I am exploring the subject of a torsion = spring=20 sensor again. I say again because I have tried this approach = before with=20 no success at all.

I took a long band saw blade cut it to = form a long=20 vertical torsion spring. Attached both ends and pulled it = tight.

In the middle of this spring I attached = a boom. On=20 both ends of the boom I attached a mass of equal value.

This boom would move around the = vertical axis with=20 very little effort, twisting the spring and then reversing to the other=20 direction, rocking back and forth for a very long time. I don't = remember=20 how long but I think it was one hour plus.

The period of oscillation was = controlled by=20 moving the masses further out on the boom. Very long periods = 30=20 seconds plus. To make a long story short, it did not record any=20 earthquakes.

I think I did two things wrong. = 1. The booms=20 of equal mass cancelled the movement of each other. And in this=20 configuration the earthquake would need to spin the house to move = the=20 masses.

2. The torsion spring needed to be = tipped, not=20 vertical.

Here is my next attempt. = 1. I=20 removed the boom, which formed a (+) on the vertical torsion spring and = replace=20 it with a short pendulum boom, this time on one side only.

it looks like a T on its side ( = l-)

2. I contained the vertical = torsion spring in=20 a strong box about 12"x12"x36". This retains all the parts and I = can add=20 tension to the spring, and mount the magnet and coil

3. I placed three leveling legs = on the base=20 of the box. Now I can tip the vertical spring (Off=20 Vertical). Similar to tipping a Lehman, pitching up or = down.

The spring now at an angle, contains a = pendulum=20 which is now (Off Horizontal).

The pendulum I am using is only about = 6" long, and=20 I get a period of about 5 seconds. I could get 20 seconds with a = 18"=20 boom. But my box could only accommodate a 6" boom.

It is now running as a = test......I will see=20 if it will record earthquakes.

It is sensitive to me moving around the = room, and=20 to drafts and tilts.

I have seen something similar somewhere = on the web,=20 but I can't fine it. This is all I could find. = If=20 someone has tried this please email me. Thanks, = Ted

Torsion Seismometer Wood = Anderson

http://www.data.sc= ec.org/Module/s3inset3.html

Hi Ted,

Sorry...I couldn't find anything along the specific line you mention either..especially the flat ribbon spring variety. If I read you email right;
the very height you're using makes it a "giant" representation; and that likely makes it much more responsive as you're seeing, and
to be fair the stresses involved will likely show all kinds of metal/structure creep over time which you'll have to adjust for.

A lot of the web sites I've seen, go out of their way to describe such as antiquated, obsolete, old etc; which is true in the sense
of what is predominately used now. On the other hand, the torsion aspect really "does away" with a few of the normal pesky pivot problems
that are found in other seismometers/tiltmeters; and that alone is a good adjustment and/or labor saving positive.

Yes indeed...explore away.....there is likely a world of different flat ribbon or round wire sizes material one could try.

Take care, Meredith

On Wed, Oct 1, 2008 at 10:38 PM, <tchannel1@............> wrote:

I am exploring the subject of a torsion spring sensor again. I say again because I have tried this approach before with no success at all.

I took a long band saw blade cut it to form a long vertical torsion spring. Attached both ends and pulled it tight.

In the middle of this spring I attached a boom. On both ends of the boom I attached a mass of equal value.

This boom would move around the vertical axis with very little effort, twisting the spring and then reversing to the other direction, rocking back and forth for a very long time. I don't remember how long but I think it was one hour plus.

The period of oscillation was controlled by moving the masses further out on the boom.   Very long periods 30 seconds plus. To make a long story short, it did not record any earthquakes.

I think I did two things wrong. 1. The booms of equal mass cancelled the movement of each other. And in this configuration the earthquake would need to spin the house to move the masses.

2. The torsion spring needed to be tipped, not vertical.

Here is my next attempt.   1. I removed the boom, which formed a (+) on the vertical torsion spring and replace it with a short pendulum boom, this time on one side only.

it looks like a T on its side ( l-)

2. I contained the vertical torsion spring in a strong box about 12"x12"x36". This retains all the parts and I can add tension to the spring, and mount the magnet and coil

3. I placed three leveling legs on the base of the box. Now I can tip the vertical spring (Off Vertical).   Similar to tipping a Lehman, pitching up or down.

The spring now at an angle, contains a pendulum which is now (Off Horizontal).

The pendulum I am using is only about 6" long, and I get a period of about 5 seconds. I could get 20 seconds with a 18" boom. But my box could only accommodate a 6" boom.

It is now running as a test......I will see if it will record earthquakes.

It is sensitive to me moving around the room, and to drafts and tilts.

I have seen something similar somewhere on the web, but I can't fine it.   This is all I could find.   If someone has tried this please email me.   Thanks, Ted

Torsion Seismometer Wood Anderson

http://www.data.scec.org/Module/s3inset3.html

Meredith, Thank you for your = reply and=20 encouragement. The first sensor I spoke of was about 8 foot = tall and=20 the boom was about 4 foot, two feet on each side of the = ribbon.

I did not keep my notes on this unit = but remember=20 the period was massive, just moving the masses further out on the=20 boom.

This present unit is only about 36" = tall and the=20 boom, one side of the ribbon only is about 6". I used a SS = thin wire=20 instead of the band saw blade ribbon. At this point I think = it will=20 respond similar to a Lehman with a 5 second period. So far it = behaves,=20 just like my Lehman.

I will let you know, if it works and = send or post=20 the=20 ..psn. &n= bsp; It=20 looks promising, very simple and if it works I will rebuild it targeting = a 20=20 second period.

Cheers, Ted = ps..............On=20 some web site I saw the concept of a Torsion Spring Long Period, = illustrated as=20 a box with a vertical torsion spring in the center of the box, and a=20 boom............but the entire box was tipped, to illustrate the = vertical=20 wire/spring needed to be off vertical, not unlike the = Lehman

----- Original Message -----

Sent: Thursday, October 02, = 2008 3:29=20 PM

Hi Ted,

Sorry...I couldn't find anything along = the=20 specific line you mention either..especially the flat ribbon spring=20 variety. If I read you email right;
the very height you're = using=20 makes it a "giant" representation; and that likely makes it much more=20 responsive as you're seeing, and
to be fair the stresses involved = will=20 likely show all kinds of metal/structure creep over time which you'll = have to=20 adjust for.

A lot of the web sites I've seen, go out of their = way to=20 describe such as antiquated, obsolete, old etc; which is true in the=20 sense
of what is predominately used now. On the other hand, = the=20 torsion aspect really "does away" with a few of the normal pesky pivot = problems
that are found in other seismometers/tiltmeters; and that = alone is=20 a good adjustment and/or labor saving positive.

Yes = indeed...explore=20 away.....there is likely a world of different flat ribbon or round = wire sizes=20 material one could try.

Take care, Meredith
=

On Wed, Oct 1, 2008 at 10:38 PM, <tchannel1@............>=20 wrote:

I am exploring the subject of a = torsion spring=20 sensor again. I say again because I have tried this approach = before=20 with no success at all.

I took a long band saw blade cut it = to form a=20 long vertical torsion spring. Attached both ends and pulled it=20 tight.

In the middle of this spring I = attached a boom.=20 On both ends of the boom I attached a mass of equal = value.

This boom would move around the = vertical axis=20 with very little effort, twisting the spring and then reversing to = the other=20 direction, rocking back and forth for a very long time. I = don't=20 remember how long but I think it was one hour plus.

The period of oscillation was = controlled=20 by moving the masses further out on the boom.   Very long = periods=20 30 seconds plus. To make a long story short, it did not record = any=20 earthquakes.

I think I did two things = wrong. 1. The=20 booms of equal mass cancelled the movement of each other. And = in this=20 configuration the earthquake would need to spin the house to = move the=20 masses.

2. The torsion spring needed to be = tipped, not=20 vertical.

Here is my next = attempt.   1. I=20 removed the boom, which formed a (+) on the vertical torsion spring = and=20 replace it with a short pendulum boom, this time on one side only.=20

it looks like a T on its side (=20 l-)

2. I contained the vertical = torsion=20 spring in a strong box about 12"x12"x36". This retains all the = parts=20 and I can add tension to the spring, and mount the magnet and=20 coil

3. I placed three leveling = legs on the=20 base of the box. Now I can tip the vertical spring (Off=20 Vertical).   Similar to tipping a Lehman, pitching = up or=20 down.

The spring now at an angle, = contains a pendulum=20 which is now (Off Horizontal).

The pendulum I am using is only = about 6" long,=20 and I get a period of about 5 seconds. I could get 20 seconds = with a=20 18" boom. But my box could only accommodate a 6" = boom.

It is now running as a = test......I will=20 see if it will record earthquakes.

It is sensitive to me moving around = the room,=20 and to drafts and tilts.

I have seen something similar = somewhere on the=20 web, but I can't fine it.   This is all I could = find.  =20 If someone has tried this please email me.   Thanks,=20 Ted

Torsion Seismometer Wood = Anderson

http://www.data.scec.org/Module/s3inset3.html<= /DIV>

Hi Ted,

The "concept" or diagram you mention is possibly this:

http://physics.mercer.edu/petepag/tilt.gif

which is a part of:

http://physics.mercer.edu/petepag/tiltm.html

and the title of the above is "Tiltmeters and Angle Measuring Equipment" by Randall Peters

but....I suppose you've already found such from Chris's reference.

Take care, Meredith

On Thu, Oct 2, 2008 at 5:11 PM, <tchannel1@............> wrote:

Meredith, Thank you for your reply and encouragement.   The first sensor I spoke of was about 8 foot tall and the boom was about 4 foot, two feet on each side of the ribbon.

I did not keep my notes on this unit but remember the period was massive, just moving the masses further out on the boom.

This present unit is only about 36" tall and the boom, one side of the ribbon only is about 6".   I used a SS thin wire instead of the band saw blade ribbon.   At this point I think it will respond similar to a Lehman with a 5 second period. So far it behaves, just like my Lehman.

I will let you know, if it works and send or post the .psn.             It looks promising, very simple and if it works I will rebuild it targeting a 20 second period.

Cheers, Ted    ps..............On some web site I saw the concept of a Torsion Spring Long Period, illustrated as a box with a vertical torsion spring in the center of the box, and a boom............but the entire box was tipped, to illustrate the vertical wire/spring needed to be off vertical, not unlike the Lehman

----- Original Message -----

From: meredith lamb

To: psn-l@..............

Sent: Thursday, October 02, 2008 3:29 PM

Subject: Re:

Hi Ted,

Sorry...I couldn't find anything along the specific line you mention either..especially the flat ribbon spring variety. If I read you email right;
the very height you're using makes it a "giant" representation; and that likely makes it much more responsive as you're seeing, and
to be fair the stresses involved will likely show all kinds of metal/structure creep over time which you'll have to adjust for.

A lot of the web sites I've seen, go out of their way to describe such as antiquated, obsolete, old etc; which is true in the sense
of what is predominately used now. On the other hand, the torsion aspect really "does away" with a few of the normal pesky pivot problems
that are found in other seismometers/tiltmeters; and that alone is a good adjustment and/or labor saving positive.

Yes indeed...explore away.....there is likely a world of different flat ribbon or round wire sizes material one could try.

Take care, Meredith


On Wed, Oct 1, 2008 at 10:38 PM, <tchannel1@............> wrote:

I am exploring the subject of a torsion spring sensor again. I say again because I have tried this approach before with no success at all.

I took a long band saw blade cut it to form a long vertical torsion spring. Attached both ends and pulled it tight.

In the middle of this spring I attached a boom. On both ends of the boom I attached a mass of equal value.

This boom would move around the vertical axis with very little effort, twisting the spring and then reversing to the other direction, rocking back and forth for a very long time. I don't remember how long but I think it was one hour plus.

The period of oscillation was controlled by moving the masses further out on the boom.   Very long periods 30 seconds plus. To make a long story short, it did not record any earthquakes.

I think I did two things wrong. 1. The booms of equal mass cancelled the movement of each other. And in this configuration the earthquake would need to spin the house to move the masses.

2. The torsion spring needed to be tipped, not vertical.

Here is my next attempt.   1. I removed the boom, which formed a (+) on the vertical torsion spring and replace it with a short pendulum boom, this time on one side only.

it looks like a T on its side ( l-)

2. I contained the vertical torsion spring in a strong box about 12"x12"x36". This retains all the parts and I can add tension to the spring, and mount the magnet and coil

3. I placed three leveling legs on the base of the box. Now I can tip the vertical spring (Off Vertical).   Similar to tipping a Lehman, pitching up or down.

The spring now at an angle, contains a pendulum which is now (Off Horizontal).

The pendulum I am using is only about 6" long, and I get a period of about 5 seconds. I could get 20 seconds with a 18" boom. But my box could only accommodate a 6" boom.

It is now running as a test......I will see if it will record earthquakes.

It is sensitive to me moving around the room, and to drafts and tilts.

I have seen something similar somewhere on the web, but I can't fine it.   This is all I could find.   If someone has tried this please email me.   Thanks, Ted

Torsion Seismometer Wood Anderson

http://www.data.scec.org/Module/s3inset3.html

Thanks, Folks, Yes this was the image I = had seen=20 before. Thanks also for the various references.

----- Original Message -----

Sent: Thursday, October 02, = 2008 6:47=20 PM

Subject: Re: Re:

Hi Ted,

The "concept" or diagram you mention is possibly this:

http://physics.mercer= ..edu/petepag/tilt.gif

which is a part of:

http://physics.merc= er.edu/petepag/tiltm.html

and the title of the above is "Tiltmeters and Angle Measuring = Equipment"=20 by Randall Peters

but....I suppose you've already found such from Chris's = reference.

Take care, Meredith

On Thu, Oct 2, 2008 at 5:11 PM, <tchannel1@............>=20 wrote:

Meredith, Thank you for your = reply and=20 encouragement.   The first sensor I spoke of was about 8 = foot tall=20 and the boom was about 4 foot, two feet on each side of the=20 ribbon.

I did not keep my notes on this = unit but=20 remember the period was massive, just moving the masses further out = on the=20 boom.

This present unit is only about 36" = tall and=20 the boom, one side of the ribbon only is about 6".   I = used a SS=20 thin wire instead of the band saw blade ribbon.   At this = point I=20 think it will respond similar to a Lehman with a 5 second = period. So=20 far it behaves, just like my Lehman.

I will let you know, if it works = and send or=20 post the=20 = ..psn.           &n= bsp;=20 It looks promising, very simple and if it works I will rebuild it = targeting=20 a 20 second period.

Cheers, Ted   =20 ps..............On some web site I saw the concept of a Torsion = Spring Long=20 Period, illustrated as a box with a vertical torsion spring in the = center of=20 the box, and a boom............but the entire box was tipped, to = illustrate=20 the vertical wire/spring needed to be off vertical, not unlike the=20 Lehman

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

From: = meredith lamb

To: psn-l@..............=20

Sent: Thursday, October 02, = 2008 3:29=20 PM

Subject: Re:

Hi Ted,

Sorry...I couldn't find anything = along the=20 specific line you mention either..especially the flat ribbon = spring=20 variety. If I read you email right;
the very height = you're using=20 makes it a "giant" representation; and that likely makes it much = more=20 responsive as you're seeing, and
to be fair the stresses = involved will=20 likely show all kinds of metal/structure creep over time which = you'll have=20 to adjust for.

A lot of the web sites I've seen, go out of = their=20 way to describe such as antiquated, obsolete, old etc; which is = true in=20 the sense
of what is predominately used now. On the other = hand,=20 the torsion aspect really "does away" with a few of the normal = pesky pivot=20 problems
that are found in other seismometers/tiltmeters; and = that=20 alone is a good adjustment and/or labor saving = positive.

Yes=20 indeed...explore away.....there is likely a world of different = flat ribbon=20 or round wire sizes material one could try.

Take care,=20 Meredith


On Wed, Oct 1, 2008 at 10:38 PM, <tchannel1@............> wrote:

I am exploring the subject of a = torsion=20 spring sensor again. I say again because I have tried this = approach before with no success at all.

I took a long band saw blade = cut it to form=20 a long vertical torsion spring. Attached both ends and pulled it = tight.

In the middle of this spring I = attached a=20 boom. On both ends of the boom I attached a mass of equal=20 value.

This boom would move around the = vertical=20 axis with very little effort, twisting the spring and then = reversing to=20 the other direction, rocking back and forth for a very long = time. =20 I don't remember how long but I think it was one hour = plus.

The period of oscillation = was=20 controlled by moving the masses further out on the = boom.  =20 Very long periods 30 seconds plus. To make a long story = short, it=20 did not record any earthquakes.

I think I did two things = wrong. 1.=20 The booms of equal mass cancelled the movement of each = other. And=20 in this configuration the earthquake would need to spin = the house=20 to move the masses.

2. The torsion spring needed to = be tipped,=20 not vertical.

Here is my next = attempt.  =20 1. I removed the boom, which formed a (+) on the vertical = torsion=20 spring and replace it with a short pendulum boom, this time on = one side=20 only.

it looks like a T on its side ( = l-)

2. I contained the = vertical torsion=20 spring in a strong box about 12"x12"x36". This retains all = the=20 parts and I can add tension to the spring, and mount the magnet = and=20 coil

3. I placed three = leveling legs on=20 the base of the box. Now I can tip the vertical = spring (Off=20 Vertical).   Similar to tipping a Lehman, = pitching up or=20 down.

The spring now at an angle, = contains a=20 pendulum which is now (Off Horizontal).

The pendulum I am using is only = about 6"=20 long, and I get a period of about 5 seconds. I could get 20 = seconds=20 with a 18" boom. But my box could only accommodate a 6"=20 boom.

It is now running as a = test......I=20 will see if it will record earthquakes.

It is sensitive to me moving = around the=20 room, and to drafts and tilts.

I have seen something similar = somewhere on=20 the web, but I can't fine it.   This is all I could=20 find.   If someone has tried this please email = me.  =20 Thanks, Ted

Torsion Seismometer Wood=20 Anderson

http://www.data.scec.org/Module/s3inset3.html<= /DIV>

I understand the necessity of using a = Damper to=20 keep the arm or boom from oscillate or belling after a signal=20 begins. I would guess, after an earthquake signal = arrives, an=20 undamper arm would continue to oscillate for many minutes, overwriting = most of=20 the incoming signature.

I also understand the importance of = minimizing the=20 friction of the sensor's hinges. The signals are very small = and they=20 must overcome the friction before any movement of the arm can take=20 place.

My question is: Does a Damper, = oil or=20 magnetic, not act the same as hinge friction?, in that, the signal must, = first,=20 overcome the resistance of the Damper?

Is an undamper sensor more = sensitive=20 than a dampered sensor? I have never tried = this. =20 Again, I know the signature would be of little value, but I am curious = about the=20 friction of the dampers.

If everything else wasn't already confusing, = check this=20 site out when you have time:

http://www.vlf.it/romer= o/seismic_rdf.htm

Hi Folks, I just recorded the = first event=20 using my Torsion wire/spring sensor. The sensor was made=20 using some bits and pieces from other units. The construction = was not=20 carefully designed or executed, as I just wanted to see if the concept = would=20 work. I will post three examples on PSN, Ch 1=3Da simple = pendulum with=20 a 2 second period, Ch 2=3DThe New Torsion Spring with a 5second = period, Ch=20 3=3D a Lehman at 20 seconds.

All three sensor recorded the 5.8M = ARCTIC OCEAN=20 today.

I have another Torsion Spring Mock-up = made of wood=20 on my bench, not to used, but to test for general dimensions and=20 period. Happy to send picts and discuss design with anyone = who is=20 interested in helping me build a proper unit. The mock up is = only=20 18"? tall, has a torsion spring of about 14" and a boom of 12". = The frame=20 looks like a Lehman, and the wire is near the vertical = support. =20 Under these conditions I could get a period of 25 seconds, but = unstable. =20 It now is adjusted to 15 seconds and seems stable. A longer or = shorter=20 period should be possible.

The Wire is not spring wire, although = it has some=20 spring to it. It is .016" ss fishing lure. Thanks to = J.P. for=20 sending me the wire. For my experiments I have used, a = bandsaw=20 blade, brass music wire, and SS fishing wire.

Anyhow the idea seems to work and and = very easy to=20 adjust. I am not sure what sensor period I should = target. =20 Deciding that will dictate many of the other dimensions and overall=20 size.

Hi Ted,

Nothing new, but; music (piano) wire is very hard to beat for its high tensile strength, durability, low cost and a good variation of diameter size
availability at a variety of hardware and hobby shops. Think you'll eventually gravitate over to this material, as the material you've tried will
stretch sag and change the period and position of the boom/mass if theirs much of any weight involved in mass/boom you have or will try in the future.

Was wondering if you're contemplating making your "T" connection or boom/wire connection to where it uses up the majority length of the wire?
If you get to this arrangement I would think if would allow more mass weight, and limit too much wire play; while still using the wire torsion aspect.
Am speculating...but say if your wire is 14" length, and your "T" length is ~ 10"; you could still see a lot of reasonable good response. Clamping down
on the wire to where the "T" doesn't gravity weight slide down over time might be a real anticipated potential problem.

I'd think the frame for such, would have to be mechanically superior to support the wire tension necessary; i.e., big bulky high strength. One may
have to even use stuff like iron plumbing pipes with its lousy temperature variations to get the high strength. Aluminum would be temperature"nicer", but
obtaining really strong thick aluminum might only be available via a metals scrap yard; and then, you'd need tools to work it down to the desired size/s.
Overcoming this frame strength necessity is a major obstacle for a long lasting torsion wire seismometer especially for a higher mass weight variety.

Musings....

Take care, Meredith

On Tue, Oct 7, 2008 at 7:39 AM, <tchannel1@............> wrote:

Hi Folks, I just recorded the first event using my Torsion wire/spring sensor.   The sensor was made using some bits and pieces from other units. The construction was not carefully designed or executed, as I just wanted to see if the concept would work.   I will post three examples on PSN, Ch 1=a simple pendulum with a 2 second period, Ch 2=The New Torsion Spring with a 5second period, Ch 3= a Lehman at 20 seconds.

All three sensor recorded the 5.8M ARCTIC OCEAN today.

I have another Torsion Spring Mock-up made of wood on my bench, not to used, but to test for general dimensions and period.   Happy to send picts and discuss design with anyone who is interested in helping me build a proper unit.   The mock up is only 18"? tall, has a torsion spring of about 14" and a boom of 12". The frame looks like a Lehman, and the wire is near the vertical support.   Under these conditions I could get a period of 25 seconds, but unstable. It now is adjusted to 15 seconds and seems stable. A longer or shorter period should be possible.

The Wire is not spring wire, although it has some spring to it. It is .016" ss fishing lure.   Thanks to J.P. for sending me the wire.   For my experiments I have used, a bandsaw blade, brass music wire, and SS fishing wire.

Anyhow the idea seems to work and and very easy to adjust. I am not sure what sensor period I should target.   Deciding that will dictate many of the other dimensions and overall size.

Cheers, Ted

Congratulations to Charles, Chris and Brett for this fine publication! I can readily see many months of work behind it.

The variety of pivot approaches and the improvements noted therein, will likely make this publication the

most interesting, useful and suggestive of important improvements of present working seismometers than has been

PSN presented at any time in the past. The "world" of the variety of pivots shown should greatly enhance

a lot of exciting interesting experimentation with them! It readily deserves a "first reader" status, for those either in entry

or any latter stage of home seismometry building comtemplation.

Again, many thanks!!!

Take care, Meredith Lamb

On Wed, Oct 15, 2008 at 12:33 AM, Charles Patton <charles.r.patton@........> wrote:

To the PSN community,
Please check out
http://www.myeclectic.info/SeismoPivots/seismopivots.htm
for the results of a series of discussions between Chris Chapman, Brett Nordgren and myself on the applicability of various pivot systems to the construction of seismometers. Comments are welcome as I view this as a work in progress.
The work on this paper got me contemplating the construction of a LIGO X-Suspension using 3/4" PVC pipe with Metglas band bearings. Something a bit different.
Regards,
Charles R Patton

Hi all,

I took a few minutes to build a non-working horizontal response model of what I think a 3 wire "x" suspension could look like. Am

trying to grasp such. I don't know if its even ~ practical actually. I would think it could have unidirectional horizontal response.

Its seemingly more likely to instead have the mass underneath the bottom "plate" for perhaps better period adjustment range. See:

http://seismometer.googlepages.com/3wirexsuspension

New and "strange" yes, but interesting. The trouble with this is that I don't think anyone has actual experience...but if they

do; I'd like to hear about it.....or.....any comments....

Take care, Meredith

I would like to join Meredith in his = praise of the=20 the work of Charles, Chris and Brett. Very thought = provoking.

----- Original Message -----

Sent: Wednesday, October 15, = 2008 10:02=20 AM

Subject: Re: Paper on = seismometer pivot=20 systems

Congratulations to Charles, Chris and Brett for this fine=20 publication! I can readily see many months of work behind = it.

The variety of pivot approaches and the improvements noted = therein, will=20 likely make this publication the

most interesting, useful and suggestive of important improvements = of=20 present working seismometers than has been

PSN presented at any time in the past. The "world" of the = variety=20 of pivots shown should greatly enhance

a lot of exciting interesting experimentation with them! It = readily=20 deserves a "first reader" status, for those either in entry

or any latter stage of home seismometry building = comtemplation.

Again, many thanks!!!

Take care, Meredith Lamb

On Wed, Oct 15, 2008 at 12:33 AM, Charles = Patton <charles.r.patton@........&g= t;=20 wrote:

To=20 the PSN community,
Please check out
http://www.myeclectic.info/SeismoPivots/seismopivots.htm<= /A>
for=20 the results of a series of discussions between Chris Chapman, Brett = Nordgren=20 and myself on the applicability of various pivot systems to = the=20 construction of seismometers. Comments are welcome as I view = this as a=20 work in progress.
The work on this paper got me contemplating = the=20 construction of a LIGO X-Suspension using 3/4" PVC pipe with Metglas = band=20 bearings. Something a bit different.
Regards,
Charles R = = Patton

Thanks for taking the time and effort to share your study - it's very interesting.

On Thu, Oct 16, 2008 at 7:37 AM, Charles Patton <charles.r.patton@........> wrote:

There was an error in the formula for the X-roll studies spreadsheet and PDF It was pointed out by Randy Pratt. Thanks! The correct papers were not used when I started putting the web site
http://www.myeclectic.info/SeismoPivots/seismopivots.htm
together, but now they're updated. The new files are
X-Roll study 2.xls
X-Roll study 2.pdf
Regards,
Charles R Patton
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Hi Chris,

Your suggestion is perplexing; perhaps you really mean rotational movement?

Being short of a actual working model, it would appear likely that the wires will touch at the "x" junctions. One thought I have is that on

the bottom plate (or on put on the top plate), one might have 2 of the 3 wires slightly vertically elevated via a spacer to get away hopefully

from such contact. Of the two spacers, they may each need to be different heights.

Take care, Meredith

On Thu, Oct 16, 2008 at 5:54 PM, <ChrisAtUpw@.......> wrote:

In a message dated 2008/10/15, paleoartifact@......... writes:

Its seemingly more likely to instead have the mass underneath the bottom "plate" for perhaps better period adjustment range. See:
http://seismometer.googlepages.com/3wirexsuspension
New and "strange" yes, but interesting.

Hi Meredith,

       I would advise making the twin wires have a wider separation at the top than the attachement to the bottom plate. This will tend to inhibit sideways motions.

       Regards,

       Chris


**************

Hi Folks, Do you know of a = website where it=20 shows earthquakes by year, by month and magnitudes?

The = list your probably want is at the IRIS site under Wilber II. See = link:

This list goes back to January 1, = 1990. Be advised it only shows the larger events, and contains = worldwide data. You can also download SAC files of the events and = then convert them to PSN events either through WinQuakes, or Bob = McClures conversion proram, available at the following web = site.

Bob Hancock

On Oct 18, 2008, at 7:56 = PM, <tchannel1@............> = <tchannel1@............> = wrote:

Hi Folks, Do you know of a website where = it shows earthquakes by year, by month and = magnitudes?

Thanks,= = Ted

= Subject: Re: earthquake listings by year and month From: Stephen & Kathy skmort@............ Date: Sat, 18 Oct 2008 22:36:39 -0700 Hi Ted, Here are the two main lists that I use. At the first link, you can select a location range, (global, rectangular circular), and from there you select a database, time frame, magnitude, depth, etc. http://neic.usgs.gov/neis/epic/ http://en.wikipedia.org/wiki/List_of_earthquakes Stephen PSN Station #55 tchannel1@............ wrote: > Hi Folks, Do you know of a website where it shows earthquakes by > year, by month and magnitudes? > > Thanks, Ted Hi Ted, Here are the two main lists that I use. At the first link, you can select alocation range, (global, rectangular circular), and from there you select adatabase, time frame, magnitude, depth, etc. http://neic.usgs.gov/neis/epic/ http://en.wikipedia.org/wiki/List_of_earthquakes Stephen PSN Station #55
tchannel1@............ wrote:

Hi Folks, Do you know of a website where it shows earthquakes by year, by month and magnitudes?

Thanks, Ted

Subject: 7.1 Tonga Quake From: "Geoff" gmvoeth@........... Date: Sat, 18 Oct 2008 23:01:22 -0700 Gee Whillikers Guys, my system is only designed to get 2Hz to 3 Second vertical (Z) waves but with this Tonga quake a few minutes ago Im getting 20 second surface waves they must be really large since my system is relatively insensitive at these periods. Can someone give me an idea of the actual peak ground deflection from this 7.1 Tonga Quake at 20 seconds period surface waves and 81 degrees away ? I do not know how to do this myself. regards geoff __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: 7.1 Tonga Quake From: Bob Hancock carpediem1@......... Date: Sat, 18 Oct 2008 23:17:54 -0700 Hi Geoff - Use the following link to a USGS program and add the appropriate information: http://neic.usgs.gov/neis/travel_times/compute_tt.html The answer you are looking for will be near the top of the page, prior to the listing of the arrival times of the phases. Cheers Bob Hancock On Oct 18, 2008, at 11:01 PM, Geoff wrote: > Gee Whillikers Guys, my system is only designed to get > 2Hz to 3 Second vertical (Z) waves but with this Tonga quake > a few minutes ago Im getting 20 second surface waves > they must be really large since my system is relatively > insensitive at these periods. Can someone give me an > idea of the actual peak ground deflection from this > 7.1 Tonga Quake at 20 seconds period surface waves and 81 degrees > away ? > I do not know how to do this myself. > 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. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: earthquake listings by year and month From: tchannel1@............ Date: Sun, 19 Oct 2008 09:36:09 -0600 Thanks All for this information. I have bookmarked several. Ted ----- Original Message -----=20 From: Stephen & Kathy=20 To: psn-l@................. Sent: Saturday, October 18, 2008 11:36 PM Subject: Re: earthquake listings by year and month Hi Ted, Here are the two main lists that I use. At the first link, you can = select a location range, (global, rectangular circular), and from there = you select a database, time frame, magnitude, depth, etc.=20 http://neic.usgs.gov/neis/epic/ http://en.wikipedia.org/wiki/List_of_earthquakes Stephen PSN Station #55 tchannel1@............ wrote:=20 Hi Folks, Do you know of a website where it shows earthquakes by = year, by month and magnitudes? Thanks, Ted

Thanks All for this = information. I have=20 bookmarked several. Ted

----- Original Message -----
From:=20 Stephen &=20 Kathy

Sent: Saturday, October 18, = 2008 11:36=20 PM

Subject: Re: earthquake = listings by year=20 and month

Hi Folks, Do you know of a = website where=20 it shows earthquakes by year, by month and magnitudes?

I like to use a resource offered by = Larry=20 Braile. He maintains a Microsoft spreadsheet on the internet of=20 earthquakes recorded by his AS-1 seismograph at Purdue University. = It is=20 at http://web.ics.purdue.edu/~braile/edumod/as1lessons/InterpSeis/= EqList.xls. =20 The nice thing about this is that you can do all the typical spreadsheet = functions like sorting, etc, once you download it. He = only=20 saves the major earthquakes and it goes back to the year = 2000.

This is a part of Larry's internet = resources for=20 learning about earthquakes and seismology. If you look at Lesson = #13 on=20 the page at http://web.ics.purdue.edu/~braile/edumod/as1lessons/as1lessons.htm= you=20 will see the spreadsheet.

Now the REALLY nice thing about this = spreadsheet is=20 that he makes available on this same page his corresponding Z files (for = those=20 of you familiar with Alan Jones Amaseis software) so that you can see = the data=20 recorded on his seismograph.

----- Original Message -----

Sent: Saturday, October 18, = 2008 7:56=20 PM

Subject: earthquake listings by = year and=20 month

Hi Folks, Do you know of a = website where it=20 shows earthquakes by year, by month and magnitudes?

your battery is an = aluminium-hypochlorite battery,=20 where the hypochlorite comes from the bleach. be aware you can get small = amounts=20 of chlorine from the carbon plates

for an overview of the electrochemistry = see http://www.dtic.mil/cgi-bin/GetTRDoc?AD=3DADD0= 19917&Location=3DU2&doc=3DGetTRDoc.pdf

----- Original Message -----

Sent: Thursday, November 13, = 2008 7:47=20 AM

Subject: A interesting home = brew=20 battery

Hi Meredith

your battery is an aluminium-hypochlorite battery, where the hypochlorite comes from the bleach. be aware you can get small amounts of chlorine from the carbon plates

for an overview of the electrochemistry see http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADD019917&Location=U2&doc=GetTRDoc.pdf

Dale

Years ago (as a interested, very amateur hobbyist) I built a Lehman=20 Seismograph, but for a long time I have not had it in operation. I = decided to=20 turn my old seismograph on again to show some young friends that have an = interest in seismology. I decided to update Amaseis also. I am surprised = and=20 confounded by the initial results of my "homemade Lehman" using it with = the new=20 version of AMASEIS. To get the trace "on screen" I had to set the = zero=20 level to approximately 28,000 instead of 2048 and the trace is = extremely=20 volatile as I approach the seismograph with it's peak hitting a height = of about=20 2 hours (above and below the 0 line, with a gain set at 20 [and no event = happening]). I was wondering if there is anything that is glaringly = wrong you=20 might advise me on. Thanks a lot . Ed.

In a message dated 16/11/2008, gel@................. writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>For the=20 last few months I have been working on a vertical=20 seismometer.

Hi Gary,

There is a reasonably good vertical design on=20 John's website at

http://jclahr.com/sci= ence/psn/hill/index.html

But I don't like either the suspension knife bl= ade=20 or the oil damping. It is quite easy to use either a twin wire or foil=20 suspension in tension or a twin blade/foil suspension in compression. A bit=20= of=20 weak spring on the input suspension doesn't matterin a vertical. Magnetic=20 damping is vastly preferable to oil. It is quite cheap, easy to adjust and=20 clean.

See http= ://jclahr.com/science/psn/chapman/as1%20damping/index.html

The longest period you can expect to get f= rom=20 a steel spring vertical is about 6 seconds. The elastic properties of steel=20= are=20 strongly temperature dependant and attempts at longer period suspensions sim= ply=20 collapse with small changes in temperature. 6 seconds is fine if you want to= =20 study microseisms, but it is not good for the surface waves from=20 earthquakes.

However, you can make a 1.5 to 2 second vertica= l=20 quite easily as shown above and then extend the period to 15 to 20 seco= nds=20 to cover the common Love and Rayleigh surface waves at about 20 seconds, usi= ng=20 an extra gain of x100.

If you do this digitally, you will need a 16 bi= t=20 ADC to give you enough signal resolution, with the normal sesimic=20 background gain set at over 100 counts.

If you use an electronic period compensating=20 amplifier, this needs to be low noise, but you can use a 12 bit ADC with it=20 (just!).

Sorry, but it is only fair to warn you=20 that you WON'T get extended periods with the vertical compression sprin= g=20 that you are trying to use. The spring + the geometry are both wrong. S= ee=20 Bob's spring calculations?

Regards,

Chris Chapman

For the last few months I have been working on a vertical seismometer.

Or................being as you're mechanically overall part way (~60%) there already.....add more upright vertical support

and a horizontal extension (and a conventional extension spring) to the mast and try out Randall Peters vertical setup.

His claims of; "at least 20s, etc." sure read enticing to verify.

I have been reading about calibration = using random=20 signals input through a half bridge. Does anyone have a rule of = thumb as=20 to resistance values and any corrections to the signal that might be=20 required? Specifically, I am looking at the CALEX5 program to = obtain=20 parameters for my systems.

From:= psn-l-request@.............. [mailto:psn-l-request@............... On = Behalf Of Robert McClure
Sent: Sunday, November 16, 2008 7:53 PM
To: psn-l@..............
Subject: Re: Vertical Seismometer with Honey = Support

From:= psn-l-request@.............. [mailto:psn-l-request@............... On = Behalf Of meredith lamb
Sent: Monday, November 17, 2008 9:08 AM
To: psn-l@..............
Subject: Re: Vertical Seismometer with Honey = Support

On Sun, Nov 16, 2008 at 4:25 PM, Gary Lindgren = <gel@.................> = wrote:

For the last few months I have been working on a vertical = seismometer.

Or................being as you're mechanically = overall part way (~60%) there already.....add more upright vertical = support

and a horizontal extension (and a conventional extension spring) to the mast and try out Randall Peters vertical = setup.

His claims of; "at least 20s, etc." sure read enticing = to verify.

http://physics.mercer= ..edu/hpage/new-z.html

Take care, Meredith

Century Spring has an online = catalog. Their=20 Z-3 spring is .15 lb/inch and there may be something closer. Many = hardware=20 stores around here carry Century in display racks.

From:= psn-l-request@.............. [mailto:psn-l-request@............... On = Behalf Of Randy Pratt
Sent: Wednesday, November 19, 2008 6:59 AM
To: psn-l@..............
Subject: Honey Jar Vertical spring

Century Spring has an online catalog. Their Z-3 spring is .15 lb/inch and = there may be something closer. Many hardware stores around here carry = Century in display racks.

In a message dated 27/11/2008 00:06:02 GMT Standard Time,=20 gel@................. writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I put=20 together a web page that describes my process for measuring the parameter,= =20 newtons/amp for 3 different coil and magnet assemblies. Check out http://sites.google.com/site/seismicsensorinfo/meas-newtons-per-amp&n= bsp;

I suggest that you use the smaller coil former,= but=20 substitute 36 gauge wire to give maybe 1500 turns. You want to keep the DC c= oil=20 resistance below about 200 Ohms. This should give you about 35 N / Amp.

The relatively low figure that you got for= the=20 large coil is due to the lower magnetic field of the quad 1/8" magnets. You=20 could probably triple the force with thicker magnets, but you are limit= ed=20 by the thickness of the iron backing plates. They are already near saturatio= n=20 with the 1" square magnets.

I can't see a DVM in our photo? You need an=20 accurate meter to measure the current.

Regards,

Chris Chapman

Subject: Measuring Newtons/Amp From: "Randy Pratt" rpratt@............. Date: Thu, 27 Nov 2008 09:23:12 -0600 Hi Gary, On the small neo magnet photo it appears the magnets are 90 degrees = turned from what I would think to locate them. Did you try the other = orientation? I have used several speaker magnets. On most the 4 bolt holes do not go = through the magnet ring itself. If you insert and tighten longer = threaded bolts against the magnet, the pole ring will pop loose and then = you can easily turn the gap wider to probably 1 cm or more on that = magnet. Even if it won't come loose it is fairly easy to open the gap = on a lathe but be careful of the turnings as they are very sharp and the = magnetic field tends to align them into finger cutting angles. = Extending the center pole into the coil with a short fat bolt after the = gap is widened also seems to increase output. =20 Randy

Hi Gary,

On the small neo magnet photo it = appears the=20 magnets are 90 degrees turned from what I would think to locate = them. Did=20 you try the other orientation?

I have used several speaker = magnets. On most=20 the 4 bolt holes do not go through the magnet ring itself. If you = insert=20 and tighten longer threaded bolts against the magnet, the pole=20 ring will pop loose and then you can easily turn the gap = wider to=20 probably 1 cm or more on that magnet. Even if it won't come loose = it is=20 fairly easy to open the gap on a lathe but be careful of the turnings as = they=20 are very sharp and the magnetic field tends to align them into finger = cutting=20 angles. Extending the center pole into the coil with a short fat = bolt=20 after the gap is widened also seems to increase output. =

Randy

Subject: RE: Measuring Newtons/Amp From: "Gary Lindgren" gel@................. Date: Thu, 27 Nov 2008 11:57:42 -0800 Randy, The configuration of the small and large coils and magnet assemblies is for the coil to move in/out through the wide dimension. The idea is that this would be used for a vertical seismometer. That's a good idea to modify the voice coil magnet. Gary From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Randy Pratt Sent: Thursday, November 27, 2008 7:23 AM To: psn-l@.............. Subject: Measuring Newtons/Amp Hi Gary, On the small neo magnet photo it appears the magnets are 90 degrees turned from what I would think to locate them. Did you try the other orientation? I have used several speaker magnets. On most the 4 bolt holes do not go through the magnet ring itself. If you insert and tighten longer threaded bolts against the magnet, the pole ring will pop loose and then you can easily turn the gap wider to probably 1 cm or more on that magnet. Even if it won't come loose it is fairly easy to open the gap on a lathe but be careful of the turnings as they are very sharp and the magnetic field tends to align them into finger cutting angles. Extending the center pole into the coil with a short fat bolt after the gap is widened also seems to increase output. Randy

Randy,

The configuration of the small and large coils and magnet assemblies is for the coil to move in/out through the wide dimension. = The idea is that this would be used for a vertical seismometer. = That’s a good idea to modify the voice coil magnet.

Gary

From:= psn-l-request@.............. [mailto:psn-l-request@............... On = Behalf Of Randy Pratt
Sent: Thursday, November 27, 2008 7:23 AM
To: psn-l@..............
Subject: Measuring Newtons/Amp

Hi Gary,

On the small neo magnet photo it appears the magnets are 90 degrees turned = from what I would think to locate them. Did you try the other = orientation?

I have used several speaker magnets. On most the 4 bolt holes do not = go through the magnet ring itself. If you insert and tighten longer = threaded bolts against the magnet, the pole = ring will pop loose and then you can easily turn the gap wider to probably 1 cm or more on that magnet. Even if it won't come loose it is fairly easy to open the = gap on a lathe but be careful of the turnings as they are very sharp and the = magnetic field tends to align them into finger cutting angles. Extending = the center pole into the coil with a short fat bolt after the gap is widened = also seems to increase output.

Randy<= o:p>

Subject: Any Info on Time Constant for Undamped Vertical Sensor From: "Gary Lindgren" gel@................. Date: Fri, 28 Nov 2008 15:41:44 -0800 I'm just getting started with my first vertical seismometer. I will be using an extension spring and supported at 90 degrees. Bearing concept is 2 sets of tungsten carbide rods and a silicon carbide ball bearings. One of the springs I have tested is a Century Spring No. 312. K factor is .28 pounds/inch and resonant period is 1.25 seconds. The tungsten rods are as received and have not been polished yet. Undamped, I measured the damping constant to be 372 seconds. I used the equation of Y=A*e-t/T. How does the 372 seconds compare to other vertical systems. Gary Gary Lindgren 585 Lincoln Ave Palo Alto CA 94301 650-326-0655 www.blue-eagle-technologies.com Check out Lastest Seismometer Reading cymonsplace.blogspot.com

I’m just getting started with my first = vertical seismometer. I will be using an extension spring and supported at 90 = degrees. Bearing concept is 2 sets of tungsten carbide rods and a silicon carbide = ball bearings. One of the springs I have tested is a Century Spring No. 312. = K factor is .28 pounds/inch and resonant period is 1.25 seconds. The = tungsten rods are as received and have not been polished yet. Undamped, I = measured the damping constant to be 372 seconds. I used the equation of Y=3DA*e-t/T. = How does the 372 seconds compare to other vertical systems.

Gary

Gary Lindgren

585 Lincoln Ave

Palo Alto CA 94301

650-326-0655<= /span>

www.blue-eagle-technologies.com &nbs= p; Check out Lastest Seismometer = Reading

cymonsplace.blogspot.com

Subject: Re: Any Info on Time Constant for Undamped Vertical Sensor From: ChrisAtUpw@....... Date: Fri, 28 Nov 2008 21:55:03 EST =20 In a message dated 28/11/2008 23:42:02 GMT Standard Time, =20 gel@................. writes: I=E2=80=99m just getting started with my first vertical seismometer. I will= be using=20 an extension spring and supported at 90 degrees. Bearing concept is 2 sets=20 of tungsten carbide rods and a silicon carbide ball bearings. One of the=20 springs I have tested is a Century Spring No. 312. K factor is .28 pounds/i= nch and=20 resonant period is 1.25 seconds. The tungsten rods are as received and have= =20 not been polished yet. Undamped, I measured the damping constant to be 372=20 seconds. I used the equation of Y=3DA*e-t/T. How does the 372 seconds compa= re to=20 other vertical systems. =20 Hi Gary, =20 If you can extend the top spring position beyond the vertical support=20 and also lower it a bit, you will get a longer period. The aim is to have t= he=20 vertical above the hinge nearer the ''zero'' length of the spring. =20 If you put a C shaped plate on the end of the horizontal beam, you coul= d=20 use two short piano wire supports in tension. I have also used a pair of=20 razor blades extracted from single blade cheap plastic razors in compressio= n. I=20 stick them between Al cross strips with acrylic adhesive with a gap of ~0.1= ". =20 You should be able to improve on 1.25 seconds. Aim for a period of 1.5=20 to 2 seconds.=20 =20 Regards, =20 Chris Chapman

In a message dated 28/11/2008 23:42:02 GMT Standard Time,=20 gel@................. writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>

I=E2=80=99m just getting started with my first vertic= al=20 seismometer. I will be using an extension spring and supported at 90 degre= es.=20 Bearing concept is 2 sets of tungsten carbide rods and a silicon carbide b= all=20 bearings. One of the springs I have tested is a Century Spring No. 312. K=20 factor is .28 pounds/inch and resonant period is 1.25 seconds. The tungste= n=20 rods are as received and have not been polished yet. Undamped, I measured=20= the=20 damping constant to be 372 seconds. I used the equation of Y=3DA*e-t/T. Ho= w does=20 the 372 seconds compare to other vertical systems.=20

Hi Gary,

If you can extend the top spring position beyon= d=20 the vertical support and also lower it a bit, you will get a longer per= iod.=20 The aim is to have the vertical above the hinge nearer the ''zero'' length o= f=20 the spring.

If you put a C shaped plate on the end of the=20 horizontal beam, you could use two short piano wire supports in tension= .. I=20 have also used a pair of razor blades extracted from single blade cheap plas= tic=20 razors in compression. I stick them between Al cross strips with=20 acrylic adhesive with a gap of ~0.1".

You should be able to improve on 1.25=20 seconds. Aim for a period of 1.5 to 2 seconds.

Regards,

Chris Chapman

Subject: a possible seismometer? From: Randall Peters PETERS_RD@.......... Date: Mon, 08 Dec 2008 16:50:11 -0500 I've been contemplating an instrument based on a piece of equipment we use in the physics department to teach hydrostatics. It is a long tube that is sealed on one end, and the open end is immersed in a larger tube filled with water. The smaller tube achieves an equilibrium position determined by its weight, overall length, and diameter of the internal air column. If one lifts the inner tube and releases it, it oscillates in simple harmonic motion with a period greater than one second. Also, because of the water, the motion is dampened. The motion depends on the compressibility of the trapped air. I've done an idealized calculation in which the water would be replaced with mineral oil and the plastic tube of the apparatus with a thinwall metal tube of length in the neighborhood of one meter. It appears that the damping would be close to optimal and the period just under two seconds for the diameter of the inner tube being one centimeter and that of the outer tube holding the mineral oil about two cm's. The inner tube should be constrained (perhaps with long triaxial threads, so that the motion is strictly vertical. I will be interested to know if any of you have considered such an apparatus. Randall Subject: Re: a possible seismometer? From: "Robert Thomasson" rlthomasson@......... Date: Tue, 9 Dec 2008 01:10:42 +0300 Randall, I haven't ever considered such a device and it sounds interesting. Without attempting to mathematically model it (which for me generally results in a learning process but very little usable results) I wonder what the effect of the trapped and compressible air column is? What would be the difference in response if the air was isolated from the water or mineral oil by a sealed partition in the tube so that it would not compress? The tube would be perforated below the partition to avoid trapping any additional air. Also, I think it will be a challenge to restrain the tube so that it moves vertically without adding friction or otherwise changing the response. What about one of your capacitance sensors set up so that it will only respond to vertical motion? I'm still studying your pendulum paper that posted a link to here some time ago. Regards, Bob On Tue, Dec 9, 2008 at 12:50 AM, Randall Peters wrote: > I've been contemplating an instrument based on a piece of equipment we > use in the physics department to teach hydrostatics. It is a long tube > that is sealed on one end, and the open end is immersed in a larger tube > filled with water. The smaller tube achieves an equilibrium position > determined by its weight, overall length, and diameter of the internal > air column. If one lifts the inner tube and releases it, it oscillates > in simple harmonic motion with a period greater than one second. Also, > because of the water, the motion is dampened. The motion depends on the > compressibility of the trapped air. > I've done an idealized calculation in which the water would be > replaced with mineral oil and the plastic tube of the apparatus with a > thinwall metal tube of length in the neighborhood of one meter. It > appears that the damping would be close to optimal and the period just > under two seconds for the diameter of the inner tube being one > centimeter and that of the outer tube holding the mineral oil about two > cm's. > The inner tube should be constrained (perhaps with long triaxial > threads, so that the motion is strictly vertical. > I will be interested to know if any of you have considered such an > apparatus. > Randall > Randall,

I haven't ever considered such a device and it sounds interesting. Without attempting to mathematically model it (which for me generally results in a learning process but very little usable results) I wonder what the effect of the trapped and compressible air column is? What would be the difference in response if the air was isolated from the water or mineral oil by a sealed partition in the tube so that it would not compress? The tube would be perforated below the partition to avoid trapping any additional air.

Also, I think it will be a challenge to restrain the tube so that it moves vertically without adding friction or otherwise changing the response. What about one of your capacitance sensors set up so that it will only respond to vertical motion?

I'm still studying your pendulum paper that posted a link to here some time ago.

Regards,

Bob

On Tue, Dec 9, 2008 at 12:50 AM, Randall Peters <PETERS_RD@..........> wrote:

I've been contemplating an instrument based on a piece of equipment we
use in the physics department to teach hydrostatics. It is a long tube
that is sealed on one end, and the open end is immersed in a larger tube
filled with water. The smaller tube achieves an equilibrium position
determined by its weight, overall length, and diameter of the internal
air column. If one lifts the inner tube and releases it, it oscillates
in simple harmonic motion with a period greater than one second. Also,
because of the water, the motion is dampened. The motion depends on the
compressibility of the trapped air.
I've done an idealized calculation in which the water would be
replaced with mineral oil and the plastic tube of the apparatus with a
thinwall metal tube of length in the neighborhood of one meter. It
appears that the damping would be close to optimal and the period just
under two seconds for the diameter of the inner tube being one
centimeter and that of the outer tube holding the mineral oil about two
cm's.
The inner tube should be constrained (perhaps with long triaxial
threads, so that the motion is strictly vertical.
I will be interested to know if any of you have considered such an
apparatus.
Randall

Subject: Re: a possible seismometer? From: "Daryl P. Dacko" mycrump@........ Date: Mon, 08 Dec 2008 18:35:25 -0500 Randall, In the old Scientific American "Amateur Scientist" column there is a discussion or two about using these as seismometers and tiltmeters. They talked about using capacitive detectors at the ends to measure the displacement, if memory serves. Some discussion on damping factors too, I believe. You can get a compilation of all of the columns on CD for a very reasonable charge on the web, highly recommended... Now where did I put that CD... ;') Daryl Randall Peters wrote: > I've been contemplating an instrument based on a piece of equipment we > use in the physics department to teach hydrostatics. It is a long tube > that is sealed on one end, and the open end is immersed in a larger tube > filled with water. The smaller tube achieves an equilibrium position > determined by its weight, overall length, and diameter of the internal > air column. If one lifts the inner tube and releases it, it oscillates > in simple harmonic motion with a period greater than one second. Also, > because of the water, the motion is dampened. The motion depends on the > compressibility of the trapped air. > I've done an idealized calculation in which the water would be > replaced with mineral oil and the plastic tube of the apparatus with a > thinwall metal tube of length in the neighborhood of one meter. It > appears that the damping would be close to optimal and the period just > under two seconds for the diameter of the inner tube being one > centimeter and that of the outer tube holding the mineral oil about two > cm's. > The inner tube should be constrained (perhaps with long triaxial > threads, so that the motion is strictly vertical. > I will be interested to know if any of you have considered such an > apparatus. > Randall > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: a possible seismometer? From: ChrisAtUpw@....... Date: Tue, 9 Dec 2008 01:00:08 EST In a message dated 08/12/2008 21:50:51 GMT Standard Time, PETERS_RD@.......... writes: I've done an idealized calculation in which the water would be replaced with mineral oil and the plastic tube of the apparatus with a thinwall metal tube of length in the neighborhood of one meter. Hi Randall, The problem with oil is that the viscosity changes by x10 for every 20 C Deg change in temperature. This is why oil damping is 'difficult' / virtually useless for seismometers. You could use a glass U tube and mercury? Since mercury is quite a good electrical conductor, you could probably use magnetic damping? But you would have to thermostat the gas pressure chamber, which could be tricky, otherwise you are just making an expensive thermometer! Another alternative would be to use a metal bellows at the bottom end of the tube, maybe with an additional spring, to provide the pressure to support a vertical liquid column. Regards, Chris Chapman

In a message dated 08/12/2008 21:50:51 GMT Standard Time,=20 PETERS_RD@.......... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2> =20 I've done an idealized calculation in which the water would be
replaced= =20 with mineral oil and the plastic tube of the apparatus with a
thinwall=20 metal tube of length in the neighborhood of one=20 meter.

Hi Randall,

The problem with oil is that the viscosity=20 changes by x10 for every 20 C Deg change in temperature. This is why oi= l=20 damping is 'difficult' / virtually useless for seismometers.

You could use a glass U tube and mercury? Since= =20 mercury is quite a good electrical conductor, you could probably use magneti= c=20 damping? But you would have to thermostat the gas pressure chamber, which co= uld=20 be tricky, otherwise you are just making an expensive thermometer!

Another alternative would be to use a metal bel= lows=20 at the bottom end of the tube, maybe with an additional spring, to provide t= he=20 pressure to support a vertical liquid column.

Regards,

Chris Chapman

Subject: Re: a possible seismometer? From: "Robert Thomasson" rlthomasson@......... Date: Tue, 9 Dec 2008 09:58:52 +0300 Daryl, I have that CD but dang if I can find the article with the built-in search function. Do you happen to recall about what month and year it was? Thanks, Bob On Tue, Dec 9, 2008 at 2:35 AM, Daryl P. Dacko wrote: > Randall, > > In the old Scientific American "Amateur Scientist" column there is a > discussion or two about using these as seismometers and tiltmeters. > They talked about using capacitive detectors at the ends to measure the > displacement, if memory serves. > Some discussion on damping factors too, I believe. > > You can get a compilation of all of the columns on CD for a very reasonable > charge on the web, highly recommended... > > Now where did I put that CD... ;') > > Daryl > > > Randall Peters wrote: > >> I've been contemplating an instrument based on a piece of equipment we >> use in the physics department to teach hydrostatics. It is a long tube >> that is sealed on one end, and the open end is immersed in a larger tube >> filled with water. The smaller tube achieves an equilibrium position >> determined by its weight, overall length, and diameter of the internal >> air column. If one lifts the inner tube and releases it, it oscillates >> in simple harmonic motion with a period greater than one second. Also, >> because of the water, the motion is dampened. The motion depends on the >> compressibility of the trapped air. >> I've done an idealized calculation in which the water would be >> replaced with mineral oil and the plastic tube of the apparatus with a >> thinwall metal tube of length in the neighborhood of one meter. It >> appears that the damping would be close to optimal and the period just >> under two seconds for the diameter of the inner tube being one >> centimeter and that of the outer tube holding the mineral oil about two >> cm's. >> The inner tube should be constrained (perhaps with long triaxial >> threads, so that the motion is strictly vertical. >> I will be interested to know if any of you have considered such an >> apparatus. >> Randall >> >> > > __________________________________________________________ > > 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. > Daryl,

I have that CD but dang if I can find the article with the built-in search function. Do you happen to recall about what month and year it was?

Thanks,

Bob

On Tue, Dec 9, 2008 at 2:35 AM, Daryl P. Dacko <mycrump@........> wrote:

Randall,

In the old Scientific American "Amateur Scientist" column there is a discussion or two about using these as seismometers and tiltmeters.
They talked about using capacitive detectors at the ends to measure the displacement, if memory serves.
Some discussion on damping factors too, I believe.

You can get a compilation of all of the columns on CD for a very reasonable charge on the web, highly recommended...

Now where did I put that CD... ;')

Daryl

Randall Peters wrote:

I've been contemplating an instrument based on a piece of equipment we
use in the physics department to teach hydrostatics. It is a long tube
that is sealed on one end, and the open end is immersed in a larger tube
filled with water. The smaller tube achieves an equilibrium position
determined by its weight, overall length, and diameter of the internal
air column. If one lifts the inner tube and releases it, it oscillates
in simple harmonic motion with a period greater than one second. Also,
because of the water, the motion is dampened. The motion depends on the
compressibility of the trapped air.
I've done an idealized calculation in which the water would be
replaced with mineral oil and the plastic tube of the apparatus with a
thinwall metal tube of length in the neighborhood of one meter. It
appears that the damping would be close to optimal and the period just
under two seconds for the diameter of the inner tube being one
centimeter and that of the outer tube holding the mineral oil about two
cm's.
The inner tube should be constrained (perhaps with long triaxial
threads, so that the motion is strictly vertical.
I will be interested to know if any of you have considered such an
apparatus.
Randall

__________________________________________________________

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: a possible seismometer? From: ChrisAtUpw@....... Date: Tue, 9 Dec 2008 07:21:56 EST In a message dated 09/12/2008, rlthomasson@......... writes: I have that CD but dang if I can find the article with the built-in search function. Do you happen to recall about what month and year it was? Hi Bob, Try Stong, CL The Amateur Scientist, Sci. Am. mag., Nov. 1973 pp 124-129 "The mercury tiltmeter." The detector electronics needs a re-design. George Bush has a good updated circuit _ke6pxp@........ (mailto:ke6pxp@........ A large professional Hg seismometer designed by Benoit is described by Gile, WW, Geophys. J. Roy. Astro. Soc. vol 36 1974 pp 153-165 "A Mercury Pendulum Seismometer" Regards, Chris Chapman

In a message dated 09/12/2008, rlthomasson@......... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I have=20 that CD but dang if I can find the article with the built-in search=20 function. Do you happen to recall about what month and year it=20 was?

Hi Bob,

Try Stong, CL The Amateur Scientist, Sci. Am. m= ag.,=20 Nov. 1973 pp 124-129 "The mercury tiltmeter."

The detector electronics needs a re-design. Geo= rge=20 Bush has a good updated circuit ke6pxp@.......

A large professional Hg seismometer designed by= =20 Benoit is described by Gile, WW, Geophys. J. Roy. Astro. Soc. vol 36 1974 pp= =20 153-165 "A Mercury Pendulum Seismometer"

Regards,

Chris Chapman

Subject: Power Supply, Amplifier, and AD From: Dayana Andrea Schonwalder Angel dayanaangel82@......... Date: Tue, 9 Dec 2008 09:47:04 -0800 (PST) Hi every one I would like to know if any body know, if there is a possibility ti buy thi= s black box for a AS1 seismometer in any place in San Francisco in USA. =C2=A0We are a mexicangropu of students and here in the city where we are w= e can't find the pieces to bulid it. So if any body can help us with this information, it will be great. Thanks Dayana Schonwalder SisVOc Postgrado en Geof=C3=ADsica UNIVERSIDAD DE GUADALAJARA Centro Universitario de la Costa Av. Universidad 203 Del. Ixtapa,=20 Puerto Vallarta, JAL, M=C3=89XICO. e-mail dayanaangel82@......... =0A=0A=0A ____________________________________________________________= ________________________=0APremios MTV 2008=C2=A1En exclusiva! Fotos, nomin= ados, videos, y mucho m=C3=A1s! Mira aqu=C3=AD http://mtvla.yahoo.com/

Hi every one

I would like to know if a= ny body know, if there is a possibility ti buy this black box for a AS1 sei= smometer in any place in San Francisco in USA.
We are a mexicangro= pu of students and here in the city where we are we can't find the pieces t= o bulid it.

So if any body can help us with this information, it wil= l be great.

Thanks

Dayana Schonwalder
SisVOc
Postgrado en Geof=C3=ADsica
UNIVERSIDAD DE GUADALAJARA
Centro Universitario de la Costa
Av. Universidad 203 Del. Ixtapa,
Puerto Vallarta, JAL, M=C3=89XICO.
e-mail dayanaangel82@.........

=0A=0A=0A=0A=0A= =0A=0A

=C2=A1Todo = sobre Amor y Sexo!
La gu=C3=ADa completa para tu vida en Mujer de Hoy:=0Ahttp://mujerdehoy.telemundo.yahoo.com/ Subject: Re: Power Supply, Amplifier, and AD From: Angel sismos@.............. Date: Tue, 9 Dec 2008 18:10:35 +0000 Hello Dayana, Don't buy the black box that you see with an AS1. you can do much better and probably less expensive or close with Larry's boards. http://psn.quake.net/serialatod.html it would be 16 bits instead of 12 and you can use a GPS. WinSDR and Winquake are great. Check it out. Angel Tuesday, December 9, 2008, 5:47:04 PM, you wrote: > Hi every one > I would like to know if any body know, if there is a possibility ti > buy this black box for a AS1 seismometer in any place in San Francisco in USA. > We are a mexicangropu of students and here in the city where we > are we can't find the pieces to bulid it. > So if any body can help us with this information, it will be great. > Thanks > Dayana Schonwalder > SisVOc > Postgrado en Geofísica > UNIVERSIDAD DE GUADALAJARA > Centro Universitario de la Costa > Av. Universidad 203 Del. Ixtapa, > Puerto Vallarta, JAL, MÉXICO. > e-mail dayanaangel82@......... > > ____________________________________________________________________________________ > Premios MTV 2008¡En exclusiva! Fotos, nominados, videos, y mucho > más! Mira aquí http://mtvla.yahoo.com/ -- Best regards, Angel __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: a possible seismometer? From: George Bush ke6pxp@....... Date: Tue, 09 Dec 2008 10:15:15 -0800 Hi all- Since Chris has mentioned me (or at least my email address), I thought I would share some of my experiences with trying to build an updated Mercury Tiltmeter. These instruments detect quakes, but my interest was in Earth tides and other low freq phemomena. I constructred a tiltmeter following the design in the Scientific American article but with a capacitance sensor as suggested by Chris. Please see http://ntweb.mcn.org/gbush/Tiltmeter/tiltmeter%20Main.html for construction details. Sorry the site is not current and doesn't have the new circuit on it as I consider it a work in progress. So far I have been defeated by the thermal problems. I have the unit mounted in a solid foam insulating chamber with a heated plate at the top to stratify the air currents. But even with all of that it is just a VERRY expensive (especially in time spent) thermometer!!! There are successful instruments based on this principle around the world, especially in Europe where one unit has cups separated by 100m of tubing and is installed in an old mine tunnel. My plans are to completely rebuild my unit with the cups separated to the ends of my gargage to increase the sensitivity and install a motor-driven compensator, as suggested in the Gile article, to balance out the thermal expansion of the Hg. I hope this helps- George At 07:21 AM 12/9/2008 EST, you wrote: >>>> In a message dated 09/12/2008, rlthomasson@......... writes: I have that CD but dang if I can find the article with the built-in search function. Do you happen to recall about what month and year it was? Hi Bob, Try Stong, CL The Amateur Scientist, Sci. Am. mag., Nov. 1973 pp 124-129 "The mercury tiltmeter." The detector electronics needs a re-design. George Bush has a good updated circuit <ke6pxp@....... A large professional Hg seismometer designed by Benoit is described by Gile, WW, Geophys. J. Roy. Astro. Soc. vol 36 1974 pp 153-165 "A Mercury Pendulum Seismometer" Regards, Chris Chapman <<<<<<<< George Subject: Re: Power Supply, Amplifier, and AD From: Thomas Dick dickthomas01@............. Date: Tue, 09 Dec 2008 12:17:04 -0600 Angel wrote: > Hello Dayana, > > Don't buy the black box that you see with an AS1. > > you can do much better and probably less expensive or close with Larry's boards. > > http://psn.quake.net/serialatod.html > I agree with Angel. I am using the setup Angel discribed from Larry. The GPS/timing aspect is a real plus. > > > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Power Supply, Amplifier, and AD From: "Kay Wyatt" kwyatt@............. Date: Tue, 9 Dec 2008 10:50:20 -0800 Dayana, I agree that Larry's amplifier, etc, is a good choice. However, keep in mind that the AS-1 is a vertical seismometer and its natural period is about 1.6 seconds. the one advantage of the original black box is that its designer, Jeff Batton, added a period extending circuit to boost the very low frequencies so that you can more easily record periods up to 20 seconds. Most people who use Larry's board use it with horizontal seismometers which have a longer natural period than the vertical AS-1. I have several vertical seismometers here which I have built or am evaluating. One has Larry's board attached. I've also two AS-1 seismometers. One with the original black box and one with a black box that has been modified using suggestions from Chris Chapman. If anybody has an add-on period extending circuit or Larry's board I would be very interested! Kay Wyatt ----- Original Message ----- From: "Thomas Dick" To: Sent: Tuesday, December 09, 2008 10:17 AM Subject: Re: Power Supply, Amplifier, and AD > Angel wrote: >> Hello Dayana, >> >> Don't buy the black box that you see with an AS1. >> >> you can do much better and probably less expensive or close with Larry's >> boards. >> >> http://psn.quake.net/serialatod.html >> I agree with Angel. I am using the setup Angel discribed from Larry. The >> GPS/timing aspect is a real plus. >> >> >> > > __________________________________________________________ > > 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: Power Supply, Amplifier, and AD From: "Robert McClure" bobmcclure90@......... Date: Tue, 9 Dec 2008 21:28:17 -0500 I have a digital inverse filter utility for PSN files. It is capable of giving long-period response to the AS-1. See http://bobmcclure90.googlepages.com/winsac Bob >If anybody has an add-on period extending circuit or Larry's board I would be very interested!< I have a digital inverse filter utility for PSN files. It is capable of giving long-period response to the AS-1. See

http://bobmcclure90.googlepages.com/winsac

Bob

>If anybody has an add-on period extending circuit or Larry's board I would
be very interested!<

Subject: Re: Power Supply, Amplifier, and AD From: ChrisAtUpw@....... Date: Tue, 9 Dec 2008 21:30:14 EST In a message dated 09/12/2008, sismos@.............. writes: Hello Dayana, Don't buy the black box that you see with an AS1. you can do much better and probably less expensive or close with Larry's boards. Hi Dayana, I believe that Jeff Batten _amateurseismo@.......... (mailto:amateurseismo@.......... will sell the electronics box and power supply separately. Seismometers like the AS1 and EQ1 try to use oil + plunge plate damping. The viscosity of oil changes by about x10 for every 20 C Deg / 36 F Deg change in temperature. If you set up the damping to be correct at your room temperature, you will only have an operating range of about +/-4 F Deg. This is LESS than the normal daily variation. If the temperature falls much below this range, the damping increases dramatically and the seismometer MAY stop recording altogether. It's sensitivity will certainly decrease and the calibration will NOT give the correct quake magnitude. I have designed a replacement magnetic damper which is NOT effected by temperature and is both easy to set up and CLEAN! No more oil creepage or spills! See _http://jclahr.com/science/psn/chapman/as1%20damping/index.html_ (http://jclahr.com/science/psn/chapman/as1%20damping/index.html) The AS1 uses a vertical swing arm with a natural period of about 1.5 seconds. So while the response is flat with velocity at periods shorter than this (like a geophone), the sensitivity will fall off as f^2 below 0.75 Hz when using a 'normal' seismic amplifier, like Larry's. The sensitivity to the 20 second period Rayleigh waves, will be down by a factor of about 180 - so you normally won't see any! A period extension circuit has been used in the AS1 'black box' to extend the sensitivity ~flat from 1.5 to about 4.5 seconds. This boosts the low frequency output. While it is OK for measuring microseisms, it is otherwise rather limiting. A further period extension can be applied with the digital compenation filter supplied with AmaSeis, but it only works well on moderately strong signals. I have extended the period to about 20 seconds by changing four capacitors and three resistors. It now seems to work satisfactorily and covers most of the normal seismic range. On the EQ1 that we examined, the compensation covered about the same compensation period range as an AS1, but the output seemed to be roughly proportional to f. This did NOT give a flat output. Since the power laws are different, I would not expect the digital frequency compensation built into AmaSeis to work adequately with an EQ1 trace. The EQ1 electronics uses miniature surface mount components, so I would NOT expect you to be able to modify EITHER the compensation range OR the power law. The relatively long springs expand and contract with temperature and may well need adjustment with the seasons. The AS1 is designed with the centre of gravity on the horizontal arm.

In a message dated 09/12/2008, sismos@.............. writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Hello=20 Dayana,
Don't buy the black box that you see with an AS1.
you can do= =20 much better and probably less expensive or close with Larry's=20 boards.

Hi Dayana,

I believe that Jeff Batten amateurseismo@......... will sel= l the=20 electronics box and power supply separately.

Seismometers like the AS1 and EQ1 try to use oi= l +=20 plunge plate damping. The viscosity of oil changes by about x10 for every 20= C=20 Deg / 36 F Deg change in temperature. If you set up the damping to be correc= t at=20 your room temperature, you will only have an operating range of about +/-4 F= =20 Deg. This is LESS than the normal daily variation. If the temperature falls=20= much=20 below this range, the damping increases dramatically and the seismometer MAY= =20 stop recording altogether. It's sensitivity will certainly decrease and the=20 calibration will NOT give the correct quake magnitude. I have designed a=20 replacement magnetic damper which is NOT effected by temperature and is=20 both easy to set up and CLEAN! No more oil creepage or spills!

See http= ://jclahr.com/science/psn/chapman/as1%20damping/index.html

The AS1 uses a vertical swing arm with a natura= l=20 period of about 1.5 seconds. So while the response is flat with velocity at=20 periods shorter than this (like a geophone), the sensitivity will fall off a= s=20 f^2 below 0.75 Hz when using a 'normal' seismic amplifier, like Larry's. The= =20 sensitivity to the 20 second period Rayleigh waves, will be down by a factor= of=20 about 180 - so you normally won't see any!

A period extension circuit has been used in the= AS1=20 'black box' to extend the sensitivity ~flat from 1.5 to about 4.5 secon= ds.=20 This boosts the low frequency output. While it is OK for measuring=20 microseisms, it is otherwise rather limiting. A further perio= d=20 extension can be applied with the digital compenation filter supplied w= ith=20 AmaSeis, but it only works well on moderately strong signals.

I have extended the period to about 20 seconds=20 by changing four capacitors and three resistors. It now seems= to=20 work satisfactorily and covers most of the normal seismic range.

On the EQ1 that we examined, the compensat= ion=20 covered about the same compensation period range as an AS1, but the output=20 seemed to be roughly proportional to f. This did NOT give a flat output. Sin= ce=20 the power laws are different, I would not expect the digital frequency=20 compensation built into AmaSeis to work adequately with an EQ1 trace. T= he=20 EQ1 electronics uses miniature surface mount components, so I would NOT=20 expect you to be able to modify EITHER the compensation range OR t= he=20 power law.

The relatively long springs expand and contract= =20 with temperature and may well need adjustment with the seasons.

The AS1 is designed with the centre of gravity=20= on=20 the horizontal arm.

Subject: Re: Power Supply, Amplifier, and AD From: ChrisAtUpw@....... Date: Tue, 9 Dec 2008 23:48:06 EST In a message dated 09/12/2008 18:50:39 GMT Standard Time, kwyatt@............. writes: If anybody has an add-on period extending circuit or Larry's board I would be very interested! Hi Kay, _http://jclahr.com/science/psn/roberts/index.html_ (http://jclahr.com/science/psn/roberts/index.html) _http://jclahr.com/science/psn/cochrane/index.html_ (http://jclahr.com/science/psn/cochrane/index.html) !! Chris

In a message dated 09/12/2008 18:50:39 GMT Standard Time,=20 kwyatt@............. writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>If=20 anybody has an add-on period extending circuit or Larry's board I would be=20 very interested!

Hi Kay,

http://jclahr.com/= science/psn/roberts/index.html

http://jclahr.com= /science/psn/cochrane/index.html

Chris

Subject: Re: Power Supply, Amplifier, and AD From: "Kareem, Heyjoojoo" system98765@............. Date: Wed, 10 Dec 2008 11:43:13 -0800 Can anyone recommend something to help with a clogging pen. I have an old PS2 recording system and the pen keeps clogging. I have contacted the manufacturer and they want a large amount of $$ to send me new pens and ink. I dont know if the ink is a problem or the paper. I'm actually using good paper, the one that is manufactured by Kenemtrics. So, I don think that the paper is what's causing the problem with the pen clogging. Maybe the ink? Is there a certain type that is less prone to clogging in pen stylus and capillary tube? Kareem ChrisAtUpw@....... wrote: > In a message dated 09/12/2008 18:50:39 GMT Standard Time, > kwyatt@............. writes: > > If anybody has an add-on period extending circuit or Larry's board > I would > be very interested! > > Hi Kay, > > http://jclahr.com/science/psn/roberts/index.html > > http://jclahr.com/science/psn/cochrane/index.html > > !! > > Chris > ------------------------------------------------------------------------ > > > No virus found in this incoming message. > Checked by AVG - http://www.avg.com > Version: 8.0.176 / Virus Database: 270.9.15/1839 - Release Date: 12/9/2008 9:59 AM > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Clogging pens From: ChrisAtUpw@....... Date: Wed, 10 Dec 2008 15:52:02 EST In a message dated 10/12/2008, system98765@............. writes: Can anyone recommend something to help with a clogging pen. I have an old PS2 recording system and the pen keeps clogging. I have contacted the manufacturer and they want a large amount of $$ to send me new pens and ink. Hi Kareem, What ink are you using? Normal 'permanent' fountain pen inks will not dissolve after they have dried out / aged. I use UNO drawing pens made by Rotring. They sell a special cleaning fluid for them, which works well. You may need to push a fine wire down the pen? Rotring use a 'built-in' tungsten wire. Try a hard drawn Nichrome wire? I have also looked at inks for chart recorder pens / inkjet printers and you can buy specialist cleaning fluid for these. Check with your local computer store / an on-line supplier? I can buy ink in ~50ml bottles and inject it into commercial ink jet printer cartriges to re-fill them. Soaking the jet plate with the cleaning fluid on a thin cover cloth does clean it. Maybe overnight in a polythene bag? Ask your manufacturer about a cleaning fluid for their pens? You don't say what type / make of pen you are using! Ideally, you should clean capillary tube pens out every few months, to prevent clogging problems. The special needles used for injecting insulin used to come with a cleaning wire. Regards, Chris Chapman

In a message dated 10/12/2008, system98765@............. writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Can=20 anyone recommend something to help with a clogging pen. I have an
old=20= PS2=20 recording system and the pen keeps clogging. I have contacted
the=20 manufacturer and they want a large amount of $$ to send me new pens
an= d=20 ink.

Hi Kareem,

What ink are you using? Normal 'permanent' foun= tain=20 pen inks will not dissolve after they have dried out / aged.

I use UNO drawing pens made by Rotring. They se= ll a=20 special cleaning fluid for them, which works well. You may need to push a fi= ne=20 wire down the pen? Rotring use a 'built-in' tungsten wire. Try a hard drawn=20 Nichrome wire?

I have also looked at inks for chart recorder p= ens=20 / inkjet printers and you can buy specialist cleaning fluid for these.=20 Check with your local computer store / an on-line supplier? I can buy ink in= =20 ~50ml bottles and inject it into commercial ink jet printer cartriges to re-= fill=20 them. Soaking the jet plate with the cleaning fluid on a thin cove= r=20 cloth does clean it. Maybe overnight in a polythene bag?

Ask your manufacturer about a cleaning fluid fo= r=20 their pens? You don't say what type / make of pen you are using!=20 Ideally, you should clean capillary tube pens out every few months, to preve= nt=20 clogging problems. The special needles used for injecting insulin used to co= me=20 with a cleaning wire.

Regards,

Chris Chapman

Subject: Lehman sensor back online From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr@......... Date: Fri, 12 Dec 2008 21:27:56 +0000 Hello all It has been some time since I have send a email to this postlist. But I have been in school for past few months. Now the school is finished for me. I have finished the modifactions to the lehman I did get help with building last spring. It appears to be working fine. The top of the frequancy of the sensor is 2,5Hz (lower end somewhere around 0.5Hz or lower) and I am not sure why that is. I hope it works with teleseismic event. But only time is going to tell. Here are the pictures of the sensor and the changes I did do to it. http://www.jonfr.com/myndir/v/geology/seismometer/pc120001.jpg.html Regards. --=20 J=F3n Fr=EDmann __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Lehman sensor back online From: Pete Rowe ptrowe@......... Date: Fri, 12 Dec 2008 15:10:27 -0800 (PST) Hi Jon It is good to have you back again. I wondered what ever happened to you. Di= d you graduate or are you on a winter break from school? What are you studying? Regards Pete --- On Fri, 12/12/08, J=F3n Fr=EDmann wrote: From: J=F3n Fr=EDmann Subject: Lehman sensor back online To: "PSN-Postlist" Date: Friday, December 12, 2008, 1:27 PM Hello all It has been some time since I have send a email to this postlist. But I have been in school for past few months. Now the school is finished for me. I have finished the modifactions to the lehman I did get help with building last spring. It appears to be working fine. The top of the frequancy of the sensor is 2,5Hz (lower end somewhere around 0.5Hz or lower) and I am not sure why that is. I hope it works with teleseismic event. But only time is going to tell. Here are the pictures of the sensor and the changes I did do to it. http://www.jonfr.com/myndir/v/geology/seismometer/pc120001.jpg.html Regards. --=20 J=F3n Fr=EDmann __________________________________________________________ Public Seismic Network Mailing List (PSN-L) =0A=0A=0A

Hi Jon
It is good to have you back again. = I wondered what ever happened to you. Did you graduate or are you on a wint= er break from school?
What are you studying?

Regards
Pete
<= br>--- On Fri, 12/12/08, J=F3n Fr=EDmann <jonfr@.........><= /b> wrote:
From: J=F3n Fr=EDmann <jonfr@jonf= r.com>
Subject: Lehman sensor back online
To: "PSN-Postlist" <P= SN-L@..............>
Date: Friday, December 12, 2008, 1:27 PM

=
Hello all

It has been some time since I have send a email to th= is postlist. But I
have been in school for past few months. Now the scho= ol is finished for
me.

I have finished the modifactions to the le= hman I did get help with
building last spring. It appears to be working = fine. The top of the
frequancy of the sensor is 2,5Hz (lower end somewhere around= 0.5Hz or
lower) and I am not sure why that is. I hope it works with tel= eseismic
event. But only time is going to tell.

Here are the pict= ures of the sensor and the changes I did do to it.
http://www.jonfr.com/= myndir/v/geology/seismometer/pc120001.jpg.html

Regards.
--
J= =F3n Fr=EDmann

_____________________________________________________= _____

Public Seismic Network Mailing List (PSN-L)

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

=0A=0A= Subject: Re: Lehman sensor back online From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr@......... Date: Fri, 12 Dec 2008 23:24:37 +0000 Hi I was just taking few classes that I wanted to learn. This time around it was about car engenes and how to build stuff out of metal. I also took a class in geology and social sience. I don't have any plans to go back to school for now. What I have learned for now is good enugh for me. Regards. J=F3n Fr=EDmann. On f=F6s, 2008-12-12 at 15:10 -0800, Pete Rowe wrote: > Hi Jon > It is good to have you back again. I wondered what ever happened to > you. Did you graduate or are you on a winter break from school? > What are you studying? >=20 > Regards > Pete >=20 > --- On Fri, 12/12/08, J=F3n Fr=EDmann wrote: > From: J=F3n Fr=EDmann > Subject: Lehman sensor back online > To: "PSN-Postlist" > Date: Friday, December 12, 2008, 1:27 PM > =20 > Hello all > =20 > It has been some time since I have send a email to this postlist.= But I > have been in school for past few months. Now the school is finish= ed for > me. > =20 > I have finished the modifactions to the lehman I did get help wit= h > building last spring. It appears to be working fine. The > top of the > frequancy of the sensor is 2,5Hz (lower end somewhere around 0.5H= z or > lower) and I am not sure why that is. I hope it works with telese= ismic > event. But only time is going to tell. > =20 > Here are the pictures of the sensor and the changes I did do to i= t. > http://www.jonfr.com/myndir/v/geology/seismometer/pc120001.jpg.ht= ml > =20 > Regards. > --=20 > J=F3n Fr=EDmann > =20 > __________________________________________________________ > =20 > Public Seismic Network Mailing List (PSN-L) > =20 > 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: Spring Constant and Temperature From: "Gary Lindgren" gel@................. Date: Fri, 12 Dec 2008 17:44:54 -0800 As we know, the spring constant changes with temperature for the typical materials used for springs. For instance, for carbon steel, the modulus of elasticity is 29.5E6 psi at 70 degrees F and then changes to 28.8E6 psi at 200 degrees F. This means that the spring constant changes with temperature. Is this a problem that I should be concerned about. My vertical seismometer is located in the wine cellar and so the temperature does not vary during the day, but the temperature may change 10 degrees F with the seasons. Does anyone use a spring made with Ni-Span-C 902? This material is extremely stable with temperature. The modulus of elasticity is 27.79E6 psi at 0, 100, and 200 degrees F. The only problem is that this material is not used very much and it's a made to order situation. Peck Springs in Connecticut ( 860-747-5715) has made springs with material from time to time. They are checking to see what the cost would be. Any thoughts? Gary Gary Lindgren 585 Lincoln Ave Palo Alto CA 94301 650-326-0655 www.blue-eagle-technologies.com Check out Lastest Seismometer Reading cymonsplace.blogspot.com

As we know, the spring constant changes with = temperature for the typical materials used for springs. For instance, for carbon steel, = the modulus of elasticity is 29.5E6 psi at 70 degrees F and then changes to 28.8E6 = psi at 200 degrees F. This means that the spring constant changes with = temperature. Is this a problem that I should be concerned about. My vertical seismometer = is located in the wine cellar and so the temperature does not vary during = the day, but the temperature may change 10 degrees F with the seasons. Does = anyone use a spring made with Ni-Span-C 902? This material is extremely stable with temperature. The modulus of elasticity is 27.79E6 psi at 0, 100, and 200 degrees F. The only problem is that this material is not used very much = and it’s a made to order situation. Peck Springs in Connecticut ( 860-747-5715) = has made springs with material from time to time. They are checking to see what = the cost would be.

Any thoughts?

Gary

Gary Lindgren

585 Lincoln Ave

Palo Alto CA 94301

650-326-0655<= /span>

www.blue-eagle-technologies.com &nbs= p; Check out Lastest Seismometer = Reading

cymonsplace.blogspot.com

Subject: Re: Spring Constant and Temperature From: ChrisAtUpw@....... Date: Fri, 12 Dec 2008 22:20:20 EST In a message dated 13/12/2008, gel@................. writes: The spring constant changes with temperature for the typical materials used for springs. For instance, for carbon steel, the modulus of elasticity is 29.5E6 psi at 70 degrees F and then changes to 28.8E6 psi at 200 degrees F. This means that the spring constant changes with temperature. Is this a problem that I should be concerned about. My vertical seismometer is located in the wine cellar and so the temperature does not vary during the day, but the temperature may change 10 degrees F with the seasons. Hi Gary, This normally limits the maximum period that you can set a steel spring vertical to about 6 seconds. The Tc of the modulus is about -2.4x10^-4 / C Deg, which is large. If you try to make a vertical with a very long natural period, it will collapse as the room temperature rises. The 'work around' for a simple amateur system is to make a vertical sensor with a 1.5 to 2 second period and then fit a 1/f^2 low frequency boost amplifier to recover the long period signals. You can get at least a factor of x10 this way before you run into noise problems, more if you use quad NdFeB magnet + coil sensor. I run a sensor of this general type and it picks up the Rayleigh waves very nicely. You can get much greater period extensions if you use a position sensor and force feedback - see the SG type pendulum seismometers on psn. You don't have to use the RF oscillator + tuned sensor circuit. Large area Si photodiodes, 10 to 20 sq mm, and a tungsten filament lamp will work OK. Small photodiodes and photo transistors both have too high noise levels. The professionals now tend to use N-SpanC springs and force feedback systems to get periods to 360 seconds. The old Sprengnether verticals used an Elinvar spring and got stable operation to 30 seconds. Sean Morrissey developed a force feedback vertical with a steel leaf spring which was OK for about +/-10 deg. It is all linked on psn, if you look! Regards, Chris Chapman

In a message dated 13/12/2008, gel@................. writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>The=20 spring constant changes with temperature for the typical materials used fo= r=20 springs. For instance, for carbon steel, the modulus of elasticity is 29.5= E6=20 psi at 70 degrees F and then changes to 28.8E6 psi at 200 degrees F. This=20 means that the spring constant changes with temperature. Is this a problem= =20 that I should be concerned about. My vertical seismometer is located in th= e=20 wine cellar and so the temperature does not vary during the day, but the=20 temperature may change 10 degrees F with the seasons. =

Hi Gary,

This normally limits the maximum period that yo= u=20 can set a steel spring vertical to about 6 seconds. The Tc of the modulus is= =20 about -2.4x10^-4 / C Deg, which is large. If you try to make a vertica= l=20 with a very long natural period, it will collapse as the room temperature=20 rises.

The 'work around' for a simple amateur system i= s to=20 make a vertical sensor with a 1.5 to 2 second period and then fit a=20 1/f^2 low frequency boost amplifier to recover the long period=20 signals. You can get at least a factor of x10 this way before you run into n= oise=20 problems, more if you use quad NdFeB magnet + coil sensor. I run a sensor of= =20 this general type and it picks up the Rayleigh waves very nicely.

You can get much greater period extensions if y= ou=20 use a position sensor and force feedback - see the SG type pendulum=20 seismometers on psn. You don't have to use the RF oscillator + tuned sensor=20 circuit. Large area Si photodiodes, 10 to 20 sq mm, and a tungsten filament=20= lamp=20 will work OK. Small photodiodes and photo transistors both have too high noi= se=20 levels.

The professionals now tend to use N-SpanC=20 springs and force feedback systems to get periods to 360 seconds. The old=20 Sprengnether verticals used an Elinvar spring and got stable operation=20= to=20 30 seconds.

Sean Morrissey developed a force feedback verti= cal=20 with a steel leaf spring which was OK for about +/-10 deg. It= is=20 all linked on psn, if you look!

Regards,

Chris Chapman

Subject: Re: Spring Constant and Temperature From: Brett Nordgren brett3nt@............. Date: Fri, 12 Dec 2008 23:26:40 -0500 Hi Gary, As Chris mentioned in his reply, feedback can help deal with support-spring drift. What can be done is to roll off the instrument response at low frequencies, in particular its response to forces/accelerations, and make it fall toward zero at DC. The effect, then, is that the loop will tend to cancel out any spring changes which are slow enough. You would probably want to put the seismo in a can and surround it with thick insulation so that ambient changes only get through to the seismo very slowly, and so can be cancelled by the loop. The integral feedback branch is the thing that does the job and if you have a good integrator circuit it could probably do enough good to allow for using a steel spring. It would be particularly effective with daily variations, though for longer-term seasonal shifts, you'd probably need to adjust the mechanical balance to re-null the loop. You don't want to be running the instrument with the integrator continuously straining hard to offset a large, permanent, spring change. The main problem with Ni-Span-C, assuming that you can get some, is that its performance is highly dependent on the way it is cold-worked and heat treated. See: http://bnordgren.org/seismo/ni-span-c_alloy_902.pdf It is also only about 2/3 as strong as steel, and so will have 'lower' performance as a spring, by some measures. Regards, Brett At 05:44 PM 12/12/2008 -0800, you wrote: >As we know, the spring constant changes with temperature for the typical >materials used for springs. For instance, for carbon steel, the modulus of >elasticity is 29.5E6 psi at 70 degrees F and then changes to 28.8E6 psi at >200 degrees F. This means that the spring constant changes with >temperature. Is this a problem that I should be concerned about. My >vertical seismometer is located in the wine cellar and so the temperature >does not vary during the day, but the temperature may change 10 degrees F >with the seasons. Does anyone use a spring made with Ni-Span-C 902? This >material is extremely stable with temperature. The modulus of elasticity >is 27.79E6 psi at 0, 100, and 200 degrees F. The only problem is that this >material is not used very much and it s a made to order situation. Peck >Springs in Connecticut ( 860-747-5715) has made springs with material from >time to time. They are checking to see what the cost would be. > >Any thoughts? > >Gary > > > >Gary Lindgren > >585 Lincoln Ave > >Palo Alto CA 94301 > > > >650-326-0655 > > > >www.blue-eagle-technologies.com >Check out Lastest Seismometer Reading > >cymonsplace.blogspot.com > > > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Lehman sensor back online From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr@......... Date: Sat, 13 Dec 2008 04:38:56 +0000 Hi all The sensor is now back online on the internet, the plot can be seen on the usual place. http://www.simnet.is/jonfr500/earthquake/tremoren.htm Regards. --=20 J=F3n Fr=EDmann __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Spring Constant and Temperature From: "Gary Lindgren" gel@................. Date: Sat, 13 Dec 2008 10:36:11 -0800 Hi Brett, I won't have a daily temperature issue because I have the seismo in the wine cellar that is well insulated and in the basement. There are no daily temperature variation, it's only the seasonal I need to worry about. Yes indeed the Ni-Span-C 902 needs to be heat treated correctly. To achieve the zero change with temperature the material needs to be heat treated at 1000 degrees F for 5 hours. Gary -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Brett Nordgren Sent: Friday, December 12, 2008 8:27 PM To: psn-l@.............. Subject: Re: Spring Constant and Temperature Hi Gary, As Chris mentioned in his reply, feedback can help deal with support-spring drift. What can be done is to roll off the instrument response at low frequencies, in particular its response to forces/accelerations, and make it fall toward zero at DC. The effect, then, is that the loop will tend to cancel out any spring changes which are slow enough. You would probably want to put the seismo in a can and surround it with thick insulation so that ambient changes only get through to the seismo very slowly, and so can be cancelled by the loop. The integral feedback branch is the thing that does the job and if you have a good integrator circuit it could probably do enough good to allow for using a steel spring. It would be particularly effective with daily variations, though for longer-term seasonal shifts, you'd probably need to adjust the mechanical balance to re-null the loop. You don't want to be running the instrument with the integrator continuously straining hard to offset a large, permanent, spring change. The main problem with Ni-Span-C, assuming that you can get some, is that its performance is highly dependent on the way it is cold-worked and heat treated. See: http://bnordgren.org/seismo/ni-span-c_alloy_902.pdf It is also only about 2/3 as strong as steel, and so will have 'lower' performance as a spring, by some measures. Regards, Brett At 05:44 PM 12/12/2008 -0800, you wrote: >As we know, the spring constant changes with temperature for the typical >materials used for springs. For instance, for carbon steel, the modulus of >elasticity is 29.5E6 psi at 70 degrees F and then changes to 28.8E6 psi at >200 degrees F. This means that the spring constant changes with >temperature. Is this a problem that I should be concerned about. My >vertical seismometer is located in the wine cellar and so the temperature >does not vary during the day, but the temperature may change 10 degrees F >with the seasons. Does anyone use a spring made with Ni-Span-C 902? This >material is extremely stable with temperature. The modulus of elasticity >is 27.79E6 psi at 0, 100, and 200 degrees F. The only problem is that this >material is not used very much and it s a made to order situation. Peck >Springs in Connecticut ( 860-747-5715) has made springs with material from >time to time. They are checking to see what the cost would be. > >Any thoughts? > >Gary > > > >Gary Lindgren > >585 Lincoln Ave > >Palo Alto CA 94301 > > > >650-326-0655 > > > >www.blue-eagle-technologies.com >Check out Lastest Seismometer Reading > >cymonsplace.blogspot.com > > > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: signal from my lehman sensor From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr@......... Date: Sun, 14 Dec 2008 01:27:39 +0000 Hi all How does the signal from my lehman sensor look ? Bad or good ? There has not been any big earthquake to check the sensor of it works or not. So an opinion on the signal it currently gives is appreciated. The signal can be found here. http://www.simnet.is/jonfr500/earthquake/tremoren.htm Regards. --=20 J=F3n Fr=EDmann __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Interesting Article on Earthquakes From: Bob Hancock carpediem1@......... Date: Sat, 13 Dec 2008 22:09:08 -0700 http://www.newswise.com/articles/view/547288/?sc=dwhn __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Spring Constant and Temperature From: Brett Nordgren brett3nt@............. Date: Sun, 14 Dec 2008 13:18:05 -0500 Hi Gary, There's also a slightly different approach you might want to consider, which is what I now think they did in the STS-1 and probably others. Heat treat the Ni-Span-C for maximum strength (~1300 deg F/5 hrs) which gets the spec. yield strength up to 173 ksi. That ends up with a relatively linear positive TCE of about +20ppm/degF. Then you can parallel the Ni-Span spring with a relatively weaker steel spring which will contribute a negative TCE. If the relative spring strengths are chosen properly you could end up with a fairly constant net zero TCE. I admit that's going pretty far for ultimate performance. That may be one of reasons why those highly respected instruments cost so much. In practice, there are going to be circuit issues which will add significantly to the instrument temp. coeff. even if the spring is perfect. Brett At 10:36 AM 12/13/2008 -0800, Gary Lindgren wrote: >Hi Brett, >I won't have a daily temperature issue because I have the seismo in the wine >cellar that is well insulated and in the basement. There are no daily >temperature variation, it's only the seasonal I need to worry about. Yes >indeed the Ni-Span-C 902 needs to be heat treated correctly. To achieve the >zero change with temperature the material needs to be heat treated at 1000 >degrees F for 5 hours. >Gary > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Spring Constant and Temperature From: Barry Lotz barry_lotz@............. Date: Tue, 16 Dec 2008 06:38:45 -0800 (PST) Chris I added a bymetal spiral spring from a dial thermometer to my Sean Morresse= y vertical to help compensate for the temperature. It is mounted off to the= side and rests on the boom in a fishing pole configuration. I move it up a= nd down the boom until I get the proper compensation Barry --- On Fri, 12/12/08, ChrisAtUpw@....... wrote: From: ChrisAtUpw@....... Subject: Re: Spring Constant and Temperature To: psn-l@.............. Date: Friday, December 12, 2008, 7:20 PM =20 In a message dated 13/12/2008, gel@................. writes: The=20 spring constant changes with temperature for the typical materials used f= or=20 springs. For instance, for carbon steel, the modulus of elasticity is 29.= 5E6=20 psi at 70 degrees F and then changes to 28.8E6 psi at 200 degrees F. This= =20 means that the spring constant changes with temperature. Is this a proble= m=20 that I should be concerned about. My vertical seismometer is located in t= he=20 wine cellar and so the temperature does not vary during the day, but the= =20 temperature may change 10 degrees F with the seasons.=20 Hi Gary, =A0 =A0=A0=A0=A0This normally limits the maximum period that you=20 can set a steel spring vertical to about 6 seconds. The Tc of the modulus i= s=20 about =A0-2.4x10^-4 / C Deg, which is large. If you try to make a vertical= =20 with a very long natural period, it will collapse as the room temperature= =20 rises. =A0 =A0=A0=A0=A0The 'work around' for a simple amateur system is to=20 make a vertical sensor with a 1.5 to 2 second period and then fit a=20 1/f^2=A0low frequency boost amplifier=A0to recover the long period=20 signals. You can get at least a factor of x10 this way before you run into = noise=20 problems, more if you use quad NdFeB magnet + coil sensor. I run a sensor o= f=20 this general type and it picks up the Rayleigh waves very nicely.=20 =A0 =A0=A0=A0=A0You can get much greater period extensions if you=20 use a position sensor and force feedback - see the SG type=A0pendulum=20 seismometers on psn. You don't have to use the RF oscillator + tuned sensor= =20 circuit. Large area Si photodiodes, 10 to 20 sq mm, and a tungsten filament= lamp=20 will work OK. Small photodiodes and photo transistors both have too high no= ise=20 levels.=20 =A0 =A0=A0=A0=A0The professionals now=A0tend to use N-SpanC=20 springs and force feedback systems to get periods to 360 seconds. The old= =20 Sprengnether verticals used an Elinvar spring and got=A0stable operation to= =20 30 seconds.=A0 =A0 =A0=A0=A0=A0Sean Morrissey developed a force feedback vertical=20 with a steel leaf spring which was OK for=A0about=A0+/-10 deg.=A0It is=20 all linked on psn, if you look! =A0 =A0=A0=A0=A0Regards, =A0 =A0=A0=A0=A0Chris Chapman

Chris
I added a bymetal spiral spring from a dial thermometer to my Sean Morressey vertical to help compensate for the temperature. It is mounted off to the side and rests on the boom in a fishing pole configuration. I move it up and down the boom until I get the proper compensation
Barry

--- On Fri, 12/12/08, ChrisAtUpw@....... <ChrisAtUpw@.......> wrote:

From: ChrisAtUpw@....... <ChrisAtUpw@.......>
Subject: Re: Spring Constant and Temperature
To: psn-l@..............
Date: Friday, December 12, 2008, 7:20 PM

In a message dated 13/12/2008, gel@................. writes:

The spring constant changes with temperature for the typical materials used for springs. For instance, for carbon steel, the modulus of elasticity is 29.5E6 psi at 70 degrees F and then changes to 28.8E6 psi at 200 degrees F. This means that the spring constant changes with temperature. Is this a problem that I should be concerned about. My vertical seismometer is located in the wine cellar and so the temperature does not vary during the day, but the temperature may change 10 degrees F with the seasons.

Hi Gary,

    This normally limits the maximum period that you can set a steel spring vertical to about 6 seconds. The Tc of the modulus is about -2.4x10^-4 / C Deg, which is large. If you try to make a vertical with a very long natural period, it will collapse as the room temperature rises.

    The 'work around' for a simple amateur system is to make a vertical sensor with a 1.5 to 2 second period and then fit a 1/f^2 low frequency boost amplifier to recover the long period signals. You can get at least a factor of x10 this way before you run into noise problems, more if you use quad NdFeB magnet + coil sensor. I run a sensor of this general type and it picks up the Rayleigh waves very nicely.

    You can get much greater period extensions if you use a position sensor and force feedback - see the SG type pendulum seismometers on psn. You don't have to use the RF oscillator + tuned sensor circuit. Large area Si photodiodes, 10 to 20 sq mm, and a tungsten filament lamp will work OK. Small photodiodes and photo transistors both have too high noise levels.

    The professionals now tend to use N-SpanC springs and force feedback systems to get periods to 360 seconds. The old Sprengnether verticals used an Elinvar spring and got stable operation to 30 seconds.

    Sean Morrissey developed a force feedback vertical with a steel leaf spring which was OK for about +/-10 deg. It is all linked on psn, if you look!

    Regards,

    Chris Chapman

Subject: Low power monitor desired From: Barry Lotz barry_lotz@............. Date: Tue, 16 Dec 2008 06:50:53 -0800 (PST) To all I was trying to find a low power monitor for my acquisition system so I can= run my system off solar. The best I could find was a 8" 12 vt DC LCD displ= ay from Lilliput but it is not as inexpensive as the=A0 the larger AC LCD's= commonly advertised. It wouldn't be on except to check sensor status. I fo= und a low power computer ( 3-5 watts) that takes VGA input Barry =A0=20

To all
I was trying to find a low power monitor for my acquisition system so I can run my system off solar. The best I could find was a 8" 12 vt DC LCD display from Lilliput but it is not as inexpensive as the the larger AC LCD's commonly advertised. It wouldn't be on except to check sensor status. I found a low power computer ( 3-5 watts) that takes VGA input

Barry

Subject: Re: Low power monitor desired From: Thomas Dick dickthomas01@............. Date: Tue, 16 Dec 2008 09:10:30 -0600 Barry Lotz wrote: > To all > I was trying to find a low power monitor for my acquisition system so > I can run my system off solar. The best I could find was a 8" 12 vt DC > LCD display from Lilliput but it is not as inexpensive as the the > larger AC LCD's commonly advertised. It wouldn't be on except to check > sensor status. I found a low power computer ( 3-5 watts) that takes > VGA input > > Barry > > Maybe a dumb suggestion but .... How about putting a wi-fi on the computer, shutting the monitor off when not needed and monitoring the computer from a remote location. I already do this. I don't connect the monitor to the backup power supply...I have wi-fi in the house but still use solid cable to the network upstairs .. waiting for the computer downstairs to "die". __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Low power monitor desired From: Barry Lotz barry_lotz@............. Date: Tue, 16 Dec 2008 17:36:13 -0800 (PST) Tom I agree. I sort of do that now. I have the seismic computer in the garage and run a networking cable into the house. I use a free software "Tight VNC" to see the sensor display in the house. The company I bought the computer from has an updated version with WiFi and a larger harddrive. I'm not familiar with WiFi capabilities. Will it go thru two walls and about 40'-50'? Do I use the same software I currently use, ie, is WiFi just a wireless network link? Wireless would be nice. Barry --- On Tue, 12/16/08, Thomas Dick wrote: From: Thomas Dick Subject: Re: Low power monitor desired To: psn-l@.............. Date: Tuesday, December 16, 2008, 7:10 AM Barry Lotz wrote: > To all > I was trying to find a low power monitor for my acquisition system so > I can run my system off solar. The best I could find was a 8" 12 vt DC > LCD display from Lilliput but it is not as inexpensive as the the > larger AC LCD's commonly advertised. It wouldn't be on except to check > sensor status. I found a low power computer ( 3-5 watts) that takes > VGA input > > Barry > > Maybe a dumb suggestion but .... How about putting a wi-fi on the computer, shutting the monitor off when not needed and monitoring the computer from a remote location. I already do this. I don't connect the monitor to the backup power supply...I have wi-fi in the house but still use solid cable to the network upstairs .. waiting for the computer downstairs to "die".

Tom
I agree. I sort of do that now. I have the seismic computer in the garage and run a networking cable into the house. I use a free software "Tight VNC" to see the sensor display in the house. The company I bought the computer from has an updated version with WiFi and a larger harddrive. I'm not familiar with WiFi capabilities. Will it go thru two walls and about 40'-50'? Do I use the same software I currently use, ie, is WiFi just a wireless network link?
Wireless would be nice.
Barry

--- On Tue, 12/16/08, Thomas Dick <dickthomas01@.............> wrote:

From: Thomas Dick <dickthomas01@.............>
Subject: Re: Low power monitor desired
To: psn-l@..............
Date: Tuesday, December 16, 2008, 7:10 AM

Barry Lotz wrote:
> To all
> I was trying to find a low power monitor for my acquisition system so 
> I can run my system off solar. The best I could find was a 8" 12 vt
DC 
> LCD display from Lilliput but it is not as inexpensive as the  the 
> larger AC LCD's commonly advertised. It wouldn't be on except to
check 
> sensor status. I found a low power computer ( 3-5 watts) that takes 
> VGA input
>
> Barry
>  
>
Maybe a dumb suggestion but ....
How about putting a wi-fi on the computer, shutting the monitor off when 
not needed and monitoring the computer from a remote location. I already 
do this. I don't connect the monitor to the backup power supply...I have 
wi-fi in the house but still use solid cable to the network upstairs .. 
waiting for the computer downstairs to "die".

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In a message dated 09/12/2008, sismos@.............. writes:

Hello Dayana,
Don't buy the black box that you see with an AS1.
you can do much better and probably less expensive or close with Larry's boards.

Hi Dayana,

I believe that Jeff Batten amateurseismo@......... will sell the electronics box and power supply separately.

Seismometers like the AS1 and EQ1 try to use oil + plunge plate damping. The viscosity of oil changes by about x10 for every 20 C Deg / 36 F Deg change in temperature. If you set up the damping to be correct at your room temperature, you will only have an operating range of about +/-4 F Deg. This is LESS than the normal daily variation. If the temperature falls much below this range, the damping increases dramatically and the seismometer MAY stop recording altogether. It's sensitivity will certainly decrease and the calibration will NOT give the correct quake magnitude. I have designed a replacement magnetic damper which is NOT effected by temperature and is both easy to set up and CLEAN! No more oil creepage or spills!

See http://jclahr.com/science/psn/chapman/as1%20damping/index.html

The AS1 uses a vertical swing arm with a natural period of about 1.5 seconds. So while the response is flat with velocity at periods shorter than this (like a geophone), the sensitivity will fall off as f^2 below 0.75 Hz when using a 'normal' seismic amplifier, like Larry's. The sensitivity to the 20 second period Rayleigh waves, will be down by a factor of about 180 - so you normally won't see any!

A period extension circuit has been used in the AS1 'black box' to extend the sensitivity ~flat from 1.5 to about 4.5 seconds. This boosts the low frequency output. While it is OK for measuring microseisms, it is otherwise rather limiting. A further period extension can be applied with the digital compenation filter supplied with AmaSeis, but it only works well on moderately strong signals.

I have extended the period to about 20 seconds by changing four capacitors and three resistors. It now seems to work satisfactorily and covers most of the normal seismic range.

On the EQ1 that we examined, the compensation covered about the same compensation period range as an AS1, but the output seemed to be roughly proportional to f. This did NOT give a flat output. Since the power laws are different, I would not expect the digital frequency compensation built into AmaSeis to work adequately with an EQ1 trace. The EQ1 electronics uses miniature surface mount components, so I would NOT expect you to be able to modify EITHER the compensation range OR the power law.

The relatively long springs expand and contract with temperature and may well need adjustment with the seasons.

The AS1 is designed with the centre of gravity on the horizontal arm.

In a message dated 20/12/2008, rlthomasson@......... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>Chris,
Thinking about the damping, it seems like a basic coil=20= and=20 magnet sensor like the AS-1 would be self damping due to the movement of t= he=20 copper winding in the magnetic field. Or is it a case of it being se= lf=20 damping but still underdamped and needing additional=20 damping?
Bob

The coil + magnet supplied with the AS1 gives v= ery=20 roughly 0.1 damping, when you actually need 0.7 damping, so a lot of additio= nal=20 damping is required.

If you make you own system with a quad NdF= eB=20 magnet block and a rectangular coil, like Bob McClure, you can put a=20 variable resistor across the coil and set the damping that way. This coil ca= n=20 give 20x the output you get from an AS1.

If you connect the coil between Earth and the += ve=20 input of an opamp, you won't see any damping, since the input resistance is=20= near=20 infinite. If you use an amplifier like Larry's, it already has a 10 k resist= or=20 across it, so you could then get significant damping.

The AS1 uses a twin LF boost amplifier to recov= er=20 longer period signals out to about 5 seconds, but it is still poor at detect= ing=20 20 second signals.

John Lahr and I run modified AS1s which work ou= t to=20 20 seconds naturally. Thie involves changing 4 capacitors and three resistor= s on=20 the AS1 board, maybe $10 maximum

Has anyone noticed that WARD'S is = selling a=20 Seismometer.

http://wardsci.com/product.asp?pn=3DIG0018602&sid=3Dmercent&am= p;mr:referralID=3D5f903f77-d083-11dd-a8aa-000423bb4e95&bhcd2=3D122998= 9485

This link may be more = direct.

In a message dated 23/12/2008, edwianni1@........... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Has anyone noticed that WARD'S is selling a=20 Seismometer.

Check out the school seismometer at http://www.b= gs.ac.uk/schoolseismology/seismometer.html

This one works well.

There is a little bit more information about the = EQ-1 on=20 this website:

http://www.nexgensci.com/store/pc/viewPrd.asp?idca= tegory=3D2&idproduct=3D1#details

If you choose to purchase the EQ-1, the Ward's = website is=20 cheaper. Also, sign up for the Ward's newsletter first. You = will=20 receive a "welcome" email from their newsletter that gives you a 10% = discount on=20 your next purchase from Ward's. This reduces the price further = from $499=20 to $449. A cover is essential, but the one they offer is = $100. You=20 can find cheap glass aquariums at your local pet store for much=20 less.

Their system still uses the older oil damping=20 method. As Chris Chapman and so many others have pointed out, it = is full=20 of problems. Most notably, the damping changes with = temperature. So=20 you would need to change it to magnetic damping. See Chris = Chapman's=20 magnetic damping design at

h= ttp://jclahr.com/science/psn/chapman/as1%20damping/index.html<= /DIV>

or John Lahr's version of Chris's design at =

http://jclahr.com/science/psn/chapman/as1%20damping/lahr/index.html

----- Original Message -----

From:=20 Edward=20 Ianni

Sent: Monday, December 22, 2008 = 4:17=20 PM

Subject: Vertical School = Seismometer |=20 WARD'S Natural Science

This link may be more = direct.

In a message dated 25/12/2008, cjburch@........... writes:

Since the posters were displayed at the meeting= s,=20 the preliminary information is in the public domain. Accessing it may be a=20 different matter. Sean was going to patent the device, but I am uncertain as= to=20 what actually happened, particularly with the long delays in processing= =20 American Patents. I did try to follow up the poster and eventually managed t= o=20 get a reference SSA / AGU number. It is listed as C23 on http://www.seismosoc= ..org/meetings/ssa2001.html

Sean presented a 30 page A4=20 poster with Brian J Mitchell of St Louis University. He is now an Emeri= tus=20 Professor mitchbj@........... in=20= the=20 Department of Earth and Atmospheric Sciences. A 70 page final NSF report was= =20 produced. I suggest that you ask him and the NSF?

It was funded by the NSF in October 1999, so th= ere=20 must be records of this and of the report. The work was completed in October= =20 2000. The NSF grant reference is 9905328. The project funding was for=20 $120,000.

See h= ttp://www.nsf.gov/awardsearch/showAward.do?AwardNumber=3D9905328

After Sean's death the prototype level equipmen= t=20 was sent to the USGS facility at Albuquerque, NM. I did contact Bob Hutt bhutt@........ about it, but he said= that=20 they had broken the suspension and that it was no longer working. Ask h= im=20 about it?

See also http://www.iris.washington.edu/stations/seisWorkshop04/abstra= cts/HuttAbstract.pdf =20 This seems to me to be a very high cost project with limited prospects of=20 success. The longest period was only about 10 seconds. An optimal design for= a=20 long period seismometer is likely to be different to that of a tiltmeter.

You can get a fair indication of the main=20 components from the page headings. I do not know how he designed the suspens= ion,=20 or how he adjusted the C of G. But I could make an educated guess of systems= =20 that you could try out. As far as I am aware, there is no very long period h= igh=20 sensitivity tiltmeter equipment available. One problem with measuring tilts=20= is=20 getting rid of near surface environmental noise at a fixed point /=20 location. Long period noise due to the daily thermal cycle and from surface=20= soil=20 movement are also likely to be observed / cause problems. It is fairly=20 easy in principle to measure tilts over say 1 km of open trough. =20 There is a 43 m H2O tiltmeter in a salt mine at Walferdange in Luxembou= rg.=20 There is no substitute for a nice deep hole! See http://www.geodesy.cwu.edu/index.html?page=3Dhttp%3A//www.geode= sy.cwu.edu/tilt/ =20 However, it may be possible to monitor the position sensor on some long peri= od=20 seismometers.

Basically it was a high inertia horizontal beam= =20 with equal mass at both ends. It was suspended at it's C of G. There were=20 position sensors at both ends and force feedback transducers. A very long=20 integration period was used, but no gravitational feedback. This could be an= =20 advantage, since it will not be sensitive to very long period / permane= nt=20 tilts, only to changes in tilt. I presume that Sean used the same varia= ble=20 reluctance sensors that he used in his seismometer. The measurement limit wi= th=20 an LVDT system is likely to be over 0.1 nm, probably over 1 nm, due to=20 Barkhausen magnetic domain noise.

Regards,

Chris Chapman

Subject: Earthquake trace of a fireball ? From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr@......... Date: Sun, 28 Dec 2008 05:04:52 +0000 Hi all. Here is a news that is worth taking a notice in. Some of those located in California might have recored this fireball on there seismometers without noticeing. CALIFORNIA FIREBALL: A remarkable fireball streaked over southern Califonia on Dec. 27th around 1:50 am Pacific time. "It was as if someone had set off a rescue flare that instantly bathed the countryside in whitish blue-green light," reports Grant Bentley of Bishop, CA. "At one point, the path of the meteor went behind a cirrus-stratus cloud that it backlit in snowy green light. After a brilliant show of less than three seconds, it was gone without a trace. This was easily the most massive object I have ever seen burning up as it entered the Earth's atmosphere." Readers, if you witnessed or photographed this event, please submit a report. http://www.spaceweather.com/ Regards. --=20 J=F3n Fr=EDmann __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Earthquake trace of a fireball ? From: Canie canie@........... Date: Sat, 27 Dec 2008 22:26:20 -0800 That must have been the 4.5 reported, then=20 deleted in Utah this morning.. it's the right time: >=3D=3D PRELIMINARY EARTHQUAKE REPORT =3D=3D > > > >Region: UTAH >Geographic coordinates: 39.853N, 112.514W >Magnitude: 4.5 Mcd >Depth: 7 km >Universal Time (UTC): 27 Dec 2008 09:18:25 >Time near the Epicenter: 27 Dec 2008 02:18:25 >Local standard time in your area: 27 Dec 2008 09:18:25 Canie At 09:04 PM 12/27/2008, you wrote: >Hi all. > >Here is a news that is worth taking a notice in. Some of those located >in California might have recored this fireball on there seismometers >without noticeing. > >CALIFORNIA FIREBALL: A remarkable fireball streaked over southern >Califonia on Dec. 27th around 1:50 am Pacific time. "It was as if >someone had set off a rescue flare that instantly bathed the countryside >in whitish blue-green light," reports Grant Bentley of Bishop, CA. "At >one point, the path of the meteor went behind a cirrus-stratus cloud >that it backlit in snowy green light. After a brilliant show of less >than three seconds, it was gone without a trace. This was easily the >most massive object I have ever seen burning up as it entered the >Earth's atmosphere." Readers, if you witnessed or photographed this >event, please submit a report. > >http://www.spaceweather.com/ > >Regards. >-- >J=F3n Fr=EDmann > >__________________________________________________________ > >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: How much movement From: Steinar Midtskogen steinar@............. Date: Tue, 30 Dec 2008 21:34:41 +0100 I wonder, how big are the movements produced by distant quakes? Since only the waves with very long periods are detectable, the shaking is of course impossible to feel since even movements of several centimeters would be difficult to feel if the period is around 20 seconds. So, if my seismometer picks up a 6.0 quake 15.000 km away, what kind of movement are we talking about? -- Steinar Midtskogen http://voksenlia.net/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: New fireball From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr@......... Date: Tue, 30 Dec 2008 22:38:04 +0000 Hi all. There was a new fireball, this time over New England. It did also explode in the sky. Some of you close to this area might have recored the fireball on the seismemtic sensors. NEW ENGLAND FIREBALL: Last night, Dec. 29th at 9:30 p.m. EST, sky watchers in Maine, New Hampshire, Massachusetts, New York and New Jersey witnessed a magnitude -9 fireball that exploded colorfully in mid-flight. No one knows if fragments of the meteoroid reached the ground. Readers, if you saw or photographed this event, please submit a report. Updated: Eye-witness accounts http://www.spaceweather.com/ http://www.spaceweather.com/glossary/fireballreports_29dec08.htm?PHPSESSID= =3D2vb1qaebkpbg5scj2s6tq23ra4 Regards. --=20 J=F3n Fr=EDmann __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: How much movement From: ChrisAtUpw@....... Date: Tue, 30 Dec 2008 17:53:41 EST In a message dated 30/12/2008 20:35:01 GMT Standard Time, steinar@............. writes: So, if my seismometer picks up a 6.0 quake 15.000 km away, what kind of movement are we talking about? Hi Steinar, Check out the various pages and tables at _http://jclahr.com/science/psn/magnitude.html_ (http://jclahr.com/science/psn/magnitude.html) Regards, Chris Chapman

In a message dated 30/12/2008 20:35:01 GMT Standard Time,=20 steinar@............. writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>So, if=20 my seismometer picks up a 6.0 quake 15.000 km away, what kind
of moveme= nt=20 are we talking about?

Hi Steinar,

Check out the various pages and tables at http://jclahr.com/scie= nce/psn/magnitude.html

Regards,

Chris Chapman

Subject: Re: How much movement From: Angel sismos@.............. Date: Tue, 30 Dec 2008 23:22:08 +0000 Hello Steinar, Your question is central to seismometry and to be able to answer it you need to calibrate your seismometer. Once you do that you can convert volts or counts to real ground motion. The basic idea is simple, you move your sensor a known distance and see what you get in volts or counts at the end of your digitizer. If you do that at a bunch of frequencies you can then figure where you sensor is linear and where it is not. The you can derive the transfer function for your system and then you are set to answer your question. Modern systems can resolve nano meters (billionth of a meter) the diameter of a molecule. here are some values for ground motion in microns (millions of meter) Dist(km) ML=0 ML=3 ML=6 100 0.000428 0.428486 428.4860279 200 0.000144 0.1441606 144.1606322 300 4.27E-05 0.0427143 42.71426138 400 1.8E-05 0.0180201 18.02007902 500 9.23E-06 0.0092263 9.226280458 600 5.34E-06 0.0053393 5.339282672 Happy New Year Angel Tuesday, December 30, 2008, 8:34:41 PM, you wrote: > I wonder, how big are the movements produced by distant quakes? Since > only the waves with very long periods are detectable, the shaking is > of course impossible to feel since even movements of several centimeters > would be difficult to feel if the period is around 20 seconds. > So, if my seismometer picks up a 6.0 quake 15.000 km away, what kind > of movement are we talking about? __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: How much movement From: Bob Hancock carpediem1@......... Date: Tue, 30 Dec 2008 23:12:41 -0700 Steiner - One more comment on the subject of seismic wave amplitudes. The USGS has a program that gives arrival times of both body and surface waves. In the header is information on the expected 20 second period surface wave amplitude, and expected 1 second period body wave amplitude. The data is listed in both velocity and displacement format. Here is the link to the program: http://neic.usgs.gov/neis/travel_times/compute_tt.html The same basic program is available for recent events within the past 14 days. Following is the link to that program: http://neic.usgs.gov/neis/travel_times/artim.html I hope this helps. Bob Hancock On Dec 30, 2008, at 1:34 PM, Steinar Midtskogen wrote: > I wonder, how big are the movements produced by distant quakes? Since > only the waves with very long periods are detectable, the shaking is > of course impossible to feel since even movements of several > centimeters > would be difficult to feel if the period is around 20 seconds. > > So, if my seismometer picks up a 6.0 quake 15.000 km away, what kind > of movement are we talking about? > > > -- > Steinar Midtskogen > http://voksenlia.net/ > __________________________________________________________ > > 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: How much movement From: Steinar Midtskogen steinar@............. Date: Wed, 31 Dec 2008 14:15:45 +0100 [ChrisAtUpw@........ > Check out the various pages and tables at http://jclahr.com/science/psn/ > magnitude.html Thanks for the link. It means that roughly 1 micron amplitude is needed for my SEP seismometer to produce a clear signal. If I had a better less noisy site for it, I guess I could make out movements of a few 100 nanometers. To detect a movement of 1 micron over 10 seconds sounds pretty impressive. I'm a bit surprised that this is even possible in a noisy city. In fact, the greatest noise problem is the ocean, which sometimes masks out quakes expected to produce 10 micron movements even if the storm is 500 km away. -- Steinar Midtskogen http://voksenlia.net/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L)