builders, > If I can be of any service to you in obtaining hardware and or electronic > parts, please feel free to check my ebay store. > http://stores.ebay.com/Alvarez-Electronic-and-Hardware Hi Raul, Can you put your items in sections, rather than all mixed up, sometime please? It makes it difficult to find an item if you have to search the whole website. We also need to know the finish of hardware. I use almost exclusively stainless steel and zinc plated mild steel bolts, nuts and washers for seismometer construction. Regards, Chris Chapman In a me= ssage dated 2006/11/11, ralvarez@........ writes:

Hello fellow builders,
If I can be of any service to you in obtaining hardware and or electronic pa= rts, please feel free to check my ebay store.
http://st= ores.ebay.com/Alvarez-Electronic-and-Hardware


Hi Raul,

       Can you put your items in sections, rat= her than all mixed up, sometime please? It makes it difficult to find an ite= m if you have to search the whole website.
       We also need to know the finish of hard= ware. I use almost exclusively stainless steel and zinc plated mild steel bo= lts, nuts and washers for seismometer construction.

       Regards,

       Chris Chapman Subject: Re: Digest from 11/11/2006 00:01:37 From: "Randy" rpratt@............. Date: Sun, 12 Nov 2006 09:01:07 -0600 For a damping plate I found a piece of copper pipe scrap, split it on one side and hammered it flat. Cost was zero. Any plumbing or hardware store will have various fittings. Randy __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Magnetic Damping From: Barry Lotz barry_lotz@............. Date: Sun, 12 Nov 2006 08:56:25 -0800 (PST) McMaster Carr http://www.mcmaster.com/ ChrisAtUpw@....... wrote: In a message dated 2006/11/11, gpayton880@....... writes: Would you please identify the part number your use from the www.amazingmagnets.com website? Correct me if I am wrong, but I believe that you are in the UK. Cu plate or sheets "might" be a challenge finding. Any sources for that to suggest? Hi Jerry, I use the P250DH size 1" x 1/2" x 1/4" which is more than adequate with a 1 kg mass. What mass are you using? You will find that Alnico U magnets are quite expensive as well as having a much lower field. Yes, I am in the UK. I have a Metals Supermarket about 5 m away! www.ksmetals.com stock 1/16" Al and 1/32" Cu. Model shops carry their products. They are not cheap, but you don't need much Can you use your phone directory to look for non ferrous metal stockists? How about Home Depot and similar places which sell hardware / plumbing / building supplies? They stock the bright mild steel strip and zinc plated mild steel set screws. You do have a huge online hardware supplier, but I can't remember the name. Steve Hammond might remember? Sean Morrissey used them a lot. I think that it began with M? Sorry, but my other computer is 'down'. Check http://www.webstersonline.com/ ? Regards, Chris Chapman
McMaster Carr    http://www.mcmaster.com/


ChrisAtUpw@....... wrote:
In a message dated 2006/11/11, gpayton880@....... writes:

Would you please identify the part number your use from the www.amazingmagnets.com website?

Correct me if I am wrong, but I believe that you are in the UK.  Cu plate or sheets "might" be a challenge finding.  Any sources for that to suggest?


Hi Jerry,

       I use the P250DH size 1" x 1/2" x 1/4" which is more than adequate with a 1 kg mass.

       What mass are you using? 

       You will find that Alnico U magnets are quite expensive as well as having a much lower field.

       Yes, I am in the UK. I have a Metals Supermarket about 5 m away!   

       www.ksmetals.com stock 1/16" Al and 1/32" Cu. Model shops carry their products. They are not cheap, but you don't need much
       Can you use your phone directory to look for non ferrous metal stockists? How about Home Depot and similar places which sell hardware / plumbing / building supplies? They stock the bright mild steel strip and zinc plated mild steel set screws.
       You do have a huge online hardware supplier, but I can't remember the name. Steve Hammond might remember? Sean Morrissey used them a lot. I think that it began with M? Sorry, but my other computer is 'down'. Check http://www.webstersonline.com/ ?

       Regards,

       Chris Chapman

Subject: Re: Magnetic Damping From: Mark Robinson mark.robinson@............... Date: Mon, 13 Nov 2006 11:26:46 +1300 Jerry Payton wrote: > Correct me if I am wrong, but I believe that you are in the UK. Cu > plate or sheets "might" be a challenge finding. Any sources for that to > suggest? Aside from the engineering and model making supply stores which are referenced by others, suitable copper plate is widely available. Any plumber will have offcuts which they will likely give you, as will many roofing companies. There are small businesses here which travel around installing copper guttering which they roll out on site. Surplus hot water cylinders end up at the house wreckers here. Lots of copper for $NZ50. There is likely a scrap metal dealer in your area who will part with suitable scraps of copper for a smile. -- 13 Nov 1956 New Jersey report links lung cancer to air pollution. 13 Nov 1971 Mariner 9 became the first spacecraft to orbit Mars. 13 Nov 1990 David Lange announces that all New Zealand hostages in Iraq are to be freed on his return from a private diplomatic mission. 13 Nov 1990 The Aramoana Massacre in which David Grey takes 13 lives before losing his own after a 24 hour seige. 13 Nov 1991 Scottish Authorites issue arrest warrants for two Libyans for bombing Pan Am flinght 103 over Lockerbie. 13 Nov 1992 The Church of England votes to allow women to enter the priesthood. 13 Nov 1996 350 people die in the world's worst mid air collision to date over India. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Event reports in WinQuake From: "Randy" rpratt@............. Date: Sun, 12 Nov 2006 19:58:02 -0600 I see things changed a bit while I was off line. I can no longer load = event reports. I did find this link to information and I have added = this to the ftp://hazards.cr.usgs.gov/cnss/merge_14.nts Network event = reports source box. It appears to download but no events appear. I = guess it is not set up in the data masks properly. Can anyone help with = another souce of reports or how to set up the information? Thanks, Randy
I see things changed a bit while I was = off=20 line.  I can no longer load event reports.  I did find this = link to=20 information and I have added this to the ftp://hazards.cr.usg= s.gov/cnss/merge_14.nts Network=20 event reports source box.  It appears to download but no events=20 appear.  I guess it is not set up in the data masks properly.  = Can=20 anyone help with another souce of reports or how to set up the=20 information?
 
Thanks,
Randy
Subject: Re: Event reports in WinQuake From: John or Jan Lahr JohnJan@........ Date: Sun, 12 Nov 2006 22:36:22 -0800 Randy, Check if this one will work: ftp://hazards.cr.usgs.gov/cnss/qed.fing or one of the other formats in the same directory. Cheers, John At 05:58 PM 11/12/2006, you wrote: >I see things changed a bit while I was off line. I can no longer >load event reports. I did find this link to information and I have >added this to the >ftp://hazards.cr.usgs.gov/cnss/merge_14.nts >Network event reports source box. It appears to download but no >events appear. I guess it is not set up in the data masks >properly. Can anyone help with another souce of reports or how to >set up the information? > >Thanks, >Randy __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Event reports in WinQuake From: Larry Cochrane lcochrane@.............. Date: Sun, 12 Nov 2006 22:48:56 -0800 Hi Randy, This zip file http://www.seismicnet.com/software/EventReportFiles.zip has some new WinQuake data files to support this event report ftp://hazards.cr.usgs.gov/cnss/cnss_14.fing. After unzipping the file copy the data files to your WinQuake directory and restart WinQuake. Regards, Larry Cochrane Redwood City,PSN Randy wrote: > > I see things changed a bit while I was off line. I can no longer load > event reports. I did find this link to information and I have added > this to the ftp://hazards.cr.usgs.gov/cnss/merge_14.nts Network event > reports source box. It appears to download but no events appear. I > guess it is not set up in the data masks properly. Can anyone help with > another souce of reports or how to set up the information? > > Thanks, > Randy __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Digest from 11/11/2006 00:01:37 From: "Geoffrey" gmvoeth@........... Date: Mon, 13 Nov 2006 00:36:38 -0700 Ever thought of possibly using a coin ? I have heard quarters are mostly copper ? But then they are not flat and pounding them are illegal. Regards; geoff ----- Original Message ----- From: "Randy" To: Sent: Sunday, November 12, 2006 8:01 AM Subject: Re: Digest from 11/11/2006 00:01:37 > > For a damping plate I found a piece of copper pipe scrap, split it on one > side and hammered it flat. Cost was zero. Any plumbing or hardware store > will have various fittings. > Randy > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Digest from 11/11/2006 00:01:37 From: ChrisAtUpw@....... Date: Mon, 13 Nov 2006 09:35:45 EST In a message dated 2006/11/13, gmvoeth@........... writes: > Ever thought of possibly using a coin ? > Hi Geoff, Copper coins are not pure copper. They are a hard alloy which is resistant to wear - NOT what we want! Regards, Chris Chapman In a me= ssage dated 2006/11/13, gmvoeth@........... writes:

Ever thought of possibly using=20= a coin ?

Hi Geoff,

       Copper coins are not pure copper. They=20= are a hard alloy which is resistant to  wear - NOT what we want!

       Regards,

       Chris Chapman
 Subject: Re: Digest from 11/11/2006 00:01:37 From: "Geoffrey" gmvoeth@........... Date: Mon, 13 Nov 2006 10:08:38 -0700 WHY ?? ----- Original Message ----- From: To: Sent: Monday, November 13, 2006 7:35 AM Subject: Re: Digest from 11/11/2006 00:01:37 > In a message dated 2006/11/13, gmvoeth@........... writes: > >> Ever thought of possibly using a coin ? >> > Hi Geoff, > > Copper coins are not pure copper. They are a hard alloy which is > resistant to wear - NOT what we want! > > Regards, > > Chris Chapman > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Digest from 11/11/2006 00:01:37 From: ChrisAtUpw@....... Date: Mon, 13 Nov 2006 14:16:26 EST In a message dated 2006/11/13, gmvoeth@........... writes: > WHY ?? > > In a message dated 2006/11/13, gmvoeth@........... writes: > >> Ever thought of possibly using a coin ? > >> > > Hi Geoff, > > Copper coins are not pure copper. They are a hard alloy which is > > resistant to wear - NOT what we want! Hi Geoff, Because hard alloys have a much greater electrical resistivity than pure Cu and hence you get a greatly diminished damping force. Try sliding a magnet down an inclined plane of Cu or Al and then try it with brass or Duralumin. Regards, Chris Chapman In a me= ssage dated 2006/11/13, gmvoeth@........... writes:

WHY ??
> In a message dated 2006/11/13, gmvoeth@........... writes:
>> Ever thought of possibly using a coin ?
>>
> Hi Geoff,
>       Copper coins are not pure copper. T= hey are a hard alloy which is
> resistant to  wear - NOT what we want!


Hi Geoff,

       Because hard alloys have a much greater= electrical resistivity than pure Cu and hence you get a greatly diminished=20= damping force. Try sliding a magnet down an inclined plane of Cu or Al and t= hen try it with brass or Duralumin.

       Regards,

       Chris Chapman Subject: Re: Digest from 11/11/2006 00:01:37 From: "Geoffrey" gmvoeth@........... Date: Mon, 13 Nov 2006 16:21:41 -0700 Thanks Chris thats the kind of answer I was hoping for. Regards; geoff ----- Original Message ----- From: To: Sent: Monday, November 13, 2006 12:16 PM Subject: Re: Digest from 11/11/2006 00:01:37 > In a message dated 2006/11/13, gmvoeth@........... writes: > >> WHY ?? >> > In a message dated 2006/11/13, gmvoeth@........... writes: >> >> Ever thought of possibly using a coin ? >> >> >> > Hi Geoff, >> > Copper coins are not pure copper. They are a hard alloy which is >> > resistant to wear - NOT what we want! > > Hi Geoff, > > Because hard alloys have a much greater electrical resistivity than > pure Cu and hence you get a greatly diminished damping force. Try sliding a > magnet down an inclined plane of Cu or Al and then try it with brass or Duralumin. > > Regards, > > Chris Chapman > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Stormy day and night.... From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Tue, 14 Nov 2006 00:40:54 +0000 Hi all It has been a stormy day where I live. That has resaulted is massive noise pickup on my geophone, it is actually so massive that my helcorder is totally black for the most part. In this type of weather my earthquake pickup is close to zero, I only think I can detect earthquakes that are larger then mag 3.5 at the moment. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Event reports From: "Randy" rpratt@............. Date: Mon, 13 Nov 2006 20:27:54 -0600 Thanks Larry and John. Both solutions were successful. Randy
Thanks Larry and John.  Both = solutions were=20 successful.
 
Randy
Subject: Re: Digest from 11/11/2006 00:01:37 From: John or Jan Lahr JohnJan@........ Date: Mon, 13 Nov 2006 19:18:50 -0800 At 11:36 PM 11/12/2006, you wrote: >I have heard quarters are mostly copper ? The dime, quarter, and half dollar are all 91.6%=20 copper and the rest nickle. See: http://www.usmint.gov/about_the_mint/index.cfm?action=3Dcoin_specifications The weight of each is in direct proportion to it's face value, so if used= for damping, the half dollar might be the best choice. Although Cu is slightly repelled by a magnet, the=20 Cu Ni alloy will be slightly attracted. However, this attraction might be small enough to ignore. http://prola.aps.org/abstract/PR/v38/i4/p828_1 The magnetic susceptibility of alloys of copper=20 and nickel in proportions ranging from 0.1 to 70=20 percent nickel have been studied. X-ray=20 photographs of the alloys show that they are a=20 homogeneous mixture of the copper and nickel=20 crystals. Although copper is only weakly=20 diamagnetic it requires 0.8 or 0.9 percent nickel=20 to neutralize this diamagnetic effect and 56=20 percent nickel is required before the alloy shows=20 ferromagnetic properties at ordinary=20 temperatures. For amounts of nickel from one=20 percent up to 30 percent the alloy, while=20 paramagnetic in most respects, does not obey any=20 known law of paramagnetism with regard to=20 temperature. As the temperature is increased the=20 susceptibility first increases and then=20 decreases, the maximum occurring in the=20 neighborhood of the Curie point for nickel. In=20 the case of alloys containing more than 30=20 percent nickel the susceptibility decreases with=20 increase of temperature for temperatures above 20=B0C. McMaster Carr charges=20 $20.84 for a 1/16" strip of Cu, 1 inch wide by 6 inches long. Maybe flattening a piece of Cu pipe is still the=20 best way to go. Have to be sure it's copper and=20 not brass=20 pipe. See:=20 http://www.copper.org/applications/plumbing/techref/tpf_stds/tube_pipe_stds.= htm Cheers, John =20 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Digest from 11/11/2006 00:01:37 From: ChrisAtUpw@....... Date: Tue, 14 Nov 2006 00:04:06 EST In a message dated 2006/11/14, JohnJan@........ writes: > At 11:36 PM 11/12/2006, you wrote: > >I have heard quarters are mostly copper ? > > The dime, quarter, and half dollar are all 91.6% copper and the rest nickel. > See: > http://www.usmint.gov/about_the_mint/index.cfm?action=coin_specifications Hi John, It is the much higher electrical resistivity which kills this application - apart from the susceptability and any implications of defacing the coinage. The damping effect on our 2p coins is far less that on pure Cu sheet. > Although Cu is slightly repelled by a magnet, the Cu Ni alloy will be > slightly attracted. However, this attraction might be small enough to ignore. Not with UK 'copper' Coins. US coins are 8.3% Nickel > http://prola.aps.org/abstract/PR/v38/i4/p828_1 > The magnetic susceptibility of alloys of copper > and nickel in proportions ranging from 0.1 to 70 > percent nickel have been studied. X-ray > photographs of the alloys show that they are a > homogeneous mixture of the copper and nickel > crystals. Although copper is only weakly > diamagnetic it requires 0.8 or 0.9 percent nickel > to neutralize this diamagnetic effect and 56 > percent nickel is required before the alloy shows > ferromagnetic properties at ordinary > temperatures. > McMaster Carr charges > $20.84 for a 1/16" strip of Cu, 1 inch wide by 6 inches long. This is an idiotic price. It is even more expensive than www.ksmetals.com! > Maybe flattening a piece of Cu pipe is still the best way to go. Have to be > sure it's copper and not brass pipe. See: > http://www.copper.org/applications/plumbing/techref/tpf_stds/tube_pipe_stds.h > tm I suspect that you may not be approaching the right sales outlets. Go to a plumbing firm and ask if they have any odd lengths of large diameter tube? How about looking up metal suppliers / stockists / non ferrous? Scrap dealers may have Cu water cylinders. If Cu is so difficult to get, you can use soft AlSi sheet, but it is a bit paramagnetic. Pure Al may be difficult to find. Regards, Chris Chapman In a me= ssage dated 2006/11/14, JohnJan@........ writes:

At 11:36 PM 11/12/2006, you wro= te:
>I have heard quarters are mostly copper ?

The dime, quarter, and half dollar are all 91.6% copper and the rest nickel.=   See:
http://www.usmint.gov/about_the_mint/index.cfm?action=3Dcoin_specifications<= /FONT>=


Hi John,

       It is the much higher electrical resist= ivity which kills this application - apart from the susceptability and any i= mplications of defacing the coinage. The damping effect on our 2p coins is f= ar less that on pure Cu sheet.

Although Cu is slightly repell= ed by a magnet, the Cu Ni alloy will be slightly attracted. However, this at= traction might be small enough to ignore.


       Not with UK 'copper' Coins. US coins a= re 8.3% Nickel

http://prola.aps.org/abstract/P= R/v38/i4/p828_1
The magnetic susceptibility of alloys of copper
and nickel in proportions ranging from 0.1 to 70
percent nickel have been studied. X-ray
photographs of the alloys show that they are a
homogeneous mixture of the copper and nickel
crystals. Although copper is only weakly
diamagnetic it requires 0.8 or 0.9 percent nickel
to neutralize this diamagnetic effect and 56
percent nickel is required before the alloy shows
ferromagnetic properties at ordinary
temperatures.


McMaster Carr <http://www.mc= master.com/> charges
$20.84 for a 1/16" strip of Cu, 1 inch wide by 6 inches long.

       This is an idiotic price. It is even m= ore expensive than www.ksmetals.com!

Maybe flattening a piece of Cu=20= pipe is still the best way to go. Have to be sure it's copper and not brass=20= pipe.  See:
http://www.copper.org/applications/plumbing/techref/tpf_stds/tube_pipe_stds.= htm


       I suspect that you may not be approachi= ng the right sales outlets. Go to a plumbing firm and ask if they have any o= dd lengths of large diameter tube? How about looking up metal suppliers / st= ockists / non ferrous? Scrap dealers may have Cu water cylinders.

       If Cu is so difficult to get, you can u= se soft AlSi sheet, but it is a bit paramagnetic. Pure Al may be difficult t= o find.
      
       Regards,

       Chris Chapman
 Subject: RE: Digest from 11/11/2006 00:01:37 From: "Jack Ivey" ivey@.......... Date: Tue, 14 Nov 2006 10:20:47 -0500 Try thewireman.com 1/4"x1"x12" for $15. Still not a bargain but about 1/10th the cost by = weight of McMaster. http://thewireman.com/wirep.html Why worry about the diagmanetism? A symmetrical arrangement should = provide=20 balanced forces. Warning: bad ascii art follows: Cross section Cu tube =20 _____________________________________ =20 ------------ <- | ->=20 S | Cylindrical |__N_______________ | | Magnet | | ------------ | ______________________________________ | | | Boom Or better yet, put the tube on the boom and the magnet on the ground (too lazy to fix artwork). The rotation of the boom might provide a small amount of unbalanced force, but I wouldn't think it would be too bad. Jack ________________________________________ From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of ChrisAtUpw@....... Sent: Tuesday, November 14, 2006 12:04 AM To: psn-l@.............. Subject: Re: Digest from 11/11/2006 00:01:37 In a message dated 2006/11/14, JohnJan@........ writes: At 11:36 PM 11/12/2006, you wrote: >I have heard quarters are mostly copper ? The dime, quarter, and half dollar are all 91.6% copper and the rest = nickel.=A0 See: http://www.usmint.gov/about_the_mint/index.cfm?action=3Dcoin_specificatio= ns Hi John, =A0=A0=A0=A0=A0=A0 It is the much higher electrical resistivity which = kills this application - apart from the susceptability and any = implications of defacing the coinage. The damping effect on our 2p coins = is far less that on pure Cu sheet. Although Cu is slightly repelled by a magnet, the Cu Ni alloy will be = slightly attracted. However, this attraction might be small enough to = ignore. =A0=A0=A0=A0=A0=A0 Not with UK 'copper' Coins. US coins are 8.3% Nickel http://prola.aps.org/abstract/PR/v38/i4/p828_1 The magnetic susceptibility of alloys of copper=20 and nickel in proportions ranging from 0.1 to 70=20 percent nickel have been studied. X-ray=20 photographs of the alloys show that they are a=20 homogeneous mixture of the copper and nickel=20 crystals. Although copper is only weakly=20 diamagnetic it requires 0.8 or 0.9 percent nickel=20 to neutralize this diamagnetic effect and 56=20 percent nickel is required before the alloy shows=20 ferromagnetic properties at ordinary=20 temperatures.=20 McMaster Carr charges=20 $20.84 for a 1/16" strip of Cu, 1 inch wide by 6 inches long. =A0=A0=A0=A0=A0=A0 This is an idiotic price. It is even more expensive = than www.ksmetals.com! Maybe flattening a piece of Cu pipe is still the best way to go. Have to = be sure it's copper and not brass pipe.=A0 See:=20 http://www.copper.org/applications/plumbing/techref/tpf_stds/tube_pipe_st= ds.htm =A0=A0=A0=A0=A0=A0 I suspect that you may not be approaching the right = sales outlets. Go to a plumbing firm and ask if they have any odd = lengths of large diameter tube? How about looking up metal suppliers / = stockists / non ferrous? Scrap dealers may have Cu water cylinders. =A0=A0=A0=A0=A0=A0 If Cu is so difficult to get, you can use soft AlSi = sheet, but it is a bit paramagnetic. Pure Al may be difficult to find. =A0=A0=A0=A0=A0=A0=20 =A0=A0=A0=A0=A0=A0 Regards, =A0=A0=A0=A0=A0=A0 Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Digest from 11/11/2006 00:01:37 From: ChrisAtUpw@....... Date: Tue, 14 Nov 2006 13:54:31 EST In a message dated 2006/11/14, ivey@.......... writes: > Why worry about the diagmanetism? A symmetrical arrangement should provide > balanced forces. Hi Jack, Sure, just so long as the ends of the damper and the magnets don't get close. You don't tend to get problems with Alnico magnets, since the field is much lower than that provided by NdFeB magnets. You need to allow for tilt drift with time with a Lehman seismometer of maybe +/-10mm. A magnet mounted inside a copper tube will provide some damping OK, but can you explain how do you plan to adjust / trim this force to be constant over a movement range of 2 cm? An alternative is to provide a cylindrical magnet system and a damping coil with a variable resistance. The quad bar NdFeB magnet system with a plate moving in between the poles can be easily set / reset over a very wide range of damping force - the amount of damping that you want depends on the set period of the pendulum and on it's mass. Regards, Chris Chapman In a me= ssage dated 2006/11/14, ivey@.......... writes:

Why worry about the diagmanetis= m? A symmetrical arrangement should provide
balanced forces.


Hi Jack,

       Sure, just so long as the ends of the d= amper and the magnets don't get close. You don't tend to get problems with A= lnico magnets, since the field is much lower than that provided by NdFeB mag= nets.

       You need to allow for tilt drift with t= ime with a Lehman seismometer of maybe +/-10mm.

       A magnet mounted inside a copper tube w= ill provide some damping OK, but can you explain how do you plan to adjust /= trim this force to be constant over a movement range of 2 cm?
       An alternative is to provide a cylindri= cal magnet system and a damping coil with a variable resistance.

       The quad bar NdFeB magnet system with a= plate moving in between the poles can be easily set / reset over a very wid= e range of damping force - the amount of damping that you want depends on th= e set period of the pendulum and on it's mass.

       Regards,

       Chris Chapman
       Subject: Homebrew 3 axis Geophone Torpedo Container From: Dave Willey davewilley@............. Date: Wed, 15 Nov 2006 01:37:40 -0800 (PST) I'm contemplating another spin-off project for burying my 3 axis geophone in a new site in the back of my property. I have one of Larry's used orange geophones (Mark Products 4.5Hz 3 component L15B Sensor) in the shape of a "margarine tub" as Larry has pictured on the PSN website, (See http://psn.quake.net/geophone/index.html), I was thinking of replacing the housing (which for me is broken and cracked in several places), and vertically stacking the 3 geophones (in the same axis orientation as the original container), and building a water-tight 6 to 8 " long 2" dia. PVC water pipe "torpedo" to be placed in the bottom of a 6 foot deep 6 inch diameter bore hole, surrounded by sand. on all 6 sides. My question for you all is will there be any noticeable magnetic interaction between the 3 units I need to worry about with stacking them about .25 - .5 inches apart inside the PVC tubing? Thanks, Dave Willey I'm contemplating another spin-off project for burying my 3 axis geophone in a new site in the back of my property.

I have one of Larry's used orange geophones (Mark Products 4.5Hz 3 component L15B Sensor) in the shape of a  "margarine tub" as Larry has pictured on the PSN website, (See http://psn.quake.net/geophone/index.html),  

I was thinking of replacing the housing (which for me is broken and cracked in several places), and vertically stacking the 3 geophones  (in the same axis orientation as the original container), and building a water-tight  6 to 8 " long  2" dia. PVC water pipe "torpedo" to be placed in the bottom of a 6 foot deep  6 inch  diameter bore hole, surrounded by sand. on all 6 sides.

My question for you all is  will there be any noticeable magnetic interaction between the 3 units I need to worry about with stacking them about .25 - .5 inches apart inside the PVC tubing?


Thanks,

Dave Willey


Subject: Re: Homebrew 3 axis Geophone Torpedo Container From: Larry Cochrane lcochrane@.............. Date: Wed, 15 Nov 2006 02:05:17 -0800 Hi Dave, Good question. I'm not sure how much spacing you need between the sensor elements. I would make the tubing a little longer and space the sensors farther apart. When stacking and burying the sensor make sure that the vertical sensor is straight up and down and the horizontal sensors are perpendicular to the vertical sensor. You should also move the aliment bubble on the L15B to the new enclosure so you can orient the sensor properly when you bury it. Regards, Larry Cochrane Redwood City, PSN Dave Willey wrote: > I'm contemplating another spin-off project for burying my 3 axis > geophone in a new site in the back of my property. > > I have one of Larry's used orange geophones (Mark Products 4.5Hz 3 > component L15B Sensor) in the shape of a "margarine tub" as Larry has > pictured on the PSN website, (See > http://psn.quake.net/geophone/index.html), > > I was thinking of replacing the housing (which for me is broken and > cracked in several places), and vertically stacking the 3 geophones (in > the same axis orientation as the original container), and building a > water-tight 6 to 8 " long 2" dia. PVC water pipe "torpedo" to be > placed in the bottom of a 6 foot deep 6 inch diameter bore hole, > surrounded by sand. on all 6 sides. > > My question for you all is will there be any noticeable magnetic > interaction between the 3 units I need to worry about with stacking them > about .25 - .5 inches apart inside the PVC tubing? > > > Thanks, > > Dave Willey > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Homebrew 3 axis Geophone Torpedo Container From: ChrisAtUpw@....... Date: Wed, 15 Nov 2006 08:33:42 EST In a message dated 2006/11/15, davewilley@............. writes: > My question for you all is will there be any noticeable magnetic > interaction between the 3 units I need to worry about with stacking them about .25 - .5 > inches apart inside the PVC tubing? Hi Dave Willey,. The geophone units should have no magnetic interactions when stacked together. However, you do need to connect them fairly accurately at right angles and they should be clamped in place. Can you provide an inner rod / tube of plastic and bore holes in this to mount / align the geophones? The 4.5 Hz geophones do have stray fields at both ends, but the barrel is the mild steel return path for the axially mounted central magnets. I would suggest a 1 cm spacing. You can get Roberts' type period extension amplifiers from www.sara.pg.it These should enable you to receive teleseismic P and S waves, which you won't otherwise see with 4.5 Hz geophones. See the note about 4.5 Hz geophones on Larry's website? When you have remounted the geophones, do make a record of the wire colours and that they are the correct way around for sensing E, N and UP signals with the correct polarity. Paint / Mark lines on the exterior of the case with the correct directions. Are you going to solder the metal film damping resistors and any RF capacitors across the geophone terminals? Remember to check the input resistance of your amplifier and use it in the calculation for the damping resistor. How about protection diodes? Do you get severe thunder storms in your area? Is the soil sandy / rocky / dry? It is over many areas in the USA and this can give problems with local lightning. Your house and system may all be exposed many feet above the local 'Earth' conducting plane. The outer case must be hermetically sealed and the cable end also sealed. Some cable types allow air to pass through between the wires when under pressure. Also seal the amplifier end of the cable. I suggest that you add a bag of inert silica gel drying crystals inside the case to absorb any moisture. Regards, Chris Chapman In a me= ssage dated 2006/11/15, davewilley@............. writes:

My question for you all is will= there be any noticeable magnetic interaction between the 3 units I need to=20= worry about with stacking them about .25 - .5 inches apart inside the PVC tu= bing?


Hi Dave Willey,.

       The geophone units should have no magne= tic interactions when stacked together. However, you do need to connect them= fairly accurately at right angles
and they should be clamped in place. Can you provide an inner rod / tube of=20= plastic and bore holes in this to mount / align the geophones?

       The 4.5 Hz geophones do have stray fiel= ds at both ends, but the barrel is the mild steel return path for the axiall= y mounted central magnets. I would suggest a 1 cm spacing.

       You can get Roberts' type period extens= ion amplifiers from www.sara.pg.it These should enable you to receive telese= ismic P and S waves, which you won't otherwise see with 4.5 Hz geophones. Se= e the note about 4.5 Hz geophones on Larry's website?

       When you have remounted the geophones,=20= do make a record of the wire colours and that they are the correct way aroun= d for sensing E, N and UP signals with the correct polarity. Paint / Mark li= nes on the exterior of the case with the correct directions.

       Are you going to solder the metal film=20= damping resistors and any RF capacitors across the geophone terminals? Remem= ber to check the input resistance of your amplifier and use it in the calcul= ation for the damping resistor.

       How about protection diodes? Do you get= severe thunder storms in your area? Is the soil sandy / rocky / dry? It is=20= over many areas in the USA and this can give problems with local lightning.=20= Your house and system may all be exposed many feet above the local 'Earth' c= onducting plane.

       The outer case must be hermetically sea= led and the cable end also sealed. Some cable types allow air to pass throug= h between the wires when under pressure. Also seal the amplifier end of the=20= cable. I suggest that you add a bag of inert silica gel drying crystals insi= de the case to absorb any moisture.

       Regards,

       Chris Chapman
       Subject: Kuril island earthquake From: jonfr500@......... Date: Wed, 15 Nov 2006 16:30:21 +0000 Hi all As you did all notice there was a Mw8.3 earthquake near Kuril island. This = earthquake was so big that the trace can actually be seen on my geophone pl= ot, at least I think so. But I will check the data when I get back home on = Friday, but I am not home at the moment. Other traces look great. Regards. J=F3n Fr=EDmann. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: plum bob seismometer From: "Allan Egleston" allane@............. Date: Wed, 15 Nov 2006 11:25:44 -0800 Has any one on the list experimented with a blumbob as a seismo and have had any sucess wit hit=3F Thanks in advance , Allan Egleston kf6uxj = Dial Broadband has arrived Nationwide! Up to 5 times faster than traditio= nal dialup connections from $13.33/month! See the demo for yourself at www.BigValley.net = __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Homebrew 3 axis Geophone Torpedo Container From: Dave Willey davewilley@............. Date: Wed, 15 Nov 2006 15:07:39 -0800 (PST) ChrisAtUpw@....... wrote: In a message dated 2006/11/15, davewilley@............. writes: My question for you all is will there be any noticeable magnetic interaction between the 3 units I need to worry about with stacking them about .25 - .5 inches apart inside the PVC tubing? Hi Dave Willey,. The geophone units should have no magnetic interactions when stacked together. However, you do need to connect them fairly accurately at right angles and they should be clamped in place. Can you provide an inner rod / tube of plastic and bore holes in this to mount / align the geophones? The 4.5 Hz geophones do have stray fields at both ends, but the barrel is the mild steel return path for the axially mounted central magnets. I would suggest a 1 cm spacing. You can get Roberts' type period extension amplifiers from www.sara.pg.it These should enable you to receive teleseismic P and S waves, which you won't otherwise see with 4.5 Hz geophones. See the note about 4.5 Hz geophones on Larry's website? When you have remounted the geophones, do make a record of the wire colours and that they are the correct way around for sensing E, N and UP signals with the correct polarity. Paint / Mark lines on the exterior of the case with the correct directions. Are you going to solder the metal film damping resistors and any RF capacitors across the geophone terminals? Remember to check the input resistance of your amplifier and use it in the calculation for the damping resistor. How about protection diodes? Do you get severe thunder storms in your area? Is the soil sandy / rocky / dry? It is over many areas in the USA and this can give problems with local lightning. Your house and system may all be exposed many feet above the local 'Earth' conducting plane. The outer case must be hermetically sealed and the cable end also sealed. Some cable types allow air to pass through between the wires when under pressure. Also seal the amplifier end of the cable. I suggest that you add a bag of inert silica gel drying crystals inside the case to absorb any moisture. Regards, Chris Chapman

ChrisAtUpw@....... wrote:
In a message dated 2006/11/15, davewilley@............. writes:

My question for you all is will there be any noticeable magnetic interaction between the 3 units I need to worry about with stacking them about .25 - .5 inches apart inside the PVC tubing?


Hi Dave Willey,.

       The geophone units should have no magnetic interactions when stacked together. However, you do need to connect them fairly accurately at right angles
and they should be clamped in place. Can you provide an inner rod / tube of plastic and bore holes in this to mount / align the geophones?

       The 4.5 Hz geophones do have stray fields at both ends, but the barrel is the mild steel return path for the axially mounted central magnets. I would suggest a 1 cm spacing.

       You can get Roberts' type period extension amplifiers from www.sara.pg.it These should enable you to receive teleseismic P and S waves, which you won't otherwise see with 4.5 Hz geophones. See the note about 4.5 Hz geophones on Larry's website?

       When you have remounted the geophones, do make a record of the wire colours and that they are the correct way around for sensing E, N and UP signals with the correct polarity. Paint / Mark lines on the exterior of the case with the correct directions.

       Are you going to solder the metal film damping resistors and any RF capacitors across the geophone terminals? Remember to check the input resistance of your amplifier and use it in the calculation for the damping resistor.

       How about protection diodes? Do you get severe thunder storms in your area? Is the soil sandy / rocky / dry? It is over many areas in the USA and this can give problems with local lightning. Your house and system may all be exposed many feet above the local 'Earth' conducting plane.

       The outer case must be hermetically sealed and the cable end also sealed. Some cable types allow air to pass through between the wires when under pressure. Also seal the amplifier end of the cable. I suggest that you add a bag of inert silica gel drying crystals inside the case to absorb any moisture.

       Regards,

       Chris Chapman
      

Subject: Re: Homebrew 3 axis Geophone Torpedo Container From: Dave Willey davewilley@............. Date: Wed, 15 Nov 2006 16:46:04 -0800 (PST) Alright. One more attempt... ChrisAtUpw@....... wrote: In a message dated 2006/11/15, davewilley@............. writes: >>My question for you all is will there be any noticeable magnetic interaction between the >>3 units I need to worry about with stacking them (vertically) about .25 - .5 inches >>apart inside the PVC tubing? > Hi Dave Willey,. > The geophone units should have no magnetic interactions when stacked together. >However, you do need to connect them fairly accurately at right angles >and they should be clamped in place. Can you provide an inner rod / tube of plastic and >bore holes in this to mount / align the geophones? Yes. I am planning use a mill with a horizontally mounted index head so as to mill at exact 90 degrees a hole perpendicular in a slightly larger (1.5”) PVC pipe, 5 inches long. (What you’re calling an inner tube.) I’ll be lightly clamping them with set screws to keep the geophones stable. The inner tube with the geophones is to be glued into the inside of a 2.5 inch threaded plug that will screw into a matching female connector on the bottom and glued to a short length of 3” pipe which acts as the over-all cover. The outer cover has a slip cap on top with a machine screw eye that will come out the top. Coax cables will come out the bottom of the plug and to the surface. Coax is covered with PVC so I should be able to glue everything together and have it waterproof. > The 4.5 Hz geophones do have stray fields at both ends, but the barrel is the mild- >steel return path for the axially mounted central magnets. I would suggest a 1 cm spacing. > > You can get Roberts' type period extension amplifiers from www.sara.pg.it >These should enable you to receive teleseismic P and S waves, which you won't other- >wise see with 4.5 Hz geophones. See the note about 4.5 Hz geophones on Larry's website? Are you referring to the 3 channel amp boards (SEMP30) and equalizer boards (SEQUA10)? If so, will the eq board work in front of Larry’s 4 channel 16-bit preamp board? (Which I already have.) I could hang this EQ board on the unused 4th channel for teleseismic work. That would be a neat setup if they play together. > When you have remounted the geophones, do make a record of the wire colours >and that they are the correct way around for sensing E, N and UP signals with the >correct polarity. Paint / Mark lines on the exterior of the case with the correct directions. Yep. Having been a (semi retired) electronic tech at True Time w/ Keith Paya I’m well aware about watching the polarity as to not be ultimately 90 or 180 degrees out of phase with the direction of the movement. > Are you going to solder the metal film damping resistors and any RF capacitors across the >geophone terminals? Remember to check the input resistance of your amplifier and use it in the >calculation for the damping resistor. I’m assuming since I bought everything from Larry several years ago as a “turn-key” system that this has been all done. It’s been playing fine on the back concrete patio for 1.5 years. Now it’s time to wrap up the test phase of this experiment and get it in the ground away from the house and the roads. > How about protection diodes? Do you get severe thunder storms in your area? Is the soil >sandy / rocky / dry? It is over many areas in the USA and this can give problems with local >lightning. Your house and system may all be exposed many feet above the local 'Earth' >conducting plane. This I’ll have to check on. I don’t think there are any clamping diodes. I’ll put some a silicon version of a 1N914 diode “nose-to-tail” across the cables center conductors and coax shield/case ground. Good thought. > The outer case must be hermetically sealed and the cable end also sealed. Some cable >types allow air to pass through between the wires when under pressure. Also seal the amplifier >end of the cable. I suggest that you add a bag of inert silica gel drying crystals inside the case > to absorb any moisture. I’ll check with Belden Cable about Plenum grade RG-174 and see how impervious to water vapor it is. Before True Time, I worked at Lemo connectors. They have several lines of space-rated and deep oil exploration-grade connectors. They seemed very over-engineered for my needs. So the connectors should stay watertight. I do like the idea of the silica gel as a last ditch effort to keep things dry inside. > Regards, > Chris Chapman One again Chris you (and the others on this list) have been a great resource of ideas. Thanks, Dave Willey Alright. One more attempt...

ChrisAtUpw@....... wrote:
 
In a message dated 2006/11/15, davewilley@............. writes:


>>My question for you all is will there be any noticeable magnetic interaction between the
>>3 units I need to worry about with stacking them (vertically) about .25 - .5 inches
>>apart inside the PVC tubing?


> Hi Dave Willey,.

>       The geophone units should have no magnetic interactions when stacked together.
>However, you do need to connect them fairly accurately at right angles
>and they should be clamped in place. Can you provide an inner rod / tube of plastic and
>bore holes in this to mount / align the geophones?

Yes.  I am planning use a mill with a horizontally mounted index head so as to mill at exact 90 degrees a hole perpendicular in a slightly larger (1.5”) PVC pipe, 5 inches long. (What you’re calling an inner tube.)  I’ll be lightly clamping them with set screws to keep the geophones stable.
 
The inner tube with the geophones is to be glued into the inside of a 2.5 inch threaded plug that will screw into a matching female connector on the bottom and glued to a short length of 3” pipe which acts as the over-all cover. The outer cover has a slip cap on top with a machine screw eye that will come out the top.  Coax cables will come out the bottom of the plug and to the surface. Coax is covered with PVC so I should be able to glue everything together and have it waterproof.
 
>      The 4.5 Hz geophones do have stray fields at both ends, but the barrel is the mild-
>steel return path for the axially mounted central magnets. I would suggest a 1 cm spacing.
>
 >      You can get Roberts' type period extension amplifiers from www.sara.pg.it
>These should enable you to receive teleseismic P and S waves, which you won't other-
>wise see with 4.5 Hz geophones. See the note about 4.5 Hz geophones on Larry's website?

Are you referring to the 3 channel amp boards (SEMP30) and equalizer boards (SEQUA10)? If so, will the eq board work in front of Larry’s 4 channel 16-bit preamp board?  (Which I already have.)   I could hang this EQ board on the unused 4th channel for teleseismic work.  That would be a neat setup if they play together.

>       When you have remounted the geophones, do make a record of the wire colours
>and that they are the correct way around for sensing E, N and UP signals with the
>correct polarity. Paint / Mark lines on the exterior of the case with the correct directions.

Yep.  Having been a (semi retired) electronic tech at True Time w/ Keith Paya I’m well aware
about watching the polarity as to not be ultimately 90 or 180 degrees out of phase with the direction of the movement.

>       Are you going to solder the metal film damping resistors and any RF capacitors across the
>geophone terminals? Remember to check the input resistance of your amplifier and use it in the
>calculation for the damping resistor.
I’m assuming since I bought everything from Larry several years ago as a “turn-key” system that this has been all done.  It’s been playing fine on the back concrete patio for 1.5 years.  Now it’s time to wrap up the test phase of this experiment and get it in the ground away from the house and the roads.

>   How about protection diodes? Do you get severe thunder storms in your area? Is the soil
>sandy / rocky / dry? It is over many areas in the USA and this can give problems with local
>lightning. Your house and system may all be exposed many feet above the local 'Earth'
>conducting plane.
This I’ll have to check on.  I don’t think there are any clamping diodes. I’ll put some a silicon version of a 1N914 diode
“nose-to-tail” across the cables center conductors and coax shield/case ground.  Good thought.

 >      The outer case must be hermetically sealed and the cable end also sealed. Some cable
>types allow air to pass through between the wires when under pressure. Also seal the amplifier
>end of the cable. I suggest that you add a bag of inert silica gel drying crystals inside the case
> to absorb any moisture.

I’ll check with Belden Cable about Plenum grade RG-174 and see how impervious to water vapor it is.
 
Before True Time, I worked at Lemo connectors.  They have several lines of space-rated and deep oil exploration-grade connectors.  They seemed very over-engineered for my needs. So the connectors should stay watertight.
 
I do like the idea of the silica gel as a last ditch effort to keep things dry inside.
 

>       Regards,

 >     Chris Chapman

 
One again Chris you (and the others on this list) have been a great resource of ideas. 
 
 
 
Thanks,
 
 
 
Dave Willey
 
Subject: Re: plum bob seismometer From: ChrisAtUpw@....... Date: Wed, 15 Nov 2006 21:18:41 EST In a message dated 2006/11/15, allane@............. writes: > Has any one on the list experimented with a blumbob as a seismo and > have had any success with it? > Thanks in advance , Allan Egleston kf6uxj Hi Allan, Only with a ~comparable type of system. You would probably need to use two sets of foils at right angles for the suspension to prevent the bob from rotating. You would need to damp the swing in two directions at right angles and provide two sensitive detectors which do not interact significantly. These might be tungsten bulb + lens + 2x Si differential photodiodes type? Maybe two coils on the bob with magnets on the baseplate? Maybe capacitor plates? I would say possible, but not an easy task and that two pendulum systems with rigid suspensions at right angles would likely give better + easier results. The period of a pendulum is proportional to the square root of the length. A 1m pendulum is ~ 2 sec. which is OK for P and S waves. To get 20 sec with a simple pendulum you would need 100 metres = 328 ft, which is likely to present practical constructional problems (even if you have access to a disused mineshaft). My 120 ft well would only give me about 12 secs and I don't fancy the climb. Long period seismic pendulums are usually of the garden gate, or of the folded type. It is relatively easy to get periods of 20 sec or longer, to allow you to detect the larger long period Love waves as well as the P & S waves. It is also possible to apply electronic feedback to a 'simple' 1 sec. pendulum to greatly extend the period - see Shackleford-Gundersen references on psn. It is also possible with a precision capacitance measuring system and a 24 bit ADC to sample and then electronically integrate to greatly extend the period. Regards, Chris Chapman In a me= ssage dated 2006/11/15, allane@............. writes:

Has any one on the list experim= ented with a blumbob as a seismo and
have had any success with it?
Thanks in advance , Allan Egleston kf6uxj


Hi Allan,

       Only with a ~comparable type of system.= You would probably need to use two sets of foils at right angles for the su= spension to prevent the bob from rotating. You would need to damp the swing=20= in two directions at right angles and provide two sensitive detectors which=20= do not interact significantly. These might be tungsten bulb + lens + 2x Si d= ifferential photodiodes type? Maybe two coils on the bob with magnets on the= baseplate? Maybe capacitor plates?
       I would say possible, but not an easy t= ask and that two pendulum systems with rigid suspensions at right angles wou= ld likely give better + easier results. The period of a pendulum is proporti= onal to the square root of the length. A 1m pendulum is ~ 2 sec. which is OK= for P and S waves. To get 20 sec with a simple pendulum you would need 100=20= metres =3D 328 ft, which is likely to present practical constructional probl= ems (even if you have access to a disused mineshaft). My 120 ft well would o= nly give me about 12 secs and I don't fancy the climb.
       Long period seismic pendulums are usual= ly of the garden gate, or of the folded type. It is relatively easy to get p= eriods of 20 sec or longer, to allow you to detect the larger long period Lo= ve waves as well as the P & S waves. It is also possible to apply electr= onic feedback to a 'simple' 1 sec. pendulum to greatly extend the period - s= ee Shackleford-Gundersen references on psn. It is also possible with a preci= sion capacitance measuring system and a 24 bit ADC to sample and then electr= onically integrate to greatly extend the period. 

       Regards,

       Chris Chapman Subject: Re: Homebrew 3 axis Geophone Torpedo Container From: ChrisAtUpw@....... Date: Wed, 15 Nov 2006 22:51:44 EST In a message dated 2006/11/16, davewilley@............. writes: > > You can get Roberts' type period extension amplifiers from=20 > www.sara.pg.it=20 > >These should enable you to receive teleseismic P and S waves, which you=20 > won't other- > >wise see with 4.5 Hz geophones. See the note about 4.5 Hz geophones on=20 > Larry's website? >=20 > Are you referring to the 3 channel amp boards (SEMP30) and equalizer board= s=20 > (SEQUA10)?=20 Correct and also the PSU supply? If so, will the eq board work in front of Larry=E2=80=99s 4 channel 16-bit p= reamp=20 board? =20 > (Which I already have.) I could hang this EQ board on the unused 4th=20 > channel for teleseismic work. That would be a neat setup if they play tog= ether. I don't have one of Larry's boards to compare, but from the circuit=20 you would likely have to break the link / rewire the connection between the=20 first and second opamps and wire in earth and supply rails for the SEQUA10.=20= They=20 are a special type of LF boost amplifier. You usually fit a SEQUA10 between=20= the=20 first low noise opamp and the low pass filter to get optimum performance /=20 lowest noise.=20 > > Are you going to solder the metal film damping resistors and any R= F=20 > capacitors across the=20 > >geophone terminals? Remember to check the input resistance of your=20 > amplifier and use it in the=20 > >calculation for the damping resistor.=20 >=20 > I=E2=80=99m assuming since I bought everything from Larry several years ag= o as a =E2=80=9C > turn-key=E2=80=9D system that this has been all done. It=E2=80=99s been pl= aying fine on the=20 > back concrete patio for 1.5 years. Now it=E2=80=99s time to wrap up the te= st phase of=20 > this experiment and get it in the ground away from the house and the roads= . I suggest that you cross check EVERYTHING - BEFORE you seal / bury=20 ANYTHING! I start to pick up fast traffic on the main road at about 1 km. > > How about protection diodes? Do you get severe thunder storms in your=20 > area? Is the soil=20 > >sandy / rocky / dry? It is over many areas in the USA and this can give=20 > problems with local=20 > >lightning. Your house and system may all be exposed many feet above the=20 > local 'Earth'=20 > >conducting plane. >=20 >=20 > This I=E2=80=99ll have to check on. I don=E2=80=99t think there are any c= lamping diodes. I=E2=80=99 > ll put some a silicon version of a 1N914 diode=20 > =E2=80=9Cnose-to-tail=E2=80=9D across the cables center conductors and coa= x shield/case=20 > ground. Good thought. I would use fast high current rectifiers to give them a chance of=20 outlasting the first thunderstorm. Having to dig up failed electronics does=20= not=20 improve your mood. Check with the Ham Radio operators on lightning protectio= n=20 for your area? How about ferrite rings? I use them on the base unit of a=20 cordless phone to ~protect it from transients. That was after the phone had=20= failed=20 twice and after the phone company had fitted their own discharge tube=20 protection.....=20 > > The outer case must be hermetically sealed and the cable end also=20 > sealed. Some cable=20 > >types allow air to pass through between the wires when under pressure. Al= so=20 > seal the amplifier=20 > >end of the cable. I suggest that you add a bag of inert silica gel drying= =20 > crystals inside the case=20 > > to absorb any moisture.=20 >=20 > I=E2=80=99ll check with Belden Cable about Plenum grade RG-174 and see how= =20 > impervious to water vapor it is. =20 I don't use coax cable. I use six core screened cable which has an=20 external braided copper screen - this one cable services the three geophones= and=20 the screen is connected to the geophone cases. CAT5 cable does not provide=20 good enough rejection, even if you can get it screened. The cable supplied f= or=20 geophones has steel reinforcing but no screen - sigh!=20 =20 Regards, Chris Chapman In a me= ssage dated 2006/11/16, davewilley@............. writes:

>    &n= bsp; You can get Roberts' type period extension amplifiers from www.sara.pg.= it
>These should enable you to receive teleseismic P and S waves, which you=20= won't other-
>wise see with 4.5 Hz geophones. See the note about 4.5 Hz geophones on L= arry's website?

Are you referring to the 3 channel amp boards (SEMP30) and equalizer boards=20= (SEQUA10)?


       Correct and also the PSU supply?

If so, will the eq board work in front of Larry=E2=80=99s 4 channel 16-bit p= reamp board? 
(Which I already have.) &= nbsp; I could hang this EQ board on the unused 4th channel for teleseismic w= ork.  That would be a neat setup if they play together.

       I don't have one of Larry's boards to=20= compare, but from the circuit you would likely have to break the link / rewi= re the connection between the first and second opamps and wire in earth and=20= supply rails for the SEQUA10. They are a special type of LF boost amplifier.= You usually fit a SEQUA10 between the first low noise opamp and the low pas= s filter to get optimum performance / lowest noise.

>    &nb= sp;  Are you going to solder the metal film damping resistors and any R= F capacitors across the
>geophone terminals? Remember to check the input resistance of your ampli= fier and use it in the
>calculation for the damping resistor.

I=E2=80=99m assuming since I bought everything from Larry several years ago=20= as a =E2=80=9Cturn-key=E2=80=9D system that this has been all done. It=E2= =80=99s been playing fine on the back concrete patio for 1.5 years. Now it= =E2=80=99s time to wrap up the test phase of this experiment and get it in t= he ground away from the house and the roads.


       I suggest that you cross check EVERYTH= ING -  BEFORE you seal / bury ANYTHING!

       I start to pick up fast traffic on the=20= main road at about 1 km.

>   How about prot= ection diodes? Do you get severe thunder storms in your area? Is the soil >sandy / rocky / dry? It is over many areas in the USA and this can give=20= problems with local
>lightning. Your house and system may all be exposed many feet above the=20= local 'Earth'
>conducting plane.


This I=E2=80=99ll have to check on.  I don=E2=80=99t think there are an= y clamping diodes. I=E2=80=99ll put some a silicon version of a 1N914 diode=20=
=E2=80=9Cnose-to-tail=E2=80=9D across the cables center conductors and coax=20= shield/case ground.  Good thought.


       I would use fast high current rectifie= rs to give them a chance of outlasting the first thunderstorm. Having to dig= up failed electronics does not improve your mood. Check with the Ham Radio=20= operators on lightning protection for your area? How about ferrite rings? I=20= use them on the base unit of a cordless phone to ~protect it from transients= .. That was after the phone had failed twice and after the phone company had=20= fitted their own discharge tube protection.....

>    &= nbsp; The outer case must be hermetically sealed and the cable end also seal= ed. Some cable
>types allow air to pass through between the wires when under pressure. A= lso seal the amplifier
>end of the cable. I suggest that you add a bag of inert silica gel dryin= g crystals inside the case
> to absorb any moisture.

I=E2=80=99ll check with Belden Cable about Plenum grade RG-174 and see how i= mpervious to water vapor it is.

      
       I don't use coax cable. I use six core=20= screened cable which has an external braided copper screen - this one cable=20= services the three geophones and the screen is connected to the geophone cas= es. CAT5 cable does not provide good enough rejection, even if you can get i= t screened. The cable supplied for geophones has steel reinforcing but no sc= reen - sigh!
      
       Regards,

       Chris Chapman Subject: Re: plum bob seismometer From: ian ian@........... Date: Thu, 16 Nov 2006 09:23:34 +0000 Hi, I'm not convinced that you need to match the period of a plum bob to the seismic motion. A plum bob will follow the tilt even if it takes 50 seconds to reach its maximum. At the end of the 50 seconds, it will still be pointing to the centre of the Earth. On top of that you will have the natural period oscillation but this can be filtered out to get the mean value. The real value of having a long plum bob is that the amount of displacement of the end weight is much larger and much easier to measure. It also helps to reduce the significance of mechanical imperfections of the mount at the other end. Ian ChrisAtUpw@....... wrote: > > I would say possible, but not an easy task and that two > pendulum systems with rigid suspensions at right angles would likely > give better + easier results. The period of a pendulum is proportional > to the square root of the length. A 1m pendulum is ~ 2 sec. which is > OK for P and S waves. To get 20 sec with a simple pendulum you would > need 100 metres = 328 ft, which is likely to present practical > constructional problems (even if you have access to a disused > mineshaft). My 120 ft well would only give me about 12 secs and I > don't fancy the climb. Hi,

I'm not convinced that you need to match the period of a plum bob to the seismic motion.  A plum bob will follow the tilt even if it takes 50 seconds to reach its maximum.  At the end of the 50 seconds, it will still be pointing to the centre of the Earth.  On top of that you will have the natural period oscillation but this can be filtered out to get the mean value. 

The real value of having a long plum bob is that the amount of displacement of the end weight is much larger and much easier to measure.  It also helps to reduce the significance of mechanical imperfections of the mount at the other end.

Ian

ChrisAtUpw@....... wrote:

       I would say possible, but not an easy task and that two pendulum systems with rigid suspensions at right angles would likely give better + easier results. The period of a pendulum is proportional to the square root of the length. A 1m pendulum is ~ 2 sec. which is OK for P and S waves. To get 20 sec with a simple pendulum you would need 100 metres = 328 ft, which is likely to present practical constructional problems (even if you have access to a disused mineshaft). My 120 ft well would only give me about 12 secs and I don't fancy the climb.

Subject: Re: plum bob seismometer From: ChrisAtUpw@....... Date: Thu, 16 Nov 2006 09:10:34 EST In a message dated 2006/11/16, ian@........... writes: > I'm not convinced that you need to match the period of a plum bob to > the seismic motion. A plum bob will follow the tilt even if it takes 50 seconds > to reach its maximum. At the end of the 50 seconds, it will still be > pointing to the centre of the Earth. On top of that you will have the natural period > oscillation but this can be filtered out to get the mean value. Hi Ian, Are you talking about tilt responses which tend to be dominant for periods over ~300 sec? At periods below this the tilt signal of a seismic wave is minor. Otherwise you have a pendulum system, which if correctly damped will give an output with velocity above the resonant period, but falling as f^2 below it. > The real value of having a long plum bob is that the amount of > displacement of the end weight is much larger and much easier to measure. It also > helps to reduce the significance of mechanical imperfections of the mount at > the other end. The problem with large pieces of equipment is keeping the air column stable. You could evacuate a tubular vertical column, but it would be costly and the column could still flex with temperature. There need not be a sensor sensitivity problem. Photocells can resolve about 15 nano metres, which is likely to be below the background noise. You can get down below 1 nm with variable capacitance methods Regards, Chris Chapman In a me= ssage dated 2006/11/16, ian@........... writes:

   
I'm not conv= inced that you need to match the period of a plum bob to the seismic motion.= A plum bob will follow the tilt even if it takes 50 seconds to reach its ma= ximum. At the end of the 50 seconds, it will still be pointing to the centre= of the Earth. On top of that you will have the natural period oscillation b= ut this can be filtered out to get the mean value.


Hi Ian,

       Are you talking about tilt responses wh= ich tend to be dominant for periods over ~300 sec? At periods below this the= tilt signal of a seismic wave is minor.
       Otherwise you have a pendulum system, w= hich if correctly damped will give an output with velocity above the resonan= t period, but falling as f^2 below it.

      
The real value of having a long plum bob is that the amount of displac= ement of the end weight is much larger and much easier to measure. It also h= elps to reduce the significance of mechanical imperfections of the mount at=20= the other end
.

       The problem with large pieces of equip= ment is keeping the air column stable. You could evacuate a tubular vertical= column, but it would be costly and the column could still flex with tempera= ture.

       There need not be a sensor sensitivity=20= problem. Photocells can resolve about 15 nano metres, which is likely to be=20= below the background noise. You can get down below 1 nm with variable capaci= tance methods

       Regards,

    Chris Chapman Subject: Re: plum bob seismometer From: Karl Cunningham karlc@.......... Date: Thu, 16 Nov 2006 13:20:35 -0800 On 11/15/2006 11:25 AM, Allan Egleston wrote: > Has any one on the list experimented with a blumbob as a seismo and > have had any sucess wit hit? > Thanks in advance , Allan Egleston kf6uxj Allan, I wont duplicate Chris Chapman's comments, but if you want something simple to construct you might consider the inverted pendulum (think rocking chair). This can be as simple as a car radio antenna with a heavy ball fastened to the top. These can be metastable and have linearity issues, but if all you want is a long period it is possible to get that for small excursions. Karl Cunningham __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: plum bob seismometer From: ian ian@........... Date: Thu, 16 Nov 2006 21:28:55 +0000 Hi, firstly, I'm not a seismologist/geologist so I could be talking total... I'm assuming that any seismic activity will cause a localised tilt of the ground. So the plum bob isn't being used as a pendulum but as a tilt meter. Referring back to some emails from Sean-Thomas on the psn email archive, circa 2000, he provided a formula for the relationship between telesiemic quake magnitudes and ground tilt. In the example discussed, I think an Ms 6.2 produced a local ground tilt of 100 micro radians. Doing a quick "back of an envelope" calculation, a 1 meter long plum bob would move by about 100 nano meters at the tip. You could get one of those glass columns (from somewhere!) to house it in and seal it. You might employ some form of galvanic spot meter type optics to magnify the movement. It all starts to sound like more effort than a standard Lehman... Cheers Ian ChrisAtUpw@....... wrote: > In a message dated 2006/11/16, ian@........... writes: > > > >> I'm not convinced that you need to match the period of a plum bob to >> the seismic motion. A plum bob will follow the tilt even if it takes >> 50 seconds to reach its maximum. At the end of the 50 seconds, it >> will still be pointing to the centre of the Earth. On top of that you >> will have the natural period oscillation but this can be filtered out >> to get the mean value. > > > > Hi Ian, > > Are you talking about tilt responses which tend to be dominant > for periods over ~300 sec? At periods below this the tilt signal of a > seismic wave is minor. > Otherwise you have a pendulum system, which if correctly damped > will give an output with velocity above the resonant period, but > falling as f^2 below it. > > > >> The real value of having a long plum bob is that the amount of >> displacement of the end weight is much larger and much easier to >> measure. It also helps to reduce the significance of mechanical >> imperfections of the mount at the other end > > . > > The problem with large pieces of equipment is keeping the air > column stable. You could evacuate a tubular vertical column, but it > would be costly and the column could still flex with temperature. > > There need not be a sensor sensitivity problem. Photocells can > resolve about 15 nano metres, which is likely to be below the > background noise. You can get down below 1 nm with variable > capacitance methods > > Regards, > > Chris Chapman Hi,

firstly, I'm not a seismologist/geologist so I could be talking total...  I'm assuming that any seismic activity will cause a localised tilt of the ground.  So the plum bob isn't being used as a pendulum but as a tilt meter.

Referring back to some emails from Sean-Thomas on the psn email archive, circa 2000, he provided a formula for the relationship between telesiemic quake magnitudes and ground tilt.  In the example discussed, I think an Ms 6.2 produced a local ground tilt of 100 micro radians.  Doing a quick "back of an envelope" calculation, a 1 meter long plum bob would move by about 100 nano meters at the tip.

You could get one of those glass columns (from somewhere!) to house it in and seal it.  You might employ some form of galvanic spot meter type optics to magnify the movement.

It all starts to sound like more effort than a standard Lehman...

Cheers

Ian

ChrisAtUpw@....... wrote:
In a message dated 2006/11/16, ian@........... writes:

   
I'm not convinced that you need to match the period of a plum bob to the seismic motion. A plum bob will follow the tilt even if it takes 50 seconds to reach its maximum. At the end of the 50 seconds, it will still be pointing to the centre of the Earth. On top of that you will have the natural period oscillation but this can be filtered out to get the mean value.


Hi Ian,

       Are you talking about tilt responses which tend to be dominant for periods over ~300 sec? At periods below this the tilt signal of a seismic wave is minor.
       Otherwise you have a pendulum system, which if correctly damped will give an output with velocity above the resonant period, but falling as f^2 below it.

      
The real value of having a long plum bob is that the amount of displacement of the end weight is much larger and much easier to measure. It also helps to reduce the significance of mechanical imperfections of the mount at the other end
..

       The problem with large pieces of equipment is keeping the air column stable. You could evacuate a tubular vertical column, but it would be costly and the column could still flex with temperature.

       There need not be a sensor sensitivity problem. Photocells can resolve about 15 nano metres, which is likely to be below the background noise. You can get down below 1 nm with variable capacitance methods

       Regards,

    Chris Chapman

Subject: Re: plum bob seismometer From: ChrisAtUpw@....... Date: Thu, 16 Nov 2006 17:51:03 EST In a message dated 2006/11/16, ian@........... writes: > Referring back to some emails from Sean-Thomas on the psn email archive, > circa 2000, he provided a formula for the relationship between telesiemic quake > magnitudes and ground tilt. In the example discussed, I think an Ms 6.2 > produced a local ground tilt of 100 micro radians. Doing a quick "back of an > envelope" calculation, a 1 meter long plum bob would move by about 100 nano > meters at the tip. Hi Ian, At what range from the epicentre? Do you have the reference? Remember that you have the microseismic background giving from 500 to 15,000 nm movement? most often 1,000 to 2,000 nm? > You could get one of those glass columns (from somewhere!) to house it in > and seal it. You might employ some form of galvanic spot meter type optics to > magnify the movement. You might start having difficulties here. The wavelength of visible light is about 500 nm, so you would be trying to see a slowly moving diffraction pattern in amongst much larger microseism movements..... > It all starts to sound like more effort than a standard Lehman... Er, how about a nice folded pendulum? Regards, Chris Chapman In a me= ssage dated 2006/11/16, ian@........... writes:

Referring back to some emails f= rom Sean-Thomas on the psn email archive, circa 2000, he provided a formula=20= for the relationship between telesiemic quake magnitudes and ground tilt. In= the example discussed, I think an Ms 6.2 produced a local ground tilt of 10= 0 micro radians. Doing a quick "back of an envelope" calculation, a 1 meter=20= long plum bob would move by about 100 nano meters at the tip.

Hi Ian,

       At what range from the epicentre?
       Do you have the reference?
       Remember that you have the microseismic= background giving from 500 to 15,000 nm movement? most often 1,000 to 2,000= nm?

You could get one of those glas= s columns (from somewhere!) to house it in and seal it.  You might empl= oy some form of galvanic spot meter type optics to magnify the movement.

       You might start having difficulties her= e. The wavelength of visible light is about 500 nm, so you would be trying t= o see a slowly moving diffraction pattern in amongst much larger microseism=20= movements.....

It all starts to sound like mor= e effort than a standard Lehman...


       Er, how about a nice folded pendulum?=20=

    Regards,

       Chris Chapman Subject: EQEvent From: "Dale Hardy" photon1@........... Date: Fri, 17 Nov 2006 14:02:41 +1100 Hello, did anyone record the event at approx 2035Z today, no reports on USGS as = to location see http://aslwww.cr.usgs.gov/Seismic_Data/telemetry_data/NWAO_24hr.gif for this event Dale
Hello,
did anyone record the event at approx = 2035Z today,=20 no reports on USGS as to location
see http://aslwww.cr.usgs.gov/Seismic_Data/telemetry_data/NWAO_24hr.gif
for this event
Dale
Subject: Re: EQEvent - AUCKLAND ISLANDS, N.Z. REGION From: Mark Robinson mark.robinson@............... Date: Fri, 17 Nov 2006 16:31:04 +1300 Dale Hardy wrote: > Hello, > did anyone record the event at approx 2035Z today, no reports on USGS as to location > see http://aslwww.cr.usgs.gov/Seismic_Data/telemetry_data/NWAO_24hr.gif > for this event Red Puma lists this: > 16Nov2006 20:29:56.1 51.8S 139.7E 33 MS=5.7 M*GSR SOUTH OF AUSTRALIA 2219 regards Mark Robinson __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: plum bob seismometer From: ian ian@........... Date: Fri, 17 Nov 2006 10:25:45 +0000 Hi, I got my nanos and micros mixed up! The back of envelope calculation concluded a movement of 100 micro meters. So no diffraction patterns involved, phew! The email with the formula is in the 2001 archive, Wed, 7 Feb 2001, subject: "tiltmeter sensitivity". The assumed distance from the epicentre was 90 degrees. No problem with folded pendulums! (or is it pendula?) Ian ChrisAtUpw@....... wrote: > In a message dated 2006/11/16, ian@........... writes: > >> Referring back to some emails from Sean-Thomas on the psn email >> archive, circa 2000, he provided a formula for the relationship >> between telesiemic quake magnitudes and ground tilt. In the example >> discussed, I think an Ms 6.2 produced a local ground tilt of 100 >> micro radians. Doing a quick "back of an envelope" calculation, a 1 >> meter long plum bob would move by about 100 nano meters at the tip. > > > > Hi Ian, > > At what range from the epicentre? > Do you have the reference? > Remember that you have the microseismic background giving from > 500 to 15,000 nm movement? most often 1,000 to 2,000 nm? > >> You could get one of those glass columns (from somewhere!) to house >> it in and seal it. You might employ some form of galvanic spot meter >> type optics to magnify the movement. > > > > You might start having difficulties here. The wavelength of > visible light is about 500 nm, so you would be trying to see a slowly > moving diffraction pattern in amongst much larger microseism > movements..... > >> It all starts to sound like more effort than a standard Lehman... > > > > Er, how about a nice folded pendulum? > > Regards, > > Chris Chapman Hi,

I got my nanos and micros mixed up!  The back of envelope calculation concluded a movement of 100 micro meters.  So no diffraction patterns involved, phew! 

The email with the formula is in the 2001 archive, Wed, 7 Feb 2001, subject: "tiltmeter sensitivity".  The assumed distance from the epicentre was 90 degrees.

No problem with folded pendulums! (or is it pendula?)

Ian

ChrisAtUpw@....... wrote:
In a message dated 2006/11/16, ian@........... writes:
Referring back to some emails from Sean-Thomas on the psn email archive, circa 2000, he provided a formula for the relationship between telesiemic quake magnitudes and ground tilt. In the example discussed, I think an Ms 6.2 produced a local ground tilt of 100 micro radians. Doing a quick "back of an envelope" calculation, a 1 meter long plum bob would move by about 100 nano meters at the tip.


Hi Ian,

       At what range from the epicentre?
       Do you have the reference?
       Remember that you have the microseismic background giving from 500 to 15,000 nm movement? most often 1,000 to 2,000 nm?

You could get one of those glass columns (from somewhere!) to house it in and seal it.  You might employ some form of galvanic spot meter type optics to magnify the movement.


       You might start having difficulties here. The wavelength of visible light is about 500 nm, so you would be trying to see a slowly moving diffraction pattern in amongst much larger microseism movements.....
It all starts to sound like more effort than a standard Lehman...


       Er, how about a nice folded pendulum?

    Regards,

       Chris Chapman


Subject: Re: EQEvent From: Pete Rowe ptrowe@......... Date: Fri, 17 Nov 2006 09:49:55 -0800 (PST) Nothing seen at my station in East San Jose. Pete --- Dale Hardy wrote: > Hello, > did anyone record the event at approx 2035Z today, > no reports on USGS as to location > see > http://aslwww.cr.usgs.gov/Seismic_Data/telemetry_data/NWAO_24hr.gif > for this event > Dale ____________________________________________________________________________________ Sponsored Link Compare mortgage rates for today. Get up to 5 free quotes. Www2.nextag.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: plum bob seismometer From: ChrisAtUpw@....... Date: Fri, 17 Nov 2006 19:33:31 EST In a message dated 2006/11/17, ian@........... writes: I> got my nanos and micros mixed up! The back of envelope calculation > concluded a movement of 100 micro meters. So no diffraction patterns involved, > phew! > > The email with the formula is in the 2001 archive, Wed, 7 Feb 2001, subject: > "tiltmeter sensitivity". The assumed distance from the epicentre was 90 > degrees. Hi Ian, Thanks for the reference. Sorry to be a bit doubtful, but are you using the formula for the vertical response? Are your formulae mixed up? The note seems to give the oscillatory response of the pendulum to the lateral seismic movement. Has the actual ground tilt been considered? > No problem with folded pendulums! (or is it pendula?) > Either are acceptable. Regards, Chris Chapman In a me= ssage dated 2006/11/17, ian@........... writes:

I
got my nanos and micros mixed= up! The back of envelope calculation concluded a movement of 100 micro mete= rs. So no diffraction patterns involved, phew! 

The email with the formula is in the 2001 archive, Wed, 7 Feb 2001, subject:= "tiltmeter sensitivity". The assumed distance from the epicentre was 90 deg= rees.


Hi Ian,

       Thanks for the reference.

       Sorry to be a bit doubtful, but are you= using the formula for the vertical response? Are your formulae mixed up?
       The note seems to give the oscillatory=20= response of the pendulum to the lateral seismic movement. Has the actual gro= und tilt been considered?

No problem with folded pendulum= s! (or is it pendula?)

       Either are acceptable.

       Regards,

       Chris Chapman Subject: Kuril island earthquake From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sat, 18 Nov 2006 02:28:32 +0000 Hi all I did record the Kuril Island earthquake really good, the trace is farly clean. Even the surface waves did record over a period of 2 hours or so. I did only see two aftershocks, the biggest ones. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Assistance needed understanding this please ! From: "Geoffrey" gmvoeth@........... Date: Sun, 19 Nov 2006 08:35:44 -0700 Does anyone understand how this circuit will affect the geophone ? If so can you show me in laymans terms what is happening ? http://gmvoeth.home.mchsi.com/geoamp01.GIF Regards; geoff __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Assistance needed understanding this please ! From: ChrisAtUpw@....... Date: Sun, 19 Nov 2006 11:04:26 EST In a message dated 2006/11/19, gmvoeth@........... writes: > Does anyone understand how this circuit will affect the geophone ? > > If so can you show me in laymans terms what is happening ? > > http://gmvoeth.home.mchsi.com/geoamp01.GIF Hi Geoff, I haven't worked out the balance equation, but this is a -ve input impedance circuit, presumably to very heavily damp the geophone. This should / could cause the output to have a 1/f characteristic, rather than the normal dogleg, flat down to the resonance and 1/f^2 below this. This type of circuit is used to 'broad band' a geophone response. Where did it come from? Regards, Chris Chapman In a me= ssage dated 2006/11/19, gmvoeth@........... writes:

Does anyone understand how this= circuit will affect the geophone ?

If so can you show me in laymans terms what is happening ?

http://gmvoeth.home.mchsi.com/geoamp01.GIF


Hi Geoff,

       I haven't worked out the balance equati= on, but this is a -ve input impedance circuit, presumably to very heavily da= mp the geophone. This should / could cause the output to have a 1/f characte= ristic, rather than the normal dogleg, flat down to the resonance and 1/f^2=20= below this.
       This type of circuit is used to 'broad=20= band' a geophone response. Where did it come from?

       Regards,

       Chris Chapman
 Subject: Re: Assistance needed understanding this please ! From: "Geoffrey" gmvoeth@........... Date: Tue, 21 Nov 2006 21:18:03 -0700 Hello Chris; I might seem to ramble here because I am not in possession of academic discipline. I have been playing around for the past 10 years (maybe several months of real time) and have learned that the only decent preamps for a geophone seem to be ones with PHANTOM grounding in the input coil. this means no matter what the coil resistance is there exists a mid point inside the coil you might call a ground. You just need to use a totally shielded line to the geophone tied to circuit ground to keep out unwanted electrical stuff. The gain will drift a bit with temp but not the baseline. you seem to need not more than X10 in the preamp to keep the gain changes small. Not less than X10 because of effects on CMMR ?? So long as you tie the geophone directly across the +/- inputs in a differential fashion you seem to get a response similar to a full blown instrumentation amplifier. It is the only way to avoid the resistance vs temp changes from affecting the class "A" operational baseline. The circuit you see is just one of many I play around with through curiosity. The original ideas most all come from the PDF files that you can download relating to whatever part the company has sold you. They are full of various circuits you can experiment with. The differential amp always shows two devices with a ground in the middle and I have found this is not necessary. Just hook a coil between + and - of an op amp and the gain is (Rf/(0.5 Rgeo)) Very similar to an instrumentation arrangement of three opamps. The internal resistance between + and - is 40 megs or so. Depends upon the op amp in question. I use OP177G from the Philippines. They can not be loaded greater than about 2K on the output. ( greater load means smaller R) The OP177F are very rugged and it takes an act of congress to destroy them but they are not made anymore I think. They have a ceramic DIP case instead of cheap plastic. What I am not certain of is there a natural DC current flow between + and - or do they always float at the same potential ?? The circuit I showed you seemed to work well but because it puts a common mode signal on the input I am reluctant to use it. Instead I am simply now using a gain of X10 on the preamp and tying the + side to the ground using a resistor matched with Rf (R feedback) within the limits of my test equipment. I have found you need to match the + and - sides of these within maybe 0.1% or your common mode rejection ratio is not so good. I could not make the negative resistance circuit work for me that is in the paper: 'Overdamping geophones using negative impedances' Bernd Ulmann ulmann@......... (may no longer be valid) It really seems to work opposite of what it says by increasing not decreasing the eigen frequency. and at the same time lowering the sensitivity of the sensor device. instead of locking the mass I think you need to somehow artificially decrease the spring constant or simulate electronically a greater mass to get the desired results. by whatever means I need to create a vertical sensor with a free period of three to four seconds. I have been considering a push-pull arrangement using unity gain amps to force/drive the opamp to behave differently than normally possibly to lower the eigen freq abnormally to 4 seconds. It is just a thought and have not seriously looked into this yet. Can you please tell me how the given circuit affectes the geophone because I never got above college algebra and that was 20 years ago. I am going to scan all the drawings of my current setup into a zip file and let anyone interested have a copy. You can all do whatever you want with my ideas I have no interest in making money or anything just having fun with the science of Geology and Electronics and programming. I just need help from those who know how to properly (electronically) lower the free period of a mass/spring system to about 4 seconds so I can use a straight forward amplification and have it be linear in gain between 3 seconds and 3 hertz. I think this might really be done somehow with a narrow band high Q feedback circuit into a push pull arrangement of X1 opamps. To artificially lower the spring constant. Never tried this and am afraid because I do not want to accidentally damage my geophone magnet or coil. To anyone else reading this links on my home page do not point to things forever. In a month or so I will remove the files meaning they will no longer be there if you try to look see. If you are interested you must save these files to your HD or contact me later and ask to see them again. Regards; geoff ----- Original Message ----- From: To: Sent: Sunday, November 19, 2006 9:04 AM Subject: Re: Assistance needed understanding this please ! > In a message dated 2006/11/19, gmvoeth@........... writes: > >> Does anyone understand how this circuit will affect the geophone ? >> >> If so can you show me in laymans terms what is happening ? >> >> http://gmvoeth.home.mchsi.com/geoamp01.GIF > > Hi Geoff, > > I haven't worked out the balance equation, but this is a -ve input > impedance circuit, presumably to very heavily damp the geophone. This should / > could cause the output to have a 1/f characteristic, rather than the normal > dogleg, flat down to the resonance and 1/f^2 below this. > This type of circuit is used to 'broad band' a geophone response. > Where did it come from? > > Regards, > > Chris Chapman > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Geophone Characteristics From: "Geoffrey" gmvoeth@........... Date: Wed, 22 Nov 2006 04:47:32 -0700 I was just thinking if you can adjust the geophone up or down a bit and apply a dc bias to either levitate or drop the mass to its center point using a steady current source you might alter its characteristics. I am afraid to do this (makes me feel whimpy to say this) but I can not endanger a geophone I may never be able to replace. Possibly one or more of you can tell me what the application of a DC bias current to a geophone will do ?? If I can find out it will not damage the coil or magnet I may try it myself. I used to have a 500# seismometer (compliments USGS)and discovered you can magnitize the thing yourself by pulsing a current into the coil so of course it is also possible to kill a magnet this way too. I gave that seismometer to my alma mater because you just try to keep it from wasting away when you have no proper place to put it. But i will tell you with certainty you will never get a better picture with anything smaller that i know of. I was getting all three waves with ease. The mass was like 200 or more lbs and the spring had a constant of like 98lbs/inch and was a ribbon like instead of wire. I wanted to take the whole thing apart but knew it was too much like an automobile and you really need a crane or something to handle that mass. Hey...I just received a nice telesismic wave while writing this. P = 11:26:44 2006NOV22 UTC at GVA (listed wrongly as currently closed) The time is crude derived from the screen and not analyzed properly. Will be happy to share my text psn file if anyone interested. Regards; geoff __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Connecting together long period and short period amp boards From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Wed, 22 Nov 2006 17:18:58 +0000 Hi all I got today new set of hardware from Larry. A new short period board and a new long period board. However, I need to connect thease boards together. When I look at them I see channel out and channel in on the board them selfs, so I assume that is to connect the channels together. However I am not sure where to connect the aux power, there is a field on the amp boards that says "aux power" it has two grounds, and +12V and -12V. My old hardware is going to be used in my first remote station that I am going to setup next early next year. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Tower cam From: 1goss@........... Date: Wed, 22 Nov 2006 21:51:30 +0000 This is a project I have been working on for a while it is a controllable web cam, on a 100ft tower. at my home I have interest in weather as well as armature seismology I thought I would share the link tell me what you think. Bryan S Goss http://www.corinthweather.com/cam.htm __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Tower cam From: Piet Beenders piet.beenders@......... Date: Thu, 23 Nov 2006 00:22:19 +0100 Great view !!! Hope to have one at my home in the future. I also have the common interest in the wheater. Regards, Piet Beenders http://www.peut.net ----- Original Message ----- From: <1goss@...........> To: Sent: Wednesday, November 22, 2006 10:51 PM Subject: Tower cam > This is a project I have been working on for a while it is a controllable > web cam, on a 100ft tower. at my home I have interest in weather as well > as armature seismology > I thought I would share the link tell me what you think. > Bryan S Goss > > http://www.corinthweather.com/cam.htm > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Assistance needed understanding this please ! From: ChrisAtUpw@....... Date: Wed, 22 Nov 2006 22:24:12 EST In a message dated 2006/11/22, gmvoeth@........... writes: > I have been playing around for the past 10 years (maybe several months of > real time) and have learned that the only decent preamps for a geophone seem > to be ones with PHANTOM grounding in the input coil. This means no matter what > the coil resistance is there exists a mid point inside the coil you might > call a ground. You just need to use a totally shielded line to the geophone > tied to circuit ground > to keep out unwanted electrical stuff. Hi Geoff, You get the lowest amplifier noise using a single +ve opamp input. Whether you need to use a differential input depends on other factors. There are usually two output pins on a geophone. I provide a two or more core cable secreened with woven copper braid. The screen braid is connected to the geophone case and connecting this to earth screens the windings. > The gain will drift a bit with temp but not the baseline. You seem to need > not more than X10 in the preamp to keep the gain changes small. > Not less than X10 because of effects on CMMR ? Low gains should not effect the CMMR. With high gains you may run out of feedback voltage if the output goes to the rails. > So long as you tie the geophone directly across the +/- inputs in a > differential fashion you seem to get a response similar to a full blown > instrumentation amplifier. Assuming that you have a full differential circuit, you need to include the damping resistors in series with the opamp inputs. > It is the only way to avoid the resistance vs temp changes from affecting > the class "A" operational baseline. You have 'lost me there'. What is a class A operational baseline? With the input to the +ve opamp input and a damping resistor across the geophone, you get very little drift with temperature - the value of the damping resistor may be 10x the resistence of the geophone winding. > The circuit you see is just one of many I play around with through > curiosity. > > The original ideas most all come from the PDF files that you can download > relating to whatever part the company has sold you. They are full of various > circuits you can > experiment with. Where are all these circuits? > The differential amp always shows two devices with a ground in the middle > and I have found this is not necessary. Just hook a coil between + and - of an > op amp and the gain is (Rf/(0.5 Rgeo)) Very similar to an instrumentation > arrangement > of three opamps. > > The internal resistance between + and - is 40 megs or so. > Depends upon the op amp in question. > I use OP177G from the Philippines. > They can not be loaded greater than about 2K on the output. > ( greater load means smaller R) > > What I am not certain of is there a natural DC current flow between + and - > or do they always float at the same potential ?? Always at the same potential - unless the output is on the rails. The gain is over 1 million. > The circuit I showed you seemed to work well but because it puts a common > mode signal on the input I am reluctant to use it. Looking at the circuit values, the +ve input to ground is FAR too high. Put in a 1 K ohm potentiometer, set it to zero and then increase it slowly. I suggest that you use the standard circuit given by Ulmann. The circuit you gave will not compensate for the resistance of the geophone. You must return the geophone to earth NOT to the +ve input !! It only puts a short circuit across the geophone. You will need to use a 1/f amplifier and also a lot more gain. > Instead I am simply now using a gain of X10 on the preamp and tying the + > side to the ground using a resistor matched with Rf (R feedback) within the > limits of my > test equipment. > > I have found you need to match the + and - sides of these within maybe 0.1% > or your common mode rejection ratio is not so good. > > I could not make the negative resistance circuit work for me that is in the > paper: > 'Overdamping geophones using negative impedances' Bernd Ulmann@......... > (may no longer be valid) Your reference copied incorrectly. > It really seems to work opposite of what it says by increasing not > decreasing the eigen frequency. and at the same time lowering the sensitivity of the > sensor device. You have got the circuit wrong. This is why it doesn't work. > instead of locking the mass I think you need to somehow artificially > decrease the > spring constant or simulate electronically a greater mass to get the desired > results. > > by whatever means I need to create a vertical sensor with a free period of > three to four seconds. Why on Earth do you want that?? This puts you into the sensitivity range of the microseisms, particularly on the Pacific coast. Do you really want to monitor them? 2 seconds should be adequate and you get this on your existing 1 Hz geophone, although at a factor of x4 down. When I extend the geophone response, I tailor it to roll off at about 0.35 to 0.4 Hz. This way you pick up the teleseismic S waves quite OK, but the microseisms are considerably reduced. > I have been considering a push-pull arrangement using unity gain amps to > force / drive the opamp to behave differently than normally possibly to lower > the eigen freq abnormally to 4 seconds. > > It is just a thought and have not seriously looked into this yet. > > Can you please tell me how the given circuit affects the geophone > because I never got above college algebra and that was 20 years ago. It gives a short circuit across the geophone, but it doesn't compensate for the resistance. I don't know where this circuit came from, but it won't do the job that you want. > I am going to scan all the drawings of my current setup into a zip file and > let anyone interested have a copy. I just need help from those who know how > to > properly (electronically) lower the free period of a mass / spring system to > about 4 seconds so I can use a straight forward amplification and have it be > linear in gain between 3 seconds and 3 hertz. OK, what website? > I think this might really be done somehow with a narrow band high Q > feedback circuit into a push pull arrangement of X1 opamps. To artificially lower > the spring constant. Never tried this and am afraid because I do not want to > accidentally damage my geophone magnet or coil. There are two OK ways of extending the geophone response to lower frequencies. The sensitivity is normally flat above the resonant frequency and falls as f^2 below this. Resonant or high Q circuits are definitely to be avoided. Your geophone is not that stable in characteristiocs. The resistance and the spring constants both change with temperature. You can provide a two stage amplifier to boost the output below the resonant frequency. This is good to 1/10 the resonant frequency, but you may run into noise problems below this. You can run the geophone into a negative impedance circuit to give an overall zero impedance input. This flattens out the charactersitic and gives a response proportional to f, so you need to amplify the signal with a single stage top cut amplifier. You can also digitally filter the output to give up to about x10 increase in period. This would be the cheapest option! But you need a lot more gain. Regards, Chris Chapman In a me= ssage dated 2006/11/22, gmvoeth@........... writes:

I have been playing around for=20= the past 10 years (maybe several months of real time) and have learned that=20= the only decent preamps for a geophone seem to be ones with PHANTOM groundin= g in the input coil. This means no matter what the coil resistance is there=20= exists a mid point inside the coil you might call a ground. You just need to= use a totally shielded line to the geophone tied to circuit ground
to keep out unwanted electrical stuff.


Hi Geoff,

       You get the lowest amplifier noise usin= g a single +ve opamp input. Whether you need to use a differential input dep= ends on other factors.
       There are usually two output pins on a=20= geophone. I provide a two or more core cable secreened with woven copper bra= id. The screen braid is connected to the geophone case and connecting this t= o earth screens the windings.

The gain will drift a bit with=20= temp but not the baseline. You seem to need not more than X10 in the preamp=20= to keep the gain changes small.
Not less than X10 because of effects on CMMR ?


       Low gains should not effect the CMMR.=20= With high gains you may run out of feedback voltage if the output goes to th= e rails.

So long as you tie the geophone= directly across the +/- inputs in a differential fashion you seem to get a=20= response similar to a full blown instrumentation amplifier.

       Assuming that you have a full differen= tial circuit, you need to include the damping resistors in series with the o= pamp inputs. 

It is the only way to avoid the= resistance vs temp changes from affecting the class "A" operational baselin= e.


       You have 'lost me there'. What is a cl= ass A operational baseline? With the input to the +ve opamp input and a damp= ing resistor across the geophone, you get very little drift with temperature= - the value of the damping resistor may be 10x the resistence of the geopho= ne winding.

The circuit you see is just one= of many I play around with through curiosity.

The original ideas most all come from the PDF files that you can download re= lating to whatever part the company has sold you. They are full of various c= ircuits you can
experiment with.


       Where are all these circuits?

The differential amp always sho= ws two devices with a ground in the middle and I have found this is not nece= ssary. Just hook a coil between + and - of an op amp and the gain is (Rf/(0.= 5 Rgeo)) Very similar to an instrumentation arrangement
of three opamps.

The internal resistance between + and - is 40 megs or so.
Depends upon the op amp in question.
I use OP177G from the Philippines.
They can not be loaded greater than about 2K on the output.
( greater load means smaller R)

What I am not certain of is there a natural DC current flow between + and -=20= or do they always float at the same potential ??


       Always at the same potential - unless=20= the output is on the rails. The gain is over 1 million.

The circuit I showed you seeme= d to work well but because it puts a common mode signal on the input I am re= luctant to use it.


       Looking at the circuit values, the +ve= input to ground is FAR too high. Put in a 1 K ohm potentiometer, set it to=20= zero and then increase it slowly.
       I suggest that you use the standard cir= cuit given by Ulmann. The circuit you gave will not compensate for the resis= tance of the geophone. You must return the geophone to earth NOT to the +ve=20= input !!
       It only puts a short circuit across the= geophone.
       You will need to use a 1/f amplifier an= d also a lot more gain.

Instead I am simply now using a= gain of X10 on the preamp and tying the + side to the ground using a resist= or matched with Rf (R feedback) within the limits of my
test equipment.

I have found you need to match the + and - sides of these within maybe 0.1%=20= or your common mode rejection ratio is not so good.

I could not make the negative resistance circuit work for me that is in the=20= paper:
'Overdamping geophones using negative impedances' Bernd Ulmann@......... (ma= y no longer be valid)


       Your reference copied incorrectly.
It really seems to work opposit= e of what it says by increasing not decreasing the eigen frequency. and at t= he same time lowering the sensitivity of the sensor device.

       You have got the circuit wrong. This is= why it doesn't work.

instead of locking the mass I t= hink you need to somehow artificially decrease the
spring constant or simulate electronically a greater mass to get the desired= results.

by whatever means I need to create a vertical sensor with a free period of three to four seconds.


       Why on Earth do you want that?? This p= uts you into the sensitivity range of the microseisms, particularly on the P= acific coast. Do you really want to monitor them? 2 seconds should be adequa= te and you get this on your existing 1 Hz geophone, although at a factor of=20= x4 down.

    When I extend the geophone response, I tailor it to roll=20= off at about 0.35 to 0.4 Hz. This way you pick up the teleseismic S waves qu= ite OK, but the microseisms are considerably reduced.

I have been considering a push-= pull arrangement using unity gain amps to force / drive the opamp to behave=20= differently than normally possibly to lower the eigen freq abnormally to 4 s= econds.

It is just a thought and have not seriously looked into this yet.

Can you please tell me how the given circuit affects the geophone
because I never got above college algebra and that was 20 years ago.<= FONT COLOR=3D"#000000" BACK=3D"#ffffff" style=3D"BACKGROUND-COLOR: #ffffff"= SIZE=3D2 PTSIZE=3D10 FAMILY=3D"SANSSERIF" FACE=3D"Arial" LANG=3D"0">

       It gives a short circuit across the ge= ophone, but it doesn't compensate for the resistance. I don't know where thi= s circuit came from, but it won't do the job that you want.

I am going to scan all the draw= ings of my current setup into a zip file and let anyone interested have a co= py. I just need help from those who know how to
properly (electronically) lower the free period of a mass / spring system to= about 4 seconds so I can use a straight forward amplification and have it b= e linear in gain between 3 seconds and 3 hertz.


       OK, what website?

I think this might really be do= ne somehow with a narrow band high Q feedback circuit into a push pull arran= gement of X1 opamps. To artificially lower the spring constant. Never tried=20= this and am afraid because I do not want to accidentally damage my geophone=20= magnet or coil.


       There are two OK ways of extending the= geophone response to lower frequencies. The sensitivity is normally flat ab= ove the resonant frequency and falls as f^2 below this. Resonant or high Q c= ircuits are definitely to be avoided. Your geophone is not that stable in ch= aracteristiocs. The resistance and the spring constants both change with tem= perature.
       You can provide a two stage amplifier t= o boost the output below the resonant frequency. This is good to 1/10 the re= sonant frequency, but you may run into noise problems below this.
       You can run the geophone into a negativ= e impedance circuit to give an overall zero impedance input. This flattens o= ut the charactersitic and gives a response proportional to f, so you need to= amplify the signal with a single stage top cut amplifier.

       You can also digitally filter the outpu= t to give up to about x10 increase in period. This would be the cheapest opt= ion! But you need a lot more gain.
      
    Regards,

    Chris Chapman
 Subject: Connecting together long period and short period amp boards From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Thu, 23 Nov 2006 05:15:41 +0000 Hi all Doesn't anyone know the answer ? I think I got the power supply to the second board correct, but I don't know how to connect the channels yet. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: zip file of GVA From: "Geoffrey" gmvoeth@........... Date: Wed, 22 Nov 2006 22:32:55 -0700 Hello PSN folks; Here is a zip file for GVA schematics and images showing current setup. I am not neat as you can see. [Password: gva ] http://home.mchsi.com/~gmvoeth/gva.zip [Password: gva ] If you can not download I will be glad to send you it as an attachment. gva.zip is about 3.21 MB (3,376,009 bytes) password is just to protect contents from alteration in transit. Regards; geoff __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Noise From: "tchannel" tchannel@.............. Date: Thu, 23 Nov 2006 11:08:14 -0700 Hi Folks, A while back I asked for help in determining the source of = some noise showing up on my Helicorder. This is an update to that = question. I have excluded auto traffic, as the noise happens weather it is = weekends or work days, at about the same time. I have excluded the schools in the area for the same reasons I have excluded construction for the same reason. I am not 100 percent sure of these exclusions, but for the most part, I = think it is something else. I have gone back several days on the Helicorder to see if I could find = patterns, and I have found that all is quiet starting about 5:00 pm = local time, 00 UTC. Things remain quiet until 08:35 am, 15:35 UTC. = During the hours 8:00 am to 5:00 pm the noise comes and goes sometimes = lasting less than one mins and sometimes lasting 5 to 10 mins. The sensor, a Lehman, is in my basement. It is on a concrete floor next = to a concrete wall, and the house above is wood and brick. Could this noise be the sun? At about the time the noise begins the sun = rises above the trees and shines on the east side of our house, which is = also the wall near the sensor. Could this warming of the wood and bricks, above the basement, and their = expansion cause the noise. As the clouds block the sun during the day, = might this cause the intermittent noise during the day? The noise = stops about the time the sun no longer hit the house. I could test this theory on a overcast day and I will do so, but I just = wanted to get your input. Thanks, Ted
Hi Folks,  A while back I asked = for help in=20 determining the source of some noise showing up on my = Helicorder.  =20 This is an update to that question.
I have excluded auto traffic, as the = noise happens=20 weather it is weekends or work days, at about the same = time.
I have excluded the schools in the area = for the=20 same reasons
I have excluded construction for the = same=20 reason.
 
I am not 100 percent sure of these = exclusions, but=20 for the most part, I think it is something else.
 
I have gone back several days on the = Helicorder to=20 see if I could find patterns, and I have found that all is quiet = starting about=20 5:00 pm local time, 00 UTC.  Things remain quiet until 08:35 am, = 15:35=20 UTC.   During the hours 8:00 am to 5:00 pm the noise comes and = goes=20 sometimes lasting less than one mins and sometimes lasting 5 to 10=20 mins.
 
The sensor, a Lehman, is in my = basement.  It=20 is on a concrete floor next to a concrete wall, and the house above is = wood and=20 brick.
Could this noise be the sun?  At = about the=20 time the noise begins the sun rises above the trees and shines on the = east side=20 of our house, which is also the wall near the sensor.
Could this warming of the wood and = bricks, above=20 the basement, and their expansion cause the noise.  As the clouds = block the=20 sun during the day, might this cause the intermittent noise during the=20 day?   The noise stops about the time the sun no longer hit = the=20 house.
 
I could test this theory on a overcast = day and I=20 will do so, but I just wanted to get your input.
 
Thanks, Ted
Subject: mb 5.0 earthquake near Hawaii From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Thu, 23 Nov 2006 20:56:29 +0000 Hi all At 19:20 there was a mb 5.0 earthquake near Hawaii, closest to the center of the earthquake is the town of Kalaoa. More info on this earthqauke can be found here, http://www.emsc-csem.org/index.php?page=current&sub=detail&id=36532 Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Noise From: ChrisAtUpw@....... Date: Thu, 23 Nov 2006 16:39:10 EST In a message dated 2006/11/23, tchannel@.............. writes: > The sensor, a Lehman, is in my basement. It is on a concrete floor next to > a concrete wall, and the house above is wood and brick. > Could this noise be the sun? At about the time the noise begins the sun > rises above the trees and shines on the east side of our house, which is also > the wall near the sensor. Hi Ted, Next to the concrete wall may not be the best place? General advice is to keep sensors away from walls. Does the house 'creek and groan' at all during the day? If it was direct sun on the house and things moving, I would expect you to be able to hear them, at least sometimes, if you try. Maybe run an audio tape recorder on high sensitivity in the basement to include one or more events? However, I would also expect house noise to be related to wind conditions. Now you have got the Lehman cosily enclosed in a thermally insulated airtight box haven't you? What is the construction of the Lehman suspension, top and bottom? What detector are you using? Do you have central heating or electrical appliances which come on between 8am and 5 pm? These times do sound suspiciously like work day activity of some type, or related to it in some way. Do you get increased environmental noise between these times? Do you have a geophone? I got mysterious thump type signals intermittently, of short but varying length, which did not seem to be related to anything obvious. I eventually connected an audio amplifier and headphones up to one of the geophones - no seismic amplifier. I found that I could hear fast traffic on the main road starting at ~1 km. The thumps seemed to be directly related to lorries when travelling round a bend in the road. When I checked the road, I found a sunken drain grating on the inside of the bend. When there was traffic in both directions, lorry drivers kept tight to the inside of the bend and ran over the recessed grating. I pointed out this traffic hazard to the authorities and they replaced the drain cover.... Regards, Chris Chapman In a me= ssage dated 2006/11/23, tchannel@.............. writes:

The sensor, a Lehman, is in my=20= basement. It is on a concrete floor next to a concrete wall, and the house a= bove is wood and brick.
Could this noise be the sun?  At about the time the noise begins the s= un rises above the trees and shines on the east side of our house, which is=20= also the wall near the sensor.


Hi Ted,

       Next to the concrete wall may not be th= e best place? General advice is to keep sensors away from walls.

       Does the house 'creek and groan' at all= during the day? If it was direct sun on the house and things moving, I woul= d expect you to be able to hear them, at least sometimes, if you try. Maybe=20= run an audio tape recorder on high sensitivity in the basement to include on= e or more events? However, I would also expect house noise to be related to=20= wind conditions.

       Now you have got the Lehman cosily encl= osed in a thermally insulated airtight box haven't you?

       What is the construction of the Lehman=20= suspension, top and bottom? What detector are you using?

       Do you have central heating or electric= al appliances which come on between 8am and 5 pm? These times do sound suspi= ciously like work day activity of some type, or related to it in some way. D= o you get increased environmental noise between these times?

       Do you have a geophone? I got mysteriou= s thump type signals intermittently, of short but varying length, which did=20= not seem to be related to anything obvious. I eventually connected an audio=20= amplifier and headphones up to one of the geophones - no seismic amplifier.=20= I found that I could hear fast traffic on the main road starting at ~1 km. T= he thumps seemed to be directly related to lorries when travelling round a b= end in the road. When I checked the road, I found a sunken drain grating on=20= the inside of the bend. When there was traffic in both directions, lorry dri= vers kept tight to the inside of the bend and ran over the recessed grating.= I pointed out this traffic hazard to the authorities and they replaced the=20= drain cover....

       Regards,

       Chris Chapman Subject: Re: Noise From: "chief.cook.nz" chief.cook.nz@............ Date: Fri, 24 Nov 2006 11:01:56 +1300 Hi Ted Which country are you in Cheers Tamati From the Castle of Tamati, Hinemoa and Karauwa the Dog From the Castle of Tom, Robyn and the Dog I'm Just a Stone's Throw Away:- NZ-021-150-33-59 or NZ-07-855-0195 Bush Telegragh:- = chief.cook.nz@............ My Regular Pitstop:- Tamati = P.O.BOX 19-356 CENTRAL = HAMILTON NEW = ZEALAND ----- Original Message -----=20 From: tchannel=20 To: psn-l@................. Sent: Friday, November 24, 2006 7:08 AM Subject: Noise Hi Folks, A while back I asked for help in determining the source of = some noise showing up on my Helicorder. This is an update to that = question. I have excluded auto traffic, as the noise happens weather it is = weekends or work days, at about the same time. I have excluded the schools in the area for the same reasons I have excluded construction for the same reason. I am not 100 percent sure of these exclusions, but for the most part, = I think it is something else. I have gone back several days on the Helicorder to see if I could find = patterns, and I have found that all is quiet starting about 5:00 pm = local time, 00 UTC. Things remain quiet until 08:35 am, 15:35 UTC. = During the hours 8:00 am to 5:00 pm the noise comes and goes sometimes = lasting less than one mins and sometimes lasting 5 to 10 mins. The sensor, a Lehman, is in my basement. It is on a concrete floor = next to a concrete wall, and the house above is wood and brick. Could this noise be the sun? At about the time the noise begins the = sun rises above the trees and shines on the east side of our house, = which is also the wall near the sensor. Could this warming of the wood and bricks, above the basement, and = their expansion cause the noise. As the clouds block the sun during the = day, might this cause the intermittent noise during the day? The noise = stops about the time the sun no longer hit the house. I could test this theory on a overcast day and I will do so, but I = just wanted to get your input. Thanks, Ted
Hi Ted
Which country are you = in
 
Cheers Tamati
From the Castle of Tamati, Hinemoa and Karauwa the = Dog
From the Castle of Tom, Robyn and the Dog
 
I'm Just a Stone's Throw Away:- NZ-021-150-33-59 or=20 NZ-07-855-0195
         &= nbsp;           &n= bsp;       =20 Bush Telegragh:- chief.cook.nz@............=
           &nb= sp;          =20 My Regular Pitstop:-=20 Tamati
          &nb= sp;           &nbs= p;            = ;            =             &= nbsp;     =20 P.O.BOX 19-356=20 CENTRAL
          &n= bsp;           &nb= sp;           &nbs= p;            = ;            =       =20 HAMILTON
          &= nbsp;           &n= bsp;           &nb= sp;           &nbs= p;            = ;      =20 NEW ZEALAND
----- Original Message -----
From:=20 tchannel
Sent: Friday, November 24, 2006 = 7:08=20 AM
Subject: Noise

Hi Folks,  A while back I asked = for help in=20 determining the source of some noise showing up on my = Helicorder.  =20 This is an update to that question.
I have excluded auto traffic, as the = noise=20 happens weather it is weekends or work days, at about the same=20 time.
I have excluded the schools in the = area for the=20 same reasons
I have excluded construction for the = same=20 reason.
 
I am not 100 percent sure of these = exclusions,=20 but for the most part, I think it is something else.
 
I have gone back several days on the = Helicorder=20 to see if I could find patterns, and I have found that all is quiet = starting=20 about 5:00 pm local time, 00 UTC.  Things remain quiet until = 08:35 am,=20 15:35 UTC.   During the hours 8:00 am to 5:00 pm the noise = comes and=20 goes sometimes lasting less than one mins and sometimes lasting 5 to = 10=20 mins.
 
The sensor, a Lehman, is in my = basement.  It=20 is on a concrete floor next to a concrete wall, and the house above is = wood=20 and brick.
Could this noise be the sun?  At = about the=20 time the noise begins the sun rises above the trees and shines on the = east=20 side of our house, which is also the wall near the = sensor.
Could this warming of the wood and = bricks, above=20 the basement, and their expansion cause the noise.  As the clouds = block=20 the sun during the day, might this cause the intermittent noise during = the=20 day?   The noise stops about the time the sun no longer hit = the=20 house.
 
I could test this theory on a = overcast day and I=20 will do so, but I just wanted to get your input.
 
Thanks, = Ted
Subject: Re: Noise From: "tchannel" tchannel@.............. Date: Thu, 23 Nov 2006 16:07:23 -0700 Hi, I don't hear any 'creeks and groans' and we have no appliances = which operate (only) during this 8 to 5 period. I have all but eliminated wind as a factor. We do set near the = mountains, could the sun warming the mountains 6 miles away cause this? The noise is typical today, a Holiday with very little traffic on our = streets. The sun has just gone behind the trees in the west, at 4pm, = yet the noise continues and will until about 5 pm, if the pattern holds = and it will. After that all will get quiet again. =20 Thanks, Ted ----- Original Message -----=20 From: ChrisAtUpw@.......... To: psn-l@................. Sent: Thursday, November 23, 2006 2:39 PM Subject: Re: Noise In a message dated 2006/11/23, tchannel@.............. writes: The sensor, a Lehman, is in my basement. It is on a concrete floor = next to a concrete wall, and the house above is wood and brick. Could this noise be the sun? At about the time the noise begins the = sun rises above the trees and shines on the east side of our house, = which is also the wall near the sensor. Hi Ted, Next to the concrete wall may not be the best place? General = advice is to keep sensors away from walls. Does the house 'creek and groan' at all during the day? If it = was direct sun on the house and things moving, I would expect you to be = able to hear them, at least sometimes, if you try. Maybe run an audio = tape recorder on high sensitivity in the basement to include one or more = events? However, I would also expect house noise to be related to wind = conditions. Now you have got the Lehman cosily enclosed in a thermally = insulated airtight box haven't you? What is the construction of the Lehman suspension, top and = bottom? What detector are you using?=20 Do you have central heating or electrical appliances which come = on between 8am and 5 pm? These times do sound suspiciously like work day = activity of some type, or related to it in some way. Do you get = increased environmental noise between these times?=20 Do you have a geophone? I got mysterious thump type signals = intermittently, of short but varying length, which did not seem to be = related to anything obvious. I eventually connected an audio amplifier = and headphones up to one of the geophones - no seismic amplifier. I = found that I could hear fast traffic on the main road starting at ~1 km. = The thumps seemed to be directly related to lorries when travelling = round a bend in the road. When I checked the road, I found a sunken = drain grating on the inside of the bend. When there was traffic in both = directions, lorry drivers kept tight to the inside of the bend and ran = over the recessed grating. I pointed out this traffic hazard to the = authorities and they replaced the drain cover.... Regards, Chris Chapman
Hi,  I don't hear any 'creeks and=20 groans'  and we have no appliances which operate (only) during this = 8 to 5=20 period.
I have all but eliminated wind as a = factor. =20 We do set near the mountains, could the sun warming the mountains 6 = miles away=20 cause this?
The noise is typical today, a Holiday = with very=20 little traffic on our streets.  The sun has just gone behind the = trees in=20 the west, at 4pm, yet the noise continues and will until about 5 pm, if = the=20 pattern holds and it will.  After that all will get quiet = again. =20
Thanks, Ted
----- Original Message -----
From:=20 ChrisAtUpw@.......
Sent: Thursday, November 23, = 2006 2:39=20 PM
Subject: Re: Noise

In a=20 message dated 2006/11/23, tchannel@..............=20 writes:

The sensor, a Lehman, is in my basement. It is on a = concrete=20 floor next to a concrete wall, and the house above is wood and=20 brick.
Could this noise be the sun?  At about the = time the=20 noise begins the sun rises above the trees and shines on the east = side of=20 our house, which is also the wall near the = sensor.


Hi=20 Ted,

       Next to the concrete = wall may=20 not be the best place? General advice is to keep sensors away from=20 walls.

       Does the house = 'creek and=20 groan' at all during the day? If it was direct sun on the house and = things=20 moving, I would expect you to be able to hear them, at least = sometimes, if you=20 try. Maybe run an audio tape recorder on high sensitivity in the = basement to=20 include one or more events? However, I would also expect house noise = to be=20 related to wind = conditions.

       Now=20 you have got the Lehman cosily enclosed in a thermally insulated = airtight box=20 haven't you?

       What is the=20 construction of the Lehman suspension, top and bottom? What detector = are you=20 using?

       Do you have = central=20 heating or electrical appliances which come on between 8am and 5 pm? = These=20 times do sound suspiciously like work day activity of some type, or = related to=20 it in some way. Do you get increased environmental noise between these = times?=20

       Do you have a geophone? I = got=20 mysterious thump type signals intermittently, of short but varying = length,=20 which did not seem to be related to anything obvious. I eventually = connected=20 an audio amplifier and headphones up to one of the geophones - no = seismic=20 amplifier. I found that I could hear fast traffic on the main road = starting at=20 ~1 km. The thumps seemed to be directly related to lorries when = travelling=20 round a bend in the road. When I checked the road, I found a sunken = drain=20 grating on the inside of the bend. When there was traffic in both = directions,=20 lorry drivers kept tight to the inside of the bend and ran over the = recessed=20 grating. I pointed out this traffic hazard to the authorities and they = replaced the drain = cover....

      =20 Regards,

       Chris = Chapman=20
Subject: Re: Noise From: Mark Robinson mark.robinson@............... Date: Fri, 24 Nov 2006 13:25:12 +1300 tchannel wrote: > Hi Folks, A while back I asked for help in determining the source of some noise showing up on my Helicorder. This is an update to that question. > I have excluded auto traffic, as the noise happens weather it is weekends or work days, at about the same time. > I have excluded the schools in the area for the same reasons > I have excluded construction for the same reason. > > I am not 100 percent sure of these exclusions, but for the most part, I think it is something else. > > I have gone back several days on the Helicorder to see if I could find patterns, and I have found that all is quiet starting about 5:00 pm local time, 00 UTC. Things remain quiet until 08:35 am, 15:35 UTC. During the hours 8:00 am to 5:00 pm the noise comes and goes sometimes lasting less than one mins and sometimes lasting 5 to 10 mins. > > The sensor, a Lehman, is in my basement. It is on a concrete floor next to a concrete wall, and the house above is wood and brick. > Could this noise be the sun? At about the time the noise begins the sun rises above the trees and shines on the east side of our house, which is also the wall near the sensor. > Could this warming of the wood and bricks, above the basement, and their expansion cause the noise. As the clouds block the sun during the day, might this cause the intermittent noise during the day? The noise stops about the time the sun no longer hit the house. > > I could test this theory on a overcast day and I will do so, but I just wanted to get your input. > > Thanks, Ted Is there any heavy industry within a few miles ? Does the noise happen on the weekends ? Could you post am image of the helicorder showing the noise ? ? -- Mark Robinson ------------- 24 Nov 1849 Frances Hodgsen Burnett born to write The Secret Garden. 24 Nov 1953 Joe MacArthey claimed the Truman administration "Crawled with communists". __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Noise From: ChrisAtUpw@....... Date: Thu, 23 Nov 2006 20:06:37 EST In a message dated 2006/11/23, tchannel@.............. writes: > What is the construction of the Lehman suspension, top and bottom? > What detector are you using? Hi Ted, Also, what day and night temperatures are you getting at the moment? What is the weather like? Regards, Chris Chapman In a me= ssage dated 2006/11/23, tchannel@.............. writes:

     &= nbsp; What is the construction of the Lehman suspension, top and bottom? Wha= t detector are you using?


Hi Ted,

       Also, what day and night temperatures a= re you getting at the moment? What is the weather like?

       Regards,

       Chris Chapman Subject: Re: GPS error message From: George Bush ke6pxp@....... Date: Fri, 24 Nov 2006 10:31:00 -0800 Larry- Years ago I bought a system from you (SDR, PSN-ADC-16, Amp/filter Board, and GPS timing system). All has been working flawlessly for the past few years. Last month I took a vacation for 10 days and turned the system and computer off for the duration. All worked well on turn-on, except the GPS is not locking the time and I get an error message that says "Time Diff: -3649616 to large"? I was wondering if the GPS board/ antenna system is working and inspected the box and the 1 pps led is working so it is getting power. Do you have any ideas of what else I could check or what might be wrong??? George __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Noise From: "Geoffrey" gmvoeth@........... Date: Fri, 24 Nov 2006 17:20:56 -0700 Hello Tamati; Whats the frequency of the noise ? If it is greater than 1.5Hz closer to 3Hz it most probably relates to human activity. If the noise is longer than one second I might seriously consider expansion and contraction or some other form of non-man made noise. I have this problem with my refrigerator being on the same circuit as my electronics. I have never been able to keep the voltage spike that happens when the refer cuts off from invading my electronics. You might want to dummy load the input to your electronics totally eliminating the sensor to see if the noise is still there then you can isolate the noise to electrical or mechanical. While "dummied" You should have zero or only tiny low freq. noise relating to temp changes of the electronics and nothing more. If the noise is asymmetrical you might consider RFI as a concern and see if someone is operating a transmitter close by. Police and fire and government and public services (utility workers) will swamp my amp when they are in the area and cause asymmetrical noises. (lopsided waveforms more positive than negative) A cell phone or CB radio does not seem to do this I think the officials are transmitting with inputs in excess of 5Watt of power. Good luck, Chris knows more than I do about this stuff. regards; geoff ----- Original Message ----- From: "chief.cook.nz" To: Sent: Thursday, November 23, 2006 3:01 PM Subject: Re: Noise Hi Ted Which country are you in Cheers Tamati From the Castle of Tamati, Hinemoa and Karauwa the Dog From the Castle of Tom, Robyn and the Dog I'm Just a Stone's Throw Away:- NZ-021-150-33-59 or NZ-07-855-0195 Bush Telegragh:- chief.cook.nz@............ My Regular Pitstop:- Tamati P.O.BOX 19-356 CENTRAL HAMILTON NEW ZEALAND ----- Original Message ----- From: tchannel To: psn-l@.............. Sent: Friday, November 24, 2006 7:08 AM Subject: Noise Hi Folks, A while back I asked for help in determining the source of some noise showing up on my Helicorder. This is an update to that question. I have excluded auto traffic, as the noise happens weather it is weekends or work days, at about the same time. I have excluded the schools in the area for the same reasons I have excluded construction for the same reason. I am not 100 percent sure of these exclusions, but for the most part, I think it is something else. I have gone back several days on the Helicorder to see if I could find patterns, and I have found that all is quiet starting about 5:00 pm local time, 00 UTC. Things remain quiet until 08:35 am, 15:35 UTC. During the hours 8:00 am to 5:00 pm the noise comes and goes sometimes lasting less than one mins and sometimes lasting 5 to 10 mins. The sensor, a Lehman, is in my basement. It is on a concrete floor next to a concrete wall, and the house above is wood and brick. Could this noise be the sun? At about the time the noise begins the sun rises above the trees and shines on the east side of our house, which is also the wall near the sensor. Could this warming of the wood and bricks, above the basement, and their expansion cause the noise. As the clouds block the sun during the day, might this cause the intermittent noise during the day? The noise stops about the time the sun no longer hit the house. I could test this theory on a overcast day and I will do so, but I just wanted to get your input. Thanks, Ted __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Noise From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sat, 25 Nov 2006 00:41:57 +0000 Hi Do you have a cable that is screened ? A sample of the noise might come a long way in figureing out what this, screenshot of the WinSDR window or what you are using are helpful in this matter. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: SDR From: "A FRIELINK" allink1@........... Date: Sat, 25 Nov 2006 16:34:28 -0500 Hi I would like to know what versions of Windows will Winsdr 3.0.3 run = on? I am using Windows 95 and when I try to open sdr, I get an error = message, a file " ws2help.dll" , is missing. Al Frielink allink1@verizon.net

Hi
I would like to = know what versions of=20  Windows will  Winsdr 3.0.3 run on? I am using Windows 95 and = when I=20 try to open sdr, I get an error message, a file " ws2help.dll" , is = missing.
Al Frielink
allink1@...........
<= /BODY> Subject: Re: SDR From: "Geoffrey" gmvoeth@........... Date: Sat, 25 Nov 2006 14:53:10 -0700 http://www.dll-files.com/dllindex/dll-files.shtml?ws2help ----- Original Message ----- From: "A FRIELINK" To: Sent: Saturday, November 25, 2006 2:34 PM Subject: SDR Hi I would like to know what versions of Windows will Winsdr 3.0.3 run on? I am using Windows 95 and when I try to open sdr, I get an error message, a file " ws2help.dll" , is missing. Al Frielink allink1@........... __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: SDR From: Larry Cochrane lcochrane@.............. Date: Sun, 26 Nov 2006 01:59:58 -0800 Hi Al, I recommend that WinSDR users use Windows 2000 or XP. These are the operating systems supported by Microsoft. I know some people are running WinSDR on Windows 98 without any problems but I'm not sure anyone is using Windows 95. Regards, Larry Cochrane Redwood City, PSN A FRIELINK wrote: > > > Hi > I would like to know what versions of Windows will Winsdr 3.0.3 run > on? I am using Windows 95 and when I try to open sdr, I get an error > message, a file " ws2help.dll" , is missing. > Al Frielink > allink1@........... __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Best Overall Geophone to have. From: "Geoffrey" gmvoeth@........... Date: Sun, 26 Nov 2006 12:55:02 -0700 Hello Everyone on PSN; I have realized after spending maybe 10 years or more playing around with seismic stuff that there is one and only one sensor that an amateur needs to receive teleseismic/regional/local earthquakes and that is a single vertical sensor with a free period of about 4(four) seconds. That is a frequency of 0.25 Hertz. A second runnerup would be a 2(two) Hertz geophone which can easily be equalized by electronics down to a period of four or so seconds. This is the single most important instrument of the entire system. Why in heck dont the experts build a standard instrument in these two ranges. All they have to do is give us amatures a standard set of plans we can build our own from ???? By expert I am talking about an experienced mechanical engineer. All he has to do is keep in mind that his design will be constructed from materials that come from like Home Depot or some Internet Supplier like a magnet shop or a copper wire dealer. The pros do not need all the info for the EQS from us amateurs. They really only want and need what you call "first time of arrival". The only thing we need is to watch the signals come in and tell roughly the size and distance. All this can be met with a single vertical sensor. It is interested to note that they really like to know if you were closest to the event and if you felt the event physically. Try buying borrowing stealing a vertical geophone that has a free period of less than 2Hz. You really must be somewhat gifted/ have your own machine shop/ be somewhat rich to buy a decent vertical sensor. If you all could solve this sensor problem then all else seems to me would just fall into place. There seems to be some kind of resistance to standardization that I do not understand. The frequency range is like 0.4 HZ to 2.4 HZ butterworth with a gain of about 80 to 86 DBv at one hertz in frq or 1 second in period. If you live close to human activity you will find things get noisy during the day. By having at least a 12 bit converter you can through programming automatically lower the overall gain in steps of two simply by dividing the results and summing in an offset. You can do this automatically in your program acording to the time of day. You always want a bit of of noise showing on your graph. You also want a modulo recorder like nine minutes of history so that you will keep that 9 minutes of history in memory until something triggers the rest of the recording. You will also want a audible alarm to sound when the recording has been triggered. All these things I have actually done with the exception of building a decent vertical sensor. To date I have only been able to puchase a worthy sensor and even it is not in the right frequency range to get easy flatness between 0.4Hz and 2 Hz. There is no reason I can see in this day and age a standard system can not exist as a kit or something for people to simply put together and build. I just wanted all you folks who love science and technology over the arts to think of this awhile and respond with great verbosity. Regards; geoff __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: 3 dimensional data From: "Geoffrey" gmvoeth@........... Date: Sun, 26 Nov 2006 13:12:43 -0700 Does anyone combine all three dimensions (x,y,z) into a single time/magnitude display ?? If so can you send me your source code and logic tree to have a look ? Regards; geoff __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: 3 dimensional data From: Angel sismos@.............. Date: Sun, 26 Nov 2006 23:17:37 +0000 Hello Geoffrey, Yes, it can be done. With one good well calibrated broadband you can calculate the back azimuth, and you have the P and S time differences, you can calculate the focal mechanism and do several different types of magnitudes calculations. One well know french commercial system call TREMORS does just that and also issues tsunami warnings. It uses just one STS2 to do the job. Many if not all of the bits and pieces to do all of the above are free software. With a well calibrated home made x y z system I suspect you could easily local local and regional events. The key words in that last line are "well calibrated". Regards, Angel Sunday, November 26, 2006, 8:12:43 PM, you wrote: > Does anyone combine all three dimensions (x,y,z) > into a single time/magnitude display ?? > If so can you send me your source code and > logic tree to have a look ? > Regards; > geoff > __________________________________________________________ > Public Seismic Network Mailing List (PSN-L) > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. -- Best regards, Angel __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Best Overall Geophone to have. From: Bobhelenmcclure@....... Date: Sun, 26 Nov 2006 22:13:37 EST Hi Geoff, I have a home-built 5 second period vertical sensor that I paid a friend to build for $500. See _http://www.jclahr.com/science/psn/mcclure/vert2.html_ (http://www.jclahr.com/science/psn/mcclure/vert2.html) I extend its natural period to 16 seconds or more with my special digital filter, implemented in "WQFilter.exe", which can be downloaded from _http://www.jclahr.com/science/psn/mcclure/wdq_utilities/index.html_ (http://www.jclahr.com/science/psn/mcclure/wdq_utilities/index.html) "WQFilter.exe" operates on WinQuake files, and its long period filter will extend the bandwidth of any open loop sensor by a factor of 5 or more. I run a 3-axis station, and I agree that the vertical sensor is the most important one to have, (but the hardest to build). Regards, Bob McClure PSN Station REM
Hi Geoff,
 
  I have a home-built 5 second period vertical sensor that I paid=20= a=20 friend to build for $500. See
 
http://www.jcl= ahr.com/science/psn/mcclure/vert2.html
 
  I extend its natural period to 16 seconds or more with my specia= l=20 digital filter, implemented in "WQFilter.exe", which can be downloaded=20 from
 
= http://www.jclahr.com/science/psn/mcclure/wdq_utilities/index.html
 
  "WQFilter.exe" operates on WinQuake files, and its long period=20 filter will extend the bandwidth of any open loop sensor by a factor of 5 or= =20 more.
 
  I run a 3-axis station, and I agree that the vertical=20 sensor is the most important one to have, (but the hardest to build).
 
Regards,
 
Bob McClure
PSN Station REM
 
 Subject: Re: Best Overall Geophone to have. From: Barry Lotz barry_lotz@............. Date: Mon, 27 Nov 2006 21:44:35 -0800 (PST) Hi Geoff 2˘ Have you checked out Sean Thomas' web site. He has a design for a broadband vertical using hardware parts. The electronics can be a little complicated though. I have two successfully operating now. I use a high pass cutoff frequency of 0.03 hz (~ 33 sec)for teleseismic events. Regards Barry Geoffrey wrote: Hello Everyone on PSN; I have realized after spending maybe 10 years or more playing around with seismic stuff that there is one and only one sensor that an amateur needs to receive teleseismic/regional/local earthquakes and that is a single vertical sensor with a free period of about 4(four) seconds. That is a frequency of 0.25 Hertz. A second runnerup would be a 2(two) Hertz geophone which can easily be equalized by electronics down to a period of four or so seconds. This is the single most important instrument of the entire system. Why in heck dont the experts build a standard instrument in these two ranges. All they have to do is give us amatures a standard set of plans we can build our own from ???? By expert I am talking about an experienced mechanical engineer. All he has to do is keep in mind that his design will be constructed from materials that come from like Home Depot or some Internet Supplier like a magnet shop or a copper wire dealer. The pros do not need all the info for the EQS from us amateurs. They really only want and need what you call "first time of arrival". The only thing we need is to watch the signals come in and tell roughly the size and distance. All this can be met with a single vertical sensor. It is interested to note that they really like to know if you were closest to the event and if you felt the event physically. Try buying borrowing stealing a vertical geophone that has a free period of less than 2Hz. You really must be somewhat gifted/ have your own machine shop/ be somewhat rich to buy a decent vertical sensor. If you all could solve this sensor problem then all else seems to me would just fall into place. There seems to be some kind of resistance to standardization that I do not understand. The frequency range is like 0.4 HZ to 2.4 HZ butterworth with a gain of about 80 to 86 DBv at one hertz in frq or 1 second in period. If you live close to human activity you will find things get noisy during the day. By having at least a 12 bit converter you can through programming automatically lower the overall gain in steps of two simply by dividing the results and summing in an offset. You can do this automatically in your program acording to the time of day. You always want a bit of of noise showing on your graph. You also want a modulo recorder like nine minutes of history so that you will keep that 9 minutes of history in memory until something triggers the rest of the recording. You will also want a audible alarm to sound when the recording has been triggered. All these things I have actually done with the exception of building a decent vertical sensor. To date I have only been able to puchase a worthy sensor and even it is not in the right frequency range to get easy flatness between 0.4Hz and 2 Hz. There is no reason I can see in this day and age a standard system can not exist as a kit or something for people to simply put together and build. I just wanted all you folks who love science and technology over the arts to think of this awhile and respond with great verbosity. Regards; geoff __________________________________________________________
Hi Geoff
 2˘
 Have you checked out Sean Thomas'  web site. He has a design for a broadband vertical using hardware parts. The electronics can be a little complicated though. I have two successfully operating now. I use a high pass cutoff frequency of 0.03 hz (~ 33 sec)for teleseismic events.
Regards
Barry
 

Geoffrey <gmvoeth@...........> wrote:
Hello Everyone on PSN;

I have realized after spending
maybe 10 years or more playing around
with seismic stuff that there is one
and only one sensor that an amateur
needs to receive teleseismic/regional/local
earthquakes and that is a single vertical sensor
with a free period of about 4(four) seconds.
That is a frequency of 0.25 Hertz.
A second runnerup would be a 2(two) Hertz
geophone which can easily be equalized by electronics
down to a period of four or so seconds.

This is the single most important instrument
of the entire system.

Why in heck dont the experts build a standard instrument
in these two ranges. All they have to do is give
us amatures a standard set of plans we can
build our own from ????

By expert I am talking about an experienced mechanical engineer.

All he has to do is keep in mind that
his design will be constructed from materials
that come from like Home Depot or some Internet
Supplier like a magnet shop or a copper wire dealer.

The pros do not need all the info for the EQS
from us amateurs. They really only want and need
what you call "first time of arrival".
The only thing we need is to watch the signals come in and tell roughly
the size and distance. All this can be met with a single
vertical sensor.

It is interested to note that they really like to
know if you were closest to the event and if you
felt the event physically.

Try buying borrowing stealing a vertical geophone that
has a free period of less than 2Hz.

You really must be somewhat gifted/ have your own machine shop/
be somewhat rich to buy a decent vertical sensor.

If you all could solve this sensor problem then all else seems to me would just fall into place.

There seems to be some kind of resistance to standardization
that I do not understand.

The frequency range is like 0.4 HZ to 2.4 HZ butterworth
with a gain of about 80 to 86 DBv at one hertz in frq or 1 second in period.


If you live close to human activity you will find
things get noisy during the day.

By having at least a 12 bit converter you can through
programming automatically lower the overall gain in steps
of two simply by dividing the results and summing in
an offset. You can do this automatically in your program
acording to the time of day. You always want a bit of
of noise showing on your graph.

You also want a modulo recorder like nine minutes of history
so that you will keep that 9 minutes of history in memory
until something triggers the rest of the recording.

You will also want a audible alarm to sound when
the recording has been triggered.

All these things I have actually done with the exception
of building a decent vertical sensor. To date I have only been able
to puchase a worthy sensor and even it is not in the right frequency range
to get easy flatness between 0.4Hz and 2 Hz.

There is no reason I can see in this day and age
a standard system can not exist as a kit or something
for people to simply put together and build.

I just wanted all you folks who love science and technology
over the arts to think of this awhile and respond with great verbosity.

Regards;
geoff
__________________________________________________________
Subject: School project From: "tchannel" tchannel@.............. Date: Tue, 28 Nov 2006 15:10:44 -0700 Hi Folks, Some discussion on a simple vertical seismometer got me to = thinking about a possible school project for the kids. At one time, I = found a simple vertical sensor on the internet, it used pvc pipe and a = small 9"? spring. I built it but never tested it because I had an idea = the coil and magnet were just too undersized. It probably works but = would require some strong amplification, further more, I have no idea = what the period would be. I wonder if one could use a "Slinky" a toy spring used by kids? They = are about 3" in dia. and collapsed about 5" tall. I think I will get = one and suspend it vertically, to check its suspended length and its = natural resonance. I have no idea how long the spring would expand = under its own weight? But let's say under 8 feet. If so, maybe it = could be hung from the ceiling and the coil and mass would be near the = floor? It just might be something kids would enjoy. =20 Q. 1. If I pull down on a spring and release it, it will move up and = down, until it come to rest, if each cycle is 1 sec, (say a very long = spring), is that its natural period? Q. 2. If I put a mass on the end of the spring, will it move slower? = If so, is that, now its period? Maybe 2 or 3 seconds? Q. 3. If I could work out the construction details, what period should I = target for a vertical sensor? Q. 4. Are there any websites or information on using long vertical = springs? Many thanks, Ted
Hi Folks,  Some discussion on a = simple=20 vertical seismometer got me to thinking about a possible school project = for the=20 kids.  At one time, I found a simple vertical sensor on the = internet, it=20 used pvc pipe and a small 9"? spring.  I built it but never tested = it=20 because I had an idea the coil and magnet were just too = undersized.  It=20 probably works but would require some strong amplification, further = more, I have=20 no idea what the period would be.
 
I wonder if one could use a = "Slinky"  a toy=20 spring used by kids? They are about 3" in dia. and collapsed about 5"=20 tall.  I think I will get one and suspend it vertically, to check = its=20 suspended length and its natural resonance.  I have no idea how = long the=20 spring would expand under its own weight?   But let's say = under 8=20 feet. If so, maybe it could be hung from the ceiling and the coil and = mass would=20 be near the floor?
 
It just might be something kids would=20 enjoy.  
Q. 1.  If I pull down on a spring = and release=20 it, it will move up and down, until it come to rest, if each cycle is 1 = sec,=20 (say a very long spring), is that its natural period?
Q. 2. If I put a mass on the end of the = spring,=20 will it move slower?   If so, is that, now its period?  = Maybe 2=20 or 3 seconds?
Q. 3. If I could work out the = construction=20 details, what period should I target for a vertical sensor?
Q. 4. Are there any websites or = information on=20 using long vertical springs?   Many thanks,=20 Ted
Subject: Re: School project From: Mauro Mariotti mariotti@......... Date: Wed, 29 Nov 2006 16:05:17 +0100 Hello, i might suggest to use the spring in a triangle configuration with a vertical axis and horizontal moving axis that sustain the mass. The priciple is called "Lacoste suspension" you can have a look here. http://mariottim.interfree.it/doc02v_i.htm#lacoste this is a very rude seismometer but it has a free period of 1.2 seconds. It is not so big. The same sensor can be built in wood (i have made one for a scientific exibition) I have some pictures but not in a web site if you want i can send them to the interested people. As transducer i used a powerful magnet from the SuperMag kids toy and the coils is stolen by a old relay. Such instrument can induce enough current to drive (not much) a microampmeter. kids like it very much. Using a small preamplifier you can get a huge signal. Damping was made using a plastic polycarbonate strip bended at U like a springleaf and made stiffy with electric tape. wooden axis can be made that can be easily assembled and disassembled without any tool i hope it helps regards mauro At 23:10 2006/11/28, you wrote: >Hi Folks, Some discussion on a simple vertical seismometer got me >to thinking about a possible school project for the kids. At one >time, I found a simple vertical sensor on the internet, it used pvc >pipe and a small 9"? spring. I built it but never tested it because >I had an idea the coil and magnet were just too undersized. It >probably works but would require some strong amplification, further >more, I have no idea what the period would be. > >I wonder if one could use a "Slinky" a toy spring used by kids? >They are about 3" in dia. and collapsed about 5" tall. I think I >will get one and suspend it vertically, to check its suspended >length and its natural resonance. I have no idea how long the >spring would expand under its own weight? But let's say under 8 >feet. If so, maybe it could be hung from the ceiling and the coil >and mass would be near the floor? > >It just might be something kids would enjoy. >Q. 1. If I pull down on a spring and release it, it will move up >and down, until it come to rest, if each cycle is 1 sec, (say a very >long spring), is that its natural period? >Q. 2. If I put a mass on the end of the spring, will it move >slower? If so, is that, now its period? Maybe 2 or 3 seconds? >Q. 3. If I could work out the construction details, what period >should I target for a vertical sensor? >Q. 4. Are there any websites or information on using long vertical >springs? Many thanks, Ted __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: School project From: John or Jan Lahr JohnJan@........ Date: Wed, 29 Nov 2006 08:55:58 -0800 I've posted pictures of a simple seismic system made from wood here:
http://jclahr.com/science/psn/wooden/
The natural period is a function of the tilt of the spring.  As it becomes more horizontal (by attaching the top of the spring lower on the mast) the period becomes longer.  However, if one tries to make the period too long the pendulum will become unstable and it will be hard to keep it from drifting to the upper or lower stop.

At 02:10 PM 11/28/2006, you wrote:
Hi Folks,  Some discussion on a simple vertical seismometer got me to thinking about a possible school project for the kids.  At one time, I found a simple vertical sensor on the internet, it used pvc pipe and a small 9"? spring.  I built it but never tested it because I had an idea the coil and magnet were just too undersized.  It probably works but would require some strong amplification, further more, I have no idea what the period would be.
 
I wonder if one could use a "Slinky"  a toy spring used by kids? They are about 3" in dia. and collapsed about 5" tall.  I think I will get one and suspend it vertically, to check its suspended length and its natural resonance.  I have no idea how long the spring would expand under its own weight?   But let's say under 8 feet. If so, maybe it could be hung from the ceiling and the coil and mass would be near the floor?


 A sensitive seismic system must be covered to prevent air currents from causing vibrations much larger than those generated by earthquakes.  A vertical system will have to be very tall, and thus difficult to enclose.

 
It just might be something kids would enjoy.  

Yes, indeed.  This would demonstrate the concept of a seismic sensor but would not be very good for detecting earthquakes.

Q. 1.  If I pull down on a spring and release it, it will move up and down, until it come to rest, if each cycle is 1 sec, (say a very long spring), is that its natural period? Yes, one full cycle is the natural period.
Q. 2. If I put a mass on the end of the spring, will it move slower?   Yes.  If so, is that, now its period?     Maybe 2 or 3 seconds?
Q. 3. If I could work out the construction details, what period should I target for a vertical sensor?  The AS-1 seismic systems have a natural period of 1.6 seconds.  To see surface waves the electronics with a period of 20 seconds, the electronics have to greatly boost the low frequencies.
Q. 4. Are there any websites or information on using long vertical springs?

 I've posted various designs on my web site:  http://jclahr.com/science/psn/

Keep us posted what you come up with!

John


   Many thanks, Ted
Subject: Re: School project From: ChrisAtUpw@....... Date: Wed, 29 Nov 2006 12:26:41 EST In a message dated 2006/11/28, tchannel@.............. writes: > Hi Folks, Some discussion on a simple vertical seismometer got me to thinking about a > possible school project for the kids. Hi Ted, Why not suggest to the school that they apply to Iris for a 'free' school seismomter? I am sure that they would be grateful for help in running it. See http://www.iris.edu/edu/AS1.htm Regards, Chris In a me= ssage dated 2006/11/28, tchannel@.............. writes:

Hi Folks, 
Some discussion on a simple vertical seismometer got me to thinking about a=
possible school project for th= e kids.


Hi Ted,

       Why not suggest to the school that they= apply to Iris for a 'free' school seismomter? I am sure that they would be=20= grateful for help in running it.
       See http://www.iris.edu/edu/AS1.htm
      
       Regards,

       Chris Subject: Re: School project From: "tchannel" tchannel@.............. Date: Wed, 29 Nov 2006 11:15:08 -0700 Hi Folks, Thanks for the advise on vertical sensors, You all have such = great incite and background on these subjects. Making the best of this = mailing list save me alot of wasted time and effort. I am still trying to eliminate my daytime noise, or at least identify = it. Thanks, to those who are trying to help. It was suggested I remove = the magnet from the coil area to see if the noise continued, if so it = might be electrical, like RF, communications etc. using the coil and = cables as antenna. During a noisy hour I remove the magnet, from the = coil. All the noise disappeared, the helicorer was just a flat line. = After a while, I reinstalled the magnet surrounding the coil and the = noise reappeared. Note: I only get these spikes between 8am and 5pm, = the night time hours are very quiet. Q. Should I conclude that this means that it can not be electrical, ie, = radio interference, but must be something creating vibrations? Q. On a different subject. Thanks to your input, I now have a better = understanding of LaCoste zero length spring suspension, and how it is = applied. But I don't understand (what is zero length) or how to find if a spring = is zero length. Perhaps someone could walk me thru this using a "screen = door spring" as an example. Thanks, Ted ----- Original Message -----=20 From: John or Jan Lahr=20 To: psn-l@................. Sent: Wednesday, November 29, 2006 9:55 AM Subject: Re: School project I've posted pictures of a simple seismic system made from wood here: http://jclahr.com/science/psn/wooden/ The natural period is a function of the tilt of the spring. As it = becomes more horizontal (by attaching the top of the spring lower on the = mast) the period becomes longer. However, if one tries to make the = period too long the pendulum will become unstable and it will be hard to = keep it from drifting to the upper or lower stop. At 02:10 PM 11/28/2006, you wrote: Hi Folks, Some discussion on a simple vertical seismometer got me = to thinking about a possible school project for the kids. At one time, = I found a simple vertical sensor on the internet, it used pvc pipe and a = small 9"? spring. I built it but never tested it because I had an idea = the coil and magnet were just too undersized. It probably works but = would require some strong amplification, further more, I have no idea = what the period would be. =20 I wonder if one could use a "Slinky" a toy spring used by kids? = They are about 3" in dia. and collapsed about 5" tall. I think I will = get one and suspend it vertically, to check its suspended length and its = natural resonance. I have no idea how long the spring would expand = under its own weight? But let's say under 8 feet. If so, maybe it = could be hung from the ceiling and the coil and mass would be near the = floor? A sensitive seismic system must be covered to prevent air currents = from causing vibrations much larger than those generated by earthquakes. = A vertical system will have to be very tall, and thus difficult to = enclose. It just might be something kids would enjoy. =20 Yes, indeed. This would demonstrate the concept of a seismic sensor = but would not be very good for detecting earthquakes. Q. 1. If I pull down on a spring and release it, it will move up = and down, until it come to rest, if each cycle is 1 sec, (say a very = long spring), is that its natural period? Yes, one full cycle is the = natural period. Q. 2. If I put a mass on the end of the spring, will it move slower? = Yes. If so, is that, now its period? Maybe 2 or 3 seconds? Q. 3. If I could work out the construction details, what period = should I target for a vertical sensor? The AS-1 seismic systems have a = natural period of 1.6 seconds. To see surface waves the electronics = with a period of 20 seconds, the electronics have to greatly boost the = low frequencies. Q. 4. Are there any websites or information on using long vertical = springs? I've posted various designs on my web site: = http://jclahr.com/science/psn/ Keep us posted what you come up with! John Many thanks, Ted
Hi Folks, Thanks for the advise on = vertical=20 sensors, You all have such great incite and background on these = subjects. =20 Making the best of this mailing list save me alot of wasted time and=20 effort.
 
I am still trying to eliminate my = daytime noise, or=20 at least identify it.  Thanks, to those who are trying to = help. =20 It was suggested I remove the magnet from the coil area to see if = the noise=20 continued, if so it might be electrical, like RF, communications=20 etc. using the coil and cables as antenna. During a noisy hour = I=20 remove the magnet, from the coil.    All the noise = disappeared,=20 the helicorer was just a flat line. After a while, I reinstalled the magnet surrounding the coil and the = noise=20 reappeared.  Note: I only get these spikes between 8am and 5pm, the = night=20 time hours are very quiet.
Q.  Should I conclude that this = means that it=20 can not be electrical, ie, radio interference, but must be something = creating=20 vibrations?
 
Q. On a different subject.  Thanks = to your=20 input, I now have a better understanding of LaCoste zero length spring=20 suspension, and how it is applied.
But I don't understand (what is zero=20 length) or how to find if a spring is zero length.  Perhaps = someone=20 could walk me thru this using a "screen door spring" as an = example.
 
Thanks, Ted
----- Original Message -----
From:=20 John or = Jan Lahr=20
Sent: Wednesday, November 29, = 2006 9:55=20 AM
Subject: Re: School = project

I've posted pictures of a simple = seismic=20 system made from wood here:
http://jclahr.com/science/psn/wooden/
The = natural=20 period is a function of the tilt of the spring.  As it becomes = more=20 horizontal (by attaching the top of the spring lower on the mast) the = period=20 becomes longer.  However, if one tries to make the period too = long the=20 pendulum will become unstable and it will be hard to keep it from = drifting to=20 the upper or lower stop.

At 02:10 PM 11/28/2006, you = wrote:
Hi = Folks,  Some=20 discussion on a simple vertical seismometer got me to thinking about = a=20 possible school project for the kids.  At one time, I found a = simple=20 vertical sensor on the internet, it used pvc pipe and a small 9"?=20 spring.  I built it but never tested it because I had an idea = the coil=20 and magnet were just too undersized.  It probably works but = would=20 require some strong amplification, further more, I have no idea what = the=20 period would be.
 
I wonder if one = could use=20 a "Slinky"  a toy spring used by kids? They are about 3" in = dia. and=20 collapsed about 5" tall.  I think I will get one and suspend it = vertically, to check its suspended length and its natural = resonance.  I=20 have no idea how long the spring would expand under its own=20 weight?   But let's say under 8 feet. If so, maybe it = could be=20 hung from the ceiling and the coil and mass would be near the=20 floor?


 A sensitive=20 seismic system must be covered to prevent air currents from causing = vibrations=20 much larger than those generated by earthquakes.  A vertical = system will=20 have to be very tall, and thus difficult to enclose.

It = just might be=20 something kids would enjoy.   =

Yes, indeed.  This would demonstrate the concept = of a=20 seismic sensor but would not be very good for detecting=20 earthquakes.
Q. = 1.  If I=20 pull down on a spring and release it, it will move up and down, = until it=20 come to rest, if each cycle is 1 sec, (say a very long spring), is = that its=20 natural period? Yes, one full = cycle is the=20 natural period.
Q. 2. If I put a mass on = the end of=20 the spring, will it move slower?   Yes.  If so, is that, now its=20 period?     Maybe 2 or 3 seconds?
Q. 3. If I = could=20 work out the construction details, what period should I target for a = vertical sensor?  The = AS-1 seismic=20 systems have a natural period of 1.6 seconds.  To see surface = waves the=20 electronics with a period of 20 seconds, the electronics have to = greatly=20 boost the low frequencies.
Q. 4. Are there = any=20 websites or information on using long vertical=20 springs?

 I've posted=20 various designs on my web site:  http://jclahr.com/science/psn/

Keep us = posted what=20 you come up with!

John
   Many=20 thanks, Ted
Subject: Re: School project From: "tchannel" tchannel@.............. Date: Wed, 29 Nov 2006 11:22:00 -0700 Hi Chirs, I will do this! I looked into it last summer, but will do so = again. I don't remember what happened last summer, their application = may have been processed, anyhow, this program would be just great for = them. Thanks, Ted ----- Original Message -----=20 From: ChrisAtUpw@.......... To: psn-l@................. Sent: Wednesday, November 29, 2006 10:26 AM Subject: Re: School project In a message dated 2006/11/28, tchannel@.............. writes: Hi Folks, =20 Some discussion on a simple vertical seismometer got me to thinking = about a=20 possible school project for the kids. Hi Ted,=20 Why not suggest to the school that they apply to Iris for a = 'free' school seismomter? I am sure that they would be grateful for help = in running it. See http://www.iris.edu/edu/AS1.htm =20 Regards, Chris
Hi Chirs,  I will do this!  I = looked into=20 it last summer, but will do so again.   I don't remember what = happened=20 last summer, their application may have been processed, anyhow, =  this=20 program would be just great for them.  Thanks, Ted
----- Original Message -----
From:=20 ChrisAtUpw@.......
Sent: Wednesday, November 29, = 2006 10:26=20 AM
Subject: Re: School = project

In a=20 message dated 2006/11/28, tchannel@..............=20 writes:

Hi Folks, 

Some discussion on = a simple=20 vertical seismometer got me to thinking about a
possible school project for the = kids.


Hi Ted,=20

       Why not suggest to the = school=20 that they apply to Iris for a 'free' school seismomter? I am sure that = they=20 would be grateful for help in running=20 it.
       See=20 = http://www.iris.edu/edu/AS1.htm
      =20
      =20 Regards,

       Chris=20
Subject: Re: School project From: ChrisAtUpw@....... Date: Wed, 29 Nov 2006 19:28:40 EST In a message dated 2006/11/29, tchannel@.............. writes: > I am still trying to eliminate my daytime noise, or at least identify it. > It was suggested I remove the magnet from the coil area to see if the noise > continued, if so it might be electrical, like RF, communications etc. using the > coil and cables as antenna. During a noisy hour I remove the magnet, from > the coil. All the noise disappeared, the helicorer was just a flat line. After > a while, I reinstalled the magnet surrounding the coil and the noise > reappeared. Note: I only get these spikes between 8am and 5pm, the night time hours > are very quiet. > Q. Should I conclude that this means that it can not be electrical, ie, > radio interference, but must be something creating vibrations? Hi Ted, This suggests very strongly that it is not RFI or pulse feedback from the power wiring. What is the construction of your seismometer? Is the pickup coil on the moving arm and the magnet on the floor / baseplate? > Q. On a different subject. Thanks to your input, I now have a better > understanding of LaCoste zero length spring suspension, and how it is applied. > But I don't understand (what is zero length) or how to find if a spring is > zero length. Perhaps someone could walk me thru this using a "screen door > spring" as an example. Extension springs are wound with a considerable internal tension - you have to pull them fairly hard to get them to extend at all. You hang the spring vertically and measure the distance between the loop ends. Then you add just enought weight to start to extend the spring, measure the separation, increase the weight etc until you have maybe 5 points of length vs weight. Then you plot the points on a graph and extend the line joining them back to the axis. If the line passes through the zero weight / zero length point, you have a zero length spring. Hopefully, it will give a -ve length for a zero load. Regards, Chris Chapman In a me= ssage dated 2006/11/29, tchannel@.............. writes:

I am still trying to eliminate=20= my daytime noise, or at least identify it. It was suggested I remove the mag= net from the coil area to see if the noise continued, if so it might be elec= trical, like RF, communications etc. using the coil and cables as antenna. D= uring a noisy hour I remove the magnet, from the coil.  All the noise d= isappeared, the helicorer was just a flat line. After a while, I reinstalled= the magnet surrounding the coil and the noise reappeared. Note: I only get=20= these spikes between 8am and 5pm, the night time hours are very quiet.
Q.  Should I conclude that this means that it can not be electrical, i= e, radio interference, but must be something creating vibrations?

 Hi Ted,

       This suggests very strongly that it is=20= not RFI or pulse feedback from the power wiring.
       What is the construction of your seismo= meter? Is the pickup coil on the moving arm and the magnet on the floor / ba= seplate?

Q. On a different subject. Tha= nks to your input, I now have a better understanding of LaCoste zero length=20= spring suspension, and how it is applied.
But I don't understand (what is zero length) or how to find if a spring is=20= zero length.  Perhaps someone could walk me thru this using a "screen d= oor spring" as an example.


       Extension springs are wound with a cons= iderable internal tension - you have to pull them fairly hard to get them to= extend at all.
       You hang the spring vertically and meas= ure the distance between the loop ends. Then you add just enought weight to=20= start to extend the spring, measure the separation, increase the weight etc=20= until you have maybe 5 points of length vs weight. Then you plot the points=20= on a graph and extend the line joining them back to the axis. If the line pa= sses through the zero weight / zero length point, you have a zero length spr= ing. Hopefully, it will give a -ve length for a zero load.

       Regards,

       Chris Chapman Subject: school project From: "tchannel" tchannel@.............. Date: Wed, 29 Nov 2006 19:00:26 -0700 Hi Chris, Yes the coil is on the arm and the magnet(assembly) is on the = baseplate. This is a Lehman similar to the one you built. Just to = repeat myself, it is now 6:30 pm here and the trace has gone from = daytime noise, to very still and will remain quiet until appx 8:37 to = 8:50am Nothing appears on the helicorer, except earthquakes, during the night. = So I don't think the sensor is sticking etc, at night all is working = perfectly. The noise doesn't start exactly on the minute, each morning, I see no = pattern, other than the first noise starts around 8:37 am all day even = on Sundays and Holidays. =20 There is some sort of pumping? station one mile away, I don't even know = what it is but it has a large engine on a concrete slab, and a block = building next to the outdoor equipment. Maybe I should drive over there = at 8:33am, and see if the ground shakes. (Is the pickup coil on the moving arm and the magnet on the floor / = baseplate?) Chris, Now on the zero length spring, do I understand that if I hang the = spring, add enough wt to start it to extend, then add 2# and measure, = then add another 2# and measure, continue doing this.........say the = first 2# expanded 1" the next 2# expanded another 1" If I did this 5 times, 2+2+2+2+2=3D 10# The expansions would be = 1"+1"+1"+1"+1"=3D 5"? In other words the same force would be required to move the same = distance thought out the length of expansion? If so, is this why they use a zero length springs on the vertical = sensors so movement is uniform? The length is not so important 20" vs 28" but it need so pull evenly, vs = easy at first and get harder at the end? -----Original Message----- From: psn-l-request@.............. = [mailto:psn-l-request@................. Behalf Of ChrisAtUpw@....... Sent: Wednesday, November 29, 2006 5:29 PM To: psn-l@.............. Subject: Re: School project In a message dated 2006/11/29, tchannel@.............. writes: I am still trying to eliminate my daytime noise, or at least identify = it. It was suggested I remove the magnet from the coil area to see if = the noise continued, if so it might be electrical, like RF, = communications etc. using the coil and cables as antenna. During a noisy = hour I remove the magnet, from the coil. All the noise disappeared, the = helicorer was just a flat line. After a while, I reinstalled the magnet = surrounding the coil and the noise reappeared. Note: I only get these = spikes between 8am and 5pm, the night time hours are very quiet. Q. Should I conclude that this means that it can not be electrical, = ie, radio interference, but must be something creating vibrations? Hi Ted, This suggests very strongly that it is not RFI or pulse feedback = from the power wiring.=20 What is the construction of your seismometer? Is the pickup coil = on the moving arm and the magnet on the floor / baseplate? Q. On a different subject. Thanks to your input, I now have a better = understanding of LaCoste zero length spring suspension, and how it is = applied. But I don't understand (what is zero length) or how to find if a = spring is zero length. Perhaps someone could walk me thru this using a = "screen door spring" as an example. Extension springs are wound with a considerable internal tension = - you have to pull them fairly hard to get them to extend at all.=20 You hang the spring vertically and measure the distance between = the loop ends. Then you add just enough weight to start to extend the = spring, measure the separation, increase the weight etc until you have = maybe 5 points of length vs weight. Then you plot the points on a graph = and extend the line joining them back to the axis. If the line passes = through the zero weight / zero length point, you have a zero length = spring. Hopefully, it will give a -ve length for a zero load. Regards, Chris Chapman
Hi Chris, Yes the coil is on the arm = and the=20 magnet(assembly) is on the baseplate. This is a Lehman similar to the = one you=20 built.  Just to repeat myself, it is now 6:30 pm here and the trace = has=20 gone from daytime noise, to very still and will = remain quiet until=20 appx 8:37 to 8:50am
Nothing appears on the helicorer, = except=20 earthquakes, during the night.  So I don't think the sensor is = sticking=20 etc, at night all is working perfectly.
The noise doesn't start exactly on the = minute, each=20 morning, I see no pattern, other than the first noise starts around 8:37 = am all=20 day even on Sundays and Holidays. 
There is some sort of pumping? station = one mile=20 away, I don't even know what it is but it has a large engine on a = concrete slab,=20 and a block building next to the outdoor equipment.  Maybe I should = drive=20 over there at 8:33am, and see if the ground shakes.
 
 
(Is the pickup coil on the moving arm = and the=20 magnet on the floor / baseplate?)
Chris, Now on the zero length spring, do = I=20 understand that if I hang the spring, add enough wt to start it to = extend, then=20 add 2# and measure, then add another 2# and measure, continue doing=20 this.........say the first 2# expanded 1" the next 2# expanded another=20 1"
If I did this 5 times, 2+2+2+2+2=3D = 10#  The=20 expansions would be 1"+1"+1"+1"+1"=3D 5"?
In other words the same force would be = required to=20 move the same distance thought out the length of=20 expansion?
If so, is this why they use a zero = length=20 springs on the vertical sensors so movement=20 is uniform?
The length is not so important 20" vs = 28" but it=20 need so pull evenly, vs easy at first and get harder at the = end?
 
 
 
-----Original Message-----
From: = psn-l-request@................. [mailto:psn-l-request@...............On Behalf Of=20 ChrisAtUpw@.......
Sent: Wednesday, November 29, 2006 5:29 = PM
To: psn-l@..............
Subject: Re: School=20 project

In a = message dated=20 2006/11/29, tchannel@.............. writes:

I am still trying to eliminate my daytime noise, or at = least=20 identify it. It was suggested I remove the magnet from the coil area = to see if=20 the noise continued, if so it might be electrical, like RF, = communications=20 etc. using the coil and cables as antenna. During a noisy hour I = remove the=20 magnet, from the coil.  All the noise disappeared, the helicorer = was just=20 a flat line. After a while, I reinstalled the magnet surrounding the = coil and=20 the noise reappeared. Note: I only get these spikes between 8am and = 5pm, the=20 night time hours are very quiet.
Q.  Should I conclude that = this means=20 that it can not be electrical, ie, radio interference, but must be = something=20 creating vibrations?


Hi=20 Ted,

       This suggests very = strongly=20 that it is not RFI or pulse feedback from the power wiring.=20
       What is the construction of = your=20 seismometer? Is the pickup coil on the moving arm and the magnet on the = floor /=20 baseplate?

Q. On a different subject. Thanks to your input, I now = have a=20 better understanding of LaCoste zero length spring suspension, and how = it is=20 applied.
But I don't understand (what is zero length) or how = to find if=20 a spring is zero length.  Perhaps someone could walk me thru this = using a=20 "screen door spring" as an example.


       Extension = springs are=20 wound with a considerable internal tension - you have to pull them = fairly hard=20 to get them to extend at all.
       = You hang=20 the spring vertically and measure the distance between the loop ends. = Then you=20 add just enough weight to start to extend the spring, measure the = separation,=20 increase the weight etc until you have maybe 5 points of length vs = weight. Then=20 you plot the points on a graph and extend the line joining them back to = the=20 axis. If the line passes through the zero weight / zero length point, = you have a=20 zero length spring. Hopefully, it will give a -ve length for a zero=20 load.

      =20 Regards,

       Chris = Chapman=20
Subject: Re: school project From: ChrisAtUpw@....... Date: Wed, 29 Nov 2006 23:43:35 EST In a message dated 2006/11/30, tchannel@.............. writes: > Nothing appears on the helicorer, except earthquakes, during the night. So > I don't think the sensor is sticking etc, at night all is working perfectly. Hi Ted, Increase the gain until you see the 5/6 second microseisms at maybe 50 counts (I normally run at about 200 counts) > The noise doesn't start exactly on the minute, each morning, I see no > pattern, other than the first noise starts around 8:37 am all day even on Sundays > and Holidays. > There is some sort of pumping? station one mile away, I don't even know what > it is but it has a large engine on a concrete slab, and a block building > next to the outdoor equipment. Maybe I should drive over there at 8:33am, and > see if the ground shakes. I don't know what you are picking up, but this seems a likely candidate. Can you ring them up and ask when the work and what they do? Is there a guard on the entrance? > Chris, Now on the zero length spring, do I understand that if I hang the > spring, add enough wt to start it to extend, then add 2# and measure, then add > another 2# and measure, continue doing this.........say the first 2# expanded > 1" the next 2# expanded another 1" > If I did this 5 times, 2+2+2+2+2= 10# The expansions would be > 1"+1"+1"+1"+1"= 5"? > In other words the same force would be required to move the same distance > thought out the length of expansion? Correct. This is substantially true except at very large extensions when the wire spiral changes. > If so, is this why they use a zero length springs on the vertical sensors > so movement is uniform? > The length is not so important 20" vs 28" but it need so pull evenly, vs > easy at first and get harder at the end? The zero length spring effect is used so that the length of a triangular side is proportional to the force. This completes the traingle of forces to give an infinite period device. Regards, Chris Chapman In a me= ssage dated 2006/11/30, tchannel@.............. writes:

Nothing appears on the helicore= r, except earthquakes, during the night.  So I don't think the sensor i= s sticking etc, at night all is working perfectly.


Hi Ted,

       Increase the gain until you see the 5/6= second microseisms at maybe 50 counts (I normally run at about 200 counts)<= /FONT>=

The noise doesn't start exactly= on the minute, each morning, I see no pattern, other than the first noise s= tarts around 8:37 am all day even on Sundays and Holidays. 
There is some sort of pumping? station one mile away, I don't even know what= it is but it has a large engine on a concrete slab, and a block building ne= xt to the outdoor equipment.  Maybe I should drive over there at 8:33am= , and see if the ground shakes.


       I don't know what you are picking up,=20= but this seems a likely candidate. Can you ring them up and ask when the wor= k and what they do? Is there a guard on the entrance?

Chris, Now on the zero length s= pring, do I understand that if I hang the spring, add enough wt to start it=20= to extend, then add 2# and measure, then add another 2# and measure, continu= e doing this.........say the first 2# expanded 1" the next 2# expanded anoth= er 1"
If I did this 5 times, 2+2+2+2+2=3D 10#  The expansions would be 1"+1"+= 1"+1"+1"=3D 5"?
In other words the same force would be required to move the same distance th= ought out the length of expansion?


       Correct. This is substantially true ex= cept at very large extensions when the wire spiral changes.

If so, is this why they use a z= ero length springs on the vertical sensors so movement is uniform?
The length is not so important 20" vs 28" but it need so pull evenly, vs eas= y at first and get harder at the end?


       The zero length spring effect is used s= o that the length of a triangular side is proportional to the force. This co= mpletes the traingle of forces to give an infinite period device.

       Regards,

       Chris Chapman Subject: Zero-length spring From: John or Jan Lahr JohnJan@........ Date: Wed, 29 Nov 2006 21:25:35 -0800 I just wrote up a page describing why a zero-length spring provides a vertical sensor with a long period response. See: http://www.jclahr.com/science/psn/zero/index.html Cheers, John At 06:00 PM 11/29/2006, you wrote: >Hi Chris, Yes the coil is on the arm and the magnet(assembly) is on >the baseplate. This is a Lehman similar to the one you built. Just >to repeat myself, it is now 6:30 pm here and the trace has gone from >daytime noise, to very still and will remain quiet until appx 8:37 to 8:50am >Nothing appears on the helicorer, except earthquakes, during the >night. So I don't think the sensor is sticking etc, at night all is >working perfectly. >The noise doesn't start exactly on the minute, each morning, I see >no pattern, other than the first noise starts around 8:37 am all day >even on Sundays and Holidays. >There is some sort of pumping? station one mile away, I don't even >know what it is but it has a large engine on a concrete slab, and a >block building next to the outdoor equipment. Maybe I should drive >over there at 8:33am, and see if the ground shakes. > > >(Is the pickup coil on the moving arm and the magnet on the floor / >baseplate?) >Chris, Now on the zero length spring, do I understand that if I hang >the spring, add enough wt to start it to extend, then add 2# and >measure, then add another 2# and measure, continue doing >this.........say the first 2# expanded 1" the next 2# expanded another 1" >If I did this 5 times, 2+2+2+2+2= 10# The expansions would be >1"+1"+1"+1"+1"= 5"? >In other words the same force would be required to move the same >distance thought out the length of expansion? >If so, is this why they use a zero length springs on the vertical >sensors so movement is uniform? >The length is not so important 20" vs 28" but it need so pull >evenly, vs easy at first and get harder at the end? > > > > >-----Original Message----- >From: psn-l-request@.............. >[mailto:psn-l-request@................. Behalf Of ChrisAtUpw@....... >Sent: Wednesday, November 29, 2006 5:29 PM >To: psn-l@.............. >Subject: Re: School project > >In a message dated 2006/11/29, tchannel@.............. writes: > >>I am still trying to eliminate my daytime noise, or at least >>identify it. It was suggested I remove the magnet from the coil >>area to see if the noise continued, if so it might be electrical, >>like RF, communications etc. using the coil and cables as antenna. >>During a noisy hour I remove the magnet, from the coil. All the >>noise disappeared, the helicorer was just a flat line. After a >>while, I reinstalled the magnet surrounding the coil and the noise >>reappeared. Note: I only get these spikes between 8am and 5pm, the >>night time hours are very quiet. >>Q. Should I conclude that this means that it can not be >>electrical, ie, radio interference, but must be something creating vibrations? > > >Hi Ted, > > This suggests very strongly that it is not RFI or pulse > feedback from the power wiring. > What is the construction of your seismometer? Is the pickup > coil on the moving arm and the magnet on the floor / baseplate? > >>Q. On a different subject. Thanks to your input, I now have a >>better understanding of LaCoste zero length spring suspension, and >>how it is applied. >>But I don't understand (what is zero length) or how to find if a >>spring is zero length. Perhaps someone could walk me thru this >>using a "screen door spring" as an example. > > > Extension springs are wound with a considerable internal > tension - you have to pull them fairly hard to get them to extend at all. > You hang the spring vertically and measure the distance > between the loop ends. Then you add just enough weight to start to > extend the spring, measure the separation, increase the weight etc > until you have maybe 5 points of length vs weight. Then you plot > the points on a graph and extend the line joining them back to the > axis. If the line passes through the zero weight / zero length > point, you have a zero length spring. Hopefully, it will give a -ve > length for a zero load. > > Regards, > > Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Zero-length spring From: "tchannel" tchannel@.............. Date: Wed, 29 Nov 2006 22:53:52 -0700 Hi John, Thank you, this is a great posting. Ted ----- Original Message ----- From: "John or Jan Lahr" To: Sent: Wednesday, November 29, 2006 10:25 PM Subject: Zero-length spring >I just wrote up a page describing why a zero-length spring provides a >vertical sensor with a long period response. See: >http://www.jclahr.com/science/psn/zero/index.html > > Cheers, > John > > At 06:00 PM 11/29/2006, you wrote: >>Hi Chris, Yes the coil is on the arm and the magnet(assembly) is on the >>baseplate. This is a Lehman similar to the one you built. Just to repeat >>myself, it is now 6:30 pm here and the trace has gone from daytime noise, >>to very still and will remain quiet until appx 8:37 to 8:50am >>Nothing appears on the helicorer, except earthquakes, during the night. >>So I don't think the sensor is sticking etc, at night all is working >>perfectly. >>The noise doesn't start exactly on the minute, each morning, I see no >>pattern, other than the first noise starts around 8:37 am all day even on >>Sundays and Holidays. >>There is some sort of pumping? station one mile away, I don't even know >>what it is but it has a large engine on a concrete slab, and a block >>building next to the outdoor equipment. Maybe I should drive over there >>at 8:33am, and see if the ground shakes. >> >> >>(Is the pickup coil on the moving arm and the magnet on the floor / >>baseplate?) >>Chris, Now on the zero length spring, do I understand that if I hang the >>spring, add enough wt to start it to extend, then add 2# and measure, then >>add another 2# and measure, continue doing this.........say the first 2# >>expanded 1" the next 2# expanded another 1" >>If I did this 5 times, 2+2+2+2+2= 10# The expansions would be >>1"+1"+1"+1"+1"= 5"? >>In other words the same force would be required to move the same distance >>thought out the length of expansion? >>If so, is this why they use a zero length springs on the vertical sensors >>so movement is uniform? >>The length is not so important 20" vs 28" but it need so pull evenly, vs >>easy at first and get harder at the end? >> >> >> >> >>-----Original Message----- >>From: psn-l-request@.............. [mailto:psn-l-request@................. >>Behalf Of ChrisAtUpw@....... >>Sent: Wednesday, November 29, 2006 5:29 PM >>To: psn-l@.............. >>Subject: Re: School project >> >>In a message dated 2006/11/29, tchannel@.............. writes: >> >>>I am still trying to eliminate my daytime noise, or at least identify it. >>>It was suggested I remove the magnet from the coil area to see if the >>>noise continued, if so it might be electrical, like RF, communications >>>etc. using the coil and cables as antenna. During a noisy hour I remove >>>the magnet, from the coil. All the noise disappeared, the helicorer was >>>just a flat line. After a while, I reinstalled the magnet surrounding the >>>coil and the noise reappeared. Note: I only get these spikes between 8am >>>and 5pm, the night time hours are very quiet. >>>Q. Should I conclude that this means that it can not be electrical, ie, >>>radio interference, but must be something creating vibrations? >> >> >>Hi Ted, >> >> This suggests very strongly that it is not RFI or pulse feedback >> from the power wiring. >> What is the construction of your seismometer? Is the pickup coil >> on the moving arm and the magnet on the floor / baseplate? >> >>>Q. On a different subject. Thanks to your input, I now have a better >>>understanding of LaCoste zero length spring suspension, and how it is >>>applied. >>>But I don't understand (what is zero length) or how to find if a spring >>>is zero length. Perhaps someone could walk me thru this using a "screen >>>door spring" as an example. >> >> >> Extension springs are wound with a considerable internal tension - >> you have to pull them fairly hard to get them to extend at all. >> You hang the spring vertically and measure the distance between >> the loop ends. Then you add just enough weight to start to extend the >> spring, measure the separation, increase the weight etc until you have >> maybe 5 points of length vs weight. Then you plot the points on a graph >> and extend the line joining them back to the axis. If the line passes >> through the zero weight / zero length point, you have a zero length >> spring. Hopefully, it will give a -ve length for a zero load. >> >> Regards, >> >> Chris Chapman > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with the body of the > message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Zero-length spring From: "tchannel" tchannel@.............. Date: Wed, 29 Nov 2006 23:29:06 -0700 Hi John, I am not too good at math, could you please plug-in some examples/numbers for this formula so I can understand it better? I think its k that I am unclear of. I understand the rest. Thanks, Ted MgA = kSY/(SA) M = kY/(Ag) ----- Original Message ----- From: "John or Jan Lahr" To: Sent: Wednesday, November 29, 2006 10:25 PM Subject: Zero-length spring >I just wrote up a page describing why a zero-length spring provides a >vertical sensor with a long period response. See: >http://www.jclahr.com/science/psn/zero/index.html > > Cheers, > John > > At 06:00 PM 11/29/2006, you wrote: >>Hi Chris, Yes the coil is on the arm and the magnet(assembly) is on the >>baseplate. This is a Lehman similar to the one you built. Just to repeat >>myself, it is now 6:30 pm here and the trace has gone from daytime noise, >>to very still and will remain quiet until appx 8:37 to 8:50am >>Nothing appears on the helicorer, except earthquakes, during the night. >>So I don't think the sensor is sticking etc, at night all is working >>perfectly. >>The noise doesn't start exactly on the minute, each morning, I see no >>pattern, other than the first noise starts around 8:37 am all day even on >>Sundays and Holidays. >>There is some sort of pumping? station one mile away, I don't even know >>what it is but it has a large engine on a concrete slab, and a block >>building next to the outdoor equipment. Maybe I should drive over there >>at 8:33am, and see if the ground shakes. >> >> >>(Is the pickup coil on the moving arm and the magnet on the floor / >>baseplate?) >>Chris, Now on the zero length spring, do I understand that if I hang the >>spring, add enough wt to start it to extend, then add 2# and measure, then >>add another 2# and measure, continue doing this.........say the first 2# >>expanded 1" the next 2# expanded another 1" >>If I did this 5 times, 2+2+2+2+2= 10# The expansions would be >>1"+1"+1"+1"+1"= 5"? >>In other words the same force would be required to move the same distance >>thought out the length of expansion? >>If so, is this why they use a zero length springs on the vertical sensors >>so movement is uniform? >>The length is not so important 20" vs 28" but it need so pull evenly, vs >>easy at first and get harder at the end? >> >> >> >> >>-----Original Message----- >>From: psn-l-request@.............. [mailto:psn-l-request@................. >>Behalf Of ChrisAtUpw@....... >>Sent: Wednesday, November 29, 2006 5:29 PM >>To: psn-l@.............. >>Subject: Re: School project >> >>In a message dated 2006/11/29, tchannel@.............. writes: >> >>>I am still trying to eliminate my daytime noise, or at least identify it. >>>It was suggested I remove the magnet from the coil area to see if the >>>noise continued, if so it might be electrical, like RF, communications >>>etc. using the coil and cables as antenna. During a noisy hour I remove >>>the magnet, from the coil. All the noise disappeared, the helicorer was >>>just a flat line. After a while, I reinstalled the magnet surrounding the >>>coil and the noise reappeared. Note: I only get these spikes between 8am >>>and 5pm, the night time hours are very quiet. >>>Q. Should I conclude that this means that it can not be electrical, ie, >>>radio interference, but must be something creating vibrations? >> >> >>Hi Ted, >> >> This suggests very strongly that it is not RFI or pulse feedback >> from the power wiring. >> What is the construction of your seismometer? Is the pickup coil >> on the moving arm and the magnet on the floor / baseplate? >> >>>Q. On a different subject. Thanks to your input, I now have a better >>>understanding of LaCoste zero length spring suspension, and how it is >>>applied. >>>But I don't understand (what is zero length) or how to find if a spring >>>is zero length. Perhaps someone could walk me thru this using a "screen >>>door spring" as an example. >> >> >> Extension springs are wound with a considerable internal tension - >> you have to pull them fairly hard to get them to extend at all. >> You hang the spring vertically and measure the distance between >> the loop ends. Then you add just enough weight to start to extend the >> spring, measure the separation, increase the weight etc until you have >> maybe 5 points of length vs weight. Then you plot the points on a graph >> and extend the line joining them back to the axis. If the line passes >> through the zero weight / zero length point, you have a zero length >> spring. Hopefully, it will give a -ve length for a zero load. >> >> Regards, >> >> Chris Chapman > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with the body of the > message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Zero-length spring From: John or Jan Lahr JohnJan@........ Date: Wed, 29 Nov 2006 23:20:45 -0800 At 10:29 PM 11/29/2006, you wrote: >Hi John, I am not too good at math, could you please plug-in some >examples/numbers for this formula so I can understand it better? I >think its k that I am unclear of. I understand the rest. Thanks, Ted >MgA = kSY/(SA) > >M = kY/(Ag) k is the spring constant. In this example I'm using k = 2 newtons/cm M is the mass Y is the height of the mast A is the length of the boom g is the acceleration of gravity The exact numbers don't really matter - the point being that the mass will be stable at any angle of the boom. There are problems of trying to actually build this device, because slight changes in k with temperature will cause instability. Even without a zero-length spring, one can extend the period by reducing the height of the mast. However, you will soon discover that this will also lead to instability if pushed to too long a period. Cheers, John __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Zero-length spring From: ChrisAtUpw@....... Date: Thu, 30 Nov 2006 11:43:13 EST In a message dated 2006/11/30, tchannel@.............. writes: > I think its k that I am unclear of. Hi Ted, 'k' is the force constant of the spring in say, pounds per inch of stretch. This is constant until you get to very large extensions which change the spiral. An example of a zero length spring is an ordinary clock spring when you pull it along it's shaft axis. Regards, Chris Chapman In a me= ssage dated 2006/11/30, tchannel@.............. writes:

I think its k that I am unclear= of.


Hi Ted,

       'k' is the force constant of the spring= in say, pounds per inch of stretch. This is constant until you get to very=20= large extensions which change the spiral.

       An example of a zero length spring is a= n ordinary clock spring when you pull it along it's shaft axis.

       Regards,

       Chris Chapman Subject: Re: Zero-length spring From: "Dave Nelson" davefnelson@....... Date: Thu, 30 Nov 2006 18:10:37 -0000 ----- Original Message -----=20 From: ChrisAtUpw@.......... To: psn-l@................. Sent: Thursday, November 30, 2006 16:43 Subject: Re: Zero-length spring In a message dated 2006/11/30, tchannel@.............. writes: I think its k that I am unclear of.=20 Hi Ted, 'k' is the force constant of the spring in say, pounds per inch = of stretch. This is constant until you get to very large extensions = which change the spiral. An example of a zero length spring is an ordinary clock spring = when you pull it along it's shaft axis.=20 Regards, Chris Chapman
 
----- Original Message -----
From:=20 ChrisAtUpw@.......
Sent: Thursday, November 30, = 2006=20 16:43
Subject: Re: Zero-length = spring

In a=20 message dated 2006/11/30, tchannel@..............=20 writes:

I think its k that I am unclear of. =


Hi=20 Ted,

       'k' is the force = constant of=20 the spring in say, pounds per inch of stretch. This is constant until = you get=20 to very large extensions which change the=20 spiral.

       An example of a = zero=20 length spring is an ordinary clock spring when you pull it along it's = shaft=20 axis.

      =20 Regards,

       Chris = Chapman=20
Subject: Noise From: "Connie and Jim Lehman" lehmancj@........... Date: Thu, 30 Nov 2006 14:27:06 -0500 PSN-folks. I have been reading with interest the troublesome noise = reference=3D=3Ddaytime beginning regularly. The noise may be entering = or radiating from the power lines. Broadband riding piggyback on power = lines have been the bane of amateur radio operators wherever it has been = allowed(Manassas, VA for example) but that is usually 24 hour noise. = Other use of the lines could be external meter reading carriers---that = would be present probably during working hours. Automatic street = lighting can be noisy as well--in off condition too This type of noise = as all noise is frustrating, and I toss these ideas out for elimination. = =20 Best Wishes Jim Lehman
PSN-folks.  I have been reading = with interest=20 the troublesome noise reference=3D=3Ddaytime beginning regularly.  = The noise=20 may be entering or radiating from the power lines.  Broadband = riding=20 piggyback on power lines have been the bane of amateur radio operators = wherever=20 it has been allowed(Manassas, VA for example) but that is usually 24 = hour=20 noise.  Other use of the lines could be external meter reading=20 carriers---that would be present probably during working hours.  = Automatic=20 street lighting can be noisy as well--in off condition too  = This type=20 of noise as all noise is frustrating, and I toss these ideas out for=20 elimination. 
    Best=20 Wishes       Jim = Lehman
Subject: Re: Noise From: "tchannel" tchannel@.............. Date: Thu, 30 Nov 2006 14:33:48 -0700 Hi Jim, At night time the noise stops as suddenly as it begins, I think = it stops at around 4:30pm, starts at 8:35 to 8:50am. Really quiet at = night, I live 1/4 mile from a school, and crossing lights, but the noise = continues during Sat, Sun and Holidays when the school is inactive. I = live 1 1/2 miles from a fire station. I did remove the magnet during the noise, and the trace was dead quite, = all the noise stopped and started again when I replaced the magnet over = the coil, so I don't think it is RFI. During the night time, and day = time I do record earthquakes, so I know the sensor is working. The list of things it is not continues to grow; It is not the sun, = clouds, weather, home appliances, TV, our telephones, wind, = construction. So Now I think it is vibrations coming from somewhere during the day = time only. The spikes are random, sometimes one, two min group per = hour, then a quiet hour, followed by groups lasting 10 mins and 10 mins = of quiet. Some hours are filled with spikes. No patterns. Everything follows what you would expect with auto traffic, but I = watched carefully on Thanksgiving and the noise took no holiday.=20 I live about 4 miles from the interstate highway. Whatever it is, I know I will have to put up with it, unless its = something in my house. Thanks, If I ever isolate it I'll let you know. = Ted ----- Original Message -----=20 From: Connie and Jim Lehman=20 To: psn-l@................. Sent: Thursday, November 30, 2006 12:27 PM Subject: Noise PSN-folks. I have been reading with interest the troublesome noise = reference=3D=3Ddaytime beginning regularly. The noise may be entering = or radiating from the power lines. Broadband riding piggyback on power = lines have been the bane of amateur radio operators wherever it has been = allowed(Manassas, VA for example) but that is usually 24 hour noise. = Other use of the lines could be external meter reading carriers---that = would be present probably during working hours. Automatic street = lighting can be noisy as well--in off condition too This type of noise = as all noise is frustrating, and I toss these ideas out for elimination. = =20 Best Wishes Jim Lehman
Hi Jim,  At night time the noise = stops as=20 suddenly as it begins, I think it stops at around 4:30pm, starts at 8:35 = to=20 8:50am.  Really quiet at night,
I live 1/4 mile from a school, and = crossing lights,=20 but the noise continues during Sat, Sun and Holidays when the school is=20 inactive.  I live 1 1/2 miles from a fire station.
I did remove the magnet during the = noise, and the=20 trace was dead quite, all the noise stopped and started again when I = replaced=20 the magnet over the coil, so I don't think it is RFI.  During the = night=20 time, and day time I do record earthquakes, so I know the sensor is=20 working.
The list of things it is not continues = to=20 grow;  It is not the sun, clouds, weather, home appliances, TV, our = telephones, wind, construction.
 
So Now I think it is vibrations coming = from=20 somewhere during the day time only.  The spikes are random, = sometimes one,=20 two min group per hour, then a quiet hour, followed by groups lasting 10 = mins=20 and 10 mins of quiet.  Some hours are filled with spikes. No=20 patterns.
Everything follows what you would = expect with auto=20 traffic, but I watched carefully on Thanksgiving and the noise took no = holiday.=20
I live about 4 miles from the = interstate=20 highway.
Whatever it is, I know I will have to = put up with=20 it, unless its something in my house.  Thanks, If I ever isolate it = I'll=20 let you know.  Ted
----- Original Message -----
From:=20 Connie and=20 Jim Lehman
Sent: Thursday, November 30, = 2006 12:27=20 PM
Subject: Noise

PSN-folks.  I have been reading = with=20 interest the troublesome noise reference=3D=3Ddaytime beginning = regularly. =20 The noise may be entering or radiating from the power lines.  = Broadband=20 riding piggyback on power lines have been the bane of amateur radio = operators=20 wherever it has been allowed(Manassas, VA for example) but that is = usually 24=20 hour noise.  Other use of the lines could be external meter = reading=20 carriers---that would be present probably during working hours. =20 Automatic street lighting can be noisy as well--in off=20 condition too  This type of noise as all noise is = frustrating, and I=20 toss these ideas out for elimination. 
    Best=20 Wishes       Jim=20 Lehman
Subject: Re: Noise From: "Thomas Dick" dickthomas01@............. Date: Thu, 30 Nov 2006 16:18:11 -0600 I have followed your discussion of noise. I, too, have notice a = cycling from quiet to "busy"; with some intervals of seemingly quiet = conditions during times that you expect quiet and vice versa. As = everyone has said, what you call noise comes from two sources natural = and man-made. I found that some of this noise can be explained with = experience and time; bad storms like Katrina hitting New Orleans(at six = hundred miles), the demolishing of old buildings with wrecking balls = (about 4 miles away), maybe even tornadoes (ten miles), the microcisms = proceeding the first cold front in the Fall, bad local storms with wind = and lightning(as far as 100 miles away), a local train that goes within = about a mile of this location about twice a week about 9:30 pm local = time and even local truck traffic like the trash pickup truck each week. = One that really had me fooled for about a week or so was a geologic = team in the area using a machine to test soil liquifaction. It created = "little" quakes which seemed to move -- and they did move, well anyway, = the truck moved!! If you limit you observations to just earthquakes you = will miss many interesting events and hopelessly stagnate and become a = dull little boy -- and that is NOT what we want out of seismology is it?
 
I have followed your discussion of noise. I, = too, have=20 notice a cycling from quiet to "busy"; with some intervals of = seemingly=20 quiet conditions during times that you expect quiet and vice = versa. As=20 everyone has said, what you call noise comes from two sources natural = and=20 man-made. I found that some of this noise can be explained with = experience and=20 time; bad storms like Katrina hitting New Orleans(at six hundred = miles), the=20 demolishing of old buildings with wrecking balls (about 4 miles away), = maybe=20 even tornadoes (ten miles), the microcisms proceeding the first = cold=20 front in the Fall, bad local storms with wind and lightning(as far as = 100=20 miles away), a local train that goes within about a mile of this = location=20 about twice a week about 9:30 pm local time and even local truck = traffic like=20 the trash pickup truck each week.  One that really had me fooled = for=20 about a week or so was a geologic team in the area using a machine to = test=20 soil liquifaction. It created "little" quakes which seemed to move -- = and they=20 did move, well anyway, the truck moved!! If you limit you observations = to just=20 earthquakes you will miss many interesting events and hopelessly = stagnate and=20 become a dull little boy -- and that is NOT what we want out of = seismology is=20 it?
Subject: Re: Noise From: ChrisAtUpw@....... Date: Thu, 30 Nov 2006 18:21:23 EST In a message dated 2006/11/30, tchannel@.............. writes: > Hi Jim, At night time the noise stops as suddenly as it begins, I think it > stops at around 4:30pm, starts at 8:35 to 8:50am. Really quiet at night, > I live 1/4 mile from a school, and crossing lights, but the noise continues > during Sat, Sun and Holidays when the school is inactive. > I did remove the magnet during the noise, and the trace was dead quite, all > the noise stopped and started again when I replaced the magnet over the coil, > so I don't think it is RFI. Hi Ted, OK. Can you identify any 'typical sequence' types of signal? Can you log the ~amplitudes? Now you have evidence that the noise isn't RFI or pickup from the house wiring, can you re-orient your sensor, say 20 degrees at a time at first, to determine the direction that it is coming from? If it is an external fixed source, there should be a direction which gives a minimum response. It can be quite difficult to identify a source just from a seismic trace. If it is a local source, there are likely to be a lot of associated high frequency signals. Do you have a geophone, or a piezo accelerometer, which you can use as a sensor to drive an audio amplifier / headphone system? Sounds carry quite a long way in the soil. I can pick up car tyre noise on the main road at about 1 km. This could help to direct your search. Regards, Chris Chapman In a me= ssage dated 2006/11/30, tchannel@.............. writes:

Hi Jim,  At night time the= noise stops as suddenly as it begins, I think it stops at around 4:30pm, st= arts at 8:35 to 8:50am.  Really quiet at night,
I live 1/4 mile from a school, and crossing lights, but the noise continues= during Sat, Sun and Holidays when the school is inactive.
I did remove the magnet during the noise, and the trace was dead quite, all= the noise stopped and started again when I replaced the magnet over the coi= l, so I don't think it is RFI.


Hi Ted,

       OK. Can you identify any 'typical seque= nce' types of signal?  Can you log the ~amplitudes?

       Now you have evidence that the noise is= n't RFI or pickup from the house wiring, can you re-orient your sensor, say=20= 20 degrees at a time at first, to determine the direction that it is coming=20= from? If it is an external fixed source, there should be a direction which g= ives a minimum response.

       It can be quite difficult to identify a= source just from a seismic trace. If it is a local source, there are likely= to be a lot of associated high frequency signals. Do you have a geophone, o= r a piezo accelerometer, which you can use as a sensor to drive an audio amp= lifier / headphone system? Sounds carry quite a long way in the soil. I can=20= pick up car tyre noise on the main road at about 1 km. This could help to di= rect your search.

       Regards,

       Chris Chapman Subject: Re: Noise From: "tchannel" tchannel@.............. Date: Thu, 30 Nov 2006 17:19:16 -0700 Hi Chris, You know these are great suggestions....I can't rotate the = sensor, where it is located, but if I could??????? I do have another sensor I could set up and rotate. I could perhaps = setup a microphone/ amp/ headset, to see if I could pick up the noise = and then isolate its direction. I tried the am radio but could not hear = the noise, I will try that again, at different frequencies. Ted ----- Original Message -----=20 From: ChrisAtUpw@.......... To: psn-l@................. Sent: Thursday, November 30, 2006 4:21 PM Subject: Re: Noise In a message dated 2006/11/30, tchannel@.............. writes: Hi Jim, At night time the noise stops as suddenly as it begins, I = think it stops at around 4:30pm, starts at 8:35 to 8:50am. Really quiet = at night, I live 1/4 mile from a school, and crossing lights, but the noise = continues during Sat, Sun and Holidays when the school is inactive. I did remove the magnet during the noise, and the trace was dead = quite, all the noise stopped and started again when I replaced the = magnet over the coil, so I don't think it is RFI.=20 Hi Ted, OK. Can you identify any 'typical sequence' types of signal? = Can you log the ~amplitudes? Now you have evidence that the noise isn't RFI or pickup from = the house wiring, can you re-orient your sensor, say 20 degrees at a = time at first, to determine the direction that it is coming from? If it = is an external fixed source, there should be a direction which gives a = minimum response. It can be quite difficult to identify a source just from a = seismic trace. If it is a local source, there are likely to be a lot of = associated high frequency signals. Do you have a geophone, or a piezo = accelerometer, which you can use as a sensor to drive an audio amplifier = / headphone system? Sounds carry quite a long way in the soil. I can = pick up car tyre noise on the main road at about 1 km. This could help = to direct your search. Regards, Chris Chapman
Hi Chris, You know these are great = suggestions....I=20 can't rotate the sensor, where it is located, but if I = could???????
I do have another sensor I could set up = and=20 rotate.  I could perhaps setup a microphone/ amp/ headset, to see = if I=20 could pick up the noise and then isolate its direction.  I tried = the am=20 radio but could not hear the noise, I will try that again, at different=20 frequencies.   Ted
  ----- Original Message ----- =
From:=20 ChrisAtUpw@.......
Sent: Thursday, November 30, = 2006 4:21=20 PM
Subject: Re: Noise

In a=20 message dated 2006/11/30, tchannel@..............=20 writes:

Hi Jim,  At night time the noise stops as suddenly = as it=20 begins, I think it stops at around 4:30pm, starts at 8:35 to = 8:50am. =20 Really quiet at night,
I live 1/4 mile from a school, and crossing lights, = but the=20 noise continues during Sat, Sun and Holidays when the school is=20 inactive.
I did remove the magnet during the noise, and the = trace was=20 dead quite, all the noise stopped and started again when I replaced = the=20 magnet over the coil, so I don't think it is RFI.


Hi=20 Ted,

       OK. Can you identify = any=20 'typical sequence' types of signal?  Can you log the=20 ~amplitudes?

       Now you have = evidence=20 that the noise isn't RFI or pickup from the house wiring, can you = re-orient=20 your sensor, say 20 degrees at a time at first, to determine the = direction=20 that it is coming from? If it is an external fixed source, there = should be a=20 direction which gives a minimum=20 response.

       It can be quite=20 difficult to identify a source just from a seismic trace. If it is a = local=20 source, there are likely to be a lot of associated high frequency = signals. Do=20 you have a geophone, or a piezo accelerometer, which you can use as a = sensor=20 to drive an audio amplifier / headphone system? Sounds carry quite a = long way=20 in the soil. I can pick up car tyre noise on the main road at about 1 = km. This=20 could help to direct your = search.

      =20 Regards,

       Chris = Chapman=20
Subject: RE: Noise From: "Bob Hancock" carpediem1@......... Date: Thu, 30 Nov 2006 19:18:12 -0700 Ted - At the risk of repeating questions that has already been asked - How sharp is the onset of noise - are there periods where you can see it build up and then slow down or quit, or is it like when you turn a switch on or off? Have you correlated the noise with weather conditions - such as overcast or minimal sun as opposed to bright sunny days? Bob Hancock _____ From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of tchannel Sent: Thursday, November 30, 2006 17:19 To: psn-l@.............. Subject: Re: Noise Hi Chris, You know these are great suggestions....I can't rotate the sensor, where it is located, but if I could??????? I do have another sensor I could set up and rotate. I could perhaps setup a microphone/ amp/ headset, to see if I could pick up the noise and then isolate its direction. I tried the am radio but could not hear the noise, I will try that again, at different frequencies. Ted

Ted = –

 

At the risk of repeating questions = that has already been asked –

 

How sharp is the onset of noise = – are there periods where you can see it build up and then slow down or quit, = or is it like when you turn a switch on or off?

 

Have you correlated the noise with = weather conditions – such as overcast or minimal sun as opposed to bright = sunny days?

 

Bob = Hancock

 

From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of tchannel
Sent: Thursday, November = 30, 2006 17:19
To: psn-l@..............
Subject: Re: = Noise

 

Hi Chris, You know these are great suggestions....I = can't rotate the sensor, where it is located, but if I = could???????

I do have another sensor I could set up and = rotate.  I could perhaps setup a microphone/ amp/ headset, to see if I could pick = up the noise and then isolate its direction.  I tried the am radio but = could not hear the noise, I will try that again, at different = frequencies.   Ted

 

Subject: Vertical Seismometer Design Aid From: Bobhelenmcclure@....... Date: Thu, 30 Nov 2006 21:29:13 EST Hi all, I have written a VB6 program which models a spring supported vertical seismometer. If you want to build a vertical seismometer, you must design it around the spring, since you cannot easily order a spring built to your specifications. So, if you go to a hardware store and buy a spring, measure its spring constant and calculate its relaxed length. You can then use my program to see what kind of sensor could use the spring. I am willing to send the program and illustrations to all who request them. Keep in mind that building an amateur sensor does not easily result in achieving a useful natural period of more than four or five seconds, but you can extend this using my "WQFilter" program. The application was written to satisfy my own curiosity, and is somewhat "user-surly". The program description follows: ----- Subj: Design tool for vertical seismometer, "SpringCalc.exe", version 1.0.0.8 November 2004 This program allows the user to model a spring-supported pendulum constrained to move in a vertical plane, and is a design aid for building a vertical seismometer. There are a lot of data entry boxes to fill in, as you will see. There are two boxes for characterizing the spring, two for point of attachment of the spring to the pendulum arm, one for pendulum mass, one for pendulum length, two for trial limits on spring angle, and one for the angle decrement step size. The picture, "SchematicA.gif", shows the model for the sensor. "SchematicB.gif" show an alternate configuration, where the spring is suspended downward from a boom attachment point on the other side of the boom hinge. In this case, Xp is negative, and the spring angle is greater than 180 degrees. A third configuration is shown in "SchematicC.gif", where a spring in compression pushes upward on the pendulum arm. One embodiment of this arrangement allows a leaf spring, approximately assuming a sideways "U" shape, to be used. This program assumes that such a spring is free to pivot at each end. Trial design numbers are already filled in. You can modify any of the entries using mouse and keyboard, and store them for future use. The data is stored in file "SeisData.bin". What the program does is to stretch the spring in the spring angle direction to balance the pendulum. The X, Y coordinates are the resulting upper attachment point of the spring. It then displaces the pendulum from horizontal by one degree up and down to determine the restoring torque on the pendulum, and from that information, calculates a natural period of oscillation. You will note that the restoring torque can be negative, indicating a non-stable solution. If you should want to save the displayed results, you will have to select the text with the mouse, and use Ctrl-C to copy it to the clipboard, and from there to a Notepad document. The program starts with the highest spring angle entered, and iterates downward one step angle at a time until either the lower limit, instability, or an iteration limit of 50 is reached, whichever occurs first. Note that if you specify a spring angle of 90 degrees, and put the mass at the same distance as Xp, you have the very nearly the equivalent of a mass dangling from a spring. The resulting period is what you would expect from the combination of spring constant and mass. At lesser spring angles, the period gets longer, until a limiting angle is reached, below which the pendulum is in unstable equilibrium. If you try a zero length spring for your model, you will find the tuning up of the sensor will be very easy. It gets harder as the relaxed length of the spring gets longer, and the value of "X" goes more negative (the upper spring attachment is farther behind the vertical drawn from the hinge). ---- Here are some links for amateur vertical seismometers _http://jclahr.com/science/psn/wooden/_ (http://jclahr.com/science/psn/wooden/) _http://www.jclahr.com/science/psn/mcclure/vert2.html_ (http://www.jclahr.com/science/psn/mcclure/vert2.html) _http://quake.eas.gatech.edu/Instruments/LPVERT0.htm_ (http://quake.eas.gatech.edu/Instruments/LPVERT0.htm) The late Sean-Thomas Morrissey built a force feedback sensor. The pendulum design is also suitable for open loop operation. See _http://www.eas.slu.edu/People/STMorrissey/index.html_ (http://www.eas.slu.edu/People/STMorrissey/index.html) Bob McClure bobhelenmcclure at aol dot com
Hi all,
 
  I have written a VB6 program which models a spring supported=20 vertical seismometer. If you want to build a vertical seismometer, you must=20 design it around the spring, since you cannot easily order a spring built to= =20 your specifications. So, if you go to a hardware store and buy a spring, mea= sure=20 its spring constant and calculate its relaxed length. You can then use my=20 program to see what kind of sensor could use the spring. I am willing to sen= d=20 the program and illustrations to all who request them. Keep in mind that=20 building an amateur sensor does not easily result in achieving a useful natu= ral=20 period of more than four or five seconds, but you can extend this using my=20 "WQFilter" program. The application was written to satisfy my own curiosity,= and=20 is somewhat "user-surly". The program description follows:
-----
Subj: Design tool for vertical seismometer, "SpringCalc.exe", version=20 1.0.0.8
November 2004
 
  This program allows the user to model a spring-supported pendulu= m=20 constrained to move in a vertical plane, and is a design aid for building a=20 vertical seismometer.
 
  There are a lot of data entry boxes to fill in, as you will see.= =20 There are two boxes for characterizing the spring, two for point of attachme= nt=20 of the spring to the pendulum arm, one for pendulum mass, one for pendulum=20 length, two for trial limits on spring angle, and one for the angle decremen= t=20 step size. The picture, "SchematicA.gif", shows the model for the sensor.=20 "SchematicB.gif" show an alternate configuration, where the spring is suspen= ded=20 downward from a boom attachment point on the other side of the boom hinge. I= n=20 this case, Xp is negative, and the spring angle is greater than 180 degrees.= A=20 third configuration is shown in "SchematicC.gif", where a spring in compress= ion=20 pushes upward on the pendulum arm. One embodiment of this arrangement allows= a=20 leaf spring, approximately assuming a sideways "U" shape, to be used. This=20 program assumes that such a spring is free to pivot at each end.
 
  Trial design numbers are already filled in. You can modify any o= f=20 the entries using mouse and keyboard, and store them for future use. The dat= a is=20 stored in file "SeisData.bin". What the program does is to stretch the sprin= g in=20 the spring angle direction to balance the pendulum. The X, Y coordinates are= the=20 resulting upper attachment point of the spring.  It then displaces the=20 pendulum from horizontal by one degree up and down to determine the restorin= g=20 torque on the pendulum, and from that information, calculates a natural peri= od=20 of oscillation. You will note that the restoring torque can be negative,=20 indicating a non-stable solution. If you should want to save the displayed=20 results, you will have to select the text with the mouse, and use Ctrl-C to=20= copy=20 it to the clipboard, and from there to a Notepad document. The program start= s=20 with the highest spring angle entered, and iterates downward one step angle=20= at a=20 time until either the lower limit, instability, or an iteration limit of 50=20= is=20 reached, whichever occurs first.
 
  Note that if you specify a spring angle of 90 degrees, and put t= he=20 mass at the same distance as Xp, you have the very nearly the equivalent of=20= a=20 mass dangling from a spring. The resulting period is what you would expect f= rom=20 the combination of spring constant and mass. At lesser spring angles, the pe= riod=20 gets longer, until a limiting angle is reached, below which the pendulum is=20= in=20 unstable equilibrium. 
 
  If you try a zero length spring for your model, you will find th= e=20 tuning up of the sensor will be very easy. It gets harder as the relaxed len= gth=20 of the spring gets longer, and the value of "X" goes more negative (the uppe= r=20 spring attachment is farther behind the vertical drawn from the hinge).
----
Here are some links for amateur vertical seismometers
 
http://jclahr.com/science/psn= /wooden/

http://www.jcl= ahr.com/science/psn/mcclure/vert2.html

http://quake.ea= s.gatech.edu/Instruments/LPVERT0.htm

The late Sean-Thomas Morrissey built a force feedback sensor. The=20 pendulum design is also suitable for open loop operation. See

http://www.eas= ..slu.edu/People/STMorrissey/index.html
 
 
Bob McClure 
bobhelenmcclure at aol dot=20 com
 Subject: Re: Noise From: "tchannel" tchannel@.............. Date: Thu, 30 Nov 2006 21:22:55 -0700 Hi Bob, To me the noise appears as if you turn on a light switch = on/off/on/off this goes on two mins?, other times it continues for 30 = mins?, it may then stop of 10 mins, and the whole thing start again. = Here is a funny but maybe meaningful thing. Quiet all night and at = 8:35, 8:37 sometimes as late as 8:50am the noise starts, it last about 8 = mins, stops for maybe 15 mins. No pattern except for the start time. I = also notice the hours of 1:00 pm and 2:00pm seem to have the most noise. = Like magic around 4:30 tp 5:00pm sometimes 6:00 all goes quiet. I thought it was the sun warming the house, but it does it sun or = clouds, overcast, warm or cold, week day and holidays. Tomorrow, I think I will drive around and look for road construction = equipment, maybe they are working on weekends and holidays to complete a = project. Does anyone know how close construction would need to be? = Ted ----- Original Message -----=20 From: Bob Hancock=20 To: psn-l@................. Sent: Thursday, November 30, 2006 7:18 PM Subject: RE: Noise Ted - =20 At the risk of repeating questions that has already been asked - =20 How sharp is the onset of noise - are there periods where you can see = it build up and then slow down or quit, or is it like when you turn a = switch on or off? =20 Have you correlated the noise with weather conditions - such as = overcast or minimal sun as opposed to bright sunny days? =20 Bob Hancock =20 -------------------------------------------------------------------------= ----- From: psn-l-request@.............. = [mailto:psn-l-request@............... On Behalf Of tchannel Sent: Thursday, November 30, 2006 17:19 To: psn-l@.............. Subject: Re: Noise =20 Hi Chris, You know these are great suggestions....I can't rotate the = sensor, where it is located, but if I could??????? I do have another sensor I could set up and rotate. I could perhaps = setup a microphone/ amp/ headset, to see if I could pick up the noise = and then isolate its direction. I tried the am radio but could not hear = the noise, I will try that again, at different frequencies. Ted =20
Hi Bob,  To me the noise appears = as if you=20 turn on a light switch on/off/on/off this goes on two mins?, other times = it=20 continues for 30 mins?, it may then stop of 10 mins, and the whole thing = start=20 again.  Here is a funny but maybe meaningful thing.  Quiet all = night=20 and at 8:35, 8:37 sometimes as late as 8:50am the noise starts, it last = about 8=20 mins, stops for maybe 15 mins.  No pattern except for the start = time. =20 I also notice the hours of 1:00 pm and 2:00pm seem to have the most = noise. =20 Like magic around 4:30 tp 5:00pm sometimes 6:00 all goes = quiet.
I thought it was the sun warming the = house, but it=20 does it sun or clouds, overcast, warm or cold, week day and=20 holidays.
Tomorrow, I think I will drive around = and look for=20 road construction equipment, maybe they are working on weekends and = holidays to=20 complete a project.  Does anyone know how close construction would = need to=20 be?      Ted
 
 
 
----- Original Message -----
From:=20 Bob=20 Hancock
Sent: Thursday, November 30, = 2006 7:18=20 PM
Subject: RE: Noise

Ted=20 =96

 

At the risk = of=20 repeating questions that has already been asked = =96

 

How sharp = is the=20 onset of noise =96 are there periods where you can see it build up and = then slow=20 down or quit, or is it like when you turn a switch on or=20 off?

 

Have you = correlated=20 the noise with weather conditions =96 such as overcast or minimal sun = as opposed=20 to bright sunny days?

 

Bob=20 Hancock

 

From:=20 psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of = tchannel
Sent: Thursday, November 30, = 2006=20 17:19
To: = psn-l@..............
Subject: Re:=20 Noise

 

Hi Chris, You know these = are great=20 suggestions....I can't rotate the sensor, where it is located, but if = I=20 could???????

I do have another sensor = I could=20 set up and rotate.  I could perhaps setup a microphone/ amp/ = headset, to=20 see if I could pick up the noise and then isolate its direction.  = I tried=20 the am radio but could not hear the noise, I will try that again, at = different=20 frequencies.   Ted

 

Subject: Re: Noise From: John or Jan Lahr JohnJan@........ Date: Thu, 30 Nov 2006 23:30:12 -0800 Ted, I would be helpful to see some examples of this=20 noise. Can you put an hour-long file on Larry's=20 site so that others can take a close look? Also, a photograph of your sensor would be of interest. Thanks, John At 08:22 PM 11/30/2006, you wrote: >Hi Bob, To me the noise appears as if you turn=20 >on a light switch on/off/on/off this goes on two=20 >mins?, other times it continues for 30 mins?, it=20 >may then stop of 10 mins, and the whole thing=20 >start again. Here is a funny but maybe=20 >meaningful thing. Quiet all night and at 8:35,=20 >8:37 sometimes as late as 8:50am the noise=20 >starts, it last about 8 mins, stops for maybe 15=20 >mins. No pattern except for the start time. I=20 >also notice the hours of 1:00 pm and 2:00pm seem=20 >to have the most noise. Like magic around 4:30=20 >tp 5:00pm sometimes 6:00 all goes quiet. >I thought it was the sun warming the house, but=20 >it does it sun or clouds, overcast, warm or cold, week day and holidays. >Tomorrow, I think I will drive around and look=20 >for road construction equipment, maybe they are=20 >working on weekends and holidays to complete a=20 >project. Does anyone know how close construction would need to be? = Ted > > > >----- Original Message ----- >From: Bob Hancock >To: psn-l@.............. >Sent: Thursday, November 30, 2006 7:18 PM >Subject: RE: Noise > >Ted =96 > >At the risk of repeating questions that has already been asked =96 > >How sharp is the onset of noise =96 are there=20 >periods where you can see it build up and then=20 >slow down or quit, or is it like when you turn a switch on or off? > >Have you correlated the noise with weather=20 >conditions =96 such as overcast or minimal sun as opposed to bright sunny= days? > >Bob Hancock > >---------- >From: psn-l-request@................. >[mailto:psn-l-request@............... On Behalf Of tchannel >Sent: Thursday, November 30, 2006 17:19 >To: psn-l@.............. >Subject: Re: Noise > >Hi Chris, You know these are great=20 >suggestions....I can't rotate the sensor, where=20 >it is located, but if I could??????? >I do have another sensor I could set up and=20 >rotate. I could perhaps setup a microphone/=20 >amp/ headset, to see if I could pick up the=20 >noise and then isolate its direction. I tried=20 >the am radio but could not hear the noise, I=20 >will try that again, at different frequencies. Ted > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Zero-length spring From: "Charles R. Patton" charles.r.patton@........ Date: Fri, 01 Dec 2006 08:26:43 -0800 I beg to differ. A standard open coil spring (where there is space between the coil turns) has a finite lenght with zero tension. The tension increases with stretch, but that tenssion starts wth that offset length. On the other hand a spring such as some types of screen door closer springs which are wound such that that even from the start position there is tension. If a plot of the tension vs length is done, it is possible for the tension to go through zero at an imaginary zero length, hence the term "zero length spring.." On the other hand, a clock spring such as you describe may be the reverse -- a constant force spring -- wherein at any length, it is exhibiting constant force. The only versions of these I'm aware of is a type of roll up spring where the spring is slightly crowned to give it a constant straightening force. I believe is is also called a "negator" spring. But I also believe that watch springs are in general just stand wind-up helical coils which really follow a small positive spring curve, i.e., increasing force for increasing wind-up and since it starts out too big and open, it fails the definition of a zero-lenght spring. Regards, Charles Patton ChrisAtUpw@....... wrote: > In a message dated 2006/11/30, tchannel@.............. writes: > >> I think its k that I am unclear of. > > > Hi Ted, > > 'k' is the force constant of the spring in say, pounds per inch > of stretch. This is constant until you get to very large extensions > which change the spiral. > > An example of a zero length spring is an ordinary clock spring > when you pull it along it's shaft axis. > > Regards, > > Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Zero-length spring From: "Jack Ivey" ivey@.......... Date: Fri, 1 Dec 2006 11:44:08 -0500 I think he was talking about using a clock spring in an odd manner. If you let the spring relax completely, it becomes an open spiral in a plane. If you take the outside end of the=20 spring as one end and the inside end as the other, then pull _axially_ (perpendicular to the plane of the coil, you have a weak spring that starts at zero force at=20 zero axial displacement, and goes up linearly in both the "negative" and "positive" direction. It's not constant force. Also, I'd just like to clarify that for a standard coil spring, having the coils contact when there is no external force applied (like a screen door spring) is a necessary but not sufficient condition to have a zero-length spring. Most such springs are not tightly wound enough to be=20 zero-length, (i.e. they have a positive length at=20 the extrapolated zero force). Jack -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Charles R. Patton Sent: Friday, December 01, 2006 11:27 AM To: psn-l@.............. Subject: Re: Zero-length spring I beg to differ. A standard open coil spring (where there is space=20 between the coil turns) has a finite lenght with zero tension. The=20 tension increases with stretch, but that tenssion starts wth that=20 offset length. On the other hand a spring such as some types of screen=20 door closer springs which are wound such that that even from the start=20 position there is tension. If a plot of the tension vs length is done, it is possible for the tension to go through zero at an imaginary zero=20 length, hence the term "zero length spring.."=20 On the other hand, a clock spring such as you describe may be the=20 reverse -- a constant force spring -- wherein at any length, it is=20 exhibiting constant force. The only versions of these I'm aware of is a type of roll up spring where the spring is slightly crowned to give it a constant straightening force. I believe is is also called a "negator"=20 spring. But I also believe that watch springs are in general just stand wind-up helical coils which really follow a small positive spring curve, i.e., increasing force for increasing wind-up and since it starts out=20 too big and open, it fails the definition of a zero-lenght spring. Regards, Charles Patton ChrisAtUpw@....... wrote: > In a message dated 2006/11/30, tchannel@.............. writes: > >> I think its k that I am unclear of.=20 > > > Hi Ted, > > 'k' is the force constant of the spring in say, pounds per inch > of stretch. This is constant until you get to very large extensions=20 > which change the spiral. > > An example of a zero length spring is an ordinary clock spring=20 > when you pull it along it's shaft axis. > > Regards, > > Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Zero-length spring From: "Charles R. Patton" charles.r.patton@........ Date: Fri, 01 Dec 2006 08:55:17 -0800 Apologies. I think I want to eat a few words! Since it is possible for a helical spring to be relaxed and exerting zero force at some arbitrary position, then increasing rotation is from zero and hence meets a zero-force spring definition. Although to be truthful, at the moment, I don't know how to usefully apply that to a seismometer. in particular a LaCoste. Regards, Charles Patton I beg to differ. A standard open coil spring (where there is space between the coil turns) has a finite lenght with zero tension. The tension increases with stretch, but that tenssion starts wth that offset length. On the other hand a spring such as some types of screen door closer springs which are wound such that that even from the start position there is tension. If a plot of the tension vs length is done, it is possible for the tension to go through zero at an imaginary zero length, hence the term "zero length spring.." On the other hand, a clock spring such as you describe may be the reverse -- a constant force spring -- wherein at any length, it is exhibiting constant force. The only versions of these I'm aware of is a type of roll up spring where the spring is slightly crowned to give it a constant straightening force. I believe is is also called a "negator" spring. But I also believe that watch springs are in general just stand wind-up helical coils which really follow a small positive spring curve, i.e., increasing force for increasing wind-up and since it starts out too big and open, it fails the definition of a zero-lenght spring. Regards, Charles Patton ChrisAtUpw@....... wrote: > In a message dated 2006/11/30, tchannel@.............. writes: > >> I think its k that I am unclear of. > > > Hi Ted, > > 'k' is the force constant of the spring in say, pounds per inch > of stretch. This is constant until you get to very large extensions > which change the spiral. > > An example of a zero length spring is an ordinary clock spring > when you pull it along it's shaft axis. > > Regards, > > Chris Chapman ChrisAtUpw@....... wrote: > In a message dated 2006/11/30, tchannel@.............. writes: > >> I think its k that I am unclear of. > > > Hi Ted, > > 'k' is the force constant of the spring in say, pounds per inch > of stretch. This is constant until you get to very large extensions > which change the spiral. > > An example of a zero length spring is an ordinary clock spring > when you pull it along it's shaft axis. > > Regards, > > Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Zero-length spring From: John or Jan Lahr JohnJan@........ Date: Fri, 01 Dec 2006 09:25:44 -0800 Hi Charles, I think that a spring with this configuration is what Chris was describing, and it would be a "zero-length" spring. I sent this just before Jack's message came in. It bounced back due to being too large with the image, so I've placed the sketch here: http://www.jclahr.com/science/psn/as1/heli/spring.GIF This isn't the same as the spring effect of a tape measure, where the metal tape is slightly crowned. I've modified my page on zero-length springs to emphasize Jack's point that not every spring that has coils touching when relaxed will have "zero-length." Cheers, John __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Noise From: "tchannel" tchannel@.............. Date: Fri, 1 Dec 2006 13:05:58 -0700 Hi John and Others, I have found the source of my mystery noise. How do I post a report with pictures? If I can do this on Larry's site, and that is the standard way to share pictures, would someone email me his www. so I don't send them to the wrong Larry? Thanks, Ted "Its a Happy Day"!! ----- Original Message ----- From: "John or Jan Lahr" To: Sent: Friday, December 01, 2006 12:30 AM Subject: Re: Noise Ted, I would be helpful to see some examples of this noise. Can you put an hour-long file on Larry's site so that others can take a close look? Also, a photograph of your sensor would be of interest. Thanks, John At 08:22 PM 11/30/2006, you wrote: >Hi Bob, To me the noise appears as if you turn on a light switch >on/off/on/off this goes on two mins?, other times it continues for 30 >mins?, it may then stop of 10 mins, and the whole thing start again. Here >is a funny but maybe meaningful thing. Quiet all night and at 8:35, 8:37 >sometimes as late as 8:50am the noise starts, it last about 8 mins, stops >for maybe 15 mins. No pattern except for the start time. I also notice >the hours of 1:00 pm and 2:00pm seem to have the most noise. Like magic >around 4:30 tp 5:00pm sometimes 6:00 all goes quiet. >I thought it was the sun warming the house, but it does it sun or clouds, >overcast, warm or cold, week day and holidays. >Tomorrow, I think I will drive around and look for road construction >equipment, maybe they are working on weekends and holidays to complete a >project. Does anyone know how close construction would need to be? >Ted > > > >----- Original Message ----- >From: Bob Hancock >To: psn-l@.............. >Sent: Thursday, November 30, 2006 7:18 PM >Subject: RE: Noise > >Ted - > >At the risk of repeating questions that has already been asked - > >How sharp is the onset of noise - are there periods where you can see it >build up and then slow down or quit, or is it like when you turn a switch >on or off? > >Have you correlated the noise with weather conditions - such as overcast or >minimal sun as opposed to bright sunny days? > >Bob Hancock > >---------- >From: psn-l-request@.............. [mailto:psn-l-request@............... On >Behalf Of tchannel >Sent: Thursday, November 30, 2006 17:19 >To: psn-l@.............. >Subject: Re: Noise > >Hi Chris, You know these are great suggestions....I can't rotate the >sensor, where it is located, but if I could??????? >I do have another sensor I could set up and rotate. I could perhaps setup >a microphone/ amp/ headset, to see if I could pick up the noise and then >isolate its direction. I tried the am radio but could not hear the noise, >I will try that again, at different frequencies. Ted > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Anyone seen this MS thesis: Improving a Geophone to Produce an From: apsn@........... Date: Fri, 1 Dec 2006 11:38:55 -0900 (AKST) http://micromachine.stanford.edu/smssl/projects/Geophones/DefenseBarzilaiFinalCopyWeb/DefenseBarzilaiFinalCopy.pdf Looks interesting. Bob Hammond Public Seismic Network - Alaska http://apsn.awcable.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Noise Located From: "tchannel" tchannel@.............. Date: Fri, 1 Dec 2006 13:22:43 -0700 Hi Folks, The mystery NOISE is solved! Thanks to your suggestions, I = removed the magnet assm. from the coil, of the sensor, and the noise=20 stopped. It started again when I replaced the magnet. RFI noise was=20 therefore unlikely. The spikes looked similar to when I approached the sensor and stood = next to=20 it, as it sensed my weigh on the concrete floor. During the night time=20 hours the noise was gone. It first I thought of road construction but = it=20 continue even on Sat and Sun.so I looked for other possibilities. On Thanksgiving, on our way to the in-laws, we had a road detour. I = gave=20 it no thought as I had turkey and pie on my mind. I drove back to the detour work area this morning before 8:37am to see = if=20 they had heavy equipment, like a bulldozer. I found a large backhoe used to remove old roadway, and someone already = at=20 the controls, but it was not running. I spoke to the guys, explained my = interest, and ask about their work schedule. They said they did not = work on=20 Sat and Sun. but pointed down the road to another crew and other = equipment,=20 saying they might work weekends. I thanked them and ask permission to = walk=20 down to the other crew. There I found a huge pile-driver, inactive. I talked to the crew and = asked=20 their schedule, it matched my noise. One of the guys volunteered to = call me=20 at home when they were ready to drive the next pile. The pile were iron = I-beams maybe 10" square x 24' long. The site is only 1.5 miles = Northwest from=20 my sensor. The sensor is pointing North/South and is a Lehman Horz.=20 Pendulum. When I got home I waited for the call, but could already see = some noise about 1/2 the size and shorter time durations, then my = earlier big spikes. Very similar to=20 what you would expect by digging up the road with a backhoe, but no 5 to = 30mins patterns. No call at this time, but=20 I figured the backhoe was now operating. Later, I got the call, from the second crew, they were ready to start=20 the pile-driver, as they did, the sensor started picking up the same = mystery=20 noises. I know this was a "DA!" moment. If I would place my ear to = the ground I=20 might hear something that huge. =20 I am going to print the signals and enlarge them, one each for the road=20 crew. The trace, to me is interesting, and I now can pick out which is = the=20 backhoe and which is the pile-driver. It was suggested to post a picture of this noise, on Larry's site and a=20 picture of the sensor. If I can do this I will try to include a = location=20 map and a picture of the heavy equipment. Many thanks to all of you for your help. Ted
Hi=20 Folks,   The mystery NOISE is solved!   Thanks to = your=20 suggestions, I
removed the magnet assm. from the coil, of the = sensor, and=20 the noise
stopped.  It started again when I replaced the = magnet. RFI=20 noise was
therefore unlikely.

 The spikes looked similar = to when=20 I approached the sensor and stood next to
it, as it sensed my weigh = on the=20 concrete floor.  During the night time
hours the noise was = gone. =20 It first I thought of road construction but it
continue even on Sat = and=20 Sun.so I looked for other possibilities.

  On Thanksgiving, = on our=20 way to the in-laws, we had a road detour.  I gave
it no thought = as I=20 had turkey and pie on my mind.
I drove back to the detour work area = this=20 morning before 8:37am to see if
they had heavy equipment, like a=20 bulldozer.
I found a large backhoe used to remove old roadway, and = someone=20 already at
the controls, but it was not running.  I spoke to = the guys,=20 explained my
interest, and ask about their work schedule.  They = said=20 they did not work on
Sat and Sun.  but pointed down the road to = another=20 crew and other equipment,
saying they might work weekends.  I = thanked=20 them and ask permission to walk
down to the other crew.
There I = found a=20 huge pile-driver, inactive.  I talked to the crew and asked =
their=20 schedule, it matched my noise.  One of the guys volunteered to call = me=20
at home when they were ready to drive the next pile.  The pile = were=20 iron
I-beams maybe 10" square x 24' long.  The site is only 1.5 = miles=20 Northwest from 
my sensor.  The sensor is pointing = North/South and=20 is a Lehman Horz.
Pendulum.  When I got home I waited for the = call, but=20 could  already see
some noise about 1/2 the size and shorter = time=20 durations, then my earlier big spikes.  Very similar to =
what you=20 would expect by digging up the road with a backhoe, but no 5 to 30mins = patterns.=20 No call at this time, but
I figured the backhoe was now=20 operating.

Later, I got the call, from the second crew, they were = ready=20 to start
the pile-driver, as they did, the sensor started picking up = the=20 same mystery
noises.   I know this was a "DA!" = moment.  If I=20 would place my ear to the ground I
might hear something that = huge. =20

I am going to print the signals and enlarge them, one each for = the road=20
crew.  The trace, to me is interesting, and I now can pick out = which is=20 the
backhoe and which is the pile-driver.

It was suggested to = post a=20 picture of this noise, on Larry's site and a
picture of the = sensor.  If=20 I can do this I will try to include a location
map and a picture of = the=20 heavy equipment.

Many thanks to all of you for your help. =20 Ted
Subject: Re: Noise Located From: "Jerry Payton" gpayton880@....... Date: Fri, 1 Dec 2006 14:38:35 -0600 SUPER job Ted. Congratulations and thanks for sharing your mystery, methods for solving and source to EVERYONE. We can all benefit. Regards, Jerry Payton ----- Original Message ----- From: tchannel To: psn-l@.............. Sent: Friday, December 01, 2006 2:22 PM Subject: Noise Located Hi Folks, The mystery NOISE is solved! Thanks to your suggestions, I removed the magnet assm. from the coil, of the sensor, and the noise stopped. It started again when I replaced the magnet. RFI noise was therefore unlikely. The spikes looked similar to when I approached the sensor and stood next to it, as it sensed my weigh on the concrete floor. During the night time hours the noise was gone. It first I thought of road construction but it continue even on Sat and Sun.so I looked for other possibilities. On Thanksgiving, on our way to the in-laws, we had a road detour. I gave it no thought as I had turkey and pie on my mind. I drove back to the detour work area this morning before 8:37am to see if they had heavy equipment, like a bulldozer. I found a large backhoe used to remove old roadway, and someone already at the controls, but it was not running. I spoke to the guys, explained my interest, and ask about their work schedule. They said they did not work on Sat and Sun. but pointed down the road to another crew and other equipment, saying they might work weekends. I thanked them and ask permission to walk down to the other crew. There I found a huge pile-driver, inactive. I talked to the crew and asked their schedule, it matched my noise. One of the guys volunteered to call me at home when they were ready to drive the next pile. The pile were iron I-beams maybe 10" square x 24' long. The site is only 1.5 miles Northwest from my sensor. The sensor is pointing North/South and is a Lehman Horz. Pendulum. When I got home I waited for the call, but could already see some noise about 1/2 the size and shorter time durations, then my earlier big spikes. Very similar to what you would expect by digging up the road with a backhoe, but no 5 to 30mins patterns. No call at this time, but I figured the backhoe was now operating. Later, I got the call, from the second crew, they were ready to start the pile-driver, as they did, the sensor started picking up the same mystery noises. I know this was a "DA!" moment. If I would place my ear to the ground I might hear something that huge. I am going to print the signals and enlarge them, one each for the road crew. The trace, to me is interesting, and I now can pick out which is the backhoe and which is the pile-driver. It was suggested to post a picture of this noise, on Larry's site and a picture of the sensor. If I can do this I will try to include a location map and a picture of the heavy equipment. Many thanks to all of you for your help. Ted
SUPER job Ted.  Congratulations and thanks for sharing your = mystery,=20 methods for solving and source to EVERYONE.  We can all = benefit.
 
Regards,
Jerry Payton
 
----- Original Message -----
From:=20 tchannel
Sent: Friday, December 01, 2006 = 2:22=20 PM
Subject: Noise Located

Hi=20 Folks,   The mystery NOISE is solved!   Thanks to = your=20 suggestions, I
removed the magnet assm. from the coil, of the = sensor, and=20 the noise
stopped.  It started again when I replaced the = magnet. RFI=20 noise was
therefore unlikely.

 The spikes looked = similar to=20 when I approached the sensor and stood next to
it, as it sensed my = weigh=20 on the concrete floor.  During the night time
hours the noise = was=20 gone.  It first I thought of road construction but it =
continue even=20 on Sat and Sun.so I looked for other possibilities.

  On=20 Thanksgiving, on our way to the in-laws, we had a road detour.  I = gave=20
it no thought as I had turkey and pie on my mind.
I drove back = to the=20 detour work area this morning before 8:37am to see if
they had = heavy=20 equipment, like a bulldozer.
I found a large backhoe used to remove = old=20 roadway, and someone already at
the controls, but it was not=20 running.  I spoke to the guys, explained my
interest, and ask = about=20 their work schedule.  They said they did not work on
Sat and=20 Sun.  but pointed down the road to another crew and other = equipment,=20
saying they might work weekends.  I thanked them and ask = permission=20 to walk
down to the other crew.
There I found a huge = pile-driver,=20 inactive.  I talked to the crew and asked
their schedule, it = matched=20 my noise.  One of the guys volunteered to call me
at home = when they=20 were ready to drive the next pile.  The pile were iron =
I-beams maybe=20 10" square x 24' long.  The site is only 1.5 miles Northwest=20 from 
my sensor.  The sensor is pointing North/South and = is a=20 Lehman Horz.
Pendulum.  When I got home I waited for the = call, but=20 could  already see
some noise about 1/2 the size and shorter = time=20 durations, then my earlier big spikes.  Very similar to =
what you=20 would expect by digging up the road with a backhoe, but no 5 to 30mins = patterns. No call at this time, but
I figured the backhoe was now=20 operating.

Later, I got the call, from the second crew, they = were ready=20 to start
the pile-driver, as they did, the sensor started picking = up the=20 same mystery
noises.   I know this was a "DA!" = moment.  If=20 I would place my ear to the ground I
might hear something that = huge. =20

I am going to print the signals and enlarge them, one each for = the=20 road
crew.  The trace, to me is interesting, and I now can = pick out=20 which is the
backhoe and which is the pile-driver.

It was = suggested=20 to post a picture of this noise, on Larry's site and a
picture of = the=20 sensor.  If I can do this I will try to include a location =
map and a=20 picture of the heavy equipment.

Many thanks to all of you for = your=20 help.  Ted
Subject: Re: Anyone seen this MS thesis: Improving a Geophone From: ChrisAtUpw@....... Date: Fri, 1 Dec 2006 16:50:24 EST In a message dated 2006/12/01, apsn@........... writes: > > http://micromachine.stanford.edu/smssl/projects/Geophones/DefenseBarzilaiFinalCopyWeb/DefenseBarzilaiFinalCopy.pdf > Looks interesting. Hi Bob, This has been around for ages. I would give him high marks for effort. I wish that I could be equally enthusiastic about the modifications themselves, or about his circuitry. The VLF noise level is high, but he does not seem to have addressed this, or cured it. Regards, Chris Chapman In a me= ssage dated 2006/12/01, apsn@........... writes:

http://micromachine.stanford.ed= u/smssl/projects/Geophones/DefenseBarzilaiFinalCopyWeb/DefenseBarzilaiFinalC= opy.pdf
Looks interesting.


Hi Bob,

       This has been around for ages.

       I would give him high marks for effort.=
       I wish that I could be equally enthusia= stic about the modifications themselves, or about his circuitry.
       The VLF noise level is high, but he doe= s not seem to have addressed this, or cured it.

       Regards,

       Chris Chapman Subject: RE: Zero-length spring From: "Coleman, Allan" allan.coleman@............ Date: Fri, 1 Dec 2006 14:08:21 -0800 Searching for information regarding LaCoste "zero length" springs a year = or two ago; I came across the following documents, which may be of some = use during this current discussion. =20 You will need to retrieve two patents. These patents are accessible as = PDFs through a free patent search web site like Free Patents Online; = however, you need to create an account, for free. Go to: http://www.freepatentsonline.com/index.html =20 LaCoste (1942) Patent 2293437: This patent illustrates a variety of different types of zero lengths = springs, including both helical tension and spiral springs. A lot of = food for thought for amteur instrument builders! Willmore (1966) Patent 3292145: This patent covers the design of a tapered leaf spring. Patent was cited = in the BSSA 1982 article describing the STS-1 Seismometer. I made a curved tapered leaf spring, cut out of a flat tempered steel = plastering knife using an abrasive cutting disc mounted in a Dremel = tool. Hand formed (curved) the metal leaf spring by partially wrapping = it around a metal bar clamped in a rigid bench vice. Spring later used = to develop a 4-5 second natural period vertical seismometer, with = feedback for closed loop period extension. If you are interested in how LaCoste and Romberg make their zero length = tension springs, download the following 3 meg PDF from: http://www.gravitymeter-repair.com/images/gdmanual.pdf It's the LaCoste and Romberg Instruction Manual for the model G & D = Gravity Meters. Starting at page 4-44, under PHYSICS OF THE SENSOR, = there are 4 pages of information. Regards, Allan -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of John or Jan Lahr Sent: Friday, December 01, 2006 9:26 AM To: psn-l@.............. Subject: Re: Zero-length spring Hi Charles, I think that a spring with this configuration is what Chris was=20 describing, and it would be a "zero-length" spring. I sent this just before Jack's message came in. It bounced back due=20 to being too large with the image, so I've placed the sketch here: http://www.jclahr.com/science/psn/as1/heli/spring.GIF This isn't the same as the spring effect of a tape measure, where the=20 metal tape is slightly crowned. I've modified my page on zero-length springs to emphasize Jack's=20 point that not every spring that has coils touching when relaxed will=20 have "zero-length." Cheers, John __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Anyone seen this MS thesis: Improving a Geophone From: apsn@........... Date: Fri, 1 Dec 2006 16:13:14 -0900 (AKST) Chris, I should have known PSNers had seen this before. I'll see if I can't find something new and post that! LOL. Bob > Hi Bob, > > This has been around for ages. > > I would give him high marks for effort. > I wish that I could be equally enthusiastic about the > modifications > themselves, or about his circuitry. > The VLF noise level is high, but he does not seem to have > addressed > this, or cured it. > > Regards, > > Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Anyone seen this MS thesis: Improving a Geophone From: Larry Cochrane lcochrane@.............. Date: Fri, 01 Dec 2006 23:07:54 -0800 Hi Everyone, This is what Sean-Thomas wrote about using a 4.5Hz geophone as a broadband sensor: "I have been experimenting for several years with making almost any seismometer into a VBB sensor if the physical parameters are suitable, like the coil resistance. THe largest is a WWNSS LP (15 second T0 and 11 kg mass) vertical that I am running at 600 seconds. As you may have gathered, the small geophones have been an attraction. I have been experimenting for about two years with making the 4.5 hz HS-1 (by Geospace, but similar to the GSC-11d and the Mark Products L-15B) into a broadband instrument. I use the VRDT displacement sensor mounted externally above the case, with the sensing vane attached to the upper mass ring. With VBB parameters set for 20 seconds and the proper coil resistance, the VBB output is 750 volts/meter/second and the calibrations fit the transfer functions. But the data is to noisy for a sensitive broadband sensor, and I am usually barely able to see the normal 6-second microseism background of 1 to 2 microns/second. Of course these were very clear (~10x) when hurricane Bonnie passed last August. I also made a nice record (from St. Louis) of the Ohio quake in September, with peak velocities of Lg of about 10 microns/second at about 8 seconds. The trouble with the 4.5hz phone is that the mass is only 23 grams, and the intrinsic damping of 0.28 means that the Q is not very high. From the Riedesel paper this would be expected to have a Brownian noise power spectral density (PSD) level of about -165db (figure 12). (For reference, the USGS low noise model has the 6-second microseism peak at about -140db, the 12-second peak at -160db, and the quiet earth minimum between 40 and 200 seconds is about -185 db.) But the Brownian noise is only one of many noise sources; the circular suspension leaf springs and the fine-wire signal output leads are significant contributors. The Reidesel paper finds that when using the velocity signal coil and a properly selected amplifier, the noise level is -130db at 1 hz, and the 6-second microseisms cannot be seen. We can do much better with a VBB fedback configuration. The PSD of several noise samples was about -145db at 6 seconds, but levels off at about -155db at 10 seconds. It has trouble recording teleseisms compared with a larger VBB seis, like a Mb5.O west of Mexico or a 6.2 in China, where the 20-second surface waves were only about 2X the noise. It did make a reasonable record of a Ms 6.0 in the Queen Charlotte Islands (51N,130W). It may be possible to reduce the suspension noise, and I have a new geophone to modify with great care to try to minimize it. Other problems are with the thermal sensitivity of the mass position and suspension resonances within the high-frequency portion of the VBB passband. THe manufacturers are mum on these; the most notorious are the resonances of the 1-hz L4-C at 16 and 22 hz. The mass position change with temperature is a "don't care" for a velocity sensor, but it causes problems with a displacement output of 250 millivolts/micron, even with reasonable VBB loop gains." Regards, Larry Cochrane Redwood City, PSN > In a message dated 2006/12/01, apsn@........... writes: > >> http://micromachine.stanford.edu/smssl/projects/Geophones/DefenseBarzilaiFinalCopyWeb/DefenseBarzilaiFinalCopy.pdf >> Looks interesting. > > > Hi Bob, > > This has been around for ages. > > I would give him high marks for effort. > I wish that I could be equally enthusiastic about the > modifications themselves, or about his circuitry. > The VLF noise level is high, but he does not seem to have > addressed this, or cured it. > > Regards, > > Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Zero-length spring From: "chief.cook.nz" chief.cook.nz@............ Date: Sun, 03 Dec 2006 03:30:16 +1300 Hi John In this formula a NEWTON is what? or how or why is called a NEWTON the rest I understand so a NEWTON:- = Cheers Tamati From the Castle of Tamati, Hinemoa and Karauwa the Dog From the Castle of Tom, Robyn and the Dog I'm Just a Stone's Throw Away:- NZ-021-150-33-59 or NZ-07-855-0195 Bush Telegragh:- chief.cook.nz@............ My Regular Pitstop:- Tamati P.O.BOX 19-356 CENTRAL HAMILTON NEW ZEALAND ----- Original Message ----- From: "John or Jan Lahr" To: Sent: Thursday, November 30, 2006 8:20 PM Subject: Re: Zero-length spring > At 10:29 PM 11/29/2006, you wrote: >>Hi John, I am not too good at math, could you please plug-in some >>examples/numbers for this formula so I can understand it better? I think >>its k that I am unclear of. I understand the rest. Thanks, Ted >>MgA = kSY/(SA) >> >>M = kY/(Ag) > > k is the spring constant. In this example I'm using k = 2 newtons/cm > > M is the mass > Y is the height of the mast > A is the length of the boom > g is the acceleration of gravity > > The exact numbers don't really matter - the point being that the mass will > be stable at any angle of the boom. > > There are problems of trying to actually build this device, because slight > changes in k with temperature will cause instability. Even without a > zero-length spring, one can extend the period by reducing the height of > the mast. However, you will soon discover that this will also lead to > instability if pushed to too long a period. > > Cheers, > John > > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with the body of the > message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Zero-length spring From: "Jerry Payton" gpayton880@....... Date: Sat, 2 Dec 2006 08:50:38 -0600 Try the Wikipedia for a definition: http://en.wikipedia.org/wiki/Newton Of course, John can answer too. Best Wishes, Jerry Payton ----- Original Message ----- From: chief.cook.nz To: psn-l@.............. Sent: Saturday, December 02, 2006 8:30 AM Subject: Re: Zero-length spring Hi John In this formula a NEWTON is what? or how or why is called a NEWTON the rest I understand so a NEWTON:- = Cheers Tamati From the Castle of Tamati, Hinemoa and Karauwa the Dog From the Castle of Tom, Robyn and the Dog I'm Just a Stone's Throw Away:- NZ-021-150-33-59 or NZ-07-855-0195 Bush Telegragh:- chief.cook.nz@............ My Regular Pitstop:- Tamati P.O.BOX 19-356 CENTRAL HAMILTON NEW ZEALAND ----- Original Message ----- From: "John or Jan Lahr" To: Sent: Thursday, November 30, 2006 8:20 PM Subject: Re: Zero-length spring > At 10:29 PM 11/29/2006, you wrote: >>Hi John, I am not too good at math, could you please plug-in some >>examples/numbers for this formula so I can understand it better? I think >>its k that I am unclear of. I understand the rest. Thanks, Ted >>MgA = kSY/(SA) >> >>M = kY/(Ag) > > k is the spring constant. In this example I'm using k = 2 newtons/cm > > M is the mass > Y is the height of the mast > A is the length of the boom > g is the acceleration of gravity > > The exact numbers don't really matter - the point being that the mass will > be stable at any angle of the boom. > > There are problems of trying to actually build this device, because slight > changes in k with temperature will cause instability. Even without a > zero-length spring, one can extend the period by reducing the height of > the mast. However, you will soon discover that this will also lead to > instability if pushed to too long a period. > > Cheers, > John > > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with the body of the > message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) To leave this list email PSN-L-REQUEST@.............. with the body of the message (first line only): unsubscribe See http://www.seismicnet.com/maillist.html for more information.
Try the Wikipedia for a definition:   http://en.wikipedia.org/wiki= /Newton Of=20 course, John can answer too.
 
Best Wishes,
Jerry Payton
----- Original Message -----
From:=20 chief.cook.nz
Sent: Saturday, December 02, = 2006 8:30=20 AM
Subject: Re: Zero-length = spring

Hi John
In this formula a NEWTON is what?  or = how or=20 why is called a NEWTON the rest
I understand so a

NEWTON:-=20 =3D

Cheers Tamati
From the Castle of Tamati, Hinemoa and = Karauwa the=20 Dog
From the Castle of Tom, Robyn and the Dog

I'm Just a = Stone's=20 Throw Away:- NZ-021-150-33-59 or=20 = NZ-07-855-0195
         &= nbsp;           &n= bsp;       =20 Bush Telegragh:- chief.cook.nz@............=
           &nb= sp;          =20 My Regular Pitstop:-=20 = Tamati
          &nb= sp;           &nbs= p;            = ;            =             &= nbsp;     =20 P.O.BOX
19-356=20 = CENTRAL
          &n= bsp;           &nb= sp;           &nbs= p;            = ;            =       =20 = HAMILTON
          &= nbsp;           &n= bsp;           &nb= sp;           &nbs= p;            = ;      =20 NEW
ZEALAND
----- Original Message -----
From: "John or Jan = Lahr"=20 <JohnJan@........>
To: <psn-l@..............>
Sent= :=20 Thursday, November 30, 2006 8:20 PM
Subject: Re: Zero-length=20 spring


> At 10:29 PM 11/29/2006, you = wrote:
>>Hi=20 John,  I am not too good at math, could you please plug-in some=20
>>examples/numbers for this formula so I can understand it = better? I=20 think
>>its k that I am unclear of.  I understand the = rest.=20 Thanks, Ted
>>MgA =3D kSY/(SA)
>>
>>M =3D=20 kY/(Ag)
>
> k is the spring constant.  In this = example I'm=20 using k =3D 2 newtons/cm
>
> M is the mass
> Y is = the height=20 of the mast
> A is the length of the boom
> g is the = acceleration=20 of gravity
>
> The exact numbers don't really matter - the = point=20 being that the mass will
> be stable at any angle of the=20 boom.
>
> There are problems of trying to actually build = this=20 device, because slight
> changes in k with temperature will = cause=20 instability.  Even without a
> zero-length spring, one can = extend=20 the period by reducing the height of
> the mast.  However, = you will=20 soon discover that this will also lead to
> instability if = pushed to=20 too long a period.
>
> Cheers,
>=20 John
>
>
>
>=20 = __________________________________________________________
>
>= ;=20 Public Seismic Network Mailing List (PSN-L)
>
> To leave = this list=20 email PSN-L-REQUEST@............... =20 with the body of the
> message (first line only): = unsubscribe
>=20 See http://www.seismicnet.co= m/maillist.html=20 for more information.=20 =

__________________________________________________________
Public=20 Seismic Network Mailing List (PSN-L)

To leave this list email = PSN-L-REQUEST@............... =20 with
the body of the message (first line only): unsubscribe
See = http://www.seismicnet.co= m/maillist.html=20 for more information.
Subject: Re: Zero-length spring From: John or Jan Lahr JohnJan@........ Date: Sat, 02 Dec 2006 08:25:43 -0800 Thanks, Jerry. A Newton is a unit of force. One Newton is approximately the attractive force between a 3.6 ounce object and the Earth at the surface of the earth. An ounce is technically a unit of mass, not a unit of force. An ounce of material is still an ounce whether it's located near the surface of the Earth or on the surface of the Moon. The attractive force between an ounce of material at the Earth's surface and the earth (the weight as measured on a scale) is called an ounce-force. Hope this helps! Cheers, John At 06:50 AM 12/2/2006, you wrote: >Try the Wikipedia for a >definition: >http://en.wikipedia.org/wiki/Newton >Of course, John can answer too. > >Best Wishes, >Jerry Payton >----- Original Message ----- >From: chief.cook.nz >To: psn-l@.............. >Sent: Saturday, December 02, 2006 8:30 AM >Subject: Re: Zero-length spring > >Hi John >In this formula a NEWTON is what? or how or why is called a NEWTON the rest >I understand so a > >NEWTON:- = > >Cheers Tamati > From the Castle of Tamati, Hinemoa and Karauwa the Dog > From the Castle of Tom, Robyn and the Dog > >I'm Just a Stone's Throw Away:- NZ-021-150-33-59 or NZ-07-855-0195 > Bush Telegragh:- > chief.cook.nz@............ > My Regular Pitstop:- Tamati > P.O.BOX >19-356 CENTRAL > HAMILTON > NEW >ZEALAND >----- Original Message ----- >From: "John or Jan Lahr" <JohnJan@........> >To: <psn-l@..............> >Sent: Thursday, November 30, 2006 8:20 PM >Subject: Re: Zero-length spring > > > > At 10:29 PM 11/29/2006, you wrote: > >>Hi John, I am not too good at math, could you please plug-in some > >>examples/numbers for this formula so I can understand it better? I think > >>its k that I am unclear of. I understand the rest. Thanks, Ted > >>MgA = kSY/(SA) > >> > >>M = kY/(Ag) > > > > k is the spring constant. In this example I'm using k = 2 newtons/cm > > > > M is the mass > > Y is the height of the mast > > A is the length of the boom > > g is the acceleration of gravity > > > > The exact numbers don't really matter - the point being that the mass will > > be stable at any angle of the boom. > > > > There are problems of trying to actually build this device, because slight > > changes in k with temperature will cause instability. Even without a > > zero-length spring, one can extend the period by reducing the height of > > the mast. However, you will soon discover that this will also lead to > > instability if pushed to too long a period. > > > > Cheers, > > John > > > > > > > > __________________________________________________________ > > > > Public Seismic Network Mailing List (PSN-L) > > > > To leave this list email > PSN-L-REQUEST@.............. > with the body of the > > message (first line only): unsubscribe > > See > http://www.seismicnet.com/maillist.html > for more information. > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email >PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See >http://www.seismicnet.com/maillist.html >for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Anyone seen this MS thesis: Improving a Geophone From: ChrisAtUpw@....... Date: Sat, 2 Dec 2006 14:38:03 EST In a message dated 2006/12/02, lcochrane@.............. writes: > Subj:Re: MS thesis: Improving a Geophone Hi All, Before reading the article below, I suggest that you visit Lennartz GMBH at http://www.lennartz-electronic.de/MamboV4.5.2/index.php They have three very successful seismic sensor lines from 40 Hz down to 1 sec, to 5 sec, and to 20 sec periods. The sensors themselves are of about 2 Hz with various types of period extension. A response flat with velocity, from 40 Hz down to 20 sec period is broad band. The 5 sec response sensors are popular, since they cover teleseismic P and S waves. Very low noise amplifiers are required. In general, a geophone type sensor may be extended to 1/10 of it's natural period, usually without problems. Getting any more out of it may be 'hard work'. It may be desireable in some cases to limit the high frequency response to 20, or even 10 Hz. It is not clear if Sean was aware of the techniques used by Lennartz. However, he used an additional in line LRDT where Barzilai used a capacitative sensor. > Hi Everyone, > > This is what Sean-Thomas wrote about using a 4.5Hz geophone as a broadband > sensor: > > "I have been experimenting for several years with making almost any > seismometer into a VBB sensor if the physical parameters are suitable, > like the coil resistance. THe largest is a WWNSS LP (15 second T0 and > 11 kg mass) vertical that I am running at 600 seconds. > > As you may have gathered, the small geophones have been an attraction. > I have been experimenting for about two years with making the 4.5 hz HS-1 > (by Geospace, but similar to the GSC-11d and the Mark Products L-15B) > into a broadband instrument. I use the VRDT displacement sensor mounted > externally above the case, with the sensing vane attached to the upper > mass ring. With VBB parameters set for 20 seconds and the proper coil > resistance, the VBB output is 750 volts/meter/second and the calibrations > fit the transfer functions. > > But the data is too noisy for a sensitive broadband sensor, and I am usually > barely able to see the normal 6-second microseism background of 1 to 2 > microns/second. Of course these were very clear (~10x) when hurricane > Bonnie passed last August. I also made a nice record (from St. Louis) > of the Ohio quake in September, with peak velocities of Lg of about 10 > microns/second at about 8 seconds. NB. Sean didn't say what were the sources of this noise. An unsealed vertical geophone will be sensitive to atmospheric density changes, wind noise etc. Also, his remarks apply to broad band use, not to limited period extension. > The trouble with the 4.5hz phone is that the mass is only 23 grams, and > the intrinsic damping of 0.28 means that the Q is not very high. > From the Riedesel paper this would be expected to have a Brownian noise > power spectral density (PSD) level of about -165db (figure 12). (For > reference, the USGS low noise model has the 6-second microseism peak > at about -140db, the 12-second peak at -160db, and the quiet earth minimum > between 40 and 200 seconds is about -185 db.) But the Brownian noise > is only one of many noise sources; the circular suspension leaf springs > and the fine-wire signal output leads are significant contributors. > The Reidesel paper finds that when using the velocity signal coil and > a properly selected amplifier, the noise level is -130db at 1 hz, and > the 6-second microseisms cannot be seen. We can do much better with a > VBB fedback configuration. Quite a lot better! > The PSD of several noise samples was about -145db at 6 seconds, but > levels off at about -155db at 10 seconds. It has trouble recording > teleseisms compared with a larger VBB seis, like a Mb5.O west of Mexico > or a 6.2 in China, where the 20-second surface waves were only about > 2X the noise. It did make a reasonable record of a Ms 6.0 in the Queen > Charlotte Islands (51N,130W). > > It may be possible to reduce the suspension noise, and I have a new > geophone to modify with great care to try to minimize it. Other > problems are with the thermal sensitivity of the mass position and > suspension resonances within the high-frequency portion of the VBB > passband. The manufacturers are mum on these; the most notorious are > the resonances of the 1-hz L4-C at 16 and 22 hz. The mass position change > with temperature is a "don't care" for a velocity sensor, but it causes > problems with a displacement output of 250 millivolts/micron, even with > reasonable VBB loop gains." > > Regards, > Larry Cochrane > Redwood City, PSN > > > In a message dated 2006/12/01, apsn@........... writes: > > > > http://micromachine.stanford.edu/smssl/projects/Geophones/DefenseBarzilaiFinalCopyWeb/DefenseBarzilaiFinalCopy.pdf> > > > > Hi Bob, > > This has been around for ages. > > I would give him high marks for effort. > > I wish that I could be equally enthusiastic about the > > modifications themselves, or about his circuitry. > > The VLF noise level is high, but he does not seem to have > > addressed this, or cured it. > > Regards, > > Chris Chapman Let us turn the question around from what we CAN'T do with a 4.5 Hz geophone, TO what we can FAIRLY EASILY DO to improve it's UTILITY + PERFORMANCE for Amateur Seismic Work? The response of a 4.5 Hz geophone is down to 1/5 at 2 Hz and it falls off rapidly below this, but this may be of use for local or volcanic quakes. However, extending a 4.5 Hz geophone's response to 1/10 of it's natural frequency (0.45 Hz) just conveniently covers most of the frequencies of interest for teleseismic P and S waves. There are three ways of doing this. You can increase your main amplifier gain by x100 and process the digital signals in software. This reduces your dynamic range by the same factor and the full period compensation will fail for small signals (may not be too important). You can add a x100 VLF boost amplifier to compensate for the f^2 roll off of the geophone characteristic below it's resonant frequency. This amplifier needs to be low noise and the compensation needs to be done in two stages to maintain the gain through the corner frequency. If you don't do this, you get zero output at 4.5 Hz, instead of the full signal. See Roberts at http://psn.quake.net/bibliography.html I modified Roberts' circuit to remove most of the excess VLF noise that he experienced. The 4.5 Hz modules are available commercially - see www.sara.pg.it You can fit the geophone with a negative input impedance pre amplifier, which converts the 'dog leg' f^2 + the flat geophone responces into a much smaller straight line response proportional to f. You then put this through a low frequency bandpass filter set at your minimum frequency of interest. See the ARRL radio handbook. This removes the slope :f and you then amplify / filter the signal further. However, this does need an extremely low noise and specialised first amplifier. See http://www.lennartz-electronic.de/MamboV4.5.2/index.php?option=com_remository&Itemid=45&func=download&filecatid=3& chk=bc273996d12702c9fc96b4f638492797 See also http://www.vaxman.de/publications/teach_gp.pdf You can download a general filter design program and application notes free from http://www.ti.com/litv/zip/slvc108f Regards, Chris Chapman In a me= ssage dated 2006/12/02, lcochrane@.............. writes:

Subj:Re: MS thesis: Improvin= g a Geophone


Hi All,

       Before reading the article below, I sug= gest that you visit Lennartz GMBH at http://www.lennartz-electronic.de/Mambo= V4.5.2/index.php
    They have three very successful seismic sensor lines fro= m 40 Hz down to 1 sec, to 5 sec, and to 20 sec periods. The sensors themselv= es are of about 2 Hz with various types of period extension.

    A response flat with velocity, from 40 Hz down to 20 sec=20= period is broad band. The 5 sec response sensors are popular, since they cov= er teleseismic P and S waves. Very low noise amplifiers are required.

    In general, a geophone type sensor may be extended to 1/1= 0 of it's natural period, usually without problems. Getting any more out of=20= it may be 'hard work'. It may be desireable in some cases to limit the high=20= frequency response to 20, or even 10 Hz.

    It is not clear if Sean was aware of the techniques used=20= by Lennartz. However, he used an additional in line LRDT where Barzilai used= a capacitative sensor.

Hi Everyone,

This is what Sean-Thomas wrote about using a 4.5Hz geophone as a broadband s= ensor:

"I have been experimenting for several years with making almost any
seismometer into a VBB sensor if the physical parameters are suitable,
like the coil resistance. THe largest is a WWNSS LP (15 second T0 and
11 kg mass) vertical that I am running at 600 seconds.

As you may have gathered, the small geophones have been an attraction.
I have been experimenting for about two years with making the 4.5 hz HS-1 (by Geospace, but similar to the GSC-11d and the Mark Products L-15B)
into a broadband instrument. I use the VRDT displacement sensor mounted
externally above the case, with the sensing vane attached to the upper
mass ring.  With VBB parameters set for 20 seconds and the proper coil<= BR> resistance, the VBB output is 750 volts/meter/second and the calibrations fit the transfer functions.

But the data is too noisy for a sensitive broadband sensor, and I am usually=
barely able to see the normal 6-second microseism background of 1 to 2
microns/second. Of course these were very clear (~10x) when hurricane
Bonnie passed last August. I also made a nice record  (from St. Louis)<= BR> of the Ohio quake in September, with peak velocities of Lg of about 10
microns/second at about 8 seconds.


       NB. Sean didn't say what were the sour= ces of this noise. An unsealed vertical geophone will be sensitive to atmosp= heric density changes, wind noise etc. Also, his remarks apply to broad band= use, not to limited period extension.

The trouble with the 4.5hz phon= e is that the mass is only 23 grams, and
the intrinsic damping of 0.28 means that the Q is not very high.
From the Riedesel paper this would be expected to have a Brownian noise
power spectral density (PSD) level of about -165db (figure 12). (For
reference, the USGS low noise model has the 6-second microseism peak
at about -140db, the 12-second peak at -160db, and the quiet earth minimum between 40 and 200 seconds is about -185 db.) But the Brownian noise
is only one of many noise sources; the circular suspension leaf springs
and the fine-wire signal output leads are significant contributors.
The Reidesel paper finds that when using the velocity signal coil and
a properly selected amplifier, the noise level is -130db at 1 hz, and
the 6-second microseisms cannot be seen. We can do much better with a
VBB fedback configuration.


       Quite a lot better!

The PSD of several noise sample= s was about -145db at 6 seconds, but
levels off at about -155db at 10 seconds. It has trouble recording
teleseisms compared with a larger VBB seis, like a Mb5.O west of Mexico
or a 6.2 in China, where the 20-second surface waves were only about
2X the noise. It did make a reasonable record of a Ms 6.0 in the Queen
Charlotte Islands (51N,130W).

It may be possible to reduce the suspension noise, and I have a new
geophone to modify with great care to try to minimize it. Other
problems are with the thermal sensitivity of the mass position and
suspension resonances within the high-frequency portion of the VBB
passband. The manufacturers are mum on these; the most notorious are
the resonances of the 1-hz L4-C at 16 and 22 hz. The mass position change with temperature is a "don't care" for a velocity sensor, but it causes
problems with a displacement output of 250 millivolts/micron, even with
reasonable VBB loop gains."

Regards,
Larry Cochrane
Redwood City, PSN

>    In a message dated 2006/12/01, apsn@........... write= s:
>
http://micromachine.stanford.edu/smssl/projects/Geophones/DefenseBarzilaiFi= nalCopyWeb/DefenseBarzilaiFinalCopy.pdf>
>
> Hi Bob,
>        This has been around for ages= ..
>        I would give him high marks f= or effort.
>        I wish that I could be equall= y enthusiastic about the
> modifications themselves, or about his circuitry.
>        The VLF noise level is high,=20= but he does not seem to have
> addressed this, or cured it.
>        Regards,
>        Chris Chapman

       Let us turn the question around fro= m what we CAN'T do with a 4.5 Hz geophone,
       TO what we can FAIRLY EASILY DO to impr= ove it's UTILITY + PERFORMANCE for Amateur Seismic Work?

       The response of a 4.5 Hz geophone is do= wn to 1/5 at 2 Hz and it falls off rapidly below this, but this may be of us= e for local or volcanic quakes.
       However, extending a 4.5 Hz geophone's=20= response to 1/10 of it's natural frequency (0.45 Hz) just conveniently cover= s most of the frequencies of interest for teleseismic P and S waves. There a= re three ways of doing this.

       You can increase your main amplifier ga= in by x100 and process the digital signals in software. This reduces your dy= namic range by the same factor and the full period compensation will fail fo= r small signals (may not be too important).

       You can add a x100 VLF boost amplifier=20= to compensate for the f^2 roll off of the geophone characteristic below it's= resonant frequency. This amplifier needs to be low noise and the compensati= on needs to be done in two stages to maintain the gain through the corner fr= equency. If you don't do this, you get zero output at 4.5 Hz, instead of the= full signal. See Roberts at http://psn.quake.net/bibliography.html I modifi= ed Roberts' circuit to remove most of the excess VLF noise that he experienc= ed. The 4.5 Hz modules are available commercially - see www.sara.pg.it

       You can fit the geophone with a negativ= e input impedance pre amplifier, which converts the 'dog leg' f^2 + the flat= geophone responces into a much smaller straight line response proportional=20= to f. You then put this through a low frequency bandpass filter set at your=20= minimum frequency of interest. See the ARRL radio handbook. This removes the= slope :f and you then amplify / filter the signal further. However, this do= es need an extremely low noise and specialised first amplifier. See http://w= ww.lennartz-electronic.de/MamboV4.5.2/index.php?option=3Dcom_remository&= Itemid=3D45&func=3Ddownload&filecatid=3D3&chk=3Dbc273996d12702c9= fc96b4f638492797
       See also http://www.vaxman.de/publicati= ons/teach_gp.pdf

       You can download a general filter desig= n program and application notes free from http://www.ti.com/litv/zip/slvc108= f

       Regards,

       Chris Chapman Subject: Technicial Terms From: "Jerry Payton" gpayton880@....... Date: Sun, 3 Dec 2006 10:40:59 -0600 Oooops. Another technical term that I am not familiar with has popped up: EIGENFREQUENCY. Is that synonymous with "natural period" (for our purposes)? Thanks, Jerry Payton
Oooops.  Another technical term that I am not familiar with = has popped=20 up: EIGENFREQUENCY.  Is that synonymous with "natural period" (for = our=20 purposes)?
 
Thanks,
Jerry Payton
Subject: Re: Technicial Terms From: ChrisAtUpw@....... Date: Sun, 3 Dec 2006 17:07:56 EST In a message dated 2006/12/03, gpayton880@....... writes: > Another technical term that I am not familiar with has popped up: > EIGENFREQUENCY. Is that synonymous with "natural period" (for our purposes)? Hi Jerry, This refers to fixed period responses, due to physical characteristics. For instance, the Earth has a wide range of possible oscillatory modes in the millihertz region commonly lumped together as Eigen Modes, with various suffixes. The frequencies are fixed, but the amplitude of the oscillations varies with the exciting source and with time. The huge quake in Sumatra excited many modes some of which took months to die away. The term was first applied to characteristic optical responses of atoms. I am too embarrassed to ask the manufacturer. Do you know the cost for the Lennartz seismometers? Or, any other mfg.? I'm just curious........ Not off hand, but I can enquire if you like? Was there any particular model that you are interested in? Single axis vertical models and triaxial models are usually marketed. Would this be for just the sensor, or for a system complete with an ADC, datalogger and timing? New prices of 4.5 Hz geophones are about $60, 2 Hz geophones about $450 and 1 Hz geophones $1,000 to $2,500 depending on the model. There may be considerable price reductions for 2 and 1 Hz units, if you want a quantity. The cost of the Guralp PEPP single vertical sensor for schools CMG EDU was about $4,000 when I last looked - response 30 Hz to 30 seconds. This is for the sensor, the ADC + electronics and GPS timing. You have to supply a PC computer + monitor. We can buy them at a reduced price since we do not need GPS timing - DCF77 timing at E10 per receiver works just fine! My severe cold flu? seems to be slowly clearing up, but I am still feeling tired and achy. Regards, Chris In a me= ssage dated 2006/12/03, gpayton880@....... writes:

Another technical term that I a= m not familiar with has popped up: EIGENFREQUENCY.  Is that synonymous=20= with "natural period" (for our purposes)?


Hi Jerry,

       This refers to fixed period responses,=20= due to physical characteristics. For instance, the Earth has a wide range of= possible oscillatory modes in the millihertz region commonly lumped togethe= r as Eigen Modes, with various suffixes. The frequencies are fixed, but the=20= amplitude of the oscillations varies with the exciting source and with time.= The huge quake in Sumatra excited many modes some of which took months to d= ie away.

       The term was first applied to character= istic optical responses of atoms.

       I am too embarrassed to ask the manufac= turer.  Do you know the cost for the Lennartz seismometers?  Or, a= ny other mfg.?  I'm just curious........

       Not off hand, but I can enquire if you=20= like? Was there any particular model that you are interested in? Single axis= vertical models and triaxial models are usually marketed. Would this be for= just the sensor, or for a system complete with an ADC, datalogger and timin= g?

       New prices of 4.5 Hz geophones are abou= t $60, 2 Hz geophones about $450 and 1 Hz geophones $1,000 to $2,500 dependi= ng on the model. There may be considerable price reductions for 2 and 1 Hz u= nits, if you want a quantity.

       The cost of the Guralp PEPP single vert= ical sensor for schools CMG EDU was about $4,000 when I last looked - respon= se 30 Hz to 30 seconds. This is for the sensor, the ADC + electronics and GP= S timing. You have to supply a PC computer + monitor. We can buy them at a r= educed price since we do not need GPS timing - DCF77 timing at E10 per recei= ver works just fine!

       My severe cold flu? seems to be slowly=20= clearing up, but I am still feeling tired and achy.

       Regards,

       Chris Subject: Re: Technicial Terms From: "Jerry Payton" gpayton880@....... Date: Sun, 3 Dec 2006 16:52:01 -0600 < My severe cold flu? seems to be slowly clearing up, but I am still feeling tired and achy. > Thank you for reply and information. No need to persue farther for me, just curious. Sorry you are sick, get well soon. Jerry
      < My severe cold = flu? seems=20 to be slowly clearing up, but I am still feeling tired and achy.=20 >

Thank you for reply and information. No need to persue = farther for=20 me, just curious.
 
Sorry you are sick, get well = soon.
 
Jerry
Subject: RE: Technical Terms From: "Coleman, Allan" allan.coleman@............ Date: Mon, 4 Dec 2006 08:39:16 -0800 Jerry, =20 Here is a useful site that contains some instrument prices (but mostly = specs) in a convenient matrix. Some info is a year or two old, but its = an eye opener. Professional seismic instrumentation is certainly not = cheap. Please go to: =20 http://sismic.am.ub.es/jvila/instrumentation/ =20 Click on any of the four different links for listings. =20 Regards, =20 Allan -----Original Message----- From: psn-l-request@.............. = [mailto:psn-l-request@................. Behalf Of ChrisAtUpw@....... Sent: Sunday, December 03, 2006 2:08 PM To: psn-l@.............. Subject: Re: Technicial Terms In a message dated 2006/12/03, gpayton880@....... writes: Another technical term that I am not familiar with has popped up: = EIGENFREQUENCY. Is that synonymous with "natural period" (for our = purposes)? Hi Jerry, This refers to fixed period responses, due to physical = characteristics. For instance, the Earth has a wide range of possible = oscillatory modes in the millihertz region commonly lumped together as = Eigen Modes, with various suffixes. The frequencies are fixed, but the = amplitude of the oscillations varies with the exciting source and with = time. The huge quake in Sumatra excited many modes some of which took = months to die away. The term was first applied to characteristic optical responses of = atoms. I am too embarrassed to ask the manufacturer. Do you know the = cost for the Lennartz seismometers? Or, any other mfg.? I'm just = curious........ Not off hand, but I can enquire if you like? Was there any = particular model that you are interested in? Single axis vertical models = and triaxial models are usually marketed. Would this be for just the = sensor, or for a system complete with an ADC, datalogger and timing? New prices of 4.5 Hz geophones are about $60, 2 Hz geophones = about $450 and 1 Hz geophones $1,000 to $2,500 depending on the model. = There may be considerable price reductions for 2 and 1 Hz units, if you = want a quantity.=20 The cost of the Guralp PEPP single vertical sensor for schools = CMG EDU was about $4,000 when I last looked - response 30 Hz to 30 = seconds. This is for the sensor, the ADC + electronics and GPS timing. = You have to supply a PC computer + monitor. We can buy them at a reduced = price since we do not need GPS timing - DCF77 timing at E10 per receiver = works just fine!=20 My severe cold flu? seems to be slowly clearing up, but I am = still feeling tired and achy.=20 Regards, Chris=20
Jerry,
 
Here=20 is a useful site that contains some instrument prices (but=20 mostly specs) in a convenient matrix. Some info is a year or = two old,=20 but its an eye opener. Professional seismic instrumentation is certainly = not=20 cheap. Please go to:
 
http://sismic.am.u= b.es/jvila/instrumentation/
 
Click=20 on any of the four different links for listings.
 
Regards,
 
Allan
-----Original Message-----
From: = psn-l-request@................. [mailto:psn-l-request@...............On Behalf Of=20 ChrisAtUpw@.......
Sent: Sunday, December 03, 2006 2:08=20 PM
To: psn-l@..............
Subject: Re: = Technicial=20 Terms

In a message dated 2006/12/03, gpayton880@....... = writes:

Another technical term that I am not familiar with has = popped=20 up: EIGENFREQUENCY.  Is that synonymous with "natural period" = (for our=20 purposes)?


Hi=20 Jerry,

       This refers to = fixed period=20 responses, due to physical characteristics. For instance, the Earth = has a wide=20 range of possible oscillatory modes in the millihertz region commonly = lumped=20 together as Eigen Modes, with various suffixes. The frequencies are = fixed, but=20 the amplitude of the oscillations varies with the exciting source and = with=20 time. The huge quake in Sumatra excited many modes some of which took = months=20 to die away.

       The term was = first=20 applied to characteristic optical responses of=20 atoms.

       I am too = embarrassed to ask=20 the manufacturer.  Do you know the cost for the Lennartz=20 seismometers?  Or, any other mfg.?  I'm just=20 curious........

       Not off = hand, but=20 I can enquire if you like? Was there any particular model that you are = interested in? Single axis vertical models and triaxial models are = usually=20 marketed. Would this be for just the sensor, or for a system complete = with an=20 ADC, datalogger and = timing?

       New=20 prices of 4.5 Hz geophones are about $60, 2 Hz geophones about $450 = and 1 Hz=20 geophones $1,000 to $2,500 depending on the model. There may be = considerable=20 price reductions for 2 and 1 Hz units, if you want a quantity.=20

       The cost of the Guralp = PEPP=20 single vertical sensor for schools CMG EDU was about $4,000 when I = last looked=20 - response 30 Hz to 30 seconds. This is for the sensor, the ADC + = electronics=20 and GPS timing. You have to supply a PC computer + monitor. We can buy = them at=20 a reduced price since we do not need GPS timing - DCF77 timing at E10 = per=20 receiver works just fine!

       = My=20 severe cold flu? seems to be slowly clearing up, but I am still = feeling tired=20 and achy.

      =20 Regards,

       Chris=20 Subject: Road Construction From: "tchannel" tchannel@.............. Date: Mon, 4 Dec 2006 09:46:13 -0700 Hi Folks, During the times when there are no earthquakes to get excited = about, I am driving around Boise, looking for Road Construction. I got a map from Ada Co. Highway District from the internet showing = various active projects and future proposals. I found three active road projects. The first one was about 2.5 miles = NE of my NS sensor, that was the one with the Pile-Driver causing most = of my mystery noise. The Second was 3.0 miles West of my NS sensor. I = was picking up strong signals on Sat, drove over to see if they were = working and they were, using a large backhoe, digging a 12' ? trench. = The third is 3.0 miles NE, using similar heavy equipment. And to make = thing more interesting 1/2 mile South, they are digging a basement under = an existing home using a small, Bobcat machine. This morning I will = walk over to see when they start work and try to isolate that activity. My sensor is in the basement. I see almost no traffic not even large = trucks. On the other hand I sure pickup these digging activities. From all this, I have a good reference, from at lease two different = directions North East and West, and as you would expect the West signal = was larger by about 1/3 even though the source about 1/2 mile further = away. The South basement project should give me another reference = signal. What might be interesting, is to come up with a homemade "thumper" = although I have no idea how. If I had one I would work my way around = my house thumping away and creating a map and corresponding signals. I = know they rent soil compactors but I am not sure that would carry any = distance. I would guess it would need to be something of considerable = weight. Has anyone done this on a homemade scale? Cheers, Ted
Hi Folks,  During the times when=20 there are no earthquakes to get excited about, I am driving around = Boise,=20 looking for Road Construction.
I got a map from Ada Co. Highway = District from the=20 internet showing various active projects and future = proposals.
I found three active road = projects.  The first=20 one was about 2.5 miles NE of my NS sensor, that was the one with the=20 Pile-Driver causing most of my mystery noise.  The Second was 3.0 = miles=20 West of my NS sensor. I was picking up strong signals on Sat, drove over = to see=20 if they were working and they were, using a large backhoe, digging a 12' = ?=20 trench.  The third is 3.0 miles NE, using similar heavy = equipment. =20 And to make thing more interesting 1/2 mile South, they are digging a = basement=20 under an existing home using a small, Bobcat machine.  This morning = I will=20 walk over to see when they start work and try to isolate that=20 activity.
 
My sensor is in the basement. I see = almost no=20 traffic not even large trucks.  On the other hand I sure pickup = these=20 digging activities.
From all this, I have a good reference, = from at=20 lease two different directions North East and West, and as you would = expect the=20 West signal was larger by about 1/3 even though the source about 1/2 = mile=20 further away.  The South basement project should give me another = reference=20 signal.
 
What might be interesting, is to come = up with a=20 homemade "thumper" although I have no idea how.   If I had one = I would=20 work my way around my house thumping away and creating a map and = corresponding=20 signals.   I know they rent soil compactors but I am not sure = that=20 would carry any distance.  I would guess it would need to be = something of=20 considerable weight.  Has anyone done this on a homemade=20 scale?
 
Cheers, Ted
Subject: Re: Road Construction From: ChrisAtUpw@....... Date: Mon, 4 Dec 2006 14:14:02 EST In a message dated 2006/12/04, tchannel@.............. writes: > What might be interesting, is to come up with a homemade "thumper" although > I have no idea how. If I had one I would work my way around my house > thumping away and creating a map and corresponding signals. I know they rent soil > compactors but I am not sure that would carry any distance. I would guess it > would need to be something of considerable weight. Has anyone done this on > a homemade scale? Hi Ted, You can buy 12 V DC solenoid actuators which have a spring return. You can drive these unloaded or loaded, either from a switched DC source, or if you need more thump, from a high voltage capacitor. Beware of the huge transient voltages that you can get on switching a high current solenoid. Check the max allowable capacitor current, maybe use several of lower capacity connected in parallel? You must not put a reverse voltage on a polarised electrolytic. It may be an advantage to incorporate the solenoid into a SCR switched bridge circuit, so that energy stored in the solenoid is subsequently returned to the capacitor. You have to mount these on a strong baseplate firmly attached to a building structure, or to the Earth. These may work at over 50 yard ranges. Regards, Chris Chapman In a me= ssage dated 2006/12/04, tchannel@.............. writes:

What might be interesting, is t= o come up with a homemade "thumper" although I have no idea how.  If I=20= had one I would work my way around my house thumping away and creating a map= and corresponding signals.  I know they rent soil compactors but I am=20= not sure that would carry any distance.  I would guess it would need to= be something of considerable weight.  Has anyone done this on a homema= de scale?


Hi Ted,

       You can buy 12 V DC solenoid actuators=20= which have a spring return. You can drive these unloaded or loaded, either f= rom a switched DC source, or if you need more thump, from a high voltage cap= acitor. Beware of the huge transient voltages that  you can get on swit= ching a high current solenoid. Check the max allowable capacitor current, ma= ybe use several of lower capacity connected in parallel? You must not put a=20= reverse voltage on a polarised electrolytic.
       It may be an advantage to incorporate t= he solenoid into a SCR switched bridge circuit, so that energy stored in the= solenoid is subsequently returned to the capacitor.
       You have to mount these on a strong bas= eplate firmly attached to a building structure, or to the Earth. These may w= ork at over 50 yard ranges.

       Regards,

       Chris Chapman Subject: Re: Anyone seen this MS thesis: Improving a Geophone From: "David Saum" DSaum@............ Date: Mon, 4 Dec 2006 14:14:16 -0500 > > This is what Sean-Thomas wrote about using a 4.5Hz geophone as a broadband > > sensor: ...... > > > > But the data is too noisy for a sensitive broadband sensor, and I am usually > > barely able to see the normal 6-second microseism background of 1 to 2 > > microns/second. Of course these were very clear (~10x) when hurricane > > Bonnie passed last August. I also made a nice record (from St. Louis) > > of the Ohio quake in September, with peak velocities of Lg of about 10 > > microns/second at about 8 seconds. I can generally see the microseism background on my 4.5 Hz geophone systems. For instance, here is some background noise data from today at ~17 UTC from a shielded geophone system http://www.infiltec.com/seismo/QM45-CL.jpg (geophone system) sitting on the carpet of my basement office slab: http://www.infiltec.com/seismo/061204N1.gif (noise spectra) The steep drop off above 4 Hz is due to the cutoff of an 8 pole Bessel filter switched capacitor chip. There is no digital filtering. The microseism peak is ~ 0.24 Hz. Here is a another example, a geophone detection of 2005 December 05 12:19 UTC Magnitude 6.8 - LAKE TANGANYIKA REGION: 11,954.0 km from Bailey's Crossroads, VA http://www.infiltec.com/seismo/051205BS.jpg (noise and quake) that shows a teleseismic peak at ~0.05 Hz as well as a microseism peak at ~0.2 Hz. Dave http://www.infiltec.com/seismo/inf-qm45.htm __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Anyone seen this MS thesis: Improving a Geophone From: "Jack Ivey" ivey@.......... Date: Mon, 4 Dec 2006 15:35:30 -0500 Chris, Great post! =20 =20 I couldn't use the url you gave for the Lennartz document, any suggestion about what to search for to find the document you=20 were pointing at? =20 Thanks, Jack =20 ________________________________ From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of ChrisAtUpw@....... Sent: Saturday, December 02, 2006 2:38 PM To: psn-l@.............. Cc: angel@............... apsn@............ mariotti@......... Subject: Re: Anyone seen this MS thesis: Improving a Geophone =20 In a message dated 2006/12/02, lcochrane@.............. writes: Subj:Re: MS thesis: Improving a Geophone=20 Hi All, Before reading the article below, I suggest that you visit Lennartz GMBH at http://www.lennartz-electronic.de/MamboV4.5.2/index.php They have three very successful seismic sensor lines from 40 Hz down to 1 sec, to 5 sec, and to 20 sec periods. The sensors themselves are of about 2 Hz with various types of period extension. A response flat with velocity, from 40 Hz down to 20 sec period is broad band. The 5 sec response sensors are popular, since they cover teleseismic P and S waves. Very low noise amplifiers are required.=20 In general, a geophone type sensor may be extended to 1/10 of it's natural period, usually without problems. Getting any more out of it may be 'hard work'. It may be desireable in some cases to limit the high frequency response to 20, or even 10 Hz. It is not clear if Sean was aware of the techniques used by Lennartz. However, he used an additional in line LRDT where Barzilai used a capacitative sensor. Hi Everyone, This is what Sean-Thomas wrote about using a 4.5Hz geophone as a broadband sensor: "I have been experimenting for several years with making almost any seismometer into a VBB sensor if the physical parameters are suitable, like the coil resistance. THe largest is a WWNSS LP (15 second T0 and 11 kg mass) vertical that I am running at 600 seconds. As you may have gathered, the small geophones have been an attraction. I have been experimenting for about two years with making the 4.5 hz HS-1 (by Geospace, but similar to the GSC-11d and the Mark Products L-15B) into a broadband instrument. I use the VRDT displacement sensor mounted externally above the case, with the sensing vane attached to the upper mass ring. With VBB parameters set for 20 seconds and the proper coil resistance, the VBB output is 750 volts/meter/second and the calibrations fit the transfer functions. But the data is too noisy for a sensitive broadband sensor, and I am usually barely able to see the normal 6-second microseism background of 1 to 2 microns/second. Of course these were very clear (~10x) when hurricane Bonnie passed last August. I also made a nice record (from St. Louis) of the Ohio quake in September, with peak velocities of Lg of about 10 microns/second at about 8 seconds. NB. Sean didn't say what were the sources of this noise. An unsealed vertical geophone will be sensitive to atmospheric density changes, wind noise etc. Also, his remarks apply to broad band use, not to limited period extension. The trouble with the 4.5hz phone is that the mass is only 23 grams, and the intrinsic damping of 0.28 means that the Q is not very high. From the Riedesel paper this would be expected to have a Brownian noise power spectral density (PSD) level of about -165db (figure 12). (For reference, the USGS low noise model has the 6-second microseism peak at about -140db, the 12-second peak at -160db, and the quiet earth minimum between 40 and 200 seconds is about -185 db.) But the Brownian noise is only one of many noise sources; the circular suspension leaf springs and the fine-wire signal output leads are significant contributors. The Reidesel paper finds that when using the velocity signal coil and a properly selected amplifier, the noise level is -130db at 1 hz, and the 6-second microseisms cannot be seen. We can do much better with a VBB fedback configuration. Quite a lot better! The PSD of several noise samples was about -145db at 6 seconds, but levels off at about -155db at 10 seconds. It has trouble recording teleseisms compared with a larger VBB seis, like a Mb5.O west of Mexico or a 6.2 in China, where the 20-second surface waves were only about 2X the noise. It did make a reasonable record of a Ms 6.0 in the Queen Charlotte Islands (51N,130W). It may be possible to reduce the suspension noise, and I have a new geophone to modify with great care to try to minimize it. Other problems are with the thermal sensitivity of the mass position and suspension resonances within the high-frequency portion of the VBB passband. The manufacturers are mum on these; the most notorious are the resonances of the 1-hz L4-C at 16 and 22 hz. The mass position change with temperature is a "don't care" for a velocity sensor, but it causes problems with a displacement output of 250 millivolts/micron, even with reasonable VBB loop gains." Regards, Larry Cochrane Redwood City, PSN > In a message dated 2006/12/01, apsn@........... writes: >=20 http://micromachine.stanford.edu/smssl/projects/Geophones/DefenseBarzila iFinalCopyWeb/DefenseBarzilaiFinalCopy.pdf>=20 >=20 > Hi Bob, > This has been around for ages. > I would give him high marks for effort. > I wish that I could be equally enthusiastic about the=20 > modifications themselves, or about his circuitry. > The VLF noise level is high, but he does not seem to have=20 > addressed this, or cured it. > Regards, > Chris Chapman Let us turn the question around from what we CAN'T do with a 4.5 Hz geophone,=20 TO what we can FAIRLY EASILY DO to improve it's UTILITY + PERFORMANCE for Amateur Seismic Work? The response of a 4.5 Hz geophone is down to 1/5 at 2 Hz and it falls off rapidly below this, but this may be of use for local or volcanic quakes. However, extending a 4.5 Hz geophone's response to 1/10 of it's natural frequency (0.45 Hz) just conveniently covers most of the frequencies of interest for teleseismic P and S waves. There are three ways of doing this.=20 You can increase your main amplifier gain by x100 and process the digital signals in software. This reduces your dynamic range by the same factor and the full period compensation will fail for small signals (may not be too important). You can add a x100 VLF boost amplifier to compensate for the f^2 roll off of the geophone characteristic below it's resonant frequency. This amplifier needs to be low noise and the compensation needs to be done in two stages to maintain the gain through the corner frequency. If you don't do this, you get zero output at 4.5 Hz, instead of the full signal. See Roberts at http://psn.quake.net/bibliography.html I modified Roberts' circuit to remove most of the excess VLF noise that he experienced. The 4.5 Hz modules are available commercially - see www.sara.pg.it You can fit the geophone with a negative input impedance pre amplifier, which converts the 'dog leg' f^2 + the flat geophone responces into a much smaller straight line response proportional to f. You then put this through a low frequency bandpass filter set at your minimum frequency of interest. See the ARRL radio handbook. This removes the slope :f and you then amplify / filter the signal further. However, this does need an extremely low noise and specialised first amplifier. See http://www.lennartz-electronic.de/MamboV4.5.2/index.php?option=3Dcom_remo= s itory&Itemid=3D45&func=3Ddownload&filecatid=3D3&chk=3Dbc273996d12702c9fc9= 6b4f638 492797 See also http://www.vaxman.de/publications/teach_gp.pdf You can download a general filter design program and application notes free from http://www.ti.com/litv/zip/slvc108f Regards, Chris Chapman

Chris,

Great post!  =

 

I couldn’t use the url you = gave for the Lennartz document,

any suggestion about what to search = for to find the document you

were pointing = at?

 

Thanks,

=

Jack

 

From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of ChrisAtUpw@.......
Sent: Saturday, December = 02, 2006 2:38 PM
To: psn-l@..............
Cc: angel@............... apsn@............ mariotti@.........
Subject: Re: Anyone seen = this MS thesis: Improving a Geophone

 

In a message dated 2006/12/02, = lcochrane@.............. writes:


Subj:Re: MS = thesis: Improving a Geophone



Hi All,

       Before reading the article below, I suggest that you visit Lennartz GMBH at http://www.lennartz-electronic.de/MamboV4.5.2/index.php
    They have three very successful seismic sensor lines = from 40 Hz down to 1 sec, to 5 sec, and to 20 sec periods. The sensors = themselves are of about 2 Hz with various types of period extension.

    A response flat with velocity, from 40 Hz down to 20 = sec period is broad band. The 5 sec response sensors are popular, since they = cover teleseismic P and S waves. Very low noise amplifiers are required.

    In general, a geophone type sensor may be extended to = 1/10 of it's natural period, usually without problems. Getting any more out = of it may be 'hard work'. It may be desireable in some cases to limit the high frequency response to 20, or even 10 Hz.

    It is not clear if Sean was aware of the techniques = used by Lennartz. However, he used an additional in line LRDT where Barzilai = used a capacitative sensor.


Hi Everyone,

This is what Sean-Thomas wrote about using a 4.5Hz geophone as a = broadband sensor:

"I have been experimenting for several years with making almost = any
seismometer into a VBB sensor if the physical parameters are = suitable,
like the coil resistance. THe largest is a WWNSS LP (15 second T0 = and
11 kg mass) vertical that I am running at 600 seconds.

As you may have gathered, the small geophones have been an = attraction.
I have been experimenting for about two years with making the 4.5 hz = HS-1
(by Geospace, but similar to the GSC-11d and the Mark Products = L-15B)
into a broadband instrument. I use the VRDT displacement sensor = mounted
externally above the case, with the sensing vane attached to the = upper
mass ring.  With VBB parameters set for 20 seconds and the proper = coil
resistance, the VBB output is 750 volts/meter/second and the = calibrations
fit the transfer functions.

But the data is too noisy for a sensitive broadband sensor, and I am = usually
barely able to see the normal 6-second microseism background of 1 to = 2
microns/second. Of course these were very clear (~10x) when = hurricane
Bonnie passed last August. I also made a nice record  (from = St. Louis)
of the Ohio quake in September, with peak velocities of Lg of about 10
microns/second at about 8 seconds.



       NB. Sean didn't say what were the = sources of this noise. An unsealed vertical geophone will be sensitive to = atmospheric density changes, wind noise etc. Also, his remarks apply to broad band = use, not to limited period extension.


The trouble with = the 4.5hz phone is that the mass is only 23 grams, and
the intrinsic damping of 0.28 means that the Q is not very high.
From the Riedesel paper this would be expected to have a Brownian = noise
power spectral density (PSD) level of about -165db (figure 12). (For
reference, the USGS low noise model has the 6-second microseism peak
at about -140db, the 12-second peak at -160db, and the quiet earth = minimum
between 40 and 200 seconds is about -185 db.) But the Brownian noise
is only one of many noise sources; the circular suspension leaf = springs
and the fine-wire signal output leads are significant contributors.
The Reidesel paper finds that when using the velocity signal coil = and
a properly selected amplifier, the noise level is -130db at 1 hz, = and
the 6-second microseisms cannot be seen. We can do much better with = a
VBB fedback configuration.



       Quite a lot better!


The PSD of = several noise samples was about -145db at 6 seconds, but
levels off at about -155db at 10 seconds. It has trouble recording
teleseisms compared with a larger VBB seis, like a Mb5.O west of = Mexico
or a 6.2 in China, where the 20-second surface waves were only about
2X the noise. It did make a reasonable record of a Ms 6.0 in the = Queen
Charlotte Islands (51N,130W).

It may be possible to reduce the suspension noise, and I have a new
geophone to modify with great care to try to minimize it. Other
problems are with the thermal sensitivity of the mass position and
suspension resonances within the high-frequency portion of the VBB
passband. The manufacturers are mum on these; the most notorious are
the resonances of the 1-hz L4-C at 16 and 22 hz. The mass position = change
with temperature is a "don't care" for a velocity sensor, but = it causes
problems with a displacement output of 250 millivolts/micron, even = with
reasonable VBB loop gains."

Regards,
Larry Cochrane
Redwood = City, PSN

>    In a message dated 2006/12/01, apsn@........... = writes:
>
http://micromachine.stanford.edu/smssl/projects/Geophones/DefenseBarzilai= FinalCopyWeb/DefenseBarzilaiFinalCopy.pdf>
>
> Hi Bob,
>        This has been around for = ages.
>        I would give him high = marks for effort.
>        I wish that I could be = equally enthusiastic about the
> modifications themselves, or about his circuitry.
>        The VLF noise level is = high, but he does not seem to have
> addressed this, or cured it.
>        Regards,
>        Chris = Chapman



       Let us turn the question around = from what we CAN'T do with a 4.5 Hz geophone,
       TO what we can FAIRLY EASILY DO to = improve it's UTILITY + PERFORMANCE for Amateur Seismic Work?

       The response of a 4.5 Hz geophone = is down to 1/5 at 2 Hz and it falls off rapidly below this, but this may be of = use for local or volcanic quakes.
       However, extending a 4.5 Hz = geophone's response to 1/10 of it's natural frequency (0.45 Hz) just conveniently = covers most of the frequencies of interest for teleseismic P and S waves. There = are three ways of doing this.

       You can increase your main = amplifier gain by x100 and process the digital signals in software. This reduces your = dynamic range by the same factor and the full period compensation will fail for = small signals (may not be too important).

       You can add a x100 VLF boost = amplifier to compensate for the f^2 roll off of the geophone characteristic below = it's resonant frequency. This amplifier needs to be low noise and the = compensation needs to be done in two stages to maintain the gain through the corner frequency. If you don't do this, you get zero output at 4.5 Hz, instead = of the full signal. See Roberts at http://psn.quake.net/bibliography.html I = modified Roberts' circuit to remove most of the excess VLF noise that he = experienced. The 4.5 Hz modules are available commercially - see www.sara.pg.it

       You can fit the geophone with a = negative input impedance pre amplifier, which converts the 'dog leg' f^2 + the = flat geophone responces into a much smaller straight line response = proportional to f. You then put this through a low frequency bandpass filter set at your minimum frequency of interest. See the ARRL radio handbook. This removes = the slope :f and you then amplify / filter the signal further. However, this = does need an extremely low noise and specialised first amplifier. See http://www.lennartz-electronic.de/MamboV4.5.2/index.php?option=3Dcom_remo= sitory&Itemid=3D45&func=3Ddownload&filecatid=3D3&chk=3Dbc= 273996d12702c9fc96b4f638492797
       See also http://www.vaxman.de/publications/teach_gp.pdf

       You can download a general filter = design program and application notes free from = http://www.ti.com/litv/zip/slvc108f

       Regards,

       Chris Chapman

Subject: Re: Anyone seen this MS thesis: Improving a Geophone From: ChrisAtUpw@....... Date: Mon, 4 Dec 2006 18:32:59 EST In a message dated 2006/12/04, ivey@.......... writes: > You can fit the geophone with a negative input impedance pre > amplifier, which converts the 'dog leg' f^2 + the flat geophone responses into a > much smaller straight line response proportional to f. You then put this through > a low frequency bandpass filter set at your minimum frequency of interest. > See the ARRL radio handbook. This removes the slope :f and you then amplify / > filter the signal further. However, this does need an extremely low noise and > specialised first amplifier. See > http://www.lennartz-electronic.de/MamboV4.5.2/ Hi Jack, Sorry about that! It worked for me. Go to http://www.lennartz-electronic.de/MamboV4.5.2/ In the left hand column under Main Menu, click on downloads; then click on PDF; then click on Brochures; then at the bottom of the page click on Seismometers Short Form and click Download. It is quite a large file ~1 MB and the relevant information is on P 13 & seq. It also has the reference on P 3 for the Erich Lippmann Patent No: DE 3307575 C2 as of 20/12/1984 Lennartz use both this method and the Roberts' boost amplifier method in their seismometers. They produce 1 sec, 5 sec and 20 sec sensors. I use a modification of the Roberts' method. I can get 0.5 Hz out of a 4.5 Hz geophone OK. Any further increase in period and you may start to see 1/f noise. With Lippmann's method, you may need a lower noise than ordinary opamps can provide. I suspect that a x10 period gain may be easier to obtain with 2 Hz geophones. The mass is greater and internal noise is lower than on a 4.5 Hz geophone. Regards, Chris Chapman In a me= ssage dated 2006/12/04, ivey@.......... writes:

     &= nbsp; You can fit the geophone with a negative input impedance pre amplifier= , which converts the 'dog leg' f^2 + the flat geophone responses into a much= smaller straight line response proportional to f. You then put this through= a low frequency bandpass filter set at your minimum frequency of interest.=20= See the ARRL radio handbook. This removes the slope :f and you then amplify=20= / filter the signal further. However, this does need an extremely low noise=20= and specialised first amplifier. See http://www.lennartz-electronic.de/Mambo= V4.5.2/


Hi Jack,

       Sorry about that! It worked for me.
       Go to http://www.lennartz-electronic.de= /MamboV4.5.2/
       In the left hand column under Main Menu= , click on downloads;
       then click on PDF;
       then click on Brochures;
       then at the bottom of the page click on= Seismometers Short Form and click Download.

       It is quite a large file ~1 MB and the=20= relevant information is on P 13 & seq. It also has the reference on P 3=20= for the Erich Lippmann Patent No: DE 3307575 C2 as of 20/12/1984
       Lennartz use both this method and the R= oberts' boost amplifier method in their seismometers. They produce 1 sec, 5=20= sec and 20 sec sensors.
       I use a modification of the Roberts' me= thod. I can get 0.5 Hz out of a 4.5 Hz geophone OK. Any further increase in=20= period and you may start to see 1/f noise. With Lippmann's method, you may n= eed a lower noise than ordinary opamps can provide. I suspect that a x10 per= iod gain may be easier to obtain with 2 Hz geophones. The mass is greater an= d internal noise is lower than on a 4.5 Hz geophone.

       Regards,

       Chris Chapman Subject: Pendulum response and Roberts' circuit From: John or Jan Lahr JohnJan@........ Date: Mon, 04 Dec 2006 21:49:04 -0800 Because I'm continually needing to refresh my memory with respect to the response of a simple pendulum to ground motion, and then thinking in terms of the output from a magnet/coil pickup, I've created this page: http://jclahr.com/science/psn/response/index.html with some notes and graphs. Broad-band systems are generally set up to have a flat response to ground velocity over a wide range of frequencies. I've posted the circuit that Peter Roberts developed to flatten the response of a velocity sensor. http://jclahr.com/science/psn/roberts/index.html Cheers, John __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Volcanao activitie in Iceland for the past ~1100 years From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Tue, 05 Dec 2006 06:17:38 +0000 Hi all Here is a intresting artical about volcanoism in Iceland for the past ~1100 years. The artical is informative on volcanoism in Iceland and explains alot of intresting things. http://tinyurl.com/yh5o36 Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Pendulum response and Roberts' circuit From: Stephen & Kathy skmort@............ Date: Tue, 05 Dec 2006 02:32:04 -0800 OK,, so which components would we change, and to what value for a 2 hz and a .222 hz (4.5 sec) system? I might have to break out my soldering iron,,, ha! Thanks, Stephen John or Jan Lahr wrote: > > Broad-band systems are generally set up to have a flat response to > ground velocity over a wide range of frequencies. I've posted the > circuit that Peter Roberts developed to flatten the response of a > velocity sensor. > http://jclahr.com/science/psn/roberts/index.html > > Cheers, > John > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Pendulum response and Roberts' circuit From: ChrisAtUpw@....... Date: Tue, 5 Dec 2006 21:13:38 EST In a message dated 2006/12/05, skmort@............ writes: > OK, so which components would we change, and to what value for a 2 > Hz and a 0.222 hz (4.5 sec) system? > I might have to break out my soldering iron, ha! > Thanks, > Stephen Hi Stephen, If f is the resonant frequency of the sensor, you make 1 / 2xPixfxCxR1 = 1.09 according to Roberts. I am not sure exactly why he chose this. It could explain the small hump in the combined characteristic. The Max gain is R2 / R1 The lower turnover frequency is 1 / 2xPixC1xR2 This has been set to ~1/2 the lowest response frequency in the Roberts circuit. You need two units in series. Roberts reported significant levels of VLF noise, so it might be a good idea to follow up the compensation circuits with a two / four pole high pass Butterworth filter set to about the lower desired frequency. If you want to use the circuit at long periods, you may need to use some CAZ opamps MAX430, LTC1150 etc. They reject 1/f noise. Otherwise LF411, OP07, LF412 etc are OK The optimum place to insert this circuit is between the first opamp and the low pass filters. How about investing in a temperature compensated soldering iron which plugs in.....? Or make an Experimenter Board plug in version first? Regards, Chris Chapman In a me= ssage dated 2006/12/05, skmort@............ writes:

OK, so which components would w= e change, and to what value for a 2
Hz and a 0.222 hz (4.5 sec) system?
I might have to break out my soldering iron, ha!
Thanks,
Stephen


Hi Stephen,

       If f is the resonant frequency of the s= ensor, you make 1 / 2xPixfxCxR1 =3D 1.09 according to Roberts. I am not sure= exactly why he chose this. It could explain the small hump in the combined=20= characteristic.
       The Max gain is R2 / R1
       The lower turnover frequency is 1 / 2xP= ixC1xR2 This has been set to ~1/2 the lowest response frequency in the Rober= ts circuit.
       You need two units in series.
       Roberts reported significant levels of=20= VLF noise, so it might be a good idea to follow up the compensation circuits= with a two / four pole high pass Butterworth filter set to about the lower=20= desired frequency.
       If you want to use the circuit at long=20= periods, you may need to use some CAZ opamps MAX430, LTC1150 etc. They rejec= t 1/f noise. Otherwise LF411, OP07, LF412 etc are OK
       The optimum place to insert this circui= t is between the first opamp and the low pass filters.

       How about investing in a temperature co= mpensated soldering iron which plugs in.....? Or make an Experimenter Board=20= plug in version first?

       Regards,

       Chris Chapman Subject: Re: Road Construction From: "Geoffrey" gmvoeth@........... Date: Tue, 5 Dec 2006 20:51:51 -0700 Traffic noise seems to center around 3Hz to 4Hz where as the noises of which you speak are much lower in freq. most possibly in the period range. I have seen these steam rollers about 300ft away but have never identified anything further than about 3000 feet away. Our steam rollers will vibrate (I would hate to use any vibrating machines thats why we have people who like working heavy equipment). You are either located on springy ground or your sensor is not fully dampened and hypersensitive at the noise freqs ?? You seem in good shape to me if you can pick up any human noises other than mine blasts you can ID at over a mile away. regards; geoff ----- Original Message ----- From: "tchannel" To: Sent: Monday, December 04, 2006 9:46 AM Subject: Road Construction Hi Folks, During the times when there are no earthquakes to get excited about, I am driving around Boise, looking for Road Construction. I got a map from Ada Co. Highway District from the internet showing various active projects and future proposals. I found three active road projects. The first one was about 2.5 miles NE of my NS sensor, that was the one with the Pile-Driver causing most of my mystery noise. The Second was 3.0 miles West of my NS sensor. I was picking up strong signals on Sat, drove over to see if they were working and they were, using a large backhoe, digging a 12' ? trench. The third is 3.0 miles NE, using similar heavy equipment. And to make thing more interesting 1/2 mile South, they are digging a basement under an existing home using a small, Bobcat machine. This morning I will walk over to see when they start work and try to isolate that activity. My sensor is in the basement. I see almost no traffic not even large trucks. On the other hand I sure pickup these digging activities. From all this, I have a good reference, from at lease two different directions North East and West, and as you would expect the West signal was larger by about 1/3 even though the source about 1/2 mile further away. The South basement project should give me another reference signal. What might be interesting, is to come up with a homemade "thumper" although I have no idea how. If I had one I would work my way around my house thumping away and creating a map and corresponding signals. I know they rent soil compactors but I am not sure that would carry any distance. I would guess it would need to be something of considerable weight. Has anyone done this on a homemade scale? Cheers, Ted __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Availability of New Book on Iceland Geodynamics From: "Erich Kern" efkern@............. Date: Tue, 5 Dec 2006 23:24:02 -0800 ******************************** AVAILABILITY OF NEW BOOK ON ICELAND GEODYNAMICS From: Robert I. Tilling ******************************** Iceland is one of the few=97as well as the largest, well-exposed, and=20 readily accessible=97areas where Earth=92s mid-oceanic ridge system = emerges=20 above sea level. Because of this unique geologic setting, Iceland serves = as an ideal natural laboratory for comprehensive, multi-disciplinary=20 investigations of the active tectonic and volcanic processes associated=20 with divergent plate boundaries, along which about 75 % of the world=92s = lava is erupted. Since it tops an inferred hotspot, Iceland also affords = a diagnostic locale to study the processes and products of the=20 interaction between a mantle plume and a mid-ocean ridge. Thus, the=20 monitoring, characterization, and interpretation of the seismicity,=20 crustal deformation, and volcanism in Iceland have immense transfer=20 value in understanding comparable dynamic processes operative along=20 other segments of the global 65,000 km-long mid-oceanic ridge=20 system=97mostly hidden deep beneath the sea and logistically challenging = for detailed study. For the reasons mentioned above, anyone interested in the tectonics and=20 volcanic activity along divergent plate boundaries will find quite=20 useful a recently published book by Dr. Freysteinn Sigmundsson that=20 succinctly synthesizes in a single volume the results of numerous=20 diverse studies made in Iceland in recent decades. The title of his book = is: ICELAND GEODYNAMICS: Crustal Deformation and Divergent Plate Tectonics=20 (2006, Springer-Praxis, Chichester, U.K., 209 pp not counting a 22-page=20 section of color illustrations; $ 169.00, as priced on=20 ). Formal reviews of this book doubtless will be forthcoming in the coming=20 months, but I simply wish to inform the volcanologic community of the=20 availability of this new reference work and to make some informal = comments. After completing his Ph.D. (1992) with Prof. Roger Bilham at the=20 University of Colorado, Dr. Sigmundsson worked at the Nordic=20 Volcanological Institute through 2004 (five years as Director,=20 1999-2004); he now is with the Nordic Volcanological Centre (Institute=20 of Earth Sciences, University of Iceland). Throughout his career, he has = focused on studies of crustal deformation and volcanology, and, not=20 surprisingly, this research thrust=97utilizing conventional and=20 satellite-based geodetic techniques=97pervades the book. While the = linking=20 common thread of the book is clearly the monitoring of crustal=20 deformation, Sigmundsson nonetheless nicely balances his treatment by=20 furnishing relevant geological, seismological, and volcanological=20 contexts. The breadth of the book is evident from the wide range of=20 topics covered in the nine chapters: 1) Introduction; 2) Mantle=20 plume-mid-ocean ridge interaction in the North Atlantic; 3) Tectonic=20 framework; 4) Crustal structure of Iceland; 5) Volcano dynamics; 6) The=20 plate-spreading deformation cycle; 7) Breaking the crust: Seismicity and = faulting; 8) Glacial isostasy and sea-level change: Rapid vertical=20 movements and changes in volcanic production rates; and 9) Iceland=20 geodynamics: Outlook. In addition to a list of abbreviations and a brief = index, the book also contains two useful appendices: Appendix A. The=20 Icelandic Language (providing examples of transliterations of Icelandic=20 names for people and places); and Appendix B. Notation (of variables in=20 formulae that appear in the book). Like seemingly all Icelandic scientists, Freysteinn Sigmundsson has a=20 masterful command of the English language even though it is not his=20 native tongue. Consequently, his tersely, but clearly, written slim=20 volume packs a wealth of information about the current state of=20 knowledge about Iceland geodynamics. There are no superfluous words in=20 his book! An added bonus is that Sigmudsson=92s summary is not only=20 comprehensive but also fully up-to-date, including the thoughtful=20 analysis of studies published in the scientific literature as recently=20 as 2005. For example, in discussions concerning the inferred Iceland=20 mantle plume, Sigmundsson considers the divergent points expressed in=20 the current, ongoing vigorous scientific debate about the existence,=20 configuration (deep vs. non-deep), fixity, and longevity of mantle=20 plumes, as well as alternative models to explain Iceland and other=20 hotspots. In the Preface (p. xi), Sigmundsson hopes that his =93=85book = will=20 provide a useful overview of selected aspects of Iceland geodynamics and = crustal deformation, provide insights into the physical processes of=20 spreading and related processes in general, and stimulate further=20 research on how the Earth deforms.=94 In my opinion, there is no doubt=20 whatsoever that his hope will be fully realized. =97Robert I. Tilling, Scientist Emeritus, Volcano Hazards Team U.S. Geological Survey, Menlo Park, California 94025, U.S.A.
 


********************************
AVAILABIL= ITY OF=20 NEW BOOK ON ICELAND GEODYNAMICS
From: Robert I. Tilling <rtilling@........>
**********= **********************

Iceland=20 is one of the few=97as well as the largest, well-exposed, and =
readily=20 accessible=97areas where Earth=92s mid-oceanic ridge system emerges =
above sea=20 level. Because of this unique geologic setting, Iceland serves
as an = ideal=20 natural laboratory for comprehensive, multi-disciplinary =
investigations of=20 the active tectonic and volcanic processes associated
with divergent = plate=20 boundaries, along which about 75 % of the world=92s
lava is erupted. = Since it=20 tops an inferred hotspot, Iceland also affords
a diagnostic locale = to study=20 the processes and products of the
interaction between a mantle plume = and a=20 mid-ocean ridge. Thus, the
monitoring, characterization, and = interpretation=20 of the seismicity,
crustal deformation, and volcanism in Iceland = have=20 immense transfer
value in understanding comparable dynamic processes = operative along
other segments of the global 65,000 km-long = mid-oceanic=20 ridge
system=97mostly hidden deep beneath the sea and logistically = challenging=20
for detailed study.

For the reasons mentioned above, anyone=20 interested in the tectonics and
volcanic activity along divergent = plate=20 boundaries will find quite
useful a recently published book by Dr.=20 Freysteinn Sigmundsson that
succinctly synthesizes in a single = volume the=20 results of numerous
diverse studies made in Iceland in recent = decades. The=20 title of his book is:

ICELAND GEODYNAMICS: Crustal Deformation = and=20 Divergent Plate Tectonics
(2006, Springer-Praxis, Chichester, U.K., = 209 pp=20 not counting a 22-page
section of color illustrations; $ 169.00, as = priced=20 on
<springeronline.com>).

Formal reviews of this book = doubtless=20 will be forthcoming in the coming
months, but I simply wish to = inform the=20 volcanologic community of the
availability of this new reference = work and to=20 make some informal comments.

After completing his Ph.D. (1992) = with Prof.=20 Roger Bilham at the
University of Colorado, Dr. Sigmundsson worked = at the=20 Nordic
Volcanological Institute through 2004 (five years as = Director,=20
1999-2004); he now is with the Nordic Volcanological Centre = (Institute=20
of Earth Sciences, University of Iceland). Throughout his career, he = has=20
focused on studies of crustal deformation and volcanology, and, not=20
surprisingly, this research thrust=97utilizing conventional and=20
satellite-based geodetic techniques=97pervades the book. While the = linking=20
common thread of the book is clearly the monitoring of crustal=20
deformation, Sigmundsson nonetheless nicely balances his treatment = by=20
furnishing relevant geological, seismological, and volcanological=20
contexts. The breadth of the book is evident from the wide range of=20
topics covered in the nine chapters: 1) Introduction; 2) Mantle=20
plume-mid-ocean ridge interaction in the North Atlantic; 3) Tectonic =
framework; 4) Crustal structure of Iceland; 5) Volcano dynamics; 6) = The=20
plate-spreading deformation cycle; 7) Breaking the crust: Seismicity = and=20
faulting; 8) Glacial isostasy and sea-level change: Rapid vertical=20
movements and changes in volcanic production rates; and 9) Iceland=20
geodynamics: Outlook. In addition to a list of abbreviations and a = brief=20
index, the book also contains two useful appendices: Appendix A. The =
Icelandic Language (providing examples of transliterations of = Icelandic=20
names for people and places); and Appendix B. Notation (of variables = in=20
formulae that appear in the book).

Like seemingly all = Icelandic=20 scientists, Freysteinn Sigmundsson has a
masterful command of the = English=20 language even though it is not his
native tongue. Consequently, his = tersely,=20 but clearly, written slim
volume packs a wealth of information about = the=20 current state of
knowledge about Iceland geodynamics. There are no=20 superfluous words in
his book! An added bonus is that Sigmudsson=92s = summary=20 is not only
comprehensive but also fully up-to-date, including the=20 thoughtful
analysis of studies published in the scientific = literature as=20 recently
as 2005. For example, in discussions concerning the = inferred=20 Iceland
mantle plume, Sigmundsson considers the divergent points = expressed=20 in
the current, ongoing vigorous scientific debate about the = existence,=20
configuration (deep vs. non-deep), fixity, and longevity of mantle=20
plumes, as well as alternative models to explain Iceland and other=20
hotspots. In the Preface (p. xi), Sigmundsson hopes that his = =93=85book will=20
provide a useful overview of selected aspects of Iceland geodynamics = and=20
crustal deformation, provide insights into the physical processes of =
spreading and related processes in general, and stimulate further=20
research on how the Earth deforms.=94 In my opinion, there is no = doubt=20
whatsoever that his hope will be fully realized.

=97Robert I. = Tilling,=20 Scientist Emeritus, Volcano Hazards Team
U.S. Geological Survey, = Menlo Park,=20 California 94025, U.S.A.

Subject: Simple pendulum response From: Larry Cochrane lcochrane@.............. Date: Wed, 06 Dec 2006 01:50:18 -0800 Hi Everyone, Dr. Randall Peters asked me to forward the following message to the list. Regards, Larry Cochrane Redwood City, PSN I've been following with interest the discussions concerning instrument characteristics. Now that my schedule is easing somewhat, I felt that I should get involved. Should it happen that any of you respond to these comments and don't hear back from me for a while, it's because I will be away for about a week to the Amer. Geophys. Union Fall Conference in San Francisco (starting 11 Dec.). There I will give a 15 minute oral presentation titled "State of the art Digital Seismograph" . The abstract is posted at http://www.agu.org/cgi-bin/sessions5?meeting=fm06&part=S14B&maxhits=400 The instrument which will be described (and also demonstrated at one of the booths) uses a "simple" compound pendulum with a natural frequency of 0.92 Hz. It employs my fully differential capacitive detector as a displacement sensor (array form), with electronics based in Analog Devices' new award winning capacitance to digital converter integrated circuit (AD7745). Kudo's to our own Larry Cochrane as the brains behind all of (i) the electronics hardware necessary to do the I2C logic operations required of the chip, and (ii) the software operating system in the form of WinSDR and WinQuake. For those of you who have been monitoring Larry’s instruments at http://seismicnet.com/quakes/images you may have noticed two real-time helicord records generated by the single-pendulum instrument (N-S orientation) that he placed online. The raw-data-train is lctst.gif, which has been high-pass filtered (corner frequency of 10 mHz) before display. The unfiltered waveform is available via download upon request from Larry. This lctst is best suited to the real-time display of earthquakes local to the Redwood City, CA site. For registering teleseismic earthquakes real-time, Larry has also provided lctst1.gif, which is the numerical integration of lctst after first doing a high-pass filter. This operation on the VolksMeter’s output provides a display similar to what is provided by ‘bandwidth extension’ using electronic means in other instruments such as geophones. I was pleased to see John Lahr provide links on his webpage describing (i) transfer function differences between velocity and position sensing, and (ii) discussion of the zero-length spring that was invented by physicist Lucien LaCoste in the early part of last century. There are some things that need seriously to be clarified concerning theory of seismometers, since there is so much confusion; not only among amateur seismologists, but also even many professional geoscientists. Ultimately, the ONLY source of seismograph excitation (no matter the instrument design) is ENERGY. Additionally, the ONLY thing that delivers energy to the seismometer is Earth’s ACCELERATION at the site of the instrument. This is true not only for the instrument’s response to earthquake waves whose periods are shorter than about 300 s, but also for earth ‘hum’ in which the instrument responds mainly to tilt, when the periods are greater than about 300 to 1000 s. Keep in mind that it is very difficult to see a 300 to 1000 s periodic signal with a velocity sensor. It is equivalent to trying to look at a very low frequency signal with an oscilloscope using a.c. coupling. Only d.c. coupling (position sensing) is appropriate in this case. There is a dramatic difference between the forcing functions of tilt as contrasted with horizontal ground acceleration. The tilt response is independent of frequency, whereas the response to earthquakes (horizontal acceleration devoid of significant eigenmode oscillatory components) is the classic response given by John Lahr at the following website: http://jclahr.com/science/psn/response/index.html If you look at John’s six transfer function plots provided at http://jclahr.com/science/psn/response/plots.jpg it is the right-most pair (response to acceleration) that ‘summarize the physics’ of how a seismometer operates. Yes, one can configure an instrument to plot data according to any one of the six possibilities John has indicated, but the response to acceleration is what ‘tells the story’ of performance. For frequencies above the natural frequency of the pendulum, a velocity sensor will always outperform a velocity sensor. On the other hand, for frequencies below the natural frequency, a position sensor will always outperform a velocity sensor (all things otherwise identical). I don’t know about you, but I’m not particularly interested in frequencies above 1 Hz. Our Volksmeter easily picks up dynamite blasts and other local disturbances that are nearly always manmade. Because the earth is so large, motions it exhibits in response to dynamic changes (earthquakes, tidal forces, ….) are at low frequencies (not high). At low frequencies where everybody seems increasingly interested in going (reason for bandwidth extension) there is no question of the superiority of position sensing over velocity sensing. Why this obvious fact is so muddled in the minds of so many is a great mystery to me. Maybe it’s because even classical physics is difficult for most everybody to understand. I have placed a paper on my webpage which speaks to this matter, titled ‘Seismometer design based on a simple theory of instrument-generated noise equivalent power: http://physics.mercer.edu/hpage/inep/inep.html For those of you who want to ‘escape the rut’ of velocity detection that has held folks captive for way too long—Larry and my other business partner, Les LaZar are positioned to provide you with reasonably-priced essential components to build your own version of the VolksMeter. Probably most of you will prefer to do this rather than pay the present $1000 ‘turnkey’ price for our single-pendulum instrument. I want to point out something that is the result of recently discovered physics—why small-mass instruments don’t perform well. Although conventional wisdom says that it’s because of Brownian motion (larger for smaller masses), this is not really the culprit. The performance limitation is really the result of internal friction problems that science is only beginning to understand. The smaller the seismic mass, the smaller the spring that supports it. The smaller the spring, the more significant is the internal friction associated with the ‘snap, crackle, pop’ of defect structural changes in the spring (processes that operate at the mesoscale). For decades we’ve recognized the all-important properties of defects in semiconductors (basis for p and n material of which devices are made), but until recently very little was understood concerning the importance of defects to internal friction that regulates the low-frequency performance of seismometers. The influence of defects is worse in instruments with springs than in those that use a pendulum, which is more inherently stable. Until better electronics came along, we were stuck with trying to improve low-frequency performance by going to lower natural frequencies of the mechanical oscillator. That is no longer the only viable solution. Although the pendulum lost favor years ago, it is making a comeback. The success of the Shackleford-Gunderson approach should have been a cue to many that the pendulum needed to be revisited. With the digital electronics of the AD7745 there are some advantages that did not exist when the S-G instrument was developed around its analog circuitry. For example, the noise of the Volksmeter electronics does not increase as rapidly with frequency-decrease as is true of analog circuitry (commercial standard in seismometry being synchronous detection). Dr. Randall Peters __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Simple pendulum response From: Pete Rowe ptrowe@......... Date: Wed, 6 Dec 2006 07:51:07 -0800 (PST) Hi Larry thanks for forwarding this good paper. There is a confusing typo in the 9th paragraph. Here is the sentence: For frequencies above the > natural frequency of the pendulum, a velocity sensor > will always outperform a > velocity sensor. I believe it should say "a velocity sensor will always outperform a position sensor" Pete --- Larry Cochrane wrote: > Hi Everyone, > > Dr. Randall Peters asked me to forward the following > message to the list. > > Regards, > Larry Cochrane > Redwood City, PSN > > I've been following with interest the discussions > concerning instrument > characteristics. Now that my schedule is easing > somewhat, I felt that I should get > involved. Should it happen that any of you respond > to these comments and don't hear > back from me for a while, it's because I will be > away for about a week to the Amer. > Geophys. Union Fall Conference in San Francisco > (starting 11 Dec.). There I will give > a 15 minute oral presentation titled "State of the > art Digital Seismograph" . The > abstract is posted at > http://www.agu.org/cgi-bin/sessions5?meeting=fm06&part=S14B&maxhits=400 > > The instrument which will be described (and also > demonstrated at one of the booths) > uses a "simple" compound pendulum with a natural > frequency of 0.92 Hz. It employs my > fully differential capacitive detector as a > displacement sensor (array form), with > electronics based in Analog Devices' new award > winning capacitance to digital > converter integrated circuit (AD7745). Kudo's to > our own Larry Cochrane as the > brains behind all of (i) the electronics hardware > necessary to do the I2C logic > operations required of the chip, and (ii) the > software operating system in the form > of WinSDR and WinQuake. > > For those of you who have been monitoring > Larry’s instruments at > http://seismicnet.com/quakes/images > you may have noticed two real-time helicord > records generated by the > single-pendulum instrument (N-S orientation) that he > placed online. The > raw-data-train is lctst.gif, which has been > high-pass filtered (corner frequency of > 10 mHz) before display. The unfiltered waveform is > available via download upon > request from Larry. This lctst is best suited to > the real-time display of > earthquakes local to the Redwood City, CA site. > > For registering teleseismic earthquakes > real-time, Larry has also provided > lctst1.gif, which is the numerical integration of > lctst after first doing a high-pass > filter. This operation on the VolksMeter’s output > provides a display similar to what > is provided by ‘bandwidth extension’ using > electronic means in other instruments such > as geophones. > > I was pleased to see John Lahr provide links > on his webpage describing (i) > transfer function differences between velocity and > position sensing, and (ii) > discussion of the zero-length spring that was > invented by physicist Lucien LaCoste in > the early part of last century. > > There are some things that need seriously to > be clarified concerning theory of > seismometers, since there is so much confusion; not > only among amateur seismologists, > but also even many professional geoscientists. > Ultimately, the ONLY source of > seismograph excitation (no matter the instrument > design) is ENERGY. Additionally, > the ONLY thing that delivers energy to the > seismometer is Earth’s ACCELERATION at the > site of the instrument. This is true not only for > the instrument’s response to > earthquake waves whose periods are shorter than > about 300 s, but also for earth ‘hum’ > in which the instrument responds mainly to tilt, > when the periods are greater than > about 300 to 1000 s. > > Keep in mind that it is very difficult to see a 300 > to 1000 s periodic signal with a > velocity sensor. It is equivalent to trying to look > at a very low frequency signal > with an oscilloscope using a.c. coupling. Only d.c. > coupling (position sensing) is > appropriate in this case. > > There is a dramatic difference between the > forcing functions of tilt as > contrasted with horizontal ground acceleration. The > tilt response is independent of > frequency, whereas the response to earthquakes > (horizontal acceleration devoid of > significant eigenmode oscillatory components) is the > classic response given by John > Lahr at the following website: > http://jclahr.com/science/psn/response/index.html > > If you look at John’s six transfer function > plots provided at > http://jclahr.com/science/psn/response/plots.jpg > it is the right-most pair (response to acceleration) > that ‘summarize the physics’ of > how a seismometer operates. Yes, one can configure > an instrument to plot data > according to any one of the six possibilities John > has indicated, but the response to > acceleration is what ‘tells the story’ of > performance. For frequencies above the > natural frequency of the pendulum, a velocity sensor > will always outperform a > velocity sensor. On the other hand, for frequencies > below the natural frequency, a > position sensor will always outperform a velocity > sensor (all things otherwise > identical). > > I don’t know about you, but I’m not > particularly interested in frequencies > above 1 Hz. Our Volksmeter easily picks up dynamite > blasts and other local > disturbances that are nearly always manmade. > Because the earth is so large, motions > it exhibits in response to dynamic changes > (earthquakes, tidal forces, ….) are at low > frequencies (not high). > > At low frequencies where everybody seems > increasingly interested in going > (reason for bandwidth extension) there is no > question of the superiority of position > sensing over velocity sensing. Why this obvious > fact is so muddled in the minds of > so many is a great mystery to me. Maybe it’s > because even classical physics is > difficult for most everybody to understand. > > I have placed a paper on my webpage which > speaks to this matter, titled > ‘Seismometer design based on a simple theory of > instrument-generated noise equivalent > power: > http://physics.mercer.edu/hpage/inep/inep.html > > For those of you who want to ‘escape the rut’ > of velocity detection that has > held folks captive for way too long—Larry and my > other business partner, Les LaZar > are positioned to provide you with reasonably-priced > essential components to build > your own version of the VolksMeter. Probably most > of you will prefer to do this > rather than pay the present $1000 ‘turnkey’ price > for our single-pendulum instrument. > > I want to point out something that is the > result of recently discovered > physics—why small-mass instruments don’t perform > well. Although conventional wisdom > says that it’s because of Brownian motion (larger > for smaller masses), this is not > really the culprit. The performance limitation is > really the result of internal > friction problems that science is only beginning to > understand. The smaller the > seismic mass, the smaller the spring that supports > it. The smaller the spring, the > more significant is the internal friction associated > with the ‘snap, crackle, pop’ of > defect structural changes in the spring (processes > that operate at the mesoscale). > For decades we’ve recognized the all-important > properties of defects in > semiconductors (basis for p and n material of which > devices are made), but until > recently very little was understood concerning the > importance of defects to internal > friction that regulates the low-frequency > performance of seismometers. > > The influence of defects is worse in > instruments with springs than in those > that use a pendulum, which is more inherently > stable. Until better electronics came > along, we were stuck with trying to improve > low-frequency performance by going to > lower natural frequencies of the mechanical > oscillator. That is no longer the only > viable solution. Although the pendulum lost favor > years === message truncated === ____________________________________________________________________________________ Want to start your own business? Learn how on Yahoo! Small Business. http://smallbusiness.yahoo.com/r-index __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: AGU meeting From: John or Jan Lahr JohnJan@........ Date: Wed, 06 Dec 2006 09:32:27 -0800 Is anyone interest in getting together this year during the AGU? Possibly dinner or lunch one day. Cheers, John #################################/ John C. Lahr ################################/ Emeritus Seismologist ###############################/ U.S. Geological Survey ==========================/ Central Region Geologic Hazards Team #############################//################################# ############################//################################## PO Box 548 /################################### Corvallis, Oregon 97339 /=============================== Phone: (541) 758-2699 /#################################### Cell: (541) 740-4844 /##################################### Fax: (413) 658-2699 /###################################### johnjan@........ /####################################### http://jclahr.com/science/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Pendulum response and Roberts' circuit From: Stephen & Kathy skmort@............ Date: Wed, 06 Dec 2006 10:31:20 -0800 Thanks Chris,, I have a little breadboard that I use to start with, then when I'm happy with the results I move it to a project board! For a while, I will crunch numbers for component values for my 4.5 second system, then we will play,, ha!! I spent about 28 years repairing aircraft electronics and test systems! Didn't do much engineering,, ha, but with the little heads up, I should be able to figure it out now. Looks like I will set the unity gain at about 4.5 sec and the cut off at about 60 seconds with a gain value of about 6 db per octave per stage and see what happens,,, hopefully that will give me a good signal response to about 30 seconds? If it proves to be a problem, I'll try a cut off of about 40 seconds and response to about 20 seconds? thanks again for the help and opamp advice, Stephen ChrisAtUpw@....... wrote: > In a message dated 2006/12/05, skmort@............ writes: > >> OK, so which components would we change, and to what value for a 2 >> Hz and a 0.222 hz (4.5 sec) system? >> I might have to break out my soldering iron, ha! >> Thanks, >> Stephen > > > Hi Stephen, > > If f is the resonant frequency of the sensor, you make 1 / > 2xPixfxCxR1 = 1.09 according to Roberts. I am not sure exactly why he > chose this. It could explain the small hump in the combined > characteristic. > The Max gain is R2 / R1 > The lower turnover frequency is 1 / 2xPixC1xR2 This has been > set to ~1/2 the lowest response frequency in the Roberts circuit. > You need two units in series. > Roberts reported significant levels of VLF noise, so it might > be a good idea to follow up the compensation circuits with a two / > four pole high pass Butterworth filter set to about the lower desired > frequency. > If you want to use the circuit at long periods, you may need to > use some CAZ opamps MAX430, LTC1150 etc. They reject 1/f noise. > Otherwise LF411, OP07, LF412 etc are OK > The optimum place to insert this circuit is between the first > opamp and the low pass filters. > > How about investing in a temperature compensated soldering iron > which plugs in.....? Or make an Experimenter Board plug in version first? > > Regards, > > Chris Chapman Thanks Chris,,   I have a little breadboard that I use to start with, then when I'm happy with the results I move it to a project board!   For a while, I will crunch numbers for component values for my 4.5 second system, then we will play,,  ha!!    I spent about 28 years repairing aircraft electronics and test systems!   Didn't do much engineering,, ha,  but with the little heads up, I should be able to figure it out now.     Looks like I will set the unity gain at about 4.5 sec  and the cut off at about 60 seconds with a gain value of about 6 db per octave  per stage  and see what happens,,,   hopefully that will give me a good signal response to about 30 seconds?    If it proves to be a problem, I'll try a cut off of about 40 seconds and response to about 20 seconds?
thanks again for the help and opamp advice,
  Stephen

ChrisAtUpw@....... wrote:
In a message dated 2006/12/05, skmort@............ writes:

OK, so which components would we change, and to what value for a 2
Hz and a 0.222 hz (4.5 sec) system?
I might have to break out my soldering iron, ha!
Thanks,
Stephen


Hi Stephen,

       If f is the resonant frequency of the sensor, you make 1 / 2xPixfxCxR1 = 1.09 according to Roberts. I am not sure exactly why he chose this. It could explain the small hump in the combined characteristic.
       The Max gain is R2 / R1
       The lower turnover frequency is 1 / 2xPixC1xR2 This has been set to ~1/2 the lowest response frequency in the Roberts circuit.
       You need two units in series.
       Roberts reported significant levels of VLF noise, so it might be a good idea to follow up the compensation circuits with a two / four pole high pass Butterworth filter set to about the lower desired frequency.
       If you want to use the circuit at long periods, you may need to use some CAZ opamps MAX430, LTC1150 etc. They reject 1/f noise. Otherwise LF411, OP07, LF412 etc are OK
       The optimum place to insert this circuit is between the first opamp and the low pass filters.

       How about investing in a temperature compensated soldering iron which plugs in.....? Or make an Experimenter Board plug in version first?

       Regards,

       Chris Chapman
Subject: Re: Simple pendulum response From: "Jerry Payton" gpayton880@....... Date: Wed, 6 Dec 2006 14:08:23 -0600 Myself, being new to the hobby, I would like more information about this "Volksmeter" devise described in this letter. Where may I find more, photos and etc. Regards, Jerry ----- Original Message ----- From: Larry Cochrane To: psn-l@.............. Sent: Wednesday, December 06, 2006 3:50 AM Subject: Simple pendulum response Hi Everyone, Dr. Randall Peters asked me to forward the following message to the list. Regards, Larry Cochrane Redwood City, PSN I've been following with interest the discussions concerning instrument characteristics. Now that my schedule is easing somewhat, I felt that I should get involved. Should it happen that any of you respond to these comments and don't hear back from me for a while, it's because I will be away for about a week to the Amer. Geophys. Union Fall Conference in San Francisco (starting 11 Dec.). There I will give a 15 minute oral presentation titled "State of the art Digital Seismograph" . The abstract is posted at http://www.agu.org/cgi-bin/sessions5?meeting=fm06&part=S14B&maxhits=400 The instrument which will be described (and also demonstrated at one of the booths) uses a "simple" compound pendulum with a natural frequency of 0.92 Hz. It employs my fully differential capacitive detector as a displacement sensor (array form), with electronics based in Analog Devices' new award winning capacitance to digital converter integrated circuit (AD7745). Kudo's to our own Larry Cochrane as the brains behind all of (i) the electronics hardware necessary to do the I2C logic operations required of the chip, and (ii) the software operating system in the form of WinSDR and WinQuake. For those of you who have been monitoring Larry's instruments at http://seismicnet.com/quakes/images you may have noticed two real-time helicord records generated by the single-pendulum instrument (N-S orientation) that he placed online. The raw-data-train is lctst.gif, which has been high-pass filtered (corner frequency of 10 mHz) before display. The unfiltered waveform is available via download upon request from Larry. This lctst is best suited to the real-time display of earthquakes local to the Redwood City, CA site. For registering teleseismic earthquakes real-time, Larry has also provided lctst1.gif, which is the numerical integration of lctst after first doing a high-pass filter. This operation on the VolksMeter's output provides a display similar to what is provided by 'bandwidth extension' using electronic means in other instruments such as geophones. I was pleased to see John Lahr provide links on his webpage describing (i) transfer function differences between velocity and position sensing, and (ii) discussion of the zero-length spring that was invented by physicist Lucien LaCoste in the early part of last century. There are some things that need seriously to be clarified concerning theory of seismometers, since there is so much confusion; not only among amateur seismologists, but also even many professional geoscientists. Ultimately, the ONLY source of seismograph excitation (no matter the instrument design) is ENERGY. Additionally, the ONLY thing that delivers energy to the seismometer is Earth's ACCELERATION at the site of the instrument. This is true not only for the instrument's response to earthquake waves whose periods are shorter than about 300 s, but also for earth 'hum' in which the instrument responds mainly to tilt, when the periods are greater than about 300 to 1000 s. Keep in mind that it is very difficult to see a 300 to 1000 s periodic signal with a velocity sensor. It is equivalent to trying to look at a very low frequency signal with an oscilloscope using a.c. coupling. Only d.c. coupling (position sensing) is appropriate in this case. There is a dramatic difference between the forcing functions of tilt as contrasted with horizontal ground acceleration. The tilt response is independent of frequency, whereas the response to earthquakes (horizontal acceleration devoid of significant eigenmode oscillatory components) is the classic response given by John Lahr at the following website: http://jclahr.com/science/psn/response/index.html If you look at John's six transfer function plots provided at http://jclahr.com/science/psn/response/plots.jpg it is the right-most pair (response to acceleration) that 'summarize the physics' of how a seismometer operates. Yes, one can configure an instrument to plot data according to any one of the six possibilities John has indicated, but the response to acceleration is what 'tells the story' of performance. For frequencies above the natural frequency of the pendulum, a velocity sensor will always outperform a velocity sensor. On the other hand, for frequencies below the natural frequency, a position sensor will always outperform a velocity sensor (all things otherwise identical). I don't know about you, but I'm not particularly interested in frequencies above 1 Hz. Our Volksmeter easily picks up dynamite blasts and other local disturbances that are nearly always manmade. Because the earth is so large, motions it exhibits in response to dynamic changes (earthquakes, tidal forces, ..) are at low frequencies (not high). At low frequencies where everybody seems increasingly interested in going (reason for bandwidth extension) there is no question of the superiority of position sensing over velocity sensing. Why this obvious fact is so muddled in the minds of so many is a great mystery to me. Maybe it's because even classical physics is difficult for most everybody to understand. I have placed a paper on my webpage which speaks to this matter, titled 'Seismometer design based on a simple theory of instrument-generated noise equivalent power: http://physics.mercer.edu/hpage/inep/inep.html For those of you who want to 'escape the rut' of velocity detection that has held folks captive for way too long-Larry and my other business partner, Les LaZar are positioned to provide you with reasonably-priced essential components to build your own version of the VolksMeter. Probably most of you will prefer to do this rather than pay the present $1000 'turnkey' price for our single-pendulum instrument. I want to point out something that is the result of recently discovered physics-why small-mass instruments don't perform well. Although conventional wisdom says that it's because of Brownian motion (larger for smaller masses), this is not really the culprit. The performance limitation is really the result of internal friction problems that science is only beginning to understand. The smaller the seismic mass, the smaller the spring that supports it. The smaller the spring, the more significant is the internal friction associated with the 'snap, crackle, pop' of defect structural changes in the spring (processes that operate at the mesoscale). For decades we've recognized the all-important properties of defects in semiconductors (basis for p and n material of which devices are made), but until recently very little was understood concerning the importance of defects to internal friction that regulates the low-frequency performance of seismometers. The influence of defects is worse in instruments with springs than in those that use a pendulum, which is more inherently stable. Until better electronics came along, we were stuck with trying to improve low-frequency performance by going to lower natural frequencies of the mechanical oscillator. That is no longer the only viable solution. Although the pendulum lost favor years ago, it is making a comeback. The success of the Shackleford-Gunderson approach should have been a cue to many that the pendulum needed to be revisited. With the digital electronics of the AD7745 there are some advantages that did not exist when the S-G instrument was developed around its analog circuitry. For example, the noise of the Volksmeter electronics does not increase as rapidly with frequency-decrease as is true of analog circuitry (commercial standard in seismometry being synchronous detection). Dr. Randall Peters __________________________________________________________ Public Seismic Network Mailing List (PSN-L) To leave this list email PSN-L-REQUEST@.............. with the body of the message (first line only): unsubscribe See http://www.seismicnet.com/maillist.html for more information.
Myself, being new to the hobby, I would like more information about = this=20 "Volksmeter" devise described in this letter.  Where may I find = more,=20 photos and etc.
 
Regards,
Jerry
 
----- Original Message -----
From:=20 Larry=20 Cochrane
Sent: Wednesday, December 06, = 2006 3:50=20 AM
Subject: Simple pendulum = response

Hi Everyone,

Dr. Randall Peters asked me to = forward the=20 following message to the list.

Regards,
Larry = Cochrane
Redwood=20 City, PSN

I've been following with interest the discussions = concerning=20 instrument
characteristics.  Now that my schedule is easing = somewhat,=20 I felt that I should get
involved.  Should it happen that any = of you=20 respond to these comments and don't hear
back from me for a while, = it's=20 because I will be away for about a week to the Amer.
Geophys. = Union Fall=20 Conference in San Francisco (starting 11 Dec.). There I will give =
a 15=20 minute oral presentation titled "State of the art Digital Seismograph" = .. =20 The
abstract is posted at
http://www.agu.org/cgi-bin/sessions5?meeting=3Dfm06= &part=3DS14B&maxhits=3D400

The=20 instrument which will be described (and also demonstrated at one of = the=20 booths)
uses a "simple" compound pendulum with a natural frequency = of 0.92=20 Hz.  It employs my
fully differential capacitive detector as = a=20 displacement sensor (array form), with
electronics based in Analog = Devices' new award winning capacitance to digital
converter = integrated=20 circuit (AD7745).  Kudo's to our own Larry Cochrane as the =
brains=20 behind all of (i) the electronics hardware necessary to do the I2C = logic=20
operations required of the chip, and (ii) the software operating = system in=20 the form
of WinSDR and WinQuake.

     = For those=20 of you who have been monitoring Larry's instruments at
http://seismicnet.com/quakes= /images
 =20 you may have noticed two real-time helicord records generated by the=20
single-pendulum instrument (N-S orientation) that he placed = online. =20 The
raw-data-train is lctst.gif, which has been high-pass filtered = (corner=20 frequency of
10 mHz) before display.  The unfiltered waveform = is=20 available via download upon
request from Larry.  This lctst = is best=20 suited to the real-time display of
earthquakes local to the = Redwood City,=20 CA site.

      For registering = teleseismic=20 earthquakes real-time, Larry has also provided
lctst1.gif, which = is the=20 numerical integration of lctst after first doing a high-pass =
filter. =20 This operation on the VolksMeter's output provides a display similar = to what=20
is provided by 'bandwidth extension' using electronic means in = other=20 instruments such
as = geophones.

      =20 I was pleased to see John Lahr provide links on his webpage describing = (i)=20
transfer function differences between velocity and position = sensing, and=20 (ii)
discussion of the zero-length spring that was invented by = physicist=20 Lucien LaCoste in
the early part of last=20 century.

      There are some things = that need=20 seriously to be clarified concerning theory of
seismometers, since = there=20 is so much confusion; not only among amateur seismologists,
but = also even=20 many professional geoscientists.  Ultimately, the ONLY source of=20
seismograph excitation (no matter the instrument design) is = ENERGY. =20 Additionally,
the ONLY thing that delivers energy to the = seismometer is=20 Earth's ACCELERATION at the
site of the instrument.  This is = true not=20 only for the instrument's response to
earthquake waves whose = periods are=20 shorter than about 300 s, but also for earth 'hum'
in which the = instrument=20 responds mainly to tilt, when the periods are greater than
about = 300 to=20 1000 s.

Keep in mind that it is very difficult to see a 300 to = 1000 s=20 periodic signal with a
velocity sensor.  It is equivalent to = trying=20 to look at a very low frequency signal
with an oscilloscope using = a.c.=20 coupling.  Only d.c. coupling (position sensing) is =
appropriate in=20 this case.

        There is = a=20 dramatic difference between the forcing functions of tilt as =
contrasted=20 with horizontal ground acceleration. The tilt response is independent = of=20
frequency, whereas the response to earthquakes (horizontal = acceleration=20 devoid of
significant eigenmode oscillatory components) is the = classic=20 response given by John
Lahr at the following website:
http://jclahr.= com/science/psn/response/index.html

   =20 If you look at John's six transfer function plots provided at
http://jclahr.c= om/science/psn/response/plots.jpg
it=20 is the right-most pair (response to acceleration) that 'summarize the = physics'=20 of
how a seismometer operates.  Yes, one can configure an = instrument=20 to plot data
according to any one of the six possibilities John = has=20 indicated, but the response to
acceleration is what 'tells the = story' of=20 performance.  For frequencies above the
natural frequency of = the=20 pendulum, a velocity sensor will always outperform a
velocity=20 sensor.  On the other hand, for frequencies below the natural = frequency,=20 a
position sensor will always outperform a velocity sensor (all = things=20 otherwise
identical).

      I = don't know=20 about you, but I'm not particularly interested in frequencies =
above 1=20 Hz.  Our Volksmeter easily picks up dynamite blasts and other = local=20
disturbances that are nearly always manmade.  Because the = earth is so=20 large, motions
it exhibits in response to dynamic changes = (earthquakes,=20 tidal forces, ..) are at low
frequencies (not=20 high).

       At low frequencies = where=20 everybody seems increasingly interested in going
(reason for = bandwidth=20 extension) there is no question of the superiority of position =
sensing=20 over velocity sensing.  Why this obvious fact is so muddled in = the minds=20 of
so many is a great mystery to me.  Maybe it's because even = classical physics is
difficult for most everybody to=20 understand.

      I have placed a = paper on my=20 webpage which speaks to this matter, titled
'Seismometer design = based on a=20 simple theory of instrument-generated noise equivalent =
power:
http://physics.me= rcer.edu/hpage/inep/inep.html

     &n= bsp;=20 For those of you who want to 'escape the rut' of velocity detection = that has=20
held folks captive for way too long-Larry and my other business = partner,=20 Les LaZar
are positioned to provide you with reasonably-priced = essential=20 components to build
your own version of the VolksMeter.  = Probably=20 most of you will prefer to do this
rather than pay the present = $1000=20 'turnkey' price for our single-pendulum=20 instrument.

     I want to point out = something that=20 is the result of recently discovered
physics-why small-mass = instruments=20 don't perform well.  Although conventional wisdom
says that = it's=20 because of Brownian motion (larger for smaller masses), this is not =
really=20 the culprit.  The performance limitation is really the result of = internal=20
friction problems that science is only beginning to = understand.  The=20 smaller the
seismic mass, the smaller the spring that supports = it. =20 The smaller the spring, the
more significant is the internal = friction=20 associated with the 'snap, crackle, pop' of
defect structural = changes in=20 the spring (processes that operate at the mesoscale).
For decades = we've=20 recognized the all-important properties of defects in =
semiconductors=20 (basis for p and n material of which devices are made), but until =
recently=20 very little was understood concerning the importance of defects to = internal=20
friction that regulates the low-frequency performance of=20 seismometers.

      The influence of = defects=20 is worse in instruments with springs than in those
that use a = pendulum,=20 which is more inherently stable.  Until better electronics came=20
along, we were stuck with trying to improve low-frequency = performance by=20 going to
lower natural frequencies of the mechanical = oscillator. =20 That is no longer the only
viable solution.  Although the = pendulum=20 lost favor years ago, it is making a
comeback.  The success = of the=20 Shackleford-Gunderson approach should have been a cue
to many that = the=20 pendulum needed to be revisited.  With the digital electronics of =
the=20 AD7745 there are some advantages that did not exist when the S-G = instrument=20 was
developed around its analog circuitry.  For example, the = noise of=20 the Volksmeter
electronics does not increase as rapidly with=20 frequency-decrease as is true of analog
circuitry (commercial = standard in=20 seismometry being synchronous detection).

Dr. Randall=20 = Peters



___________________________________________________= _______

Public=20 Seismic Network Mailing List (PSN-L)

To leave this list email = PSN-L-REQUEST@............... =20 with
the body of the message (first line only): unsubscribe
See = http://www.seismicnet.co= m/maillist.html=20 for more information.
Subject: Re: AGU meeting From: Dave Willey davewilley@............. Date: Wed, 6 Dec 2006 14:49:30 -0800 (PST) Depending on the date/time that the group decides,, I might be able to make a face to face meeting during my end of semester crunch. Dave Willey John or Jan Lahr wrote: Is anyone interest in getting together this year during the AGU? Possibly dinner or lunch one day. Cheers, John #################################/ John C. Lahr ################################/ Emeritus Seismologist ###############################/ U.S. Geological Survey ==========================/ Central Region Geologic Hazards Team #############################//################################# ############################//################################## PO Box 548 /################################### Corvallis, Oregon 97339 /=============================== Phone: (541) 758-2699 /#################################### Cell: (541) 740-4844 /##################################### Fax: (413) 658-2699 /###################################### johnjan@........ /####################################### http://jclahr.com/science/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Depending on the date/time that the group decides,, I might be able to make a face to face meeting during my end of semester crunch.


Dave Willey


John or Jan Lahr <JohnJan@........> wrote:
Is anyone interest in getting together this year during the
AGU? Possibly dinner or lunch one day.

Cheers,
John


#################################/ John C. Lahr
################################/ Emeritus Seismologist
###############################/ U.S. Geological Survey
==========================/ Central Region Geologic Hazards Team
#############################//#################################
############################//##################################
PO Box 548 /###################################
Corvallis, Oregon 97339 /===============================
Phone: (541) 758-2699 /####################################
Cell: (541) 740-4844 /#####################################
Fax: (413) 658-2699 /######################################
johnjan@lahr.org /#######################################
http://jclahr.com/science/


__________________________________________________________

Public Seismic Network Mailing List (PSN-L)

To leave this list email PSN-L-REQUEST@SEISMICNET.COM with
the body of the message (first line only): unsubscribe
See http://www.seismicnet.com/maillist.html for more information.

Subject: Re: AGU meeting From: Larry Cochrane lcochrane@.............. Date: Wed, 06 Dec 2006 18:24:07 -0800 Hi John, I'm interested. I will be at the AGU meeting all week long, so any day except Wednesday the 13th works for me. Regards, Larry Cochrane Redwood City, PSN John or Jan Lahr wrote: > Is anyone interest in getting together this year during the > AGU? Possibly dinner or lunch one day. > > Cheers, > John > > > #################################/ John C. Lahr > ################################/ Emeritus Seismologist > ###############################/ U.S. Geological Survey > ==========================/ Central Region Geologic Hazards Team > #############################//################################# > ############################//################################## > PO Box 548 /################################### > Corvallis, Oregon 97339 /=============================== > Phone: (541) 758-2699 /#################################### > Cell: (541) 740-4844 /##################################### > Fax: (413) 658-2699 /###################################### > johnjan@........ /####################################### > http://jclahr.com/science/ > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Simple pendulum response From: Larry Cochrane lcochrane@.............. Date: Wed, 06 Dec 2006 18:39:17 -0800 Hi Pete, You are correct, it should have read "velocity sensor will always outperform a position sensor" Regards, -Larry Pete Rowe wrote: > Hi Larry > thanks for forwarding this good paper. There is a > confusing typo in the 9th paragraph. Here is the > sentence: > For frequencies above the >> natural frequency of the pendulum, a velocity sensor >> will always outperform a >> velocity sensor. > > I believe it should say "a velocity sensor will always > outperform a position sensor" > > Pete > > --- Larry Cochrane wrote: > >> Hi Everyone, >> >> Dr. Randall Peters asked me to forward the following >> message to the list. >> >> Regards, >> Larry Cochrane >> Redwood City, PSN >> >> I've been following with interest the discussions >> concerning instrument >> characteristics. Now that my schedule is easing >> somewhat, I felt that I should get >> involved. Should it happen that any of you respond >> to these comments and don't hear >> back from me for a while, it's because I will be >> away for about a week to the Amer. >> Geophys. Union Fall Conference in San Francisco >> (starting 11 Dec.). There I will give >> a 15 minute oral presentation titled "State of the >> art Digital Seismograph" . The >> abstract is posted at >> > http://www.agu.org/cgi-bin/sessions5?meeting=fm06&part=S14B&maxhits=400 >> >> The instrument which will be described (and also >> demonstrated at one of the booths) >> uses a "simple" compound pendulum with a natural >> frequency of 0.92 Hz. It employs my >> fully differential capacitive detector as a >> displacement sensor (array form), with >> electronics based in Analog Devices' new award >> winning capacitance to digital >> converter integrated circuit (AD7745). Kudo's to >> our own Larry Cochrane as the >> brains behind all of (i) the electronics hardware >> necessary to do the I2C logic >> operations required of the chip, and (ii) the >> software operating system in the form >> of WinSDR and WinQuake. >> >> For those of you who have been monitoring >> Larry’s instruments at >> http://seismicnet.com/quakes/images >> you may have noticed two real-time helicord >> records generated by the >> single-pendulum instrument (N-S orientation) that he >> placed online. The >> raw-data-train is lctst.gif, which has been >> high-pass filtered (corner frequency of >> 10 mHz) before display. The unfiltered waveform is >> available via download upon >> request from Larry. This lctst is best suited to >> the real-time display of >> earthquakes local to the Redwood City, CA site. >> >> For registering teleseismic earthquakes >> real-time, Larry has also provided >> lctst1.gif, which is the numerical integration of >> lctst after first doing a high-pass >> filter. This operation on the VolksMeter’s output >> provides a display similar to what >> is provided by ‘bandwidth extension’ using >> electronic means in other instruments such >> as geophones. >> >> I was pleased to see John Lahr provide links >> on his webpage describing (i) >> transfer function differences between velocity and >> position sensing, and (ii) >> discussion of the zero-length spring that was >> invented by physicist Lucien LaCoste in >> the early part of last century. >> >> There are some things that need seriously to >> be clarified concerning theory of >> seismometers, since there is so much confusion; not >> only among amateur seismologists, >> but also even many professional geoscientists. >> Ultimately, the ONLY source of >> seismograph excitation (no matter the instrument >> design) is ENERGY. Additionally, >> the ONLY thing that delivers energy to the >> seismometer is Earth’s ACCELERATION at the >> site of the instrument. This is true not only for >> the instrument’s response to >> earthquake waves whose periods are shorter than >> about 300 s, but also for earth ‘hum’ >> in which the instrument responds mainly to tilt, >> when the periods are greater than >> about 300 to 1000 s. >> >> Keep in mind that it is very difficult to see a 300 >> to 1000 s periodic signal with a >> velocity sensor. It is equivalent to trying to look >> at a very low frequency signal >> with an oscilloscope using a.c. coupling. Only d.c. >> coupling (position sensing) is >> appropriate in this case. >> >> There is a dramatic difference between the >> forcing functions of tilt as >> contrasted with horizontal ground acceleration. The >> tilt response is independent of >> frequency, whereas the response to earthquakes >> (horizontal acceleration devoid of >> significant eigenmode oscillatory components) is the >> classic response given by John >> Lahr at the following website: >> http://jclahr.com/science/psn/response/index.html >> >> If you look at John’s six transfer function >> plots provided at >> http://jclahr.com/science/psn/response/plots.jpg >> it is the right-most pair (response to acceleration) >> that ‘summarize the physics’ of >> how a seismometer operates. Yes, one can configure >> an instrument to plot data >> according to any one of the six possibilities John >> has indicated, but the response to >> acceleration is what ‘tells the story’ of >> performance. For frequencies above the >> natural frequency of the pendulum, a velocity sensor >> will always outperform a >> velocity sensor. On the other hand, for frequencies >> below the natural frequency, a >> position sensor will always outperform a velocity >> sensor (all things otherwise >> identical). >> >> I don’t know about you, but I’m not >> particularly interested in frequencies >> above 1 Hz. Our Volksmeter easily picks up dynamite >> blasts and other local >> disturbances that are nearly always manmade. >> Because the earth is so large, motions >> it exhibits in response to dynamic changes >> (earthquakes, tidal forces, ….) are at low >> frequencies (not high). >> >> At low frequencies where everybody seems >> increasingly interested in going >> (reason for bandwidth extension) there is no >> question of the superiority of position >> sensing over velocity sensing. Why this obvious >> fact is so muddled in the minds of >> so many is a great mystery to me. Maybe it’s >> because even classical physics is >> difficult for most everybody to understand. >> >> I have placed a paper on my webpage which >> speaks to this matter, titled >> ‘Seismometer design based on a simple theory of >> instrument-generated noise equivalent >> power: >> http://physics.mercer.edu/hpage/inep/inep.html >> >> For those of you who want to ‘escape the rut’ >> of velocity detection that has >> held folks captive for way too long—Larry and my >> other business partner, Les LaZar >> are positioned to provide you with reasonably-priced >> essential components to build >> your own version of the VolksMeter. Probably most >> of you will prefer to do this >> rather than pay the present $1000 ‘turnkey’ price >> for our single-pendulum instrument. >> >> I want to point out something that is the >> result of recently discovered >> physics—why small-mass instruments don’t perform >> well. Although conventional wisdom >> says that it’s because of Brownian motion (larger >> for smaller masses), this is not >> really the culprit. The performance limitation is >> really the result of internal >> friction problems that science is only beginning to >> understand. The smaller the >> seismic mass, the smaller the spring that supports >> it. The smaller the spring, the >> more significant is the internal friction associated >> with the ‘snap, crackle, pop’ of >> defect structural changes in the spring (processes >> that operate at the mesoscale). >> For decades we’ve recognized the all-important >> properties of defects in >> semiconductors (basis for p and n material of which >> devices are made), but until >> recently very little was understood concerning the >> importance of defects to internal >> friction that regulates the low-frequency >> performance of seismometers. >> >> The influence of defects is worse in >> instruments with springs than in those >> that use a pendulum, which is more inherently >> stable. Until better electronics came >> along, we were stuck with trying to improve >> low-frequency performance by going to >> lower natural frequencies of the mechanical >> oscillator. That is no longer the only >> viable solution. Although the pendulum lost favor >> years > === message truncated === > > > > > ____________________________________________________________________________________ > Want to start your own business? > Learn how on Yahoo! Small Business. > http://smallbusiness.yahoo.com/r-index > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: AGU meeting From: John or Jan Lahr JohnJan@........ Date: Wed, 06 Dec 2006 21:15:20 -0800 I can make any day but Tuesday or Friday. Larry can't make it Wednesday. That leaves Monday or Thursday. Dave Willey, which would be better for you? John At 06:24 PM 12/6/2006, you wrote: >Hi John, > >I'm interested. I will be at the AGU meeting all week long, so any >day except Wednesday the 13th works for me. > >Regards, >Larry Cochrane >Redwood City, PSN > >John or Jan Lahr wrote: >>Is anyone interest in getting together this year during the >>AGU? Possibly dinner or lunch one day. >>Cheers, >>John >> >>#################################/ John C. Lahr >>################################/ Emeritus Seismologist >>###############################/ U.S. Geological Survey >>==========================/ Central Region Geologic Hazards Team >>#############################//################################# >>############################//################################## >> PO Box >> 548 /################################### >> Corvallis, Oregon 97339 /=============================== >> Phone: (541) 758-2699 /#################################### >> Cell: (541) 740-4844 /##################################### >> Fax: (413) 658-2699 /###################################### >> johnjan@........ /####################################### >> http://jclahr.com/science __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Volksmeter information From: Larry Cochrane lcochrane@.............. Date: Wed, 06 Dec 2006 23:23:46 -0800 All, With Randall's permission I placed his Power Point presentation on my web site here: http://www.seismicnet.com/info/State-of-the-art_Digital_Seismograph.ppt Using the Power Point file I created this web page: http://www.seismicnet.com/volksmeter/Volksmeter.html But this web page may not work with all browsers. Regards, Larry Cochrane Redwood City, PSN Jerry Payton wrote: > > Myself, being new to the hobby, I would like more information about this > "Volksmeter" devise described in this letter. Where may I find more, > photos and etc. > > Regards, > Jerry > > > ----- Original Message ----- > *From:* Larry Cochrane > *To:* psn-l@.............. > *Sent:* Wednesday, December 06, 2006 3:50 AM > *Subject:* Simple pendulum response > > Hi Everyone, > > Dr. Randall Peters asked me to forward the following message to the > list. > > Regards, > Larry Cochrane > Redwood City, PSN > > I've been following with interest the discussions concerning instrument > characteristics. Now that my schedule is easing somewhat, I felt > that I should get > involved. Should it happen that any of you respond to these > comments and don't hear > back from me for a while, it's because I will be away for about a > week to the Amer. > Geophys. Union Fall Conference in San Francisco (starting 11 Dec.). > There I will give > a 15 minute oral presentation titled "State of the art Digital > Seismograph" . The > abstract is posted at > http://www.agu.org/cgi-bin/sessions5?meeting=fm06&part=S14B&maxhits=400 > > > The instrument which will be described (and also demonstrated at one > of the booths) > uses a "simple" compound pendulum with a natural frequency of 0.92 > Hz. It employs my > fully differential capacitive detector as a displacement sensor > (array form), with > electronics based in Analog Devices' new award winning capacitance > to digital > converter integrated circuit (AD7745). Kudo's to our own Larry > Cochrane as the > brains behind all of (i) the electronics hardware necessary to do > the I2C logic > operations required of the chip, and (ii) the software operating > system in the form > of WinSDR and WinQuake. > > For those of you who have been monitoring Larry's instruments at > http://seismicnet.com/quakes/images > you may have noticed two real-time helicord records generated by the > single-pendulum instrument (N-S orientation) that he placed online. > The > raw-data-train is lctst.gif, which has been high-pass filtered > (corner frequency of > 10 mHz) before display. The unfiltered waveform is available via > download upon > request from Larry. This lctst is best suited to the real-time > display of > earthquakes local to the Redwood City, CA site. > > For registering teleseismic earthquakes real-time, Larry has > also provided > lctst1.gif, which is the numerical integration of lctst after first > doing a high-pass > filter. This operation on the VolksMeter's output provides a > display similar to what > is provided by 'bandwidth extension' using electronic means in other > instruments such > as geophones. > > I was pleased to see John Lahr provide links on his webpage > describing (i) > transfer function differences between velocity and position sensing, > and (ii) > discussion of the zero-length spring that was invented by physicist > Lucien LaCoste in > the early part of last century. > > There are some things that need seriously to be clarified > concerning theory of > seismometers, since there is so much confusion; not only among > amateur seismologists, > but also even many professional geoscientists. Ultimately, the ONLY > source of > seismograph excitation (no matter the instrument design) is ENERGY. > Additionally, > the ONLY thing that delivers energy to the seismometer is Earth's > ACCELERATION at the > site of the instrument. This is true not only for the instrument's > response to > earthquake waves whose periods are shorter than about 300 s, but > also for earth 'hum' > in which the instrument responds mainly to tilt, when the periods > are greater than > about 300 to 1000 s. > > Keep in mind that it is very difficult to see a 300 to 1000 s > periodic signal with a > velocity sensor. It is equivalent to trying to look at a very low > frequency signal > with an oscilloscope using a.c. coupling. Only d.c. coupling > (position sensing) is > appropriate in this case. > > There is a dramatic difference between the forcing functions > of tilt as > contrasted with horizontal ground acceleration. The tilt response is > independent of > frequency, whereas the response to earthquakes (horizontal > acceleration devoid of > significant eigenmode oscillatory components) is the classic > response given by John > Lahr at the following website: > http://jclahr.com/science/psn/response/index.html > > If you look at John's six transfer function plots provided at > http://jclahr.com/science/psn/response/plots.jpg > it is the right-most pair (response to acceleration) that 'summarize > the physics' of > how a seismometer operates. Yes, one can configure an instrument to > plot data > according to any one of the six possibilities John has indicated, > but the response to > acceleration is what 'tells the story' of performance. For > frequencies above the > natural frequency of the pendulum, a velocity sensor will always > outperform a > velocity sensor. On the other hand, for frequencies below the > natural frequency, a > position sensor will always outperform a velocity sensor (all things > otherwise > identical). > > I don't know about you, but I'm not particularly interested in > frequencies > above 1 Hz. Our Volksmeter easily picks up dynamite blasts and > other local > disturbances that are nearly always manmade. Because the earth is > so large, motions > it exhibits in response to dynamic changes (earthquakes, tidal > forces, ..) are at low > frequencies (not high). > > At low frequencies where everybody seems increasingly > interested in going > (reason for bandwidth extension) there is no question of the > superiority of position > sensing over velocity sensing. Why this obvious fact is so muddled > in the minds of > so many is a great mystery to me. Maybe it's because even classical > physics is > difficult for most everybody to understand. > > I have placed a paper on my webpage which speaks to this > matter, titled > 'Seismometer design based on a simple theory of instrument-generated > noise equivalent > power: > http://physics.mercer.edu/hpage/inep/inep.html > > For those of you who want to 'escape the rut' of velocity > detection that has > held folks captive for way too long-Larry and my other business > partner, Les LaZar > are positioned to provide you with reasonably-priced essential > components to build > your own version of the VolksMeter. Probably most of you will > prefer to do this > rather than pay the present $1000 'turnkey' price for our > single-pendulum instrument. > > I want to point out something that is the result of recently > discovered > physics-why small-mass instruments don't perform well. Although > conventional wisdom > says that it's because of Brownian motion (larger for smaller > masses), this is not > really the culprit. The performance limitation is really the result > of internal > friction problems that science is only beginning to understand. The > smaller the > seismic mass, the smaller the spring that supports it. The smaller > the spring, the > more significant is the internal friction associated with the 'snap, > crackle, pop' of > defect structural changes in the spring (processes that operate at > the mesoscale). > For decades we've recognized the all-important properties of defects in > semiconductors (basis for p and n material of which devices are > made), but until > recently very little was understood concerning the importance of > defects to internal > friction that regulates the low-frequency performance of seismometers. > > The influence of defects is worse in instruments with springs > than in those > that use a pendulum, which is more inherently stable. Until better > electronics came > along, we were stuck with trying to improve low-frequency > performance by going to > lower natural frequencies of the mechanical oscillator. That is no > longer the only > viable solution. Although the pendulum lost favor years ago, it is > making a > comeback. The success of the Shackleford-Gunderson approach should > have been a cue > to many that the pendulum needed to be revisited. With the digital > electronics of > the AD7745 there are some advantages that did not exist when the S-G > instrument was > developed around its analog circuitry. For example, the noise of > the Volksmeter > electronics does not increase as rapidly with frequency-decrease as > is true of analog > circuitry (commercial standard in seismometry being synchronous > detection). > > Dr. Randall Peters > > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. > with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: AGU meeting From: Larry Cochrane lcochrane@.............. Date: Wed, 06 Dec 2006 23:26:42 -0800 Sorry, I was thinking Tuesday through Friday. I can't make it on Monday, so I guess we will have to do it on Thursday. -Larry John or Jan Lahr wrote: > I can make any day but Tuesday or Friday. Larry can't make it > Wednesday. That leaves Monday or Thursday. Dave Willey, which would > be better for you? > > John > > At 06:24 PM 12/6/2006, you wrote: >>Hi John, >> >>I'm interested. I will be at the AGU meeting all week long, so any >>day except Wednesday the 13th works for me. >> >>Regards, >>Larry Cochrane >>Redwood City, PSN >> >>John or Jan Lahr wrote: >>>Is anyone interest in getting together this year during the >>>AGU? Possibly dinner or lunch one day. >>>Cheers, >>>John >>> >>>#################################/ John C. Lahr >>>################################/ Emeritus Seismologist >>>###############################/ U.S. Geological Survey >>>==========================/ Central Region Geologic Hazards Team >>>#############################//################################# >>>############################//################################## >>> PO Box >>> 548 /################################### >>> Corvallis, Oregon 97339 /=============================== >>> Phone: (541) 758-2699 /#################################### >>> Cell: (541) 740-4844 /##################################### >>> Fax: (413) 658-2699 /###################################### >>> johnjan@........ /####################################### >>> http://jclahr.com/science > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: PSN Meeting after the AGU on Thursday From: Larry Cochrane lcochrane@.............. Date: Fri, 08 Dec 2006 20:47:01 -0800 Hi Everyone, We will be meeting at the address below around 6:00PM on Thursday. Max's on the Square 398 Geary St San Francisco, CA 94102-1802 View Map (650) 873-6297 Cross Street: Mason Street Regards, Larry Cochrane Redwood City, PSN __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Source for Desiccant Packs? From: Dave Willey davewilley@............. Date: Sat, 9 Dec 2006 15:02:48 -0800 (PST) Does anyone have a source for small amounts of desiccant packs such as bentonite clay or silica gel? (Something non-corrosive.) Similar to the canisters/capsules found in the bottom of some medicine pill bottles. I've found a bunch of suppliers on the web. But I only need 2 or 3 , not 4000 per 25 lbs pail!! I'm trying not to hit up the local druggist/chemist if I can help it. But I will if I cannot find another source I'm about ready to seal up a 2" PVC container with three Mark L15b's geophones & bury it 10 feet down. As an aside: As Chris pointed out in a separate e-mail to me, don't forget to seal the OTHER end of the cable. Water and air can still enter inside the "sealed" container via the inside air space between the wires in cables. I used to work/run a engineering reliability lab & have autopsied 100's of marine shore power cables that boaters had carelessly dropped one or both ends into the water. Water gets wicked up inside the cable amazingly far. Even after only a very brief dunking. Water traveling 10 to 30 feet or more inside a 50 or 100 foot long cable wasn't all that unusual with some of the fiber twine used in power cable. Many of the data cables I've looked at often use some sort of thread added along with the individual wires in the bundle. Perfect path for water and damp air to travel down. So the desiccant packs would be a great last ditch effort to keep things dry around the geophones.. Dave Willey  Does anyone have a source for small amounts of desiccant packs such as bentonite clay or silica gel?  (Something non-corrosive.)  Similar to the canisters/capsules  found in the bottom of some medicine pill bottles.  I've found a bunch of suppliers on the web.  But I only need 2 or 3 , not 4000 per 25 lbs pail!!

I'm trying not to hit up the local druggist/chemist if I can help it.  But I will if I cannot find another source

I'm about ready to seal up a 2" PVC container with three Mark L15b's geophones & bury it 10 feet down.

As an aside:
As Chris pointed out in a separate e-mail to me, don't forget to seal the OTHER end of the cable.  Water and air can still enter inside the "sealed" container via the inside air space between the wires in cables. 

I used to work/run a engineering reliability lab & have autopsied 100's of marine shore power cables that boaters had carelessly dropped one or both ends into the water.  Water gets wicked up inside the cable amazingly far.  Even after only a very brief dunking. 

Water traveling 10 to 30 feet or more inside a 50 or 100 foot long cable wasn't all that unusual with some of the fiber twine used in power cable.  Many of the data cables I've looked at often use some sort of thread added along with the individual wires in the bundle. Perfect path for water and damp air to travel down.

So the desiccant packs would be a great last ditch effort to keep things dry around the geophones..


Dave Willey




Subject: Re: Source for Desiccant Packs? From: ChrisAtUpw@....... Date: Sat, 9 Dec 2006 21:17:02 EST In a message dated 2006/12/09, davewilley@............. writes: > Does anyone have a source for small amounts of desiccant packs such as > bentonite clay or silica gel? Hi Dave, You used to be able to buy 'sausages' of cloth + silica gel about 2" in dia x 10" long for drying out rubber boots...! Try marine suppliers? Suppliers of horse riding equipment? Also try electronic component suppliers? I know that uk.farnell.com in the UK sell individual packs of silica gel in 10, 50 and 100 gm sizes. Do any photographic shops chuck out drying packs? A lot of camera accessories are packed with a dessicant pack. How about pharmacists? Laboratory suppliers should carry it. Regards, Chris Chapman In a me= ssage dated 2006/12/09, davewilley@............. writes:

Does anyone have a source for=20= small amounts of desiccant packs such as bentonite clay or silica gel?

Hi Dave,

       You used to be able to buy 'sausages' o= f cloth + silica gel about 2" in dia x 10" long for drying out rubber boots.= ...! Try marine suppliers? Suppliers of horse riding equipment?

       Also try electronic component suppliers= ? I know that uk.farnell.com in the UK sell individual packs of silica gel i= n 10, 50 and 100 gm sizes.

       Do any photographic shops chuck out dry= ing packs? A lot of camera accessories are packed with a dessicant pack.&nbs= p; How about pharmacists? Laboratory suppliers should carry it.

       Regards,

       Chris Chapman Subject: RE: Source for Desiccant Packs? From: "Timothy Carpenter" geodynamics@....... Date: Sat, 9 Dec 2006 23:50:35 -0500 Silica gel is also used for drying flowers - craft shops and some = florists should carry supplies. =20 I noted in looking for a source of the silica gel that borax is often = used as a desiccant. It's cheap and you can use what's left over for washing. However, with my weak chemistry background, I cannot recommend it = because I know nothing of its reactivity. Perhaps someone else can tell us if it = is safe or not. =20 Regards, -Tim Carpenter- =20 -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of Dave Willey Sent: Saturday, December 09, 2006 6:03 PM To: psn-l@.............. Subject: Source for Desiccant Packs? =20 Does anyone have a source for small amounts of desiccant packs such as bentonite clay or silica gel? (Something non-corrosive.) Similar to = the canisters/capsules found in the bottom of some medicine pill bottles. = I've found a bunch of suppliers on the web. But I only need 2 or 3 , not = 4000 per 25 lbs pail!! I'm trying not to hit up the local druggist/chemist if I can help it. = But I will if I cannot find another source I'm about ready to seal up a 2" PVC container with three Mark L15b's geophones & bury it 10 feet down. As an aside: As Chris pointed out in a separate e-mail to me, don't forget to seal = the OTHER end of the cable. Water and air can still enter inside the = "sealed" container via the inside air space between the wires in cables. =20 I used to work/run a engineering reliability lab & have autopsied 100's = of marine shore power cables that boaters had carelessly dropped one or = both ends into the water. Water gets wicked up inside the cable amazingly = far. Even after only a very brief dunking. =20 Water traveling 10 to 30 feet or more inside a 50 or 100 foot long cable wasn't all that unusual with some of the fiber twine used in power = cable. Many of the data cables I've looked at often use some sort of thread = added along with the individual wires in the bundle. Perfect path for water = and damp air to travel down. So the desiccant packs would be a great last ditch effort to keep things = dry around the geophones.. Dave Willey

Silica gel is also used for drying = flowers – craft shops and some florists should carry = supplies.

 

I noted in looking for a source of = the silica gel that borax is often used as a desiccant. It’s cheap and = you can use what’s left over for washing. However, with my weak = chemistry background, I cannot recommend it because I know nothing of its = reactivity. Perhaps someone else can tell us if it is safe or not.

 

Regards,

-Tim Carpenter-

 

-----Original = Message-----
From: = psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Dave Willey
Sent: Saturday, December 09, 2006 6:03 PM
To: psn-l@..............=
Subject: Source for = Desiccant Packs?

 

 Does anyone have a source for small amounts of desiccant packs such as = bentonite clay or silica gel?  (Something non-corrosive.)  Similar to = the canisters/capsules  found in the bottom of some medicine pill bottles.  I've found a bunch of suppliers on the web.  But I = only need 2 or 3 , not 4000 per 25 lbs pail!!

I'm trying not to hit up the local druggist/chemist if I can help = it.  But I will if I cannot find another source

I'm about ready to seal up a 2" PVC container with three Mark = L15b's geophones & bury it 10 feet down.

As an aside:
As Chris pointed out in a separate e-mail to me, don't forget to seal = the OTHER end of the cable.  Water and air can still enter inside the "sealed" container via the inside air space between the wires = in cables. 

I used to work/run a engineering reliability lab & have autopsied = 100's of marine shore power cables that boaters had carelessly dropped one or = both ends into the water.  Water gets wicked up inside the cable amazingly far.  Even after only a very brief dunking. 

Water traveling 10 to 30 feet or more inside a 50 or 100 foot long cable = wasn't all that unusual with some of the fiber twine used in power cable.  = Many of the data cables I've looked at often use some sort of thread added = along with the individual wires in the bundle. Perfect path for water and damp = air to travel down.

So the desiccant packs would be a great last ditch effort to keep things = dry around the geophones..


Dave Willey



Subject: Re: Source for Desiccant Packs? From: ChrisAtUpw@....... Date: Sun, 10 Dec 2006 00:42:29 EST In a message dated 2006/12/10, geodynamics@....... writes: > borax is often used as a desiccant. However, with my weak chemistry > background, I cannot recommend it because I know nothing of its reactivity. Perhaps > someone else can tell us if it is safe or not. Hi Tim, I definitely wouldn't use it, or any metal salts. Stick to silica gel. Regards, Chris Chapman In a me= ssage dated 2006/12/10, geodynamics@....... writes:

borax is often used as a desic= cant. However, with my weak chemistry background, I cannot recommend it beca= use I know nothing of its reactivity. Perhaps someone else can tell us if it= is safe or not.


Hi Tim,

       I definitely wouldn't use it, or any me= tal salts. Stick to silica gel.

       Regards,

       Chris Chapman Subject: RE: Source for Desiccant Packs? From: "Timothy Carpenter" geodynamics@....... Date: Sun, 10 Dec 2006 03:05:25 -0500 Thanks Chris, I'll file that one away as an unconditional no-no. -Tim Carpenter- -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of ChrisAtUpw@....... Sent: Sunday, December 10, 2006 12:42 AM To: psn-l@.............. Subject: Re: Source for Desiccant Packs? In a message dated 2006/12/10, geodynamics@....... writes: borax is often used as a desiccant. However, with my weak chemistry background, I cannot recommend it because I know nothing of its reactivity. Perhaps someone else can tell us if it is safe or not. Hi Tim, I definitely wouldn't use it, or any metal salts. Stick to silica gel. Regards, Chris Chapman

Thanks = Chris,

I’ll file that one away as an = unconditional no-no.

-Tim Carpenter-

 

-----Original = Message-----
From: = psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of ChrisAtUpw@.......
Sent: Sunday, December 10, 2006 12:42 = AM
To: psn-l@..............=
Subject: Re: Source for = Desiccant Packs?

 

In a message dated = 2006/12/10, geodynamics@....... writes:


= borax is often used as a desiccant. However, with my weak chemistry background, I = cannot recommend it because I know nothing of its reactivity. Perhaps someone = else can tell us if it is safe or not.



Hi Tim,

       I definitely wouldn't use it, or = any metal salts. Stick to silica gel.

       Regards,

       Chris Chapman

Subject: Re: Volksmeter information From: Larry Cochrane lcochrane@.............. Date: Sun, 10 Dec 2006 01:13:03 -0800 Hi Chris, One of the PSN list members converted the Power Point file to pdf format. Here's the link to the file: http://www.seismicnet.com/volksmeter/State-of-the-art_Digital_Seismograph.pdf Regards, -Larry ChrisAtUpw@....... wrote: > In a message dated 2006/12/07 07:24:21 GMT Standard Time, > lcochrane@.............. writes: > >> Using the Power Point file I created this web page: >> http://www.seismicnet.com/volksmeter/Volksmeter.html > > > Hi Larry, > > The text downloads for me, but the diagrams don't. > > Regards, > > Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Vertical Sensor From: "tchannel" tchannel@.............. Date: Sun, 10 Dec 2006 09:15:38 -0700 Hi Everyone, The Horz. Pendulum Sensor, I finished weeks ago, is = working fine but will be relocated, as part of a new display at the = Museum of Mining and Geology, in the spring. They are closed during the = Winter months. So I will need to replace everything, if I am to = continue these endeavors. I am thinking I would like to build a = vertical sensor. I have read that the AS1 has a period of 1.5 seconds, = but is extended electronically. Q 1 Is there a program which does this? Maybe an article which explains = it. Q 2 I have articles on the AS1 which shows its basic design. Is there = an article showing "how to" build your own Vertical? My basic questions would be over all dimensions, and locating the proper = spring. Q 3 On a different subject. I am in Idaho and sure would like to find = someone in Idaho to share .PSN files and notes with. When I record an = event I would love to compare my signal with other local stations. = Please if you are in the area or know of a station, near Boise, let me = know. Thanks, Ted
Hi Everyone,  The Horz. Pendulum = Sensor, I=20 finished weeks ago, is working fine but will be relocated, as part of a = new=20 display at the Museum of Mining and Geology, in the spring.  They = are=20 closed during the Winter months.  So I will need to replace = everything, if=20 I am to continue these endeavors.   I am thinking I would like = to=20 build a vertical sensor.  I have read that the AS1 has a period of = 1.5=20 seconds, but is extended electronically.
 
Q 1  Is there a program which does = this? Maybe=20 an article which explains it.
 
Q 2  I have articles on the AS1 = which shows=20 its basic design.  Is there an article showing "how to" build your = own=20 Vertical?
My basic questions would be over all = dimensions,=20 and locating the proper spring.
 
Q 3  On a different subject.  = I am in=20 Idaho and sure would like to find someone in Idaho to share .PSN files = and notes=20 with. When I record an event I would love to compare my signal with = other=20 local stations.  Please if you are in the area or know of a = station, near=20 Boise, let me know.
 
Thanks, Ted
 
 
Subject: Re: Vertical Sensor From: Bobhelenmcclure@....... Date: Sun, 10 Dec 2006 12:00:23 EST Hi Ted, I have designed a digital period extending filter. It is now incorporated into AmaSeis. For filtering WinQuake files, you can use my "WQFilter.exe" program. To obtain the program, download "seismic_dataq.zip" from _http://www.jclahr.com/science/psn/mcclure/wdq_utilities/index.html_ (http://www.jclahr.com/science/psn/mcclure/wdq_utilities/index.html) Extract the files "WQFilter.exe" and "WQFilterHlp.txt" from the zip. I can send you a description of the filter, if you ask. Regards, Bob >Hi Everyone, The Horz. Pendulum Sensor, I finished weeks ago, is working fine but will be relocated, as part of a new display at the Museum of Mining and Geology, in the spring. They are closed during the Winter months. So I will need to replace everything, if I am to continue these endeavors. I am thinking I would like to build a vertical sensor. I have read that the AS1 has a period of 1.5 seconds, but is extended electronically. Is there a program which does this? Maybe an article which explains it?<
Hi Ted,
 
  I have designed a digital period extending filter. It is now=20 incorporated into AmaSeis. For filtering WinQuake files, you can use my=20 "WQFilter.exe" program. To obtain the program, download "seismic_dataq.zip"=20= from=20
 
= http://www.jclahr.com/science/psn/mcclure/wdq_utilities/index.html
 
 Extract the files "WQFilter.exe" and "WQFilterHlp.txt" from the=20 zip.
 
  I can send you a description of the filter, if you ask.
 
Regards,
 
Bob
 
>Hi Everyone,  The Horz. Pendulum Sensor, I finished weeks ago,= is=20 working fine but will be relocated, as part of a new display at the Museum o= f=20 Mining and Geology, in the spring.  They are closed during the Winter=20 months.  So I will need to replace everything, if I am to continue thes= e=20 endeavors.   I am thinking I would like to build a vertical=20 sensor.  I have read that the AS1 has a period of 1.5 seconds, but is=20 extended electronically.
 
 Is there a program which does this? Maybe an article which explai= ns=20 it?<
 Subject: Re: Digest from 12/09/2006 00:00:39 From: "Randy" rpratt@............. Date: Sun, 10 Dec 2006 14:56:46 -0600 You can get small packs of desicant from Cabela's. It is used in gun safes and comes in sizes $4.99 to $27.99. http://cabelas.com/cabelas/en/templates/links/link.jsp?id=0005567220673a&type=product&cmCat=search&returnPage=search-results1.jsp&QueryText=dehumidifier&N=4887&Ntk=Products&Ntx=mode+matchall&Nty=1&Ntt=dehumidifier&noImage=0 Randy __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Low period noise From: jonfr500@......... Date: Sun, 10 Dec 2006 22:31:39 +0000 Hi all I am suffering from a hard disk failure at my main computer, so I am using = my secondary computer to send this email. I won't be able to fix it until T= uesday at the first. The hard disk is giving up, being 3 years old and all = that. But that is not what I did want to speak about. On my sensor I see a low pe= riod noise. This is not the weather, the weather is fine so far. This low p= eriod noise is so low that it registers from 0.1Hz and to 1Hz, but the main= peak is around 0.2Hz. This would not have been interesting except for the = fact that this low period noise also appears on the sensors that IMO is run= ning. This has also mean that there is a increase in noise on frequency's a= round 4Hz. This might be a storm related noise, but if someone has a differ= ent idea what this might be. Please let me know. My first idea on this that this might be related to change in volcano press= ure somewhere. I am not sure however on that, yet. I saw something like thi= s happen before Grimsvotn eruption in 2004, but on a lot smaller scale. The= n there was a increase in background noises few hours before the eruption, = I saw it back then on IMO sensor. I didn't have a sensor at that time. Regards. J=F3n Fr=EDmann. =20 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Low period noise From: ChrisAtUpw@....... Date: Sun, 10 Dec 2006 17:51:26 EST In a message dated 2006/12/10, jonfr500@......... writes: > This low period noise is so low that it registers from 0.1Hz and to 1Hz, > but the main peak is around 0.2Hz. This would not have been interesting except > for the fact that this low period noise also appears on the sensors that IMO > is running. Hi Jon, This sounds like ocean microseismic noise. It varies in amplitude between quiet periods at about 0.5 micron and ocean storm conditions at maybe 15 microns, mostly at around 6 secs period. The generating centre may be S / SE of Greenland - relatively close to you! Go to http://www.earthquakes.bgs.ac.uk/helicorder/heli.html and look at the Very Long Period traces for Lerwick in the Shetland Islands north of Scotland. Regards, Chris Chapman In a me= ssage dated 2006/12/10, jonfr500@......... writes:

This low period noise is so low= that it registers from 0.1Hz and to 1Hz, but the main peak is around 0.2Hz.= This would not have been interesting except for the fact that this low peri= od noise also appears on the sensors that IMO is running.


Hi Jon,

       This sounds like ocean microseismic noi= se. It varies in amplitude between quiet periods at about 0.5 micron and oce= an storm conditions at maybe 15 microns, mostly at around 6 secs period. The= generating centre may be S / SE of Greenland - relatively close to you!
       Go to http://www.earthquakes.bgs.ac.uk/= helicorder/heli.html and look at the Very Long Period traces for Lerwick in=20= the Shetland Islands north of Scotland.

       Regards,

       Chris Chapman Subject: Re: Source for Desiccant Packs? From: George Bush ke6pxp@....... Date: Sun, 10 Dec 2006 15:10:22 -0800 Recently I was looking for small sources of Silica gel to place in a jar and dry my hearing aids between uses. Someone suggested that I check my local pharmacy store as drugs are sometimes shipped with dessicants. I went to my pharmicist and he was delighted to give me a whole shopping bag-full that he had collected! It sems that he felt bad about just throwing them away and was collecting them for someone like me to come around! So, I suggest you contact your local pharmacy, they may have some, or can save some for you. At 03:02 PM 12/9/2006 -0800, you wrote: >>>> Does anyone have a source for small amounts of desiccant packs such as bentonite clay or silica gel? <<<<<<<< George Subject: RE: Low period noise From: "Bob Hancock" carpediem1@......... Date: Sun, 10 Dec 2006 16:17:13 -0700 Jon - The current US Navy wave height projection shows major activity just = south of Greenland and also another area of high wave height southeast of = Iceland. You can reference the data at the following web site https://www.fnmoc.navy.mil/PUBLIC/WAM/all_glbl.html Cheers Bob Hancock -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of jonfr500@......... Sent: Sunday, December 10, 2006 15:32 To: psn-l@.............. Subject: Low period noise Hi all I am suffering from a hard disk failure at my main computer, so I am = using my secondary computer to send this email. I won't be able to fix it = until Tuesday at the first. The hard disk is giving up, being 3 years old and = all that. But that is not what I did want to speak about. On my sensor I see a low period noise. This is not the weather, the weather is fine so far. This = low period noise is so low that it registers from 0.1Hz and to 1Hz, but the = main peak is around 0.2Hz. This would not have been interesting except for = the fact that this low period noise also appears on the sensors that IMO is running. This has also mean that there is a increase in noise on = frequency's around 4Hz. This might be a storm related noise, but if someone has a different idea what this might be. Please let me know. My first idea on this that this might be related to change in volcano pressure somewhere. I am not sure however on that, yet. I saw something = like this happen before Grimsvotn eruption in 2004, but on a lot smaller = scale. Then there was a increase in background noises few hours before the eruption, I saw it back then on IMO sensor. I didn't have a sensor at = that time. Regards. J=F3n Fr=EDmann. =20 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Source for Desiccant Packs? From: Philip Schmidt pgschmidt@............... Date: Mon, 11 Dec 2006 10:02:00 +1030 Hello Dave and others I looked on a website in Australia called "Farnell in one" They have 6 different amounts of desiccant. They are also partners with there US arm called Newark in one see link below http://www.newark.com/ They have similar product lines so if your local pharmacy or chemist can't help you try them. I am a bit late with my reply but I hope this info helps with your search. Phil Schmidt Dave Willey wrote: > Does anyone have a source for small amounts of desiccant packs such as > bentonite clay or silica gel? > Dave Willey > > > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Source for Desiccant Packs? From: Mark Robinson mark.robinson@............... Date: Mon, 11 Dec 2006 12:44:25 +1300 Dave Willey wrote: > Does anyone have a source for small amounts of desiccant packs such as bentonite clay or silica gel? (Something non-corrosive.) Similar to the canisters/capsules found in the bottom of some medicine pill bottles. I've found a bunch of suppliers on the web. But I only need 2 or 3 , not 4000 per 25 lbs pail!! Garden shops here sell Watersorb crystals in quantity as a hydroponic medium. -- Mark Robinson ------------- 11 Dec 1951 Yankee slugger Joe DiMaggio announces his retirement from baseball. 11 Dec 1991 EEC aggrees to political federation and common currency by 1999. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Vertical Sensor From: ChrisAtUpw@....... Date: Sun, 10 Dec 2006 20:03:24 EST In a message dated 2006/12/10, tchannel@.............. writes: > I am thinking I would like to build a vertical sensor. I have read that > the AS1 has a period of 1.5 seconds, but is extended electronically. > > Q 1 Is there a program which does this? Maybe an article which explains it. Hi Ted, In thinking that, remember that vertical seismometers are more difficult to build and to set up than horizontal ones. Having access to a small metal turning lathe and a drilling / milling machine are very helpful. Quite a lot of 'practical machanics' are involved and also various sources of constructional materials. Some drawings for the AS-1 are on John Lahr's website. See http://jclahr.com/science/psn/as1/index.html An electromagnetic damper to replace the messy oil damper is described at http://jclahr.com/science/psn/chapman/as1%20damping/index.html The period can be extended with the Robert' circuit or an adaption of it. See http://jclahr.com/science/psn/roberts/index.html You can get stable periods out to about 4.5 secs with steel springs, but any further extension needs springs wound with / made of Ni-SpanC alloy to control the stiffness / temperature variations. A 'fairly happy' compromise might be to set up the seismometer with a steel spring for ~3 secs period and to then extend this to 30 secs, electronically or in software. If you do it in software, you really need a 16 bit ADC, since your dynamic range is reduced by maybe x100. Plan to cover the periods around 20 secs fairly typical of Rayleigh waves. > Q 2 I have articles on the AS1 which shows its basic design. Is there an > article showing "how to" build your own Vertical? > My basic questions would be over all dimensions, and locating the proper > spring. There is a drawing of a similar device built by Dewayne Hill See http://jclahr.com/science/psn/hill/index.html and a prototype of a rather better construction at http://quake.eas.gatech.edu/Instruments/LPVERT0.htm It might be possible to build one like this inside a glass vessel or a tubular enclosure. Allan Coleman used an Al damper casing from a scrap yard. A serious problem with vertical sensors is that they are sensitive to air density changes / wind noise. These noise levels can be 100 times that of a horizontal seismometer. Also have a look at the EAS vertical and the drawings in the EAS Manual at http://www.eaiinfo.com/EAI2004/Index.htm This uses the ready made 60 deg agate bearings produced for chemical balances. However, there is no reason why you should not use a crossed rod Carbide suspension, or the dual foil one of the LPVERTO. The LP construction would enable you to add an air flotation chamber on the opposite side of the arm to the mass to greatly reduce atmospheric noise. Something like a miniature Al drinks can, drilled, emptied, rinsed out and then resealed? Have a look at the STM-8 designed by Sean Morrissey at http://www.eas.slu.edu/People/STMorrissey/index.html and read his notes at http://psn.quake.net/info/stm-mail.zip Keith has a working seisometer of this type with photos at http://www.bryantlabs.net/seismo.html > Q 3 On a different subject. I am in Idaho and sure would like to find > someone in Idaho to share .PSN files and notes with. When I record an event I > would love to compare my signal with other local stations. Please if you are > in the area or know of a station, near Boise, let me know. Look up all registered American stations? See links on the World Map at http://www.sydneystormcity.com/map.htm There is Don Sieber in Boise and Jan Marshall in Nampa, both close to you. There is also an associated contact and equipment list. There are also several educational groups operating across the USA. Since P waves travel at maybe 8 km / sec you might also consider anyone 100 to 300 km distant? Can you set up a website with photos of your seismometer / alternatively send photos to John Lahr to display? Regards, Chris Chapman In a me= ssage dated 2006/12/10, tchannel@.............. writes:

I am thinking I would like to=20= build a vertical sensor.  I have read that the AS1 has a period of 1.5=20= seconds, but is extended electronically.

Q 1  Is there a program which does this? Maybe an article which explain= s it.


Hi Ted,

       In thinking that, remember that vertica= l seismometers are more difficult to build and to set up than horizontal one= s. Having access to a small metal turning lathe and a drilling / milling mac= hine are very helpful. Quite a lot of 'practical machanics' are involved and= also various sources of constructional materials.

       Some drawings for the AS-1 are on John=20= Lahr's website. See http://jclahr.com/science/psn/as1/index.html

       An electromagnetic damper to replace th= e messy oil damper is described at http://jclahr.com/science/psn/chapman/as1= %20damping/index.html
      
       The period can be extended with the Rob= ert' circuit or an adaption of it. See http://jclahr.com/science/psn/roberts= /index.html

       You can get stable periods out to about= 4.5 secs with steel springs, but any further extension needs springs wound=20= with / made of Ni-SpanC alloy to control the stiffness / temperature variati= ons. A 'fairly happy' compromise might be to set up the seismometer with a s= teel spring for ~3 secs period and to then extend this to 30 secs, electroni= cally or in software. If you do it in software, you really need a 16 bit ADC= , since your dynamic range is reduced by maybe x100. Plan to cover the perio= ds around 20 secs fairly typical of Rayleigh waves.

Q 2  I have articles on th= e AS1 which shows its basic design. Is there an article showing "how to" bui= ld your own Vertical?
My basic questions would be over all dimensions, and locating the proper spr= ing.


       There is a drawing of a similar device=20= built by Dewayne Hill See http://jclahr.com/science/psn/hill/index.html

and a prototype of a rather better construction at http://quake.eas.gatech.e= du/Instruments/LPVERT0.htm

    It might be possible to build one like this inside a glas= s vessel or a tubular enclosure. Allan Coleman used an Al damper casing from= a scrap yard. A serious problem with vertical sensors is that they are sens= itive to air density changes / wind noise. These noise levels can be 100 tim= es that of a horizontal seismometer.

    Also have a look at the EAS vertical and the drawings in=20= the EAS Manual at http://www.eaiinfo.com/EAI2004/Index.htm This uses the rea= dy made 60 deg agate bearings produced for chemical balances. However, there= is no reason why you should not use a crossed rod Carbide suspension, or th= e dual foil one of the LPVERTO. The LP construction would enable you to add=20= an air flotation chamber on the opposite side of the arm to the mass to grea= tly reduce atmospheric noise. Something like a miniature Al drinks can, dril= led, emptied, rinsed out and then resealed? 

    Have a look at the STM-8 designed by Sean Morrissey at ht= tp://www.eas.slu.edu/People/STMorrissey/index.html and read his notes at htt= p://psn.quake.net/info/stm-mail.zip
Keith has a working seisometer of this type with photos at http://www.bryant= labs.net/seismo.html 

Q 3  On a different subjec= t.  I am in Idaho and sure would like to find someone in Idaho to share= .PSN files and notes with. When I record an event I would love to compare m= y signal with other local stations.  Please if you are in the area or k= now of a station, near Boise, let me know.


       Look up all registered American station= s? See links on the World Map at http://www.sydneystormcity.com/map.htm Ther= e is Don Sieber in Boise and Jan Marshall in Nampa, both close to you. There= is also an associated contact and equipment list. There are also several ed= ucational groups operating across the USA.

       Since P waves travel at maybe 8 km = ; / sec you might also consider anyone 100 to 300 km distant?

       Can you set up a website with photos of= your seismometer / alternatively send photos to John Lahr to display?

       Regards,

       Chris Chapman Subject: Re: Source for Desiccant Packs? From: ChrisAtUpw@....... Date: Sun, 10 Dec 2006 20:16:40 EST In a message dated 2006/12/10, mark.robinson@............... writes: > Garden shops here sell Watersorb crystals in quantity as a hydroponic > medium. > Hi Mark, Watersorb is a polyacrylamide gel which absorbs / releases large amounts of liquid water, while still remaining 'semi solid' - a bit like gelatine in your dessert jelly, but chemically more stable. It will not work as a good drying agent for seismometers. Regards, Chris Chapman In a me= ssage dated 2006/12/10, mark.robinson@............... writes:

Garden shops here sell Watersor= b crystals in quantity as a hydroponic medium.

Hi Mark,

       Watersorb is a polyacrylamide gel which= absorbs / releases large amounts of liquid water, while still remaining 'se= mi solid' - a bit like gelatine in your dessert jelly, but chemically more s= table.
       It will not work as a good drying agent= for seismometers.

       Regards,

       Chris Chapman
 Subject: Re: Low period noise From: jonfr500@......... Date: Mon, 11 Dec 2006 01:25:41 +0000 Hi This might be storms, there is at the moment a low pressure system somewher= e south of Iceland. This actually creates small wave forms in my plot, on the computer screen. = But it doesn't show on the online plot. Regards. J=F3n Fr=EDmann. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Vertical Sensor From: "tchannel" tchannel@.............. Date: Sun, 10 Dec 2006 18:51:39 -0700 Chris, Thanks, these are great sites, and just what I needed. Ted ----- Original Message -----=20 From: ChrisAtUpw@.......... To: psn-l@................. Sent: Sunday, December 10, 2006 6:03 PM Subject: Re: Vertical Sensor In a message dated 2006/12/10, tchannel@.............. writes: I am thinking I would like to build a vertical sensor. I have read = that the AS1 has a period of 1.5 seconds, but is extended = electronically. Q 1 Is there a program which does this? Maybe an article which = explains it. Hi Ted, In thinking that, remember that vertical seismometers are more = difficult to build and to set up than horizontal ones. Having access to = a small metal turning lathe and a drilling / milling machine are very = helpful. Quite a lot of 'practical machanics' are involved and also = various sources of constructional materials.=20 Some drawings for the AS-1 are on John Lahr's website. See = http://jclahr.com/science/psn/as1/index.html=20 An electromagnetic damper to replace the messy oil damper is = described at = http://jclahr.com/science/psn/chapman/as1%20damping/index.html =20 The period can be extended with the Robert' circuit or an = adaption of it. See http://jclahr.com/science/psn/roberts/index.html=20 You can get stable periods out to about 4.5 secs with steel = springs, but any further extension needs springs wound with / made of = Ni-SpanC alloy to control the stiffness / temperature variations. A = 'fairly happy' compromise might be to set up the seismometer with a = steel spring for ~3 secs period and to then extend this to 30 secs, = electronically or in software. If you do it in software, you really need = a 16 bit ADC, since your dynamic range is reduced by maybe x100. Plan to = cover the periods around 20 secs fairly typical of Rayleigh waves. Q 2 I have articles on the AS1 which shows its basic design. Is = there an article showing "how to" build your own Vertical? My basic questions would be over all dimensions, and locating the = proper spring. There is a drawing of a similar device built by Dewayne Hill = See http://jclahr.com/science/psn/hill/index.html and a prototype of a rather better construction at = http://quake.eas.gatech.edu/Instruments/LPVERT0.htm It might be possible to build one like this inside a glass vessel = or a tubular enclosure. Allan Coleman used an Al damper casing from a = scrap yard. A serious problem with vertical sensors is that they are = sensitive to air density changes / wind noise. These noise levels can be = 100 times that of a horizontal seismometer. Also have a look at the EAS vertical and the drawings in the EAS = Manual at http://www.eaiinfo.com/EAI2004/Index.htm This uses the ready = made 60 deg agate bearings produced for chemical balances. However, = there is no reason why you should not use a crossed rod Carbide = suspension, or the dual foil one of the LPVERTO. The LP construction = would enable you to add an air flotation chamber on the opposite side of = the arm to the mass to greatly reduce atmospheric noise. Something like = a miniature Al drinks can, drilled, emptied, rinsed out and then = resealed? =20 Have a look at the STM-8 designed by Sean Morrissey at = http://www.eas.slu.edu/People/STMorrissey/index.html and read his notes = at http://psn.quake.net/info/stm-mail.zip Keith has a working seisometer of this type with photos at = http://www.bryantlabs.net/seismo.html =20 Q 3 On a different subject. I am in Idaho and sure would like to = find someone in Idaho to share .PSN files and notes with. When I record = an event I would love to compare my signal with other local stations. = Please if you are in the area or know of a station, near Boise, let me = know. Look up all registered American stations? See links on the = World Map at http://www.sydneystormcity.com/map.htm There is Don Sieber = in Boise and Jan Marshall in Nampa, both close to you. There is also an = associated contact and equipment list. There are also several = educational groups operating across the USA. Since P waves travel at maybe 8 km / sec you might also = consider anyone 100 to 300 km distant? Can you set up a website with photos of your seismometer / = alternatively send photos to John Lahr to display? Regards, Chris Chapman
Chris,  Thanks, these are great = sites, and=20 just what I needed.  Ted
----- Original Message -----
From:=20 ChrisAtUpw@.......
Sent: Sunday, December 10, 2006 = 6:03=20 PM
Subject: Re: Vertical = Sensor

In a=20 message dated 2006/12/10, tchannel@..............=20 writes:

I am thinking I would like to build a vertical = sensor.  I=20 have read that the AS1 has a period of 1.5 seconds, but is extended=20 electronically.

Q 1  Is there a program which does this? = Maybe=20 an article which explains it.


Hi=20 Ted,

       In thinking that, = remember=20 that vertical seismometers are more difficult to build and to set up = than=20 horizontal ones. Having access to a small metal turning lathe and a = drilling /=20 milling machine are very helpful. Quite a lot of 'practical machanics' = are=20 involved and also various sources of constructional materials.=20

       Some drawings for the = AS-1 are on=20 John Lahr's website. See http://jclahr.com/science/psn/as1/index.html=20

       An electromagnetic damper = to=20 replace the messy oil damper is described at=20 = http://jclahr.com/science/psn/chapman/as1%20damping/index.html
 &= nbsp;    =20
       The period can be extended = with the=20 Robert' circuit or an adaption of it. See=20 http://jclahr.com/science/psn/roberts/index.html=20

       You can get stable = periods out to=20 about 4.5 secs with steel springs, but any further extension needs = springs=20 wound with / made of Ni-SpanC alloy to control the stiffness / = temperature=20 variations. A 'fairly happy' compromise might be to set up the = seismometer=20 with a steel spring for ~3 secs period and to then extend this to 30 = secs,=20 electronically or in software. If you do it in software, you really = need a 16=20 bit ADC, since your dynamic range is reduced by maybe x100. Plan to = cover the=20 periods around 20 secs fairly typical of Rayleigh waves.

Q 2  I have articles on the AS1 which shows its = basic=20 design. Is there an article showing "how to" build your own = Vertical?
My=20 basic questions would be over all dimensions, and locating the = proper=20 spring.

       There = is a=20 drawing of a similar device built by Dewayne Hill See=20 http://jclahr.com/science/psn/hill/index.html

and a prototype = of a=20 rather better construction at=20 = http://quake.eas.gatech.edu/Instruments/LPVERT0.htm

  &n= bsp;=20 It might be possible to build one like this inside a glass vessel or a = tubular=20 enclosure. Allan Coleman used an Al damper casing from a scrap yard. A = serious=20 problem with vertical sensors is that they are sensitive to air = density=20 changes / wind noise. These noise levels can be 100 times that of a = horizontal=20 seismometer.

    Also have a look at the EAS = vertical=20 and the drawings in the EAS Manual at = http://www.eaiinfo.com/EAI2004/Index.htm=20 This uses the ready made 60 deg agate bearings produced for chemical = balances.=20 However, there is no reason why you should not use a crossed rod = Carbide=20 suspension, or the dual foil one of the LPVERTO. The LP construction = would=20 enable you to add an air flotation chamber on the opposite side of the = arm to=20 the mass to greatly reduce atmospheric noise. Something like a = miniature Al=20 drinks can, drilled, emptied, rinsed out and then resealed? =20

    Have a look at the STM-8 designed by Sean = Morrissey=20 at http://www.eas.slu.edu/People/STMorrissey/index.html and read his = notes at=20 http://psn.quake.net/info/stm-mail.zip
Keith has a working = seisometer of=20 this type with photos at http://www.bryantlabs.net/seismo.html  =

Q 3  On a different subject.  I am in Idaho = and sure=20 would like to find someone in Idaho to share .PSN files and notes = with. When=20 I record an event I would love to compare my signal with other local = stations.  Please if you are in the area or know of a station, = near=20 Boise, let me = know.

      =20 Look up all registered American stations? See links on the World Map = at=20 http://www.sydneystormcity.com/map.htm There is Don Sieber in Boise = and Jan=20 Marshall in Nampa, both close to you. There is also an associated = contact and=20 equipment list. There are also several educational groups operating = across the=20 USA.

       Since P waves travel = at maybe=20 8 km  / sec you might also consider anyone 100 to 300 km=20 distant?

       Can you set up a = website=20 with photos of your seismometer / alternatively send photos to John = Lahr to=20 display?

      =20 Regards,

       Chris = Chapman=20 Subject: Re: Source for Desiccant Packs? From: Canie canie@........... Date: Sun, 10 Dec 2006 17:57:42 -0800 If Bentonite clay is what you are looking for, it's easy enough to make something to hold it - Clumping cat litter is Bentonite clay - there are some very dust-free ones if dust could be an issue - the best dust free is made by Dr. Elsey's - precious cat Ultra. Petsmart carries it. Canie At 03:10 PM 12/10/2006, you wrote: >Recently I was looking for small sources of Silica gel to place in a >jar and dry my hearing aids between uses. Someone suggested that I >check my local pharmacy store as drugs are sometimes shipped with >dessicants. I went to my pharmicist and he was delighted to give me >a whole shopping bag-full that he had collected! It sems that he >felt bad about just throwing them away and was collecting them for >someone like me to come around! > >So, I suggest you contact your local pharmacy, they may have some, >or can save some for you. > >At 03:02 PM 12/9/2006 -0800, you wrote: > >>>> >Does anyone have a source for small amounts of desiccant packs such >as bentonite clay or silica gel? > > > > > ><<<< > > > >George __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Low period noise From: "Bob Hancock" carpediem1@......... Date: Sun, 10 Dec 2006 19:41:54 -0700 Hi Jon - One other thought to keep in mind. The passband on your instrument is = 4.5 hz. This is in the range of short period seismometers that are = displayed. I don't know what filtering is used on the displays you have access to = in Iceland, but there may be significant differences in what you see from = your instrument and what is displayed due to filtering unless you are looking = at short period information. For example the displays of the STS-1 run by the University of Arizona = are as follows: http://saso.geo.arizona.edu/saso/Earthquakes/Current/tuc_nf.html http://saso.geo.arizona.edu/saso/Earthquakes/Current/tuc_lp.html http://saso.geo.arizona.edu/saso/Earthquakes/Current/tuc_sp.html Broadband No Filter Long Period 0.011 - 0.067 hz Short Period 1.00 - 2.00 hz The Lamont-Daugherty Earth Observatory (LDEO), just north of New York = City uses the following: http://www.ldeo.columbia.edu/cgi-bin/LCSN/WebSeis/24hr_heli.pl Broadband No Filter Long Period 0.003 - .1 hz Short Period 0.6 - 5.0 hz The displays from IU Network - Albuquerque Seismological Laboratory = (ASL) are all long period and filtered at 0.02 hz http://aslwww.cr.usgs.gov/Seismic_Data/heli2.shtml You can see significant differences in the displays of short period, = long period and broadband at the University of Arizona, and LDEO. Cheers Bob Hancock -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of jonfr500@......... Sent: Sunday, December 10, 2006 18:26 To: psn-l@.............. Subject: Re: Low period noise Hi This might be storms, there is at the moment a low pressure system = somewhere south of Iceland. This actually creates small wave forms in my plot, on the computer = screen. But it doesn't show on the online plot. Regards. J=F3n Fr=EDmann. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Source for Desiccant Packs? From: Dave Willey davewilley@............. Date: Sun, 10 Dec 2006 23:11:19 -0800 (PST) Thanks for all of the suggestions. This afternoon I went to the nearby national crafts store chain. (Michaels, "The arts and crafts store" as the bag says.) After trying to convince two different sales people that yes, dried flowers are indeed "arts and crafts" (go figure) they each pointed me to the same place, the basket isle. Close, but no cigar. Being stubborn, I started walking up & down the isles around there and found two sizes of silica gel for (GASP!) drying flowers in the dried flower area next isle over. (Hello??) The two sales folks must have been trainees. "Flower Drying Art" by Activa Products Inc. out of Marshall Texas, USA. Stock #2604 Silica Gel. Link: http://www.michaels.com/art/online/displayProductPage?productNum=fl0161&channelid= The two sizes are 1.5 lbs (quart) for US$8.99, and 5 lbs for about US$15.99. Cheap enough for me. I'll sew up a cotton pouch & put some in before I close up and seal the geophone housing. Probably 200+ times what I need but hey, I'll find a use. Thanks again for the suggestions. The list once again come through. Dave Willey Timothy Carpenter wrote: Silica gel is also used for drying flowers – craft shops and some florists should carry supplies. Regards, -Tim Carpenter- -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Dave Willey Sent: Saturday, December 09, 2006 6:03 PM To: psn-l@.............. Subject: Source for Desiccant Packs? Does anyone have a source for small amounts of desiccant packs such as bentonite clay or silica gel? (Something non-corrosive.) Similar to the canisters/capsules found in the bottom of some medicine pill bottles. I've found a bunch of suppliers on the web. But I only need 2 or 3 , not 4000 per 25 lbs pail!! I'm trying not to hit up the local druggist/chemist if I can help it. But I will if I cannot find another source I'm about ready to seal up a 2" PVC container with three Mark L15b's geophones & bury it 10 feet down. As an aside: As Chris pointed out in a separate e-mail to me, don't forget to seal the OTHER end of the cable. Water and air can still enter inside the "sealed" container via the inside air space between the wires in cables. I used to work/run a engineering reliability lab & have autopsied 100's of marine shore power cables that boaters had carelessly dropped one or both ends into the water. Water gets wicked up inside the cable amazingly far. Even after only a very brief dunking. Water traveling 10 to 30 feet or more inside a 50 or 100 foot long cable wasn't all that unusual with some of the fiber twine used in power cable. Many of the data cables I've looked at often use some sort of thread added along with the individual wires in the bundle. Perfect path for water and damp air to travel down. So the desiccant packs would be a great last ditch effort to keep things dry around the geophones.. Dave Willey Thanks for all of the suggestions.  This afternoon I went to the nearby national crafts store chain. (Michaels, "The arts and crafts store" as the bag says.)

After trying to convince two different sales people that yes, dried flowers are indeed "arts and crafts" (go figure) they each pointed me to the same place, the basket isle. Close, but no cigar.

Being stubborn, I started walking up & down the isles around there and found two sizes of silica gel for (GASP!) drying flowers in the dried flower area next isle over.  (Hello??)  The two sales folks must have been trainees.

"Flower Drying Art" by Activa Products Inc. out of Marshall Texas, USA.  Stock #2604 Silica Gel.

Link:
http://www.michaels.com/art/online/displayProductPage?productNum=fl0161&channelid=


The two sizes are 1.5 lbs (quart) for US$8.99, and 5 lbs for about US$15.99.  Cheap enough for me.  I'll sew up a cotton pouch & put some in before I close up and seal  the geophone housing. Probably 200+ times what I need but hey, I'll find a use.

 Thanks again for the suggestions.  The list once again come through.

Dave Willey


Timothy Carpenter <geodynamics@.......> wrote:
Silica gel is also used for drying flowers – craft shops and some florists should carry supplies.
 
 
Regards,
-Tim Carpenter-
 
-----Original Message-----
From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Dave Willey
Sent: Saturday, December 09, 2006 6:03 PM
To: psn-l@..............
Subject: Source for Desiccant Packs?
 
 Does anyone have a source for small amounts of desiccant packs such as bentonite clay or silica gel?  (Something non-corrosive.)  Similar to the canisters/capsules  found in the bottom of some medicine pill bottles.  I've found a bunch of suppliers on the web.  But I only need 2 or 3 , not 4000 per 25 lbs pail!!

I'm trying not to hit up the local druggist/chemist if I can help it.  But I will if I cannot find another source

I'm about ready to seal up a 2" PVC container with three Mark L15b's geophones & bury it 10 feet down.

As an aside:
As Chris pointed out in a separate e-mail to me, don't forget to seal the OTHER end of the cable.  Water and air can still enter inside the "sealed" container via the inside air space between the wires in cables. 

I used to work/run a engineering reliability lab & have autopsied 100's of marine shore power cables that boaters had carelessly dropped one or both ends into the water.  Water gets wicked up inside the cable amazingly far.  Even after only a very brief dunking. 

Water traveling 10 to 30 feet or more inside a 50 or 100 foot long cable wasn't all that unusual with some of the fiber twine used in power cable.  Many of the data cables I've looked at often use some sort of thread added along with the individual wires in the bundle. Perfect path for water and damp air to travel down.

So the desiccant packs would be a great last ditch effort to keep things dry around the geophones..


Dave Willey




Subject: Re: Low period noise From: jonfr500@......... Date: Mon, 11 Dec 2006 18:52:56 +0000 Hi The noise can be seen in my newest psn trace that I did send in today. But = there was a ML3.2 earthquake in TFZ today. The low period noise plus other = weather reated noise that I almost didn't record the earthquake. Regards. J=F3n Fr=EDmann. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Vertical Sensor From: "tchannel" tchannel@.............. Date: Mon, 11 Dec 2006 18:17:46 -0700 Hi Chris and All, Chris, I was very pleased with the coil/magnet = arrangement you suggested, the one which sandwiched the four magnets = between two plates. It was simple and effective. If I were to make = another sensor, this time a vertical like the AS1, would you suggest the = same approach, but modified for vertical rather than horz? Or to use the = horseshoe magnet and coil? I am sure both would work, but I would like = opinions on it. Thanks, Ted
Hi Chris and All,  Chris, I was = very pleased=20 with the coil/magnet arrangement you suggested, the one which sandwiched = the=20 four magnets between two plates.  It was simple and = effective.  =20 If I were to make another sensor, this time a vertical like the AS1, = would you=20 suggest the same approach, but modified for vertical rather than horz? = Or to use=20 the horseshoe magnet and coil?   I am sure both would work, = but I=20 would like opinions on it.
Thanks, Ted
Subject: From: 1goss@........... Date: Tue, 12 Dec 2006 02:40:07 +0000 I have relocated my live controllable Weather-cam to the City of Corinth MS we put it on a 175ft tower overlooking the city "well small town" tell me what you think.. http://www.corinthweather.com/cam.htm Bryan Goss __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Volksmeter From: ChrisAtUpw@....... Date: Mon, 11 Dec 2006 21:58:09 EST In a message dated 2006/12/08, dickthomas01@............. writes: > Have you followed this? Am I missing something? I have followed it. And I suspect that you are missing 'quite a lot' ! This instrument is broadband -- that is great, but this device is horizontal. I thought > we were interested in P wave transmission ....first. Even if this is truly > broadbanded, it isn't going to pick up P wave propagation as well as vertical > orientation will? > If you just want to pick up vertical P waves, a quite narrow band response of 0.5 to about 3 Hz, correctly damped, will give optimum results. You don't need a broad band vertical seismometer to do it. But you may well need the associated surface waves, either L or R, to 'mark' the event clearly. P waves on their own can be quite difficult to pick out of the background and you can only receive them directly up to ~103 degrees. The Volksmeter. The Volksmeter is a clever new development which can allow a ''simple'' pendulum sensor to register seismic movements out to 3000 sec period. There is growing interest in the Earth's natural vibrations (earth hum) from 0.3 to several tens of milli Hertz. If it does prove possible to predict at least some earthquakes, this is a likely sensor to be able to do it. Transient vibrations of just a few cycles have be observed as the Earth's crust flexes during Earth Tide oscillations. Commercial production seismometers are limited to about 360 secs max, more typically 120 sec. For Amateur Lehman designs, it is relatively difficult to get stable operation much above 30 secs and the instrument is highly tilt sensitive. Amateur instruments also use coil + magnet velocity coupling and the output voltage falls as the signal frequency decreases. In commercial terms, the Volksmeter is inexpensive and it offers very long period, very high sensitivity responses. This new design ALSO allows the tilt to be measured directly. This could be very useful in predicting / monitoring which quakes are likely to produce tsunamis, particularly for 'near shore' quakes from the subduction zones off the west coast of north and south America. History and Background. For the last 30 years seismometer development has mostly been concentrated on a few designs using sprung elements. A lot of effort has gone into the design and manufacture of 'better' springs, reducing / compensating the effects of temperature, providing prestressed shapes, reducing natural resonance effects and reducing the 'internal noise' by alloying and heat treatment. However, metals are not 'perfectly elastic', but show very tiny 'steps' in their extension / relaxation behaviour which ultimately limits their performance - it is not completely smooth (Portevin Le Chatelier effect) This is all reflected in the high cost of production of the very long period instruments. A precursor to the Volksmeter design is the Shackleford-Gundersen Seismometer which also used a simple pendulum. I suspect that the full potential of the S-G design was not realised at the time due to drift and noise in it's resonant circuit variable capacitance distance transducer and in the difficulty at that time of making a long period electronic integrator. This 1970s design was moderately temperature sensitive. When you are looking for ppm stability, it is not too helpful if your capacitors and inductors are all temperature sensitive and the rectified output voltage depends both on the temperatures of two diodes and on their power dissipation. The original integrator and other circuits were later updated with FET input and low noise opamps. However, the capacitance variation was still provided by varying the separation of ~parallel capacitor plates. This gives a non linear position output. As the central plate moves, air is pumped out of one side and into the other. This air pumping effect is highly non linear with varying gap width and it can seriously effect the damping. Negative feedback was provided, but this also effects the signal to noise ratio. The new capacitative sensor uses a central moving 'electrostatic shadow mask' plate sliding in between an AC driver plate with two parallel strips and a sensor plate with four cross linked elements. The shadow mask plate does not need to be earthed, so it is completely free to move and it experiences no air damping. The output is highly linear with displacement over several mm. Electromagnetic damping is provided. A specialised capacitative bridge measurement chip, the AD7745, has been used. This and the 24 bit ADC are controlled by a dedicated microprocessor. The extremely high resolution and the use of position sensing, rather than a velocity output, allows digital processing of the signals to hugely extend the period. For surface waves with periods above about 300 sec, the tilt component of the signal becomes very significant and this can be measured independent of the period. This new sensor development should be a very significant addition to the science of Seismology. See http://www.seismicnet.com/volksmeter/State-of-the-art_Digital_Seismograph.pdf and http://physics.mercer.edu/hpage/peters.html Regards, Chris Chapman MA In a me= ssage dated 2006/12/08, dickthomas01@............. writes:

Have you followed this? Am I mi= ssing something?


       I have followed it. And I suspect that=20= you are missing 'quite a lot' !

This instrument is broadband -- that is great, but this device is horizontal= .. I thought
we were interested in P wave tr= ansmission ....first. Even if this is truly broadbanded, it isn't going to p= ick up P wave propagation as well as vertical orientation will?

    If you just want to pick up vertical P waves, a quite na= rrow band response of 0.5 to about 3 Hz, correctly damped, will give optimum= results. You don't need a broad band vertical seismometer to do it. But you= may well need the associated surface waves, either L or R, to 'mark' the ev= ent clearly. P waves on their own can be quite difficult to pick out of the=20= background and you can only receive them directly up to ~103 degrees.

The Volksmeter.

       The Volksmeter is a clever new develop= ment which can allow a ''simple'' pendulum sensor to register seismic moveme= nts out to 3000 sec period. There is growing interest in the Earth's natural= vibrations (earth hum) from 0.3 to several tens of milli Hertz. If it does=20= prove possible to predict at least some earthquakes, this is a likely sensor= to be able to do it. Transient vibrations of just a few cycles have be obse= rved as the Earth's crust flexes during Earth Tide oscillations.  =
       Commercial production seismometers are=20= limited to about 360 secs max, more typically 120 sec. For Amateur Lehman de= signs, it is relatively difficult to get stable operation much above 30 secs= and the instrument is highly tilt sensitive. Amateur instruments also use c= oil + magnet velocity coupling and the output voltage falls as the signal fr= equency decreases. In commercial terms, the Volksmeter is inexpensive and it= offers very long period, very high sensitivity responses.
       This new design ALSO allows the tilt to= be measured directly. This could be very useful in predicting / monitoring=20= which quakes are likely to produce tsunamis, particularly for 'near shore' q= uakes from the subduction zones off the west coast of north and south Americ= a.
    
History and Background.

       For the last 30 years seismometer devel= opment has mostly been concentrated on a few designs using sprung elements.=20= A lot of effort has gone into the design and manufacture of 'better' springs= , reducing / compensating the effects of temperature, providing prestressed=20= shapes, reducing natural resonance effects and reducing the 'internal noise'= by alloying and heat treatment. However, metals are not 'perfectly elastic'= , but show very tiny 'steps' in their extension / relaxation behaviour which= ultimately limits their performance - it is not completely smooth (Portevin= Le Chatelier effect) This is all reflected in the high cost of production o= f the very long period instruments.

       A precursor to the Volksmeter design is= the Shackleford-Gundersen Sei= smometer  which also used a simple pendulum. I suspect that the ful= l potential of the S-G design was not realised at the time due to drift and=20= noise in it's resonant circuit variable capacitance distance transducer and=20= in the difficulty at that time of making a long period electronic integrator= .. This 1970s design was moderately temperature sensitive. When you are looki= ng for ppm stability, it is not too helpful if your capacitors and inductors= are all temperature sensitive and the rectified output voltage depends both= on the temperatures of two diodes and on their power dissipation. The origi= nal integrator and other circuits were later updated with FET input and low=20= noise opamps. However, the capacitance variation was still provided by varyi= ng the separation of ~parallel capacitor plates. This gives a non linear pos= ition output. As the central plate moves, air is pumped out of one side and=20= into the other. This air pumping effect is highly non linear with varying ga= p width and it can seriously effect the damping. Negative feedback was provi= ded, but this also effects the signal to noise ratio.
      
       The new capacitative sensor uses a cent= ral moving 'electrostatic shadow mask' plate sliding in between an AC driver= plate with two parallel strips and a sensor plate with four cross linked el= ements. The shadow mask plate does not need to be earthed, so it is complete= ly free to move and it experiences no air damping. The output is highly line= ar with displacement over several mm. Electromagnetic damping is provided.
       A specialised capacitative bridge measu= rement chip, the AD7745, has been used. This and the 24 bit ADC are controll= ed by a dedicated microprocessor. The extremely high resolution and the use=20= of position sensing, rather than a velocity output, allows digital processin= g of the signals to hugely extend the period. For surface waves with periods= above about 300 sec, the tilt component of the signal becomes very signific= ant and this can be measured independent of the period.

       This new sensor development should be a= very significant addition to the science of Seismology. See http://www.seis= micnet.com/volksmeter/State-of-the-art_Digital_Seismograph.pdf and http://ph= ysics.mercer.edu/hpage/peters.html

       Regards,

       Chris Chapman MA Subject: Re: Vertical Sensor From: ChrisAtUpw@....... Date: Tue, 12 Dec 2006 00:18:21 EST In a message dated 2006/12/12, tchannel@.............. writes: > Chris, I was very pleased with the coil/magnet arrangement you suggested, > the one which sandwiched the four magnets between two plates. It was simple > and effective. If I were to make another sensor, this time a vertical like the > AS1, would you suggest the same approach, but modified for vertical rather > than horz? Or to use the horseshoe magnet and coil? I am sure both would work, > but I would like opinions on it. Hi Ted, Entirely up to you. I am not quite sure what you want as 'an opinion'? Quad 1" square NdFeB magnets on mild steel backing plates are likely to give you a much higher magnetic field than a U form Alnico magnet. They are almost certainly cheaper. Large new Alnico magnets are now quite expensive. If you wind a rectangular form coil, you can get a highly linear output and you won't need more than ~3,000 turns. Also, you get very little external stray field. Put the coil on the arm and the magnet assembly on the baseplate. Don't put any ferromagnetic material or a magnet on a seismometer arm - this makes the system very noisy. Just an opinion..... You have my drawings.... Chris Chapman In a me= ssage dated 2006/12/12, tchannel@.............. writes:

Chris, I was very pleased with=20= the coil/magnet arrangement you suggested, the one which sandwiched the four= magnets between two plates. It was simple and effective. If I were to make=20= another sensor, this time a vertical like the AS1, would you suggest the sam= e approach, but modified for vertical rather than horz? Or to use the horses= hoe magnet and coil? I am sure both would work, but I would like opinions on= it.


Hi Ted,

       Entirely up to you. I am not quite sure= what you want as 'an opinion'?

       Quad 1" square NdFeB magnets on mild st= eel backing plates are likely to give you a much higher magnetic field than=20= a U form Alnico magnet. They are almost certainly cheaper. Large new Alnico=20= magnets are now quite expensive.
       If you wind a rectangular form coil, yo= u can get a highly linear output and you won't need more than ~3,000 turns.=20= Also, you get very little external stray field. Put the coil on the arm and=20= the magnet assembly on the baseplate.
       Don't put any ferromagnetic material or= a magnet on a seismometer arm - this makes the system very noisy.

       Just an opinion..... You have my drawin= gs....

       Chris Chapman Subject: Re: Vertical Sensor From: "tchannel" tchannel@.............. Date: Tue, 12 Dec 2006 09:06:01 -0700 Chris, By "an opinion" I guess I was thinking about the best hinge to = use. I have seen fishing line, thin metal hinges, wire hinges and knife = points. I know I would need lateral stability, so the arm would not bob side to = side, but I also know it would need to have minimal friction. On the AS1 it looks as if they just use a wide knife point approach. = Thanks, Ted ----- Original Message -----=20 From: ChrisAtUpw@.......... To: psn-l@................. Sent: Monday, December 11, 2006 10:18 PM Subject: Re: Vertical Sensor In a message dated 2006/12/12, tchannel@.............. writes: Chris, I was very pleased with the coil/magnet arrangement you = suggested, the one which sandwiched the four magnets between two plates. = It was simple and effective. If I were to make another sensor, this time = a vertical like the AS1, would you suggest the same approach, but = modified for vertical rather than horz? Or to use the horseshoe magnet = and coil? I am sure both would work, but I would like opinions on it. Hi Ted, Entirely up to you. I am not quite sure what you want as 'an = opinion'? Quad 1" square NdFeB magnets on mild steel backing plates are = likely to give you a much higher magnetic field than a U form Alnico = magnet. They are almost certainly cheaper. Large new Alnico magnets are = now quite expensive.=20 If you wind a rectangular form coil, you can get a highly = linear output and you won't need more than ~3,000 turns. Also, you get = very little external stray field. Put the coil on the arm and the magnet = assembly on the baseplate.=20 Don't put any ferromagnetic material or a magnet on a = seismometer arm - this makes the system very noisy. Just an opinion..... You have my drawings.... Chris Chapman
Chris,  By "an opinion" I guess I = was thinking=20 about the best hinge to use.  I have seen fishing line, thin metal = hinges,=20 wire hinges and knife points.
I know I would need lateral stability, = so the arm=20 would not bob side to side, but I also know it would need to have = minimal=20 friction.
On the AS1 it looks as if they just use = a wide=20 knife point approach.   Thanks, Ted
----- Original Message -----
From:=20 ChrisAtUpw@.......
Sent: Monday, December 11, 2006 = 10:18=20 PM
Subject: Re: Vertical = Sensor

In a=20 message dated 2006/12/12, tchannel@..............=20 writes:

Chris, I was very pleased with the coil/magnet = arrangement you=20 suggested, the one which sandwiched the four magnets between two = plates. It=20 was simple and effective. If I were to make another sensor, this = time a=20 vertical like the AS1, would you suggest the same approach, but = modified for=20 vertical rather than horz? Or to use the horseshoe magnet and coil? = I am=20 sure both would work, but I would like opinions on it.

Hi=20 Ted,

       Entirely up to you. I = am not=20 quite sure what you want as 'an=20 opinion'?

       Quad 1" square = NdFeB=20 magnets on mild steel backing plates are likely to give you a much = higher=20 magnetic field than a U form Alnico magnet. They are almost certainly = cheaper.=20 Large new Alnico magnets are now quite expensive.=20
       If you wind a rectangular = form coil,=20 you can get a highly linear output and you won't need more than ~3,000 = turns.=20 Also, you get very little external stray field. Put the coil on the = arm and=20 the magnet assembly on the baseplate. =
      =20 Don't put any ferromagnetic material or a magnet on a seismometer arm = - this=20 makes the system very = noisy.

       Just=20 an opinion..... You have my=20 drawings....

       Chris = Chapman=20 Subject: Re: Vertical Sensor From: ChrisAtUpw@....... Date: Tue, 12 Dec 2006 12:06:44 EST In a message dated 2006/12/12, tchannel@.............. writes: > Chris, By "an opinion" I guess I was thinking about the best hinge to use. > I have seen fishing line, thin metal hinges, wire hinges and knife points. > I know I would need lateral stability, so the arm would not bob side to > side, but I also know it would need to have minimal friction. > On the AS1 it looks as if they just use a wide knife point approach. > Thanks, Ted Hi Ted, I suggest that you DON'T use point in a cup, knife edge, or fishing line. Cardan type metal foil or wire, crossed metal foil or wires, ball on a plane, crossed cylinders, rolling metal foil or wires all work OK in that order. On the LPVERTO or STM8 you need crossed foils. If you are using an AS1 type, a pair of crossed cylinders would be fine, alternatively pairs of Cardan foils or wires. Cardan type is a single short flexing element in tension. Hope that this helps. Regards, Chris Chapman In a me= ssage dated 2006/12/12, tchannel@.............. writes:

Chris,  By "an opinion" I=20= guess I was thinking about the best hinge to use.  I have seen fishing=20= line, thin metal hinges, wire hinges and knife points.
I know I would need lateral stability, so the arm would not bob side to sid= e, but I also know it would need to have minimal friction.
On the AS1 it looks as if they just use a wide knife point approach. &= nbsp; Thanks, Ted


Hi Ted,

       I suggest that you DON'T use point in a= cup, knife edge, or fishing line.

       Cardan type metal foil or wire, crossed= metal foil or wires, ball on a plane, crossed cylinders, rolling metal foil= or wires all work OK in that order.
       On the LPVERTO or STM8 you need crossed= foils. If you are using an AS1 type, a pair of crossed cylinders would be f= ine, alternatively pairs of Cardan foils or wires.
       Cardan type is a single short flexing e= lement in tension.
       Hope that this helps.

       Regards,

       Chris Chapman Subject: Quiet times in earthquakes From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sat, 16 Dec 2006 18:02:33 +0000 Hi all I find it to be too quiet in earthquakes at the moment. Besides some micro-quake to mid-size quake activie nothing specal seems to be going on. This reminds me on what happened before christmas 2004, the mag 9.3 earthquake. I did check the data and few weeks before that great earthquake there was a sharp drop in large earthquakes globally. I am unsure what is up, but I do think something is building up at this moment. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Quiet times in earthquakes From: "tchannel" tchannel@.............. Date: Sat, 16 Dec 2006 12:15:51 -0700 Hi Folks, Rather quiet here too, we have had many days of cold fronts which now have cleared, so I'm ready and watching. Has anyone done some sort of probability of events based on past time frames? I have seen charts which show numbers of events in columns by magnitude, by month, by year. Ted ----- Original Message ----- From: "Jón Frímann" To: "PSN-Postlist" Sent: Saturday, December 16, 2006 11:02 AM Subject: Quiet times in earthquakes > Hi all > > I find it to be too quiet in earthquakes at the moment. Besides some > micro-quake to mid-size quake activie nothing specal seems to be going > on. This reminds me on what happened before christmas 2004, the mag 9.3 > earthquake. I did check the data and few weeks before that great > earthquake there was a sharp drop in large earthquakes globally. I am > unsure what is up, but I do think something is building up at this > moment. > > Regards. > -- > Jón Frímann > http://www.jonfr.com > http://www.simnet.is/jonfr500/earthquake/ > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Early Earthquake static 2006 (ISPSN) From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Mon, 18 Dec 2006 01:15:48 +0000 Hi all Here are some numbers about how many earthquakes I have recorded this year, this is not the final number. Since the year is not over yet. If my calcuation are correct, I have recorded 238 earthquakes in 2006. But my earthquake folder contains 714 files so far (all three channels). I've would be intrested in hearing how many earthquakes have been recorded by other stations around the globe. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Shadow Zone Graphics From: "Connie and Jim Lehman" lehmancj@........... Date: Sun, 17 Dec 2006 20:10:57 -0500 PSN folks--for those of you interested and have access to the Journal = of Geoscience Education the November '06 issue has an article on: = Techniques for Mapping Theoretical Shadow Zone for Direct P and S Waves = Propagated as Rays from an Earthquake Epicenter. One of the authors, = Prof. Richard Kroll has done a splendid piece of work for the past 20 = years with amateur type long period sensors in a classroom setting at = Kean Un. in New Jersey. Any College or University offering Geological = courses would have this Journal around as it is the official publication = of the National Associatioin of Geoscience Teachers. http://www.nagt.org=20 The shadow zone for any seismic sensor location is 103-143 degrees = distant. For us in Virginia, we get lots of shadow zone profiles as the = "hot" South Pacific region falls over those limits. A wall mounted = world map showing the shadow zone for your station location would make = an nice addition for quick reference. Although Prof. Kroll did not include this feature, a bold line about = 152 degrees would identify the locations where "seismic caustics" are = noted in the signature. Of course bagging a "caustic" is more rare, as = the open window for the caustic profile must have the epicenter distance = within a degree or so of 152 degrees. A long period 'Caustic' profile = shows the first waveforms arriving to be greater or equal in amplitude = than found elsewhere in the record. =20 Season's Greetings to All Jim Lehman =20 =20
PSN folks--for those of you=20 interested  and have access to the Journal of Geoscience = Education=20 the November '06 issue has an article on: Techniques for = Mapping=20 Theoretical Shadow Zone for Direct P and S Waves Propagated as Rays from = an=20 Earthquake Epicenter.  One of the authors, Prof. Richard Kroll = has=20 done a splendid piece of work for the past 20 = years with =20 amateur type long period sensors in a classroom setting at Kean Un. in = New=20 Jersey.  Any College or University  offering Geological = courses would=20 have this Journal around as it is the official publication of the = National=20 Associatioin of Geoscience Teachers.
http://www.nagt.org =
   The shadow = zone for any=20 seismic sensor location is 103-143 degrees distant.  For us in = Virginia, we=20 get lots of shadow zone profiles as the "hot" South Pacific region=20 falls  over those limits.  A wall mounted world map showing = the=20 shadow zone for your station location would make an nice = addition for=20 quick reference.
   Although Prof. = Kroll did not=20 include this feature,  a bold line about 152 degrees would identify = the=20 locations where "seismic caustics" are noted in the signature.  Of = course=20 bagging a "caustic" is more rare, as the open window for the caustic = profile=20 must have the epicenter distance within a degree or so of 152=20 degrees.  A long period 'Caustic' profile shows the first waveforms = arriving to be greater or equal in amplitude  than found=20 elsewhere in the record. 
    Season's = Greetings to=20 All           &nbs= p;            = ; =20 Jim Lehman
 
 
 
Subject: Hawaiian quake redux From: Mark Robinson mark.robinson@............... Date: Tue, 19 Dec 2006 11:25:28 +1300 http://www.livescience.com/forcesofnature/061215_hawaii_quake.html Big Hawaiian Earthquake Had Surprising Trigger LiveScience 15 December 2006 SAN FRANCISCO—A new fault formed off the northwest coast of Hawaii on Oct. 15 of this year, and now scientists are figuring out what caused the crack and the ensuing 6.7 magnitude earthquake. The surprising results were announced here today at a meeting of the American Geophysical Union. The crack extends about 9 miles in length in the oceanic plate that supports the island. It formed about 35 miles below the sea-surface level, much deeper than quakes typically originate in that region. The temblor set off a chain of events, including a shallower earthquake of magnitude 6.0 and more than 80 aftershocks within a 24-hour period. .... -- Mark Robinson ------------- 19 Dec 1642 Maori kill 4 men in Zeehauen cockboat. 19 Dec 1688 Robinson Crusoe leaves his island after 28 years shipwrecked. 19 Dec 1843 Charles Dickens' A Christmas Carol is published in the United Kingdom. 19 Dec 1848 Emily Bronte died aged 30. 19 Dec 1959 Last Veteran of American civil war dies in Texas. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Quiet times in earthquakes From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Wed, 20 Dec 2006 04:25:27 +0000 Hi It is still rather quiet, both locally and on a global scale. There are few mid-size earthquakes and micro-earthquakes happening, but other then that there is nothing specal going on. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: One year From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Wed, 20 Dec 2006 16:25:35 +0000 Hi all Today it has been a one year since I did start recording earthquakes. But I got my equitment today and I did start to set it up. But I didn't record the first earthquakes until January 2006. Becose I had not setup my hardware properly and also there was a quiet time going on in 2005 around this date. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Scientific American Airtcles From: "Bob Hancock" carpediem1@......... Date: Wed, 20 Dec 2006 09:45:02 -0700 Hi All - The January 2007 issue of Scientific American (arrived by mail yesterday) has two articles of interest for amateur seismologists. Seismic Sentries - Why Underground Nuclear Tests Are So Hard To Hide - The article looks at detection of underground nuclear tests and the difficulties encountered in detecting them The Mississippi's Curious Origins - This article discusses the mountain range that once separated the continental interior of the US from the Gulf of Mexico. It also looks at previous geologic events which could have led to the intra-plate earthquakes in New Madrid, circa 1811-1812, and the Charleston, South Carolina event on 1886. Bob Hancock

Hi All - 

 

The January 2007 issue of Scientific American (arrived by mail yesterday) = has two articles of interest for amateur = seismologists.

 

Seismic Sentries – Why Underground Nuclear Tests Are So Hard To Hide - The article looks at detection of underground nuclear tests and the = difficulties encountered in detecting them

 

The Mississippi’s Curious Origins - This = article discusses the mountain range that once separated the continental = interior of the US from the = Gulf of Mexico.  It also looks at previous = geologic events which could have led to the intra-plate earthquakes in New = Madrid, circa 1811-1812, and the Charleston, South Carolina event on = 1886.

 

Bob Hancock

Subject: Zero length spring discusion From: "Randy" rpratt@............. Date: Wed, 20 Dec 2006 20:01:59 -0600 Hi All, Continuing the spring discussion, what are the practical implications of = a non-zero length? Suppose one wants a 1.5 - 2.0 second vertical = similar to an AS-1. It isn't difficult to get there with a variety of = springs. If the chosen spring has zero force at say mid length how will = that influence the operation over a zero length spring? Isn't it period = that matters and the zero length is important only for getting the = longest possible length in period? Randy
Hi All,
 
Continuing the spring discussion, what = are the=20 practical implications of a non-zero length?  Suppose one wants a = 1.5 -=20 2.0 second vertical similar to an AS-1.  It isn't difficult to = get=20 there with a variety of springs.  If the chosen spring has = zero force=20 at say mid length how will that influence the operation over a zero = length=20 spring?  Isn't it period that matters and the zero length is = important only=20 for getting the longest possible length in period?
 
Randy
Subject: Re: Zero length spring discusion From: ChrisAtUpw@....... Date: Thu, 21 Dec 2006 05:13:35 EST In a message dated 2006/12/21, rpratt@............. writes: > Continuing the spring discussion, what are the practical implications of a > non-zero length? Suppose one wants a 1.5 - 2.0 second vertical similar to an > AS-1. It isn't difficult to get there with a variety of springs. Hi Randy, I suggest that you look up the LaCoste papers at http://psn.quake.net/bibliography.html As you say it is not too difficult to get about a 1 sec period, maybe a bit longer. However if you want to get longer periods, you do need the right geometry / spring load vs extension relationship. You won't get much above 5 secs period with a steel spring anyway. The large temperature coefficient of the steel eventually makes the compensation point highly unstable. You are trying to balance a gravitational load with a spring force. Professional equipment used Ni-SpanC springs which have a ~zero temperature coefficient. Also go to http://quake.eas.gatech.edu/Instruments/LPVERT0.htm If the chosen spring has zero force at say mid length how will that influence the > operation over a zero length spring? Isn't it period that matters and the > zero length is important only for getting the longest possible length in > period? A zero length spring has a plot of physical length versus load which goes through zero. It is very tightly wound and it takes an appreciable force to extend it at all. You ''don't count'' any load which simply does not extend the tension spring. If your spring has a zero force at some mid length, you just won't be able to satisfy the balance conditions - even approximately - and you won't be able to use it to give long periods. The maths is not very complicated, BUT IT IS IMMUTABLE! It sets out the conditions required to get A STABLE BALANCE POINT. Regards, Chris Chapman In a me= ssage dated 2006/12/21, rpratt@............. writes:

Continuing the spring discussio= n, what are the practical implications of a non-zero length?  Suppose o= ne wants a 1.5 - 2.0 second vertical similar to an AS-1. It isn't difficult=20= to get there with a variety of springs. 


Hi Randy,

       I suggest that you look up the LaCoste=20= papers at http://psn.quake.net/bibliography.html
       As you say it is not too difficult to g= et about a 1 sec period, maybe a bit longer. However if you want to get long= er periods, you do need the right geometry / spring load vs extension relati= onship. You won't get much above 5 secs period with a steel spring anyway. T= he large temperature coefficient of the steel eventually makes the compensat= ion point highly unstable. You are trying to balance a gravitational load wi= th a spring force. Professional equipment used Ni-SpanC springs which have a= ~zero temperature coefficient.

       Also go to http://quake.eas.gatech.edu/= Instruments/LPVERT0.htm

If the chosen spring has zero force at say mid length how will that influenc= e the
operation over a zero length s= pring? Isn't it period that matters and the zero length is important only fo= r getting the longest possible length in period?


       A zero length spring has a plot of phys= ical length versus load which goes through zero. It is very tightly wound an= d it takes an appreciable force to extend it at all. You ''don't count'' any= load which simply does not extend the tension spring.
       If your spring has a zero force at some= mid length, you just won't be able to satisfy the balance conditions - even= approximately - and you won't be able to use it to give long periods. The m= aths is not very complicated, BUT IT IS IMMUTABLE! It sets out the condition= s required to get A STABLE BALANCE POINT.

       Regards,

       Chris Chapman Subject: Re: Zero length spring discusion From: "tchannel" tchannel@.............. Date: Thu, 21 Dec 2006 08:29:06 -0700 Hi Randy, As a great tool, have you seen Bob's "springcalc.exe"? Ted ----- Original Message -----=20 From: ChrisAtUpw@.......... To: psn-l@................. Sent: Thursday, December 21, 2006 3:13 AM Subject: Re: Zero length spring discusion In a message dated 2006/12/21, rpratt@............. writes: Continuing the spring discussion, what are the practical = implications of a non-zero length? Suppose one wants a 1.5 - 2.0 second = vertical similar to an AS-1. It isn't difficult to get there with a = variety of springs. =20 Hi Randy, I suggest that you look up the LaCoste papers at = http://psn.quake.net/bibliography.html=20 As you say it is not too difficult to get about a 1 sec period, = maybe a bit longer. However if you want to get longer periods, you do = need the right geometry / spring load vs extension relationship. You = won't get much above 5 secs period with a steel spring anyway. The large = temperature coefficient of the steel eventually makes the compensation = point highly unstable. You are trying to balance a gravitational load = with a spring force. Professional equipment used Ni-SpanC springs which = have a ~zero temperature coefficient.=20 Also go to http://quake.eas.gatech.edu/Instruments/LPVERT0.htm If the chosen spring has zero force at say mid length how will that = influence the=20 operation over a zero length spring? Isn't it period that matters = and the zero length is important only for getting the longest possible = length in period? A zero length spring has a plot of physical length versus load = which goes through zero. It is very tightly wound and it takes an = appreciable force to extend it at all. You ''don't count'' any load = which simply does not extend the tension spring. If your spring has a zero force at some mid length, you just = won't be able to satisfy the balance conditions - even approximately - = and you won't be able to use it to give long periods. The maths is not = very complicated, BUT IT IS IMMUTABLE! It sets out the conditions = required to get A STABLE BALANCE POINT. Regards, Chris Chapman
Hi Randy,  As a great tool, have = you seen=20 Bob's "springcalc.exe"?   Ted
----- Original Message -----
From:=20 ChrisAtUpw@.......
Sent: Thursday, December 21, = 2006 3:13=20 AM
Subject: Re: Zero length spring = discusion

In a=20 message dated 2006/12/21, rpratt@............. = writes:

Continuing the spring discussion, what are the practical = implications of a non-zero length?  Suppose one wants a 1.5 - = 2.0=20 second vertical similar to an AS-1. It isn't difficult to get there = with a=20 variety of springs. 

Hi=20 Randy,

       I suggest that you = look up=20 the LaCoste papers at http://psn.quake.net/bibliography.html=20
       As you say it is not too = difficult to=20 get about a 1 sec period, maybe a bit longer. However if you want to = get=20 longer periods, you do need the right geometry / spring load vs = extension=20 relationship. You won't get much above 5 secs period with a steel = spring=20 anyway. The large temperature coefficient of the steel eventually = makes the=20 compensation point highly unstable. You are trying to balance a = gravitational=20 load with a spring force. Professional equipment used Ni-SpanC springs = which=20 have a ~zero temperature coefficient.=20

       Also go to=20 http://quake.eas.gatech.edu/Instruments/LPVERT0.htm

If the = chosen=20 spring has zero force at say mid length how will that influence the=20
operation over a zero length spring? Isn't it period = that=20 matters and the zero length is important only for getting the = longest=20 possible length in period?

       A zero = length spring=20 has a plot of physical length versus load which goes through zero. It = is very=20 tightly wound and it takes an appreciable force to extend it at all. = You=20 ''don't count'' any load which simply does not extend the tension=20 spring.
       If your spring has a = zero=20 force at some mid length, you just won't be able to satisfy the = balance=20 conditions - even approximately - and you won't be able to use it to = give long=20 periods. The maths is not very complicated, BUT IT IS IMMUTABLE! It = sets out=20 the conditions required to get A STABLE BALANCE=20 POINT.

      =20 Regards,

       Chris = Chapman=20 Subject: Fw: Salvadoran-Guatemalan border From: "Thomas Dick" dickthomas01@............. Date: Fri, 22 Dec 2006 12:56:05 -0600 Subject: Salvadoran-Guatemalan border Local paper has article today about an earthquake swarm of more than 100 = earthquakes between 2.3 and 4.3 since Wednesday with no injuries near = Atiquizaya City.
 
Subject: Salvadoran-Guatemalan border

Local paper has article today about an = earthquake=20 swarm of more than 100 earthquakes between 2.3 and 4.3 since Wednesday = with no=20 injuries near Atiquizaya City.
Subject: WinSDR settings for Mark Products 4.5 Hz 3 Component L15B Sensor From: Dave Willey davewilley@............. Date: Fri, 22 Dec 2006 14:25:32 -0800 (PST) Hi Everyone, After spending way too much time beating myself up trying to setup the WinSDR's filters, I want to ask the group for pointers. My setup includes 3 axis Mark L15B 4.5Hz sensors, Larry's A/D & filter boards. Where I'm at is in the suburbs of Santa Rosa California, with some local street traffic a few hundred feet, and some nearby highway traffic 1/2 mile away. (So I know it's not ideal. But that's what I've got to work with.) What I'm aiming for is local activity around 200 miles out. No teleseismic stuff yet. (I have an unused 4th channel on the board earmarked for this someday.) I'm just about 25 miles south from the geothermal fields here in Northern California, So there's just about always something to watch everyday. (Besides auto traffic! If I can get this dialed in better.) Specifically. How do folks have their low / hi pass filters set? (Specific freq & number of poles would be a REAL help.) Just as a starting point. Anything I missed in the setup I should be concerned with? Any other questions about my setup please feel free to ask. Thanks for the help in advance. Dave Willey Hi Everyone,

After spending way too much time beating myself up trying to setup the WinSDR's filters, I want to ask the group for pointers.

My setup includes 3 axis Mark L15B 4.5Hz sensors, Larry's A/D & filter boards.

Where I'm at is in the suburbs of Santa Rosa California, with some local  street traffic a few hundred feet, and some nearby highway traffic  1/2 mile away.  (So I know it's not ideal.  But that's what I've got to work with.)

What I'm aiming for is local activity around 200 miles out. No teleseismic stuff yet. (I have an unused 4th channel on the board earmarked for this someday.)  I'm just about 25 miles south from the geothermal fields here in Northern California,  So there's just about always something to watch everyday. (Besides auto traffic!  If I can get this dialed in better.)

Specifically. How do folks have their low / hi pass filters set? (Specific freq & number of poles would be a REAL help.)  Just as a starting point.

Anything I missed in the setup I should be concerned with?

Any other questions about my setup please feel free to ask.


Thanks for the help in advance.


Dave Willey





Subject: Re: WinSDR settings for Mark Products 4.5 Hz 3 Component L15B From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 22 Dec 2006 22:59:23 +0000 Hi I use the raw output on the computer screen, that is seeing all the noise there. If nessary I lowpass filter the psn files down to 4Hz or whatever I need. But my online plots are filtered at 4Hz. To detect local activite at ~320 km you need to increase the amplifeing on your winsdr board (removing the jumpers to start with). That is what I did and that did improve the resaults and what I was detecting earthquake wise. That did also enable me to record teleseismic earthquakes with 4.5Hz geophone, but only really large one, mostly earthquakes above mag 6.0+ at size. But it is location dependent for me and problay is for you too. I also recommend a screened cable or some form of properly ground connected cable, in order to prevent electronic interferance in your instruments. I hope that this can help you something. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: WinSDR settings for Mark Products 4.5 Hz 3 Component L15B Sensor From: Larry Cochrane lcochrane@.............. Date: Sat, 23 Dec 2006 15:03:21 -0800 Hi Dave, There is no need to use a high-pass filter with a 4.5Hz sensor since there is no low frequency information that you should need to filter out. For the low-pass filter you could use a 4 pole 2 or 3 hz filter to filter out some of the local ground noise. Regards, Larry Cochrane Redwood City, PSN Dave Willey wrote: > Hi Everyone, > > After spending way too much time beating myself up trying to setup the > WinSDR's filters, I want to ask the group for pointers. > > My setup includes 3 axis Mark L15B 4.5Hz sensors, Larry's A/D & filter > boards. > > Where I'm at is in the suburbs of Santa Rosa California, with some > local street traffic a few hundred feet, and some nearby highway > traffic 1/2 mile away. (So I know it's not ideal. But that's what > I've got to work with.) > > What I'm aiming for is local activity around 200 miles out. No > teleseismic stuff yet. (I have an unused 4th channel on the board > earmarked for this someday.) I'm just about 25 miles south from the > geothermal fields here in Northern California, So there's just about > always something to watch everyday. (Besides auto traffic! If I can get > this dialed in better.) > > Specifically. How do folks have their low / hi pass filters set? > (Specific freq & number of poles would be a REAL help.) Just as a > starting point. > > Anything I missed in the setup I should be concerned with? > > Any other questions about my setup please feel free to ask. > > > Thanks for the help in advance. > > > Dave Willey > > > > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Shadow Zones From: "Jerry Payton" gpayton880@....... Date: Sat, 23 Dec 2006 18:31:35 -0600 If given my exact location on the earth (lat/Long), is there a software program to show WHERE my "shadow zone" is located? What area(s) would be excluded? I understand Lat. / Long., but the degrees described with a shadow zone is a little confusing to me. Happy Holliday Season Regards, Jerry Payton
If given my exact location on the earth (lat/Long), is there a = software=20 program to show WHERE my "shadow zone" is located?   What = area(s)=20 would be excluded?
 
I understand Lat. / Long., but the degrees described with a shadow = zone is=20 a little confusing to me.
 
Happy Holliday Season
 
Regards,
Jerry Payton
Subject: Re: Shadow Zones From: Mark Robinson mark.robinson@............... Date: Sun, 24 Dec 2006 14:09:51 +1300 Jerry Payton wrote: > If given my exact location on the earth (lat/Long), is there a software > program to show WHERE my "shadow zone" is located? What area(s) would be > excluded? > > I understand Lat. / Long., but the degrees described with a shadow zone is a > little confusing to me. > > Happy Holliday Season > > Regards, > Jerry Payton > http://gc.kls2.com/ is a great circle map generator one degree = 60 nautical miles: 103 degrees =~ 6180 nm (start of shadow zone) 143 degrees =~ 8580 nm (end of shadow zone) 152 degrees =~ 9120 nm (caustic) You can enter your lat/long or specify a nearby airport as your origin For Wellington, New Zealand: http://gc.kls2.com/cgi-bin/gc?RANGE=6180nm%40WLG http://gc.kls2.com/cgi-bin/gc?RANGE=8580nm%40WLG http://gc.kls2.com/cgi-bin/gc?RANGE=9120nm%40WLG -- cheers Mark Robinson ------------- 24 Dec 1953 151 people die when the Limited express plunges into the river at Tangiwai, after the bridge is washed out following the rupture of the crater lake of Mount Ruapehu. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Building vertical spring sensor From: "tchannel" tchannel@.............. Date: Sat, 23 Dec 2006 21:23:27 -0700 Hi Folks, Merry Christmas and a Happy New Year to all. I am building = a vertical spring sensor, using 1" and 1/2" copper water pipe and all = the common tees, elbows etc, avail at any Home Building Supply store. = I have seen sensor made from wood, aluminum so I thought I would use = copper pipe simply because I had some left over pieces. Interesting to = me is that it seems to be working just fine. The unit is about half = done, and here are some things I like about it so far. The shape is = basically similar to a AS1, it has a "T" for the base, an "Arm", a = vertical column which forms a "L" to the base, a "zero length" 6" = spring, and lots of tees and fittings. 1. If you have some copper tubing, and fittings, the cost is not too = bad, because the sensor is so small, about 20" long 9" wide and 11" = tall. I chose the dims to fit inside a fish aquarium, which I will invert = and use as a cover for the sensor. This too was from the salvage pile. 2. I soldered the fitting together, using just a little solder to hold = it without big, ugly, globs of solder around the joints, as it doesn't = need to hold water. It will look better when I polish the copper up. 3. Some joints I wanted to rotate. Not too loose, but loose enough to = rotate with your hands. On these joints, which were too loose to hold = their position when connected, but not soldered, I used a punch and = created a dimple on the outside of the tube. When I inserted the tube = into a tee or elbow, it became very tight and would hold it position, = until you twisted it to a new location. 4. At this point, the frame is done, the three adjusting leveling feet = and the spring. I still need to build the damper, the coil/magnet and = mass, but so far so good. Q. My question at this point is: What is the target for the period? = The sensor is adjustable, the spring can be tightened, the hinge and arm = can be lower, etc. Any adjust I make, changes the period, if I tweak it = I can get 4 seconds, but the stable position on the arm is small. If I = change the period to 3 seconds, I seem to get a larger area of stability = in the arc of the arm. By unstable I mean, If I move the horizontal = spring loaded arm up or down a little it will return to center, however, = If I move it too far up it will fall toward the spring. Should I = target the longest period I can get, even thought the arm is touchy and = could fall up or down? Or should I target less the maximum in order to = get a more stable arm? I can send pictures, of the frame, if anyone is interested...... I am = not sure this will be the best design, but it may provide food for = thought. Seeing something different can often generate new ideas. Thanks, Ted
Hi Folks,  Merry Christmas and a = Happy New=20 Year to all.   I am building a vertical spring sensor, using = 1" and=20 1/2" copper water pipe and all the common tees, elbows etc, avail at any = Home=20 Building Supply store.   I have seen sensor made from wood, = aluminum=20 so I thought I would use copper pipe simply because I had some left over = pieces.  Interesting to me is that it seems to be working just = fine. =20 The unit is about half done, and here are some things I like about it so = far.   The shape is basically similar to a AS1, it has = a "T"=20 for the base, an  "Arm", a vertical column which forms a "L" to the = base,=20 a  "zero length" 6" spring, and lots of tees and = fittings.
1.  If you have some copper = tubing, and=20 fittings, the cost is not too bad, because the sensor is so small, about = 20"=20 long 9" wide and 11" tall.
     I chose the = dims to fit=20 inside a fish aquarium, which I will invert and use as a cover for the=20 sensor.  This too was from the salvage pile.
2.  I soldered the fitting = together, using=20 just a little solder to hold it without big, ugly, globs of solder = around the=20 joints, as it doesn't  need to hold water.
     It will look = better when I=20 polish the copper up.
3.  Some joints I wanted =  to rotate.  Not too loose, but loose enough = to rotate=20 with your hands.  On these joints, which were too loose to hold = their=20 position when connected, but not soldered,  I used a punch and = created a=20 dimple on the outside of the tube.  When I inserted the tube into a = tee or=20 elbow, it became very tight and would hold it position, until you = twisted it to=20 a new location.
4.   At this point, the frame = is done,=20 the three adjusting leveling feet and the spring.   I still = need to=20 build the damper, the coil/magnet and mass, but so far so = good.
 
Q.   My question at this = point is: What=20 is the target for the period?   The sensor is adjustable, the = spring=20 can be tightened, the hinge and arm can be lower, etc.  Any adjust = I make,=20 changes the period, if I tweak it I can get 4 seconds, but the stable = position=20 on the arm is small.  If I change the period to 3 seconds, I seem = to get a=20 larger area of stability in the arc of the arm.   By unstable = I mean,=20 If I move the horizontal spring loaded arm up or down a little it will = return to=20 center, however,  If I move it too far up it will fall toward the=20 spring.    Should I target the longest period I can get, = even=20 thought the arm is touchy and could fall up or down?  Or should I = target=20 less the maximum in order to get a more stable arm?
 
I can send pictures, of the = frame, if anyone=20 is interested...... I am not sure this will be the best design, but it = may=20 provide food for thought.  Seeing something different can = often=20 generate new ideas.
Thanks, Ted
Subject: Re: Building vertical spring sensor From: chrisatupw@....... Date: Sun, 24 Dec 2006 09:56:02 -0500 From: tchannel@.............. Subject: Building vertical spring sensor 2. I soldered the fitting together, using just a little solder to hold it without big, ugly, globs of solder around the joints, as it doesn't need to hold water. Hi Ted, Solder it properly, leaving a fillet around the end. You need the joints to be firm and rigid 3. Some joints I wanted to rotate. Not too loose, but loose enough to rotate with your hands. Then use compression fittings, not a push fit distorted tube - it won't be satisfactory long term. 4. At this point, the frame is done, the three adjusting leveling feet and the spring. I still need to build the damper, the coil/magnet and mass, but so far so good. Q. My question at this point is: What is the target for the period? The sensor is adjustable, the spring can be tightened, the hinge and arm can be lower, etc. Any adjust I make, changes the period, if I tweak it I can get 4 seconds, but the stable position on the arm is small. If I change the period to 3 seconds, I seem to get a larger area of stability in the arc of the arm. By unstable I mean, If I move the horizontal spring loaded arm up or down a little it will return to center, however, If I move it too far up it will fall toward the spring. Should I target the longest period I can get, even thought the arm is touchy and could fall up or down? If you try for a long period, the sensor will literally fall out of balance as the temperature changes. Steel springs are very sensitive to temperature. I suggest that you try for 2 to 3 seconds and then extend the period electronically, or in software. Regards, Chris Chapman
 From: tchannel@..............
Subject: Building vertical spring sensor

2.  I soldered the fitting together, using just a little solder to hold it without big, ugly, globs of solder around the joints, as it doesn't  need to hold water.
 
Hi Ted,
 
Solder it properly, leaving a fillet around the end. You need the joints to be firm and rigid
 
3.  Some joints I wanted  to rotate.  Not too loose, but loose enough to rotate with your hands. 
 
Then use compression fittings, not a push fit distorted tube - it won't be satisfactory long term.
 
 4.   At this point, the frame is done, the three adjusting leveling feet and the spring.   I still need to build the damper, the coil/magnet and mass, but so far so good.
 
Q.   My question at this point is: What is the target for the period?   The sensor is adjustable, the spring can be tightened, the hinge and arm can be lower, etc.  Any adjust I make, changes the period, if I tweak it I can get 4 seconds, but the stable position on the arm is small.  If I change the period to 3 seconds, I seem to get a larger area of stability in the arc of the arm.   By unstable I mean, If I move the horizontal spring loaded arm up or down a little it will return to center, however,  If I move it too far up it will fall toward the spring. Should I target the longest period I can get, even thought the arm is touchy and could fall up or down?  
 
If you try for a long period, the sensor will literally fall out of balance as the temperature changes. Steel springs are very sensitive to temperature. I suggest that you try for 2 to 3 seconds and then extend the period electronically, or in software.
 
Regards,
 
Chris Chapman
 
Subject: Happy Christmas From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Mon, 25 Dec 2006 00:13:04 +0000 Hi all I want to with all members of the psn postlist a happy christmas and a good holydays. Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Earthquake in Scotland From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Tue, 26 Dec 2006 11:04:20 +0000 Hi all I just noticed that there was a ML 3.8 earthquake in Scotland. Here is the time info from emsc-csem. Magnitude ML 3.8 Region SCOTLAND, UNITED KINGDOM Southern Scotland Date time 2006-12-26 at 10:40:03.8 UTC Location 55.16 N ; 3.64 W Depth 40 km http://www.emsc-csem.org/index.php?page=current&sub=detail&id=37725 Regards. -- Jón Frímann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Shadow Zones From: chrisatupw@....... Date: Tue, 26 Dec 2006 06:57:56 -0500 From: gpayton880@....... Subject: Shadow Zones If given my exact location on the earth (lat/Long), is there a software program to show WHERE my "shadow zone" is located? What area(s) would be excluded? I understand Lat. / Long., but the degrees described with a shadow zone is a little confusing to me. Hi Jerry, Can you get yourself a globe? Then take a strip of cardboard, measure the correct anglar length at the equator, put one end on your home location and use the other to scribe the circular zones with a crayon or similar. You are probably only interested in locations where the circles cross active quake zones. Regards, Chris Chapman
From: gpayton880@.......
Subject: Shadow Zones

If given my exact location on the earth (lat/Long), is there a software program to show WHERE my "shadow zone" is located?   What area(s) would be excluded?
 
I understand Lat. / Long., but the degrees described with a shadow zone is a little confusing to me.
 
Hi Jerry,
 
     Can you get yourself a globe? Then take a strip of cardboard, measure the correct anglar length at the equator, put one end on your home location and use the other to scribe the circular zones with a crayon or similar. You are probably only interested in locations where the circles cross active quake zones.
 
Regards,
 
Chris Chapman
Subject: Re[2]: Shadow Zones From: Angel sismos@.............. Date: Tue, 26 Dec 2006 12:18:58 +0000 Hello Chris, Merry Christmas to all. Jerry, maybe this poster will help a bit. http://www.iris.edu/gifs/ExplorEarthPoster.jpg regards, Angnel Tuesday, December 26, 2006, 11:57:56 AM, you wrote: > > From: gpayton880@....... > Subject: Shadow Zones > > > > If given my exact location on the earth (lat/Long), is there a > software program to show WHERE my "shadow zone" is located?   What area(s) would be excluded? >   > I understand Lat. / Long., but the degrees described with a > shadow zone is a little confusing to me. >   > Hi Jerry, >   >      Can you get yourself a globe? Then take a strip of > cardboard, measure the correct anglar length at the equator, put one > end on your home location and use the other to scribe the circular > zones with a crayon or similar. You are probably only interested in > locations where the circles cross active quake zones. >   > Regards, >   > Chris Chapman > -- Best regards, Angel __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Building vertical spring sensor From: "Geoffrey" gmvoeth@........... Date: Wed, 27 Dec 2006 18:20:49 -0700 Depends upon what kind of electronics you intend to use. If you make it two hertz then it is quite simple to equalize down to two seconds or so. If you make it three seconds then all you need is a band pass filter of N=4 at the low end of 3.5 to 4 seconds and the high end being 2 HZ or so. Then you can get the P waves and some S but none of the surface stuff for teleseismic events. If you want to use prebuilt electronics you probably should study the specification before setting your free period. it is really much more complex then it seems at first glance. regards and happy holidays; geoff ----- Original Message ----- From: "tchannel" To: Sent: Saturday, December 23, 2006 9:23 PM Subject: Building vertical spring sensor Hi Folks, Merry Christmas and a Happy New Year to all. I am building a vertical spring sensor, using 1" and 1/2" copper water pipe and all the common tees, elbows etc, avail at any Home Building Supply store. I have seen sensor made from wood, aluminum so I thought I would use copper pipe simply because I had some left over pieces. Interesting to me is that it seems to be working just fine. The unit is about half done, and here are some things I like about it so far. The shape is basically similar to a AS1, it has a "T" for the base, an "Arm", a vertical column which forms a "L" to the base, a "zero length" 6" spring, and lots of tees and fittings. 1. If you have some copper tubing, and fittings, the cost is not too bad, because the sensor is so small, about 20" long 9" wide and 11" tall. I chose the dims to fit inside a fish aquarium, which I will invert and use as a cover for the sensor. This too was from the salvage pile. 2. I soldered the fitting together, using just a little solder to hold it without big, ugly, globs of solder around the joints, as it doesn't need to hold water. It will look better when I polish the copper up. 3. Some joints I wanted to rotate. Not too loose, but loose enough to rotate with your hands. On these joints, which were too loose to hold their position when connected, but not soldered, I used a punch and created a dimple on the outside of the tube. When I inserted the tube into a tee or elbow, it became very tight and would hold it position, until you twisted it to a new location. 4. At this point, the frame is done, the three adjusting leveling feet and the spring. I still need to build the damper, the coil/magnet and mass, but so far so good. Q. My question at this point is: What is the target for the period? The sensor is adjustable, the spring can be tightened, the hinge and arm can be lower, etc. Any adjust I make, changes the period, if I tweak it I can get 4 seconds, but the stable position on the arm is small. If I change the period to 3 seconds, I seem to get a larger area of stability in the arc of the arm. By unstable I mean, If I move the horizontal spring loaded arm up or down a little it will return to center, however, If I move it too far up it will fall toward the spring. Should I target the longest period I can get, even thought the arm is touchy and could fall up or down? Or should I target less the maximum in order to get a more stable arm? I can send pictures, of the frame, if anyone is interested...... I am not sure this will be the best design, but it may provide food for thought. Seeing something different can often generate new ideas. Thanks, Ted __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Zero Length Spring From: "Randy" rpratt@............. Date: Wed, 27 Dec 2006 20:25:26 -0600 Hi Again, Thanks for the earlier replies. I spent a few wonderful days in North = Dakota for the holiday so have just gotten back to it. Bob can you = explain the SeisK in your program? Is it a derived spring constant for = the geometric conditions created or a stability factor? I note that = negative is always unstable but a negative length spring does not create = instability. I still have not answered my original question though. I have 3 = examples from Bob's program below. The first is similar to a spring I = have currently set up. The second is a zero length spring with the same = spring K and attachment point on the boom set to the same period. The = third is a softer spring of 0 length. Given 2 springs and the same = period, will one operate noticably better at a given period in practice? = =20 SpringAngle=3D 25, Force=3D 1.3898, Length=3D 0.2247 X and Y -0.0076,0.1079 TorqueUp=3D -0.000339, Down=3D 0.000337 SeisK=3D 0.6622, Period=3D 1.44=20 SpringAngle=3D 12, Force=3D 2.4595, Length=3D 0.1783 X and Y 0.0216,0.0501 TorqueUp=3D -0.000337, Down=3D 0.000337 SeisK=3D 0.6604, Period=3D 1.44 SpringAngle=3D 35, Force=3D 1.0685, Length=3D 0.1797 X and Y 0.0488,0.1161 TorqueUp=3D -0.000329, Down=3D 0.000329 SeisK=3D 0.6454, Period=3D 1.45 Randy
Hi Again,
 
Thanks for the earlier replies.  I = spent a few=20 wonderful days in North Dakota for the holiday so have just gotten back = to=20 it.  Bob can you explain the SeisK in your program?  Is it a = derived=20 spring constant for the geometric conditions created or a stability=20 factor?  I note that negative is always unstable but a negative = length=20 spring does not create instability.
 
I still have not answered my original = question=20 though.   I have 3 examples from Bob's program = below.  The=20 first is similar to a spring I have currently set up.  The second = is a zero=20 length spring with the same spring K and attachment point on the boom = set to the=20 same period.  The third is a softer spring of 0 length.  Given = 2=20 springs and the same period, will one operate noticably better at a = given=20 period in practice?   
 
SpringAngle=3D 25, Force=3D 1.3898, = Length=3D 0.2247
X=20 and Y -0.0076,0.1079
TorqueUp=3D -0.000339, Down=3D = 0.000337
SeisK=3D=20 0.6622,  Period=3D 1.44 
 
SpringAngle=3D 12, Force=3D 2.4595, = Length=3D 0.1783
X=20 and Y 0.0216,0.0501
TorqueUp=3D -0.000337, Down=3D = 0.000337
SeisK=3D=20 0.6604,  Period=3D 1.44
 
SpringAngle=3D 35, Force=3D 1.0685, = Length=3D 0.1797
X=20 and Y 0.0488,0.1161
TorqueUp=3D -0.000329, Down=3D = 0.000329
SeisK=3D=20 0.6454,  Period=3D 1.45
 
Randy
Subject: Re: Zero Length Spring From: "Geoffrey" gmvoeth@........... Date: Thu, 28 Dec 2006 08:29:55 -0700 I understand Damping and Q are simply inverses of each other. Q is quite complex in that it requires the knowledge of the 3db (0.7071) cutoff points as relating to the frq of interest. Can anyone tell me the proper way to express damping ?? I sort of understand Q but not how you arrive at the proper numbers for damping alone. Regards; geoff ----- Original Message ----- From: "Randy" To: Sent: Wednesday, December 27, 2006 7:25 PM Subject: Zero Length Spring Hi Again, Thanks for the earlier replies. I spent a few wonderful days in North Dakota for the holiday so have just gotten back to it. Bob can you explain the SeisK in your program? Is it a derived spring constant for the geometric conditions created or a stability factor? I note that negative is always unstable but a negative length spring does not create instability. I still have not answered my original question though. I have 3 examples from Bob's program below. The first is similar to a spring I have currently set up. The second is a zero length spring with the same spring K and attachment point on the boom set to the same period. The third is a softer spring of 0 length. Given 2 springs and the same period, will one operate noticably better at a given period in practice? SpringAngle= 25, Force= 1.3898, Length= 0.2247 X and Y -0.0076,0.1079 TorqueUp= -0.000339, Down= 0.000337 SeisK= 0.6622, Period= 1.44 SpringAngle= 12, Force= 2.4595, Length= 0.1783 X and Y 0.0216,0.0501 TorqueUp= -0.000337, Down= 0.000337 SeisK= 0.6604, Period= 1.44 SpringAngle= 35, Force= 1.0685, Length= 0.1797 X and Y 0.0488,0.1161 TorqueUp= -0.000329, Down= 0.000329 SeisK= 0.6454, Period= 1.45 Randy __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Earthquake in Scotland From: ian ian@........... Date: Thu, 28 Dec 2006 17:40:34 +0000 Hi, I managed to record it with my geophone but despite being only about 100 miles away, I didn't get a good trace. My two amplifier/filters are showing their age... Cheers Ian Jón Frímann wrote: >Hi all > >I just noticed that there was a ML 3.8 earthquake in Scotland. Here is >the time info from emsc-csem. > >Magnitude ML 3.8 Region SCOTLAND, UNITED KINGDOM Southern Scotland Date >time 2006-12-26 at 10:40:03.8 UTC Location 55.16 N ; 3.64 W Depth 40 km > >http://www.emsc-csem.org/index.php?page=current&sub=detail&id=37725 > >Regards. > > Hi,

I managed to record it with my geophone but despite being only about 100 miles away, I didn't get a good trace.  My two amplifier/filters are showing their age...

Cheers

Ian

Jón Frímann wrote:
Hi all

I just noticed that there was a ML 3.8 earthquake in Scotland. Here is
the time info from emsc-csem.

Magnitude ML 3.8 Region SCOTLAND, UNITED KINGDOM  Southern Scotland Date
time 2006-12-26 at 10:40:03.8 UTC Location 55.16 N ; 3.64 W Depth 40 km

http://www.emsc-csem.org/index.php?page=current&sub=detail&id=37725

Regards.


Subject: Re: Zero Length Spring From: Bobhelenmcclure@....... Date: Fri, 29 Dec 2006 12:53:54 EST Randy wrote: I still have not answered my original question though. I have 3 examples from Bob's program below. The first is similar to a spring I have currently set up. The second is a zero length spring with the same spring K and attachment point on the boom set to the same period. The third is a softer spring of 0 length. Given 2 springs and the same period, will one operate noticably better at a given period in practice? ~~~~~~~~~~~ Hi Randy, The best spring to use is one of zero length. One of higher spring constant will have to be mounted nearer the pendulum hinge, and will exert greater force on the hinge and spring mounts. It is better to have as low a spring constant as possible. It should be mounted at a point on the arm where the spring ends up making an angle of about 45 degrees to the arm. It is best to adjust for a period of no more than 5 seconds. Ambient temperature changes cause too much pendulum shift and instability at longer periods. The effective period can be extended by a factor of 5 or more by use of my "WQFilter.exe" utility. This utility accepts and outputs PSN Type 4 files. "WQFilter.exe" is contained in "seismic_dataq.zip", which can be downloaded from Web page _http://www.jclahr.com/science/psn/mcclure/wdq_utilities/index.html_ (http://www.jclahr.com/science/psn/mcclure/wdq_utilities/index.html) I urge all who operate open loop vertical sensors and Mini-Lehman sensors to consider using this utility. It does wonders for me. Bob
Randy wrote:
 
I still have not answered my original question though.   I ha= ve 3=20
examples from Bob's program below.  The first is similar to a sprin= g I=20
have currently set up.  The second is a zero length spring with the= =20 same
spring K and attachment point on the boom set to the same period.&n= bsp;=20 The
third is a softer spring of 0 length.  Given 2 springs and the=20= same=20
period, will one operate noticably better at a given period in practice?= =20
~~~~~~~~~~~
 
Hi Randy,
 
  The best spring to use is one of zero length. One of higher spri= ng=20 constant will have to be mounted nearer the pendulum hinge, and will exert=20 greater force on the hinge and spring mounts. It is better to have as low a=20 spring constant as possible. It should be mounted at a point on the arm wher= e=20 the spring ends up making an angle of about 45 degrees to the arm.
 
  It is best to adjust for a period of no more than 5 seconds. Amb= ient=20 temperature changes cause too much pendulum shift and instability at longer=20 periods. The effective period can be extended by a factor of 5 or more by us= e of=20 my "WQFilter.exe" utility. This utility accepts and outputs PSN Type 4=20 files.
 
 "WQFilter.exe" is contained in "seismic_dataq.zip", which can be=20 downloaded from Web page
 
  = http://www.jclahr.com/science/psn/mcclure/wdq_utilities/index.html
 
  I urge all who operate open loop vertical sensors and Mini-Lehma= n=20 sensors to consider using this utility. It does wonders for me.
 
Bob
 
 
 Subject: Public Seismic Network - Alaska has a new URL From: "Bob Hammond" propgrinder@......... Date: Fri, 29 Dec 2006 12:32:10 -0900 My ISP shut down and I've moved my PSN web site to a new URL: Public Seismic Network - Alaska . Please make note of the new URL. and Happy New Year to all. Bob Hammond Fairbanks, AK http://wulik.com
My ISP shut down and I've moved my PSN web site to a new URL:
 
Please make note of the new URL.
 
and Happy New Year to all.
 
Bob Hammond
Fairbanks, AK
Subject: Re: Public Seismic Network - Alaska has a new URL From: ian ian@........... Date: Fri, 29 Dec 2006 22:37:40 +0000 alaskapsn, psnalaska, psn-alaska and alaska-psn (.com, .net & .org) are all available. If you buy one you can point it at your webspace. Next time your isp shuts down, you change where your domain points to. Just a thought... Ian www.iasmith.com Bob Hammond wrote: > My ISP shut down and I've moved my PSN web site to a new URL: > Public Seismic Network - Alaska . > > Please make note of the new URL. > > and Happy New Year to all. > > Bob Hammond > Fairbanks, AK > http://wulik.com alaskapsn, psnalaska, psn-alaska and alaska-psn (.com, .net & .org) are all available.  If you buy one you can point it at your webspace.  Next time your isp shuts down, you change where your domain points to.  Just a thought...

Ian
www.iasmith.com

Bob Hammond wrote:
My ISP shut down and I've moved my PSN web site to a new URL:
 
Please make note of the new URL.
 
and Happy New Year to all.
 
Bob Hammond
Fairbanks, AK

Subject: Re: Zero Length Spring From: Brett Nordgren Brett3mr@............. Date: Fri, 29 Dec 2006 17:50:03 -0500 Geoff, The relationships between mechanical damping, Damping Factor and Q aren't too involved. If you assume an undamped spring-mass system with a mass of M, kg, and a spring constant K, Newtons/m , it will vibrate with a natural frequency of omega-zero = 2 sqrt(K/M) radians per second. (You can divide radians per second by 2 Pi to get cps or Hz ). If you then add velocity damping, which means you add a resistance force which is exactly proportional to the instantaneous velocity of the mass, of an amount = R, Newtons / meter/second, you can then calculate the Damping Factor, zeta and Quality factor, Q . Quality Factor, Q, = M / R or Q = 1 / (2 * omega-zero * zeta) and Damping Factor, zeta, = R / ( 2 * sqrt (M * K)) or zeta = R / (2 * M * omega-zero) = 1 / (2 * omega-zero * Q) Regarding dimensions, since one kilogram meter/sec^2 = 1 Newton, the units all cancel for both Q and zeta, so they are both dimensionless. The zero in omega-zero signifies the *undamped* natural frequency. As you add damping, looking at the frequency response of the spring-mass system, its amplitude peak gets lower and at the same time moves somewhat in frequency before the damping gets so great that the peak disappears altogether. You can see the same equations in a much prettier form near the end of http://bnordgren.org/seismo/feedback_in_seismic_sensors.pdf (underscored spaces) Though it's pretty big - a couple of MB, I think. Regards, Brett At 08:29 AM 12/28/2006 -0700, you wrote: >I understand Damping and Q >are simply inverses of each other. >Q is quite complex in that it >requires the knowledge of the >3db (0.7071) cutoff points as >relating to the frq of interest. > >Can anyone tell me the proper way >to express damping ?? >I sort of understand Q but not >how you arrive at the proper numbers >for damping alone. > >Regards; >geoff __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Zero Length Spring From: Brett Nordgren Brett3mr@............. Date: Fri, 29 Dec 2006 17:50:03 -0500 Geoff, The relationships between mechanical damping, Damping Factor and Q aren't too involved. If you assume an undamped spring-mass system with a mass of M, kg, and a spring constant K, Newtons/m , it will vibrate with a natural frequency of omega-zero = 2 sqrt(K/M) radians per second. (You can divide radians per second by 2 Pi to get cps or Hz ). If you then add velocity damping, which means you add a resistance force which is exactly proportional to the instantaneous velocity of the mass, of an amount = R, Newtons / meter/second, you can then calculate the Damping Factor, zeta and Quality factor, Q . Quality Factor, Q, = M / R or Q = 1 / (2 * omega-zero * zeta) and Damping Factor, zeta, = R / ( 2 * sqrt (M * K)) or zeta = R / (2 * M * omega-zero) = 1 / (2 * omega-zero * Q) Regarding dimensions, since one kilogram meter/sec^2 = 1 Newton, the units all cancel for both Q and zeta, so they are both dimensionless. The zero in omega-zero signifies the *undamped* natural frequency. As you add damping, looking at the frequency response of the spring-mass system, its amplitude peak gets lower and at the same time moves somewhat in frequency before the damping gets so great that the peak disappears altogether. You can see the same equations in a much prettier form near the end of http://bnordgren.org/seismo/feedback_in_seismic_sensors.pdf (underscored spaces) Though it's pretty big - a couple of MB, I think. Regards, Brett At 08:29 AM 12/28/2006 -0700, you wrote: >I understand Damping and Q >are simply inverses of each other. >Q is quite complex in that it >requires the knowledge of the >3db (0.7071) cutoff points as >relating to the frq of interest. > >Can anyone tell me the proper way >to express damping ?? >I sort of understand Q but not >how you arrive at the proper numbers >for damping alone. > >Regards; >geoff __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: vertical sensor From: "tchannel" tchannel@.............. Date: Fri, 29 Dec 2006 16:42:14 -0700 Hi All, I am moving right along on the small vertical spring sensor I = am building. At this point I would like to ask two questions; 1. I have made an adjustable magnetic damper, which I can slide in and = out to increase or decrease the effect. Chris, gave me a very good = example of how to adjust the damper on the Horz Lehman, I finished a few = months ago. It was something like, "move the arm 10mm and release it, = it should move past center and extend 5mm past center, it then should = return to center and stop;" Would it be the same for a vertical spring = sensor? 2. The coil measures 847 ohms. If I were to use a resistor to act as a = damper, what would the ohms value be for the resistor? Is there a formula? Thanks, Ted
Hi All,  I am moving right along = on the small=20 vertical spring sensor I am building.  At this point I would like = to ask=20 two questions;
 
1.  I have made an adjustable = magnetic damper,=20 which I can slide in and out to increase or decrease the effect.  = Chris,=20 gave me a very good example of how to adjust the damper on the Horz = Lehman, I=20 finished a few months ago.  It was something like, "move the arm = 10mm and=20 release it, it should move past center and extend 5mm past center, it = then=20 should return to center and stop;"   Would it be the same for = a=20 vertical spring sensor?
 
2.  The coil measures 847 = ohms.  If I=20 were to use a resistor to act as a damper, what would the ohms value be = for the=20 resistor?
     Is there a=20 formula?
 
Thanks, Ted
 
Subject: Head-Banging Snakes May Predict Quakes From: "Jerry Payton" gpayton880@....... Date: Fri, 29 Dec 2006 19:06:11 -0600 Humorous article everyone should read. Jerry Payton http://abcnews.go.com/US/wireStory?id=2755645
Humorous article everyone should read.
Jerry Payton
 
http://abcnews.g= o.com/US/wireStory?id=3D2755645
Subject: Re: vertical sensor From: ChrisAtUpw@....... Date: Fri, 29 Dec 2006 20:07:46 EST In a message dated 29/12/2006, tchannel@.............. writes: 1. I have made an adjustable magnetic damper, which I can slide in and out to increase or decrease the effect. Chris, gave me a very good example of how to adjust the damper on the Horz Lehman, I finished a few months ago. It was something like, "move the arm 10mm and release it, it should move past center and extend 5mm past center, it then should return to center and stop;" Would it be the same for a vertical spring sensor? Hi Ted, Correct damping is when you get ~ 0.5 mm overshoot, NOT 5 mm, from a 10 mm deflection! It is the same for both sorts of sensor, but the vertical damping usually has to be stronger - the damping force required is inversely proportional to the period. 2. The coil measures 847 ohms. If I were to use a resistor to act as a damper, what would the ohms value be for the resistor? Is there a formula? Yes, but it may be easier to just measure and see. You need a closely coupled coil with a fairly intense magnetic field. Remember that drawing off a damping current both reduces the output voltage and increases the circuit noise. The resistance also depends on the mass, the set pendulum period and the magnetic field. More mass - lower resistance, greater period - higher resistance, higher field - higher resistance. Remember that most amplifiers have an input resistor which needs to be 'taken into account'. Regards, Chris Chapman
In a message dated 29/12/2006, tchannel@.............. writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
1.  I have made an adjustable magnet= ic=20 damper, which I can slide in and out to increase or decrease the effect.&n= bsp;=20 Chris, gave me a very good example of how to adjust the damper on the Horz= =20 Lehman, I finished a few months ago.  It was something like, "move th= e=20 arm 10mm and release it, it should move past center and extend 5mm past=20 center, it then should return to center and stop;"   Would it be= the=20 same for a vertical spring sensor?
Hi Ted,
 
    Correct damping is when you get ~ 0.5 mm oversh= oot,=20 NOT 5 mm, from a 10 mm deflection!
 
    It is the same for both sorts of sensor, but th= e=20 vertical damping usually has to be stronger - the damping force required is=20 inversely proportional to the period.
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
2.  The coil measures 847 ohms. = ; If I=20 were to use a resistor to act as a damper, what would the ohms value be fo= r=20 the resistor?
     Is there a=20 formula?
    Yes, but it may be easier to just measure and s= ee.=20 You need a closely coupled coil with a fairly intense magnetic field. Rememb= er=20 that drawing off a damping current both reduces the output voltage and incre= ases=20 the circuit noise. The resistance also depends on the mass, the set pendulum= =20 period and the magnetic field. More mass - lower resistance, greater pe= riod=20 - higher resistance, higher field - higher resistance.  Remember t= hat=20 most amplifiers have an input resistor which needs to be 'taken into=20 account'.
 
    Regards,
 
    Chris Chapman
Subject: Re: Head-Banging Snakes May Predict Quakes From: "Geoffrey" gmvoeth@........... Date: Sat, 30 Dec 2006 16:36:27 -0700 Have any of yous guys ever heard of hoop snakes ? ----- Original Message ----- From: "Jerry Payton" To: "PSN-L" Sent: Friday, December 29, 2006 6:06 PM Subject: Head-Banging Snakes May Predict Quakes > Humorous article everyone should read. > Jerry Payton > > http://abcnews.go.com/US/wireStory?id=2755645 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: vertical sensor From: "Geoffrey" gmvoeth@........... Date: Sat, 30 Dec 2006 16:38:36 -0700 I understand maximum power transfer happens when the source and load have the same impedances. ----- Original Message ----- From: "tchannel" To: Sent: Friday, December 29, 2006 4:42 PM Subject: vertical sensor Hi All, I am moving right along on the small vertical spring sensor I am building. At this point I would like to ask two questions; 1. I have made an adjustable magnetic damper, which I can slide in and out to increase or decrease the effect. Chris, gave me a very good example of how to adjust the damper on the Horz Lehman, I finished a few months ago. It was something like, "move the arm 10mm and release it, it should move past center and extend 5mm past center, it then should return to center and stop;" Would it be the same for a vertical spring sensor? 2. The coil measures 847 ohms. If I were to use a resistor to act as a damper, what would the ohms value be for the resistor? Is there a formula? Thanks, Ted __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: fresh pumice From: Mark Robinson mark.robinson@............... Date: Sun, 31 Dec 2006 13:45:06 +1300 PSNers may be interested to see photos of a new island in formation at http://yacht-maiken.blogspot.com/2006/08/stone-sea-and-volcano.html I also stumbled on a new offering from the European Commission Joint Research Centre's new tsunami modelling service at http://tsunami.jrc.it/model/index.asp That allows you to plot transit time maps for tsunami based on the size and location of an arbitrary undersea quake of Mag 7 or greater. The site automatically plots a variety of flash laden graphics which crash my browser for earthquakes over mag7 underwater which you can get to from http://tsunami.jrc.it/model/equakes.asp?type=2 -- all the best to everyone for the new year Mark Robinson ------------- 31 Dec 1999 Boris Yeltsin resigns from the Russian Presidency in favour of Vladimir Putin. __________________________________________________________ Public Seismic Network Mailing List (PSN-L)