Date: Tue, 1 Oct 1996 08:33:22 -0500 From: Les Subject: Radio Shack Voltmeter? Still working on setting up a seismograph here in bedrock, Alabama...It looks like I may purchase a system or parts of one from Larry Cochran. Thanks to all who've responded with advice. Next question...Has anyone ever used the Radio Shack logging DVM for seismograph applications? It seems to just be a basic AD converter with some software included. It retails for around $120 but I've seen it on sale here for less than $100. Les Rayburn, KT4OZ Les Rayburn http://www.phpad.com/whitley New Machine: The Chris Whitley Website +++++++++++++++++++++++++++++++++++++++++++++++++++ Home: (205) 980-8332 Work: (205) 324-3900 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) Date: Tue, 01 Oct 1996 10:21:16 -0500 From: ct@....... (Charlie Thompson) Subject: Re: Radio Shack Voltmeter? Les, One reason not to consider the Radio Shack approach is the lack of time/date stamp on the recorded data. If you don't have time info you don't have a way to correlate your events with the rest of the world. My recommendation is to go with something that allows you to share data files with everyone else. SDR and WinQuake are hard to beat! Regards, Charlie WB4HVD _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: cochrane@.............. Subject: Vancover Island Region Ms 6.3 event and uploading event files Date: Mon, 07 Oct 1996 14:23:22 -0700 Hi There, The Vancover Island Region had a Ms 6.3 yesterday (10/06). Both my SG sensor and Lehman sensor recorded nice seismograms of the event. I updated the following web page at http://psn.quake.net/teleseis.html with links to my event files. If anyone recorded the event this would be a good time to try a new email feature I added to my system. You can now upload/send PSN formatted event files using email. If you attach a PSN formatted event file in a email message to event@............. your event file will automatically be archived on my system. The event file must be encoded using MIME. This is the most efficient way of sending binary files using email. If you have a popular email program that does not have the ability to send attachments in MIME format let me know and I can try and add other formats like uuencode or BinHex. Too upload one or more event files all you need to do is attach the file(s) and send it to event@.............. The subject line and the body of the message are currently not used so can be left blank. When my system receives the email message it will decode the message and archive your event file(s). My system will then send back a email message acknowledging your upload. All event files uploaded using this method will have the name of the file normalized by using the date in the header and placed in the appropriate sub-directory. The directory location is based on the year and month (/quakes/YYMM/). The file name will have the following format: YYMMDDx.SID where YY=year MM=month DD=day and x is the letter A-Z. The first file uploaded for a given day will start with YYMMDDA.SID the next file would be YYMMDDB.SID etc. The .SID is the station ID. By sending your event files using this method your event file will show up on both the finger quake@............. list and the "New Earthquake Event Files" (http://psn.quake.net/cgi-dos/event.exe) on my PSN Web site. In the future I hope to add the ability for my system to send back MIME encoded event files (and other program files) by placing a get or send command and a list of files in the body of a email message. I could also setup another mailing list, say newevents@.............. that could be used to automatically inform the members that a new event file(s) has been uploaded. Let me know if you have any problems using the event@ mailbox. Regards, Larry Cochrane Redwood City PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: My quake files Date: Wed, 09 Oct 1996 13:19:11 -0600 Robert L Barns wrote: > The remnents of a tropical storm passed by here yesterday and dumped 2" of > rain. My seismic noise level went up by a factor of 6 or so. It is down > somewhat today. I suspect that all this noise was due to wave action on the > shore since I'm only 30 miles from the Atlantic. What do you think? The last > big rain we had was also accompanied by a noise level increase and I thought it > might be due to the ground getting wet. Skolnic sez that his noise changes from > fall to winter and then back again from winter to spring. The noise in the period range 5-10 seconds are called microseisms and are principally caused by ocean waves hitting the continental shelf. When I was a gradute student at Lamont-Doherty Geological Observatory of Columbia University near New York, we would see the microseism level on our seismographs increase in the winter, particularly when there were storms off the Atlantic coast. Several papers have been written on the subject with respect to locating the "source region" and using the noise as a means of comparing the site response of adjacent sites. Pretty sharp of you all to come to similar conclusions yourselves. -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie Thompson) Subject: Re: My quake files Date: Wed, 09 Oct 1996 14:46:17 -0500 As luck would have it...my computer was DEAD for the 6.3Ms Vancouver event. Got it fixed last night and (as luck would have it again!) I captured the smaller Vancouver 5.3Mb event of 10/9/96 at 7:12:28 UTC. My seismic noise level is high for some reason as well (re: Robert Barns comment) so you can't make out the P and S of this smaller event. As usual I cheated, used my GPS to calculate the distance from Buda, and set the P and S spacing so the distance was correct and then moved them as a pair until the origin time was correct. I then turned on the PHASES mode to see if the easily visible L wave was in the correct place. I'll try out the new event@ mailing address and upload this smaller Vancouver event. -Charlie Thompson Buda, Texas ct@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: My quake files Date: Wed, 09 Oct 1996 18:20:13 -0700 Hi, Unfortunately this won't work. You must use a email program that can do the encoding and make the proper message needed for attachments to work. Just sending a text file with the encoded message will not work. If you are running Windows I would recommend using Eudora Light or Pro. The Light version is free and is one of the most used email programs. The Pro version costs around $60.00 and has a few other features like a built in spell checker (something I dearly need). You can down load the free version from any Windows software archive. Eudora is very easy to setup and use. To send an attachment all you need to do is select Attach File and then click on the file to send. Now when you click on Send your file will be encoded and formatted so any email program (with the ability to handle attachments) can read and un-attach you binary file. Regards, Larry Cochrane Redwood City, Cal PSN At 02:36 PM 10/9/96 EDT, Robert wrote: >Larry, > I will try to send 2 of my quake files which are MIME encoded. I encoded >them with ENCODE64.EXE. and they will be sent to event@............. per your >instructions. > This prog. and its mate DECODE64.EXE were obtained from BASE64.ZIP at > http://sunsite.doc.ic.ac.uk/public/pub/packages/simtel-msd > Both run under DOS and seem very easy to use. This URL included to help others with MIME. > My file 1006.rlb was for the Vancouver quake. .... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie & Terri Thompson -- Buda MicroRanch ) Subject: Question about Pendulum Modelling Date: Tue, 15 Oct 1996 08:44:00 -0500 I've been reading the Shackelford-Gunderson material thats available on the PSN page and had a few questions about what's going on with this type of sensor and particularly the electonics associated with the S-G sensor. Firstly, Am I correct in assuming that a pendulum has two modes of sensitivy? 1. Above the natural frequency: it acts like a displacement sensor 2. Below the natural frequency: it acts like an accelerometer. If this assumption is true then the roll-off in frequency response below the natural frequency must be 2nd order or 40 dB per decade or 12 dB per octave (if you prefer octaves). I am getting the 2nd order notion from the fact that the pendulum can be equivocated to a spring-mass oscillator which is a 2nd order system. Also note that the difference in displacement and acceleration is a "double derivative". Seems like we might be able to characterize the pendulum's response and "build a better equalizer" in the DSP domain giving a flat displacement response from say 60 seconds to 20 Hz. What puzzled me about the SG article was that the integrator used to boost the low end is only 1st order yet I think the rolloff in pendulum response is most likely 2nd order. Hence we can do better! Any comments, corrections, appreciated. Regards, Charlie Thompson Buda Seismic Station ct@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Larry P. Thomas WAOGWA" Subject: Re: Question about Pendulum Modelling Date: Wed, 16 Oct 1996 07:25:57 -0500 I'm confused! I was just about to make up my mind which type of seismometer to build and then got confused. Maybe some could help unconfuse me so i can go on and build my sensor. I had initially convinced myself to that I should build a Shackleford-Gundersen design because I want mostly teleseismic activity monitoring and thought it would be the best because of it's long period. I dug out an old physics book (two kids, four grand kids ago!) and looked up pendulums and of course saw that the period is related to pendulum length and gravitational force. The restoring force gravity acting on the mass, etc. etc. This got to thinking that the Lehman design should have a longer time period than the Shackleford-Gundersen design because the Lehman design has an effective pendulum length that is very long. I'm looking at the arc that the mass swings through as an indicator of effective pendulum length. My first thought was to pick the mechanical system that was the best and then use the sensor/detector electronics that I thought was best. I'm wondering now if the Lehman mechanical design with the Shackleford-Gundersen RF detector scheme as the business end would not be the best. It seems that the signals from the magnet/coil detector configuration are just too low an into the noise floor for teleseismic. From an electronic standpoint I kind of like the RF detector scheme used in the Shackleford-Gundersen design and no reason it would not work well with the Lehman mechanical structure. If anyone has time to respond I gladly share the results of any work I do on a sensor using part of both designs. Thanks Larry --------------------------------------------------------------------------- Larry P. Thomas wa0gwa voice : 1 913 888-0282 Krell Technologies fax : 1 913 782-9359 8960 Bond pager : 1 816 989-HELP Overland Park, KS 66214-1764 e-mail : lpthomas@................ --------------------------------------------------------------------------- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie & Terri Thompson -- Buda MicroRanch ) Subject: Re: Question about Pendulum Modelling Date: Wed, 16 Oct 1996 08:31:32 -0500 >I'm confused! I was just about to make up my mind which type of seismometer >to build and then got confused. Maybe some could help unconfuse me so i can >go on and build my sensor. (other text deleted) Larry, You are exactly right about the pendulum periods. I like your idea about the RF detector on the Lehman pendulum! I've built a Lehman and have the period set at about 10-14 seconds. It's very easy to build a Lehman and common sense changes to the original design work fine. You can look at my sensor at: http://www.onr.com/user/ct/ct.html I have a couple of photos on the above URL. Also at the bottom of photo #1 is a seismogram the sensor recorded of a teleseismic event in the Easter Islands. Another important difference between the coil/magnet and the RF pickup response is the "1st derivative". That is, the voltage in the coil is proportional to the RATE OF CHANGE of POSITION (pendulum velocity) or what we call dPhi/dT in EE terms. There's only one sticky part...you must power the RF oscillator by connecting very fine wires which will flex with the Lehman pivots. I propose getting around this problem by the following diagram. (Note: use a fixed-pitch font to correctly view the following diagram:) __________ | | <----- pair of plates on pendulum shorted at top | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | <---- Staionary sense plates A and B | | | | A | | B C D <------ Stationary driven plates C and D The scheme allows both the driven and sensed plates to be stationary. As the pendulum moves you couple, for example, from driven plate C to the moving pair which are electrically shorted and then to sense plate A or B. The sense plates can still be double sided PC board with the outside layer gounded to help form the resonating cap in parallel with the inductor. Any comments, suggestions, concerns? regards, Charlie Thompson ct@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: Question about Pendulum Modelling Date: Wed, 16 Oct 1996 11:50:42 -0700 Greetings -- Yes, I believe you are right that the pendulum system is second order. I worked out some equations and you're right -- it boils down to a second-order differential equation. Since my differential-equation solving abilities leave a lot to be desired, I modeled it using a spreadsheet with a delta-time for each step that is small compared to the resonance period of the pendulum or the period of earthquakes. It did show second-order response with respect to earthquake waveform period. Jim Hannon wrote -- >I have a good model for >the pendulum, sensor and of course the support electronics but I am stumped >on how to represent the feedback from the coil/magnet to the pendulum. >I can't seem to come up with a circuit that would act like the real system. >Anybody have any ideas? If I can get the Spice model working the response, >damping and stability can be studied. The force from an electromagnet is more or less proportional to the current through it. I'm no magnetics expert, but I think the linearity of the B-H curve (and eventual saturation) of any core you might be using for the coil will be a factor too. I believe this is why most magnets like this (ie. speaker coils) are air-core devices. I don't have any good ideas on how to do a Spice model for the non-linear behavior of any core you might be using. I think that your Spice model should also include the dc resistance as well as the inductance of the electromagnet coil. I think if you intruduce a small-value shunt resistor in your model in series with the coil to sense current, then amplify the voltage across the resistor by a factor related to the geometry of the coil and the strength of the permanent magnet (use the calibration device described by Robert L. Barns earlier on this list to measure the current-to-force relationship), you'll have a parameter (voltage or current) in the Spice model proportional to the force on your mass. Since F = Ma, and displacement is the double integral of acceleration, you can run this voltage (or current) through two electronic integrators (Spice models) in series, and then feed it as a current to your mass capacitor (I'm assuming you're modeling the mass as a capacitor). Since in a capacitor, i = C * dv/dt, your capacitor's dv/dt will be equivalent to dx/dt (velocity) for a real mass, and the voltage on the capacitor will be equivalent to displacement of a real mass. I've done some computer modeling (not using Spice) of the force-balance system I'm working on and it seemed to work quite well after I adjusted the roll-offs of the various stages. I've yet to try the real thing, though. I hope this helps. Please ask more questions if I can help more. -- Karl Cunningham karlc@......... La Mesa, CA. 116.9775W 32.7705N +308M interested in almost anything to do with science _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie Thompson) Subject: Guatemala Quake detected Date: Wed, 16 Oct 1996 17:04:00 -0500 Looks like I recorded a somewhat noisy but discernable waveform from the Guatemala Coast 4.9 that occurred at 8:42 UTC 10/16/96. I need to check the distance estimate to make sure I have the P/S marked correctly and I'll upload it. Did anyone else record this quake? I know it's not big one but Texas is not too far from Central America. Charlie ct@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Warner Lindholm Subject: Re: Question about Pendulum Modelling Date: Thu, 17 Oct 1996 07:08:09 -0700 (PDT) On Wed, 16 Oct 1996, Jim Hannon wrote: [ ..... ] > As for the rolloff compensation of the Shackleford-Gundersen design I think > there is another rolloff here that needs to be considered. It runs in the > other direction so it might cancel out with the instrument. That is I think > the seismic waves themselves have higher displacments at the lower ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > frequencies. This may cancel with the remaining rolloff of the sensor. ^^^^^^^^^^^^ This has been my observation using the fft feature of Larry Cochrane's Winquake on records obtained with a sensor sensitive to displacements ( and tilt). I think seismic noise might be 1/f just as many other natural processes are. -Warner > (Someone correct me if I am wrong.) > > Jim Hannon > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: Question about Pendulum Modelling Date: Thu, 17 Oct 1996 12:09:43 -0600 Warner Lindholm wrote: > > On Wed, 16 Oct 1996, Jim Hannon wrote: > > [ ..... ] > > > As for the rolloff compensation of the Shackleford-Gundersen design I think > > there is another rolloff here that needs to be considered. It runs in the > > other direction so it might cancel out with the instrument. That is I think > > the seismic waves themselves have higher displacments at the lower > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > frequencies. This may cancel with the remaining rolloff of the sensor. > ^^^^^^^^^^^^ > This has been my observation using the fft feature of Larry Cochrane's > Winquake on records obtained with a sensor sensitive to displacements > ( and tilt). I think seismic noise might be 1/f just as many other natural > processes are. > -Warner > > > (Someone correct me if I am wrong.) > > > > Jim Hannon > > > > Subject: Re: My quake files Date: Wed, 09 Oct 1996 13:19:11 -0600 From: Edward Cranswick Organization: US Geological Survey To: PSN-L Mailing List References: 1 >Robert L Barns wrote: >> The remnents of a tropical storm passed by here yesterday and dumped 2" of >> rain. My seismic noise level went up by a factor of 6 or so. It is down >> somewhat today. I suspect that all this noise was due to wave action on the >> shore since I'm only 30 miles from the Atlantic. What do you think? The last >> big rain we had was also accompanied by a noise level increase and I thought it >> might be due to the ground getting wet. Skolnic sez that his noise changes from >> fall to winter and then back again from winter to spring. >The noise in the period range 5-10 seconds are called microseisms and >are principally caused by ocean waves hitting the continental shelf. >When I was a gradute student at Lamont-Doherty Geological Observatory of >Columbia University near New York, we would see the microseism level on >our seismographs increase in the winter, particularly when there were >storms off the Atlantic coast. Several papers have been written on the >subject with respect to locating the "source region" and using the noise >as a means of comparing the site response of adjacent sites. >Pretty sharp of you all to come to similar conclusions yourselves. The microseismic noise exhibits a fairly sharp peak at about 7 s period (0.14 Hz), and at higher frequencies, it does have approximately a 1/f decay. -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: JAMES CRISTIANO Subject: QuakeAlert Date: Tue, 22 Oct 1996 14:57:52 -0700 Anyone hear about a new device called "QuakeAlert"? It's made by a place called Tectonics Reaserch Group, Inc. up in Canada. Haven't received my sample and info pack yet. I got a fax with some info on it. The maker claims that it senses only seismic generated "P" waves and turns on a loud alarm to provide early warning of an earthquake. If anyone knows anything about it please r.s.v.p. Thanks, James Cristiano P.S. Sorry bout that Larry, I'm new a this and I didn't mean to YELL. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@................. (Dr. John Lahr (USGS-GI Seismologist)) Subject: Re: QuakeAlert Date: Tue, 22 Oct 1996 14:07:40 -0800 ... "QuakeAlert"? The maker claims that it senses only seismic generated "P" waves.... ***************************************************************** That's the problem. There is no way that this device can distinguish P-waves from any other source of vibration! I saw something like this a few years ago and it was a novelty item, not a useful warning system. JCLahr ################################# John C. Lahr ################################ U.S. Geological Survey ############################### c/o Geophysical Institute ############################## 903 Koyukuk Drive From: ct@....... (Charlie Thompson) Subject: Effects of temperature on Lehman Sensor Date: Wed, 23 Oct 1996 13:10:28 -0500 Well believe it or not it has actually cooled off here in Texas. My Lehman sensor in the last few days has shown very high 1/f noise levels. I believe this to be associated with the fact that my PSN preamp is in the same insulated box with the Lehman sensor. Here's the theory as to why the noise level went up when the temperature went down: The preamp dissipates power. Normally it's pretty hot in the garage due to the Texas summer temperatures. Now that it's 50 degrees F in the garage the thermal currents from the "warm" preamp are making thermal air currents inside the sensor box. The air currents as we all know are bad news for noise levels as the currents push the Lehman boom around. Tonight I will remove the preamp from inside the Lehman housing and house it separately. Hopefully the air current noise will go down. My question to PSN readers is: Has anyone else experienced such conditions with fall approaching? thanks in advance, Charlie Thompson ct@....... Buda, Texas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lyzenga@................. (Greg Lyzenga) Subject: Re: Effects of temperature on Lehman Sensor Date: Wed, 23 Oct 1996 12:04:52 -0700 >My Lehman sensor in the last few days has shown very high 1/f noise >levels. I believe this to be associated with the fact that my >PSN preamp is in the same insulated box with the Lehman sensor. > >Here's the theory as to why the noise level went up when the temperature >went down: .. .. (stuff deleted...) .. >My question to PSN readers is: > >Has anyone else experienced such conditions with fall approaching? > Hi Charlie: I've been operating my Lehman now for about 6 years, and I continue to be totally BAFFLED by this problem. I have tried every possible permutation of preamp near the sensor vs. preamp near computer, etc. and I've never been able to make it go away. I hope you are more successful and can enlighten us! At the risk of boring you with a long narrative, I'll try to summarize my experience with this problem. For me (in southern California) the effect is definitely temperature related, but it is a time-of-day thing, rather than seasonal. Basically, my noise level is dramatically increased between the nighttime hours of about 10 pm and 10 am local each day. It always happens, although it tends to be worse during generally cold/wet weather and less severe when the weather is warm at night. One by one I have *tried* to eliminate all the possibilities for causes. I eliminated all sources of air currents in the sensor box - no joy. I tried putting the preamp close to the sensor and sending the amplified signal via 100 ft of wire to the house. I tried the reverse, sending the raw low-level signal via the long wires and amplifying in the house. These two seemed to give the same results. For a while, I felt that it was actual motion of the concrete floor in my garage, caused by thermal expansion and contraction, but lately I'm skeptical of that idea. Most recently, I have wondered if it is possible that some kind of temperature-dependent feedback could be driving an amplified noise current back through the pickup coil, causing the boom/magnet to move in response. I haven't really figured out how to test this hypothesis, except that I do not see any noise if the boom is physically restrained from moving. This may or may not support the theory. But I'm also skeptical about this because I don't really see much difference if the circuit is indoors or out in the unheated garage. (By the way, I should mention that my circuit is a homegrown beast, not the PSN design, so your mileage may vary!) I know it is *not* microseisms, because I pick those up routinely, and know that they are completely different from this. So after (apparently) eliminating all sources of mechanical, electronic, environmental and thermal disturbance, I'm about to go crazy trying to track it down! I would dearly love to figure it out, because if fixed, it would effectively double the amount of useful data I can record! You can imagine how frustrating it is to have a good teleseism come in during the night, only to find it drowned out by the nightly 10x increase in background noise. Although I don't have any solution at this point, I hope my experience might spark someone's imagination or insight into the phenomenon. - Greg |Gregory A. Lyzenga *** (909) 621-8378 |Dept. of Physics, Harvey Mudd College *** fax (909) 621-8887 |Claremont, CA 91711-5990 |http://www.physics.hmc.edu/profs/lyzenga.html _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie & Terri Thompson -- Buda MicroRanch ) Subject: Temperature Sensitivity of Lehman sensor Date: Wed, 23 Oct 1996 23:26:05 -0500 Tonight I tried placing a 40 watt appliance light bulb in the box covering my Lehman sensor. I then monitored the noise level over the period of one hour. The noise was really reduced at one point and then went back up somewhat. This proved a definite relationship between interior box temperature and outside air temp. Larry's idea of "stuffing" the enclosure may be one way of reducing this "cold weather" problem. I also belive that air density at low temperatures, coupled with convection turbulence, is the cause of this noise problem. more later as I have time to experiment during the cool evening hours.... -Charlie Thompson ct@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: JAMES CRISTIANO Subject: HALL EFFECT Date: Thu, 24 Oct 1996 12:30:09 -0700 Sometime back someone suggested trying a hall effect sensor as the signal sensor for a seismic sensor. Having toyed around with the idea before and having samples, I got out the samples and data book. The samples are Allegro UGN3503U linear hall effect sensors. Specs are for a +6v regulated supply. Noise: 90uV Sensitivity: 1.72mV/gauss Using a push-push head-on magnet configuration with two Alinco 8, .212 Dia. x .187 magnets with .210 spacing produces a linear 8.44G change per .001" displacement. BOOM W/ MAGNETS <--------------------> N----S 1 S-----N 1 ___1___ sensor on base Since the sensitivity of the sensor is 1.72mV per Gauss and with the above setup the Gauss change per .001" is 8.44 then the output should be .014V per .001" displacement. Switching to metric I get .56V/mm. This signal is absolute displacement and not frequency sensitive. The problem I have with the coil/magnet setup is that the current induced in the coil by the magnet drops with decreasing frequency. With this method, the signal would be a copy of earth movement/displacement. The magnets could be mounted on the end of the boom and the sensor mounted on the base. Does this sound like it would be worth trying? Any ideas? James Cristiano weitech@.......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: JAMES CRISTIANO Subject: Re: HALL EFFECT Date: Thu, 24 Oct 1996 14:18:29 -0700 RDJM@....... wrote: > > Jim, > > How much are the Hall effect sensors? Did you get free samples either through > yourself or your company? I have wondered how these would work. Thanks for > the info. > > Ron Moeller rdjm@....... Ron, I got the hall effect sensors as samples directly from Allegro. You can call them @(508)853-5000 and ask for a sample or two. It helps if you have a co. name to throw in. I called a distributor and the price was $1.42 (not bad). They include the data sheet also. The gal at Allegro said they have a new line ( 3506) that has higher sensitivity. I have a couple of those coming. Good Luck, Jim Cristiano _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Info: 1891 Nobi (Mino-Owari), Japan, earthquake Date: Thu, 24 Oct 1996 15:29:48 -0700 I am looking for information regarding of the 1891 Nobi (Mino-Owari), Japan, earthquake. Can some one refer me to some articles? --- Charles P. Watson, Consulting Geologist Advanced Geologic Exploration Seismo-Watch / Earthquake Information Services Voice: 702-852-0992 / Fax: 702-852-3226 watson@................ http://www.seismo-watch.com _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ACole65464@....... Subject: Thermal Effects on the Long Period Lehman Date: Thu, 24 Oct 1996 21:53:35 -0400 To Charlie and others effected by this problem, I had experienced problems with thermal noise on my long period horizontal instrument several years ago and it took me a long time to figure out if that was really the problem. To be certain that the instrument was being influenced by the air I disconnected the seismometer from the preamp. I shorted a 5K resistor to the first op-amp's input and to ground, then recorded the output signal during the usually bad times. The op-amps were OK in the preamp so the problem was with the seismometer. I already had a dust/draft cover over the instrument but it was not apparently adequate. The fix was a styrofoam box, 1" thick, use a drink cooler if you can find one large enough to go over everything. Certainly remove the electronics from the same enclosed space with the seismometer. Use a white glue like Elmers to glue the custom box together. Fill any gaps in the corners with fiberglas insulation then put duct tape over the gaps to prevent drafts from entering inside the box. Place this 5 sided box upside down over the instrument and then use duct tape to to seal off any small cracks between the cover and the concrete slab that the instrument is resting on. Thermal effects can contort the structure (building) attached to the concrete slab. I have read that people have sometimes placed a small electric lamp inside the styro box at the very top to ensure a more stable temperature. The thermal engine runs on warm air rising, coming into contact with a cooler surface then sinking again to the bottom. What is needed for our box are stratified layers of trapped air. If the exposed concrete slab is fairly temperature stable then the box temp will stabilize at that. Stryofoam is a great insulator. Buildings create a lot of thermal noise so it may be necessary to move the instrument tempoarily to another spot to see if that is the case. I hope this is usefull information, it helped me, and if this or something else worked better for you, then please tell us what the cure was. Allan Coleman _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: tblank@.......... (Ted Blank) Subject: Stratifying air in the enclosure Date: Thu, 24 Oct 1996 21:16:19 -0700 One of the professional sensors I inherited has a heater in the top of the enclosure to induce a stable gradient of temperature with hottest at the top and coolest at the bottom. If you are putting a light bulb inside the case/cover, I'd try putting it at the top. Even better would probably be a low wattage "flat" heat unit. Careful though, styrofoam is highly flammable. I wouldn't put a light bulb anywhere near sytyrofoam. (I really can spell...but this emulator doesn't have a ac...backspace key!) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L)) From: Al Allworth Subject: Re: Thermal Effects on the Long Period Lehman Date: Thu, 24 Oct 1996 22:59:13 -0700 At 09:53 PM 10/24/96 -0400, you wrote: >To Charlie and others effected by this problem, About the Lehman noise problem: I think I came on the list in the middle of this one, but have a few comments and questions. Are the coils provided with a Faraday shield to stop them from picking up external electric fields? If signals are picked up above the cutoff frequency of the filters, strange things can happen in the input stage. It is also possible for the input stage to go into oscillation with a large inductance (The coil) on its input. This might be controlled by the resistance of the coil which will be a function of temperature. What is the frequency of the noise? This is an interesting problem but not directly to my system. I am using Mark Products model L4 vertical seismometer. About the Hall effect pickup: This still doesn't measure displacement. It changes the time constant to that of the pendulum instead of that of the coil and input impedance. It does come closer to measuring displacement, though. Just a technicality. I think there are several advantages to Hall effect, one being its lower impedance. One possible negative effect might be any influence changes in earth's field during an EQ. I know people are measuring fluctuations in earth field and are trying to eliminate effects of movement in their systems. Here we are talking about the reverse effect. Interesting list. Al Allworth, Pasadena CA aallworth@........ ____________________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Al Allworth Subject: Re: Thermal Effects on the Long Period Lehman Date: Thu, 24 Oct 1996 23:00:16 -0700 At 09:53 PM 10/24/96 -0400, you wrote: >To Charlie and others effected by this problem, About the Lehman noise problem: I think I came on the list in the middle of this one, but have a few comments and questions. Are the coils provided with a Faraday shield to stop them from picking up external electric fields? If signals are picked up above the cutoff frequency of the filters, strange things can happen in the input stage. It is also possible for the input stage to go into oscillation with a large inductance (The coil) on its input. This might be controlled by the resistance of the coil which will be a function of temperature. What is the frequency of the noise? This is an interesting problem but not directly to my system. I am using Mark Products model L4 vertical seismometer. About the Hall effect pickup: This still doesn't measure displacement. It changes the time constant to that of the pendulum instead of that of the coil and input impedance. It does come closer to measuring displacement, though. Just a technicality. I think there are several advantages to Hall effect, one being its lower impedance. One possible negative effect might be any influence changes in earth's field during an EQ. I know people are measuring fluctuations in earth field and are trying to eliminate effects of movement in their systems. Here we are talking about the reverse effect. Interesting list. Al Allworth, Pasadena CA aallworth@........ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie Thompson) Subject: Re: Stratifying air in the enclosure Date: Fri, 25 Oct 1996 09:56:57 -0500 I had a new clue on the Lehman thermal noise problem last night. I took the lid off the sensor housing for a few minutes and replaced it. I then covered the housing with plastic "moisture barrier" like the material used to seal out moisture in concrete slabs before pouring. I started SDR and the noise level was VERY LOW! I was pleased that I had solved the problem.....then....about an hour later the noise had slowly crept back up again to the same obnoxious levels. Here's what I believed happened: Opening the lid caused the air in the box to equalize in temperature with the outside surrounding air. After the lid was replaced the slab started heating the air at the bottom of the box...as more and more air in the box became heated the thermal covection currents started circulating again. My lid is NOT perfectly sealed. There may have been some heated air exchanging with cooler outside air via the cracks where the lid sits on the top of the housing. I will test this hypothesis again. If I can repeat the experiment we'll at least have a handle on the problem. My guess is that insulating the BOTTOM of the box from the heat-producing slab will help as well as hermetically sealing the lid in place. If that doesn't work I'll try the light bulb at the TOP this time. -Charlie ct@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: JAMES CRISTIANO Subject: Re: HALL EFFECT Date: Fri, 25 Oct 1996 11:47:53 -0700 Al Allworth wrote: > > About the Hall effect pickup: This still doesn't measure displacement. It > changes the time constant to that of the pendulum instead of that of the > coil and input impedance. It does come closer to measuring displacement, > though. Just a technicality. I think there are several advantages to Hall > effect, one being its lower impedance. One possible negative effect might be > any influence changes in earth's field during an EQ. I know people are > measuring fluctuations in earth field and are trying to eliminate effects of > movement in their systems. Here we are talking about the reverse effect. > > Al Allworth. Pasadena,CA aallworth@........ Al, I'm talking about a Lehman type, horizontal swinging mass without dampening and a microscopic return to zero. Correct me if I'm wrong, but isn't the idea of suspending an inertial mass on a hinge to decouple it from the earth and to provide a zero point from where measurements of earth movements are taken? The inertial mass of the weight stays in one place as the earth move back and forth. If a movement of 1mm/sec came through, the generated signal would be an offset displacement signal in real time with the initial offset indicating which side of the boom ( perpendicular to the boom) the first push came from. Wouldn't the earths magnetic field influence a coil/magnet assembly type sensor? You mentioned shielding in the coil/magnet type, This could work for a Hall sensor also. Other question: Why isn't the coil/magnet assembly on a Lehman mounted on the end of the boom where most of the offset/movement takes place? Jim Cristiano weitech@.......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: mgray1@................ (Mike Gray) Subject: Re: Stratifying air in the enclosure Date: Fri, 25 Oct 1996 18:34:01 -0500 Bear with me as to a different take on this issue. Concrete and other dense materials, including rock, of course, have what is called thermal lag. This allows a basement to stay at relatively the same temperature year round. In the summer the ground is soaking up heat. In the winter it releases it to the basement via the basement walls. In the fall and spring, with what is often wide temperature variations over the course of a day (even hours), the lag can go in both directions until there is a constant trend one way or the other. In a confined environment such as the seismic sensors', a fluctuating lag results in changes sufficient to cause disturbances in baseline noise levels, etc. You don't notice a constant trend so much because it occurs over a much longer period and is slower to change on top of that. Add to this the direct effect of the sun's heat, especially on what is a normally shaded (in the summer) or non-shaded (in the winter) sensor due to the sun angle, and you have even more fluctuation. Mike Gray MO Bureau of Emergency Medical Services (Dept of Health) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie & Terri Thompson -- Buda MicroRanch ) Subject: Closing in on the thermal noise problem Date: Fri, 25 Oct 1996 20:50:48 -0500 Mike Gray writes: >Bear with me as to a different take on this issue. Concrete and other dense >materials, including rock, of course, have what is called thermal lag. This >allows a basement to stay at relatively the same temperature year round. In >the summer the ground is soaking up heat. In the winter it releases it to >the basement via the basement walls. > I think Mike is correct. The change can be ABRUPT from one day to the next. As soon as the AIR TEMP falls below the CONCRETE TEMP convection currents will cause the warm air at the bottom of the box to move upwards...then cool off and drift downwards...a constant perpetual motion machine. The fix is simple. Make sure the slab-warmed air is always the COOLEST air in the box by putting a heater at the top. Heavy air on bottom (cool) and lighter warm air always on top will allow stratification occur stopping the convection cycle. Tonight the Texas air has become warmer than the slab and the sensor is again quiet. I'm going to set up my indoor/outdoor thermometer such that the outdoor sensor probe is taped to the concrete slab. I can then switch the electronic thermometer between outdoors (slab temp) and indoors (air temp). [Radio Shack has a nifty LCD readout indoor/outdoor thermometer on sale for $9.95.] A noisy Lehaman sensor should correlate to a slab temp GREATER than the air temp thus causing upward convection currents. Now I have to wait for the next cold front to test this theory! -Charlie ct@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Al Allworth Subject: Re: HALL EFFECT Date: Fri, 25 Oct 1996 20:02:24 -0700 > Al, > I'm talking about a Lehman type, horizontal swinging mass without > dampening and a microscopic return to zero. Correct me if I'm wrong, > but isn't the idea of suspending an inertial mass on a hinge to > decouple it from the earth and to provide a zero point from where > measurements of earth movements are taken? The inertial mass of the > weight stays in one place as the earth move back and forth. If a > movement of 1mm/sec came through, the generated signal would be > an offset displacement signal in real time with the initial offset > indicating which side of the boom ( perpendicular to the boom) > the first push came from. You have described exactly what is happening and how we use the instruments. In reality, though, we are measuring acceleration. In other words, even though the weighted horizontal pendulum stands still and the mounting post moves, it is the rate of movement that produces the signal. A short sharp displacement will produce a greater signal amplitude than a slow displacement of greater distance. This is the same principle that causes a bicycle generator to produce a greater voltage if you pedal faster. A true displacement transducer will produce a continuous signal showing its position. If it is a voltage output device there will be a continuous voltage output when displaced. With the horizontal pendulum if you displace the base quickly 1/2 inch the weight will eventually move over 1/2 inch as well and in the process will generate a voltage oposite but much less than what it generated when moved quickly. It will also probably overshoot and settle out in an oscillatory pattern. If the pendulum is critically damped the overshoot will be minimal but damping slows the initial swing and lowers the output. If displacement indication is needed it can calculated from the acceleration data but I don't remember the equation at the moment. The process is integration. I hope this helps understanding what I was getting at. > Wouldn't the earths magnetic field influence a coil/magnet assembly > type sensor? You mentioned shielding in the coil/magnet type, This > could work for a Hall sensor also. The type of shielding needed on the Lehman coil is electrostatic, and can be accomplished with aluminum foil. The foil must not form a shorted turn around the coil or the output will be effectively shorted out even though the foil is insulated from the wire. The foil must be wrapped through the coil just as you would tape the coil to keep all the wires in place. When you get completely around and are about to wrap the foil strip over the place where you started insulate the part where you started and then complete the shield by continueing to wrap over the foil covered by insulating tape, not allowing the finishing layer to touch the beginning layer. The foil should be connected to the shield if you are using coax cable. I use shielded twisted pair and connect the foil to the shield and the coil to the twisted pair. The shield for a Hall device must be of magnetic material such as Mumetal or some of the more recent exotic alloys. Hall devices should not need electrostatic shields as described above. > Other question: Why isn't the coil/magnet assembly on a Lehman > mounted on the end of the boom where most of the offset/movement > takes place? There are many variations of the horizontal (nearly, would not have a recentering action if not tilted slightly) pendulum. Mechanical construction and designers choices often play as large a part as the physics of the device. If you built it that way it would probably work as well but it probably should not be called a Lehman. > Jim Cristiano weitech@.......... *************************** Al Allworth, Pasadena, CA aallworth@........ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lyzenga@................. (Greg Lyzenga) Subject: Re: Macintosh software Date: Mon, 28 Oct 1996 14:26:50 -0700 >Does anyone know about Macintosh software that would work? I could, I >suppose get another computer, but I'd rather not. Todd: I have a Macintosh-based Lehman seismometer system. It's all home-grown, and as yet I have not got around to writing the software necessary to make it "Winquake-compatible". However it's just a matter of my devoting the time to the task, so if I get some encouragement, I'll be more likely get on it. If you'd like to find out more about my system, feel free to get in touch with me and I'll try to help you out. - Greg P.S. Theoretically, I suppose another option might be to use some kind of an emulation scheme with SoftWindows, but I don't have any experience in that direction. |Gregory A. Lyzenga *** (909) 621-8378 |Dept. of Physics, Harvey Mudd College *** fax (909) 621-8887 |Claremont, CA 91711-5990 |http://www.physics.hmc.edu/profs/lyzenga.html _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bob@................. (Bob Hammond (USGS-AVO Geophysicist)) Subject: Re: Status at Rainier Date: Mon, 28 Oct 1996 16:39:00 -0900 From: watson@................ (Charles Watson) Subject: Re: Macintosh software Date: Mon, 28 Oct 1996 19:00:24 -0800 Greg Lyzenga wrote: > > >Does anyone know about Macintosh software that would work? I could, I > >suppose get another computer, but I'd rather not. > > Todd: > I have a Macintosh-based Lehman seismometer system. It's all > home-grown, and as yet I have not got around to writing the software > necessary to make it "Winquake-compatible". However it's just a matter of > my devoting the time to the task, so if I get some encouragement, I'll be > more likely get on it. If you'd like to find out more about my system, > feel free to get in touch with me and I'll try to help you out. > Greg, I would be interested in a Mac-based seismometer system. I have been lurking in the background to this group for a couple years, listening to the "Winquake" stuff, thinking "oh, gosh, one of these days, I've got to blow the dust off the ol' PC and get on with this monitoring thing..." But, I'd rather use the half dozen Macs that I regularly use to process Seismo-Watch material anyway. There so much easier to use, ya know. They even come with a trash can... :-) Just loaded the upgrade to System 7.5.5 over the weekend and, whee, it made my PowerBook 5300cs really scoot! So if you need more words of encouragement, I would be glad nudge you. --- Charles P. Watson, Consulting Geologist Advanced Geologic Exploration Seismo-Watch / Earthquake Information Services Voice: 702-852-0992 / Fax: 702-852-3226 watson@................ http://www.seismo-watch.com _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: Reduce convection near seismometers Date: 29 Oct 96 10:44:01 EST Hi, There has been a lot of traffic about the source of noise with Lehman and other seismometers. I think that there is general agreement that air currents can be a source of noise (but obviously not the only source). I can offer a little quantitative data which may help thinking about this. My Lehman sits on the concrete floor of my basement. I built a box of 2" thick styrafoam. This material is available from lumber yards. Styrafoam this thick is nearly a perfect insulator under the conditions discussed. The pre-amp is outside the box. The box is 16" wide by 39" long by 24" high (inside dimensions) and has a lid of the 2" stuff which just sits on the top. The gap between the lid and the box nowhere exceeds 1/8". The 4 sides of the box were glued together with Elmer's white glue. The box is taller than necessary but this required less cutting and probably does no harm. A resistor is attached to the center of the lid and spaced about 1" from the lid. The 5 ohm resistor is supplied with 9V AC from a flea market transformer. This dissapates 16 watts. Using a thermistor and an ohmmeter, I measured the temperatures shown in the following table: Location inches from floor deg F Room air 36 65 Floor outside box 0 63.0 Inside box 24 (top) 78.6 " 18 76.5 " 12 74.5 " 6 72.4 The temperatures inside the box are quite constant over a period of a few minutes but variations are seen in the room temp. over this sort of time. The floor temp. was measured by placing the thermistor beneath a square of styrafoam pressed against the floor. Observations:1. The rather small heater power (16 watts) raises the temperature in the box quite a bit. 2. There is a considerable temperature gradient in the box with the top hotter than the bottom. My intuition (unsupported by any evidence) sez that this temp. gradient is plenty to stagnate the air in the box and prevent convection since the longitudinal temp. gradient should be small given the good insulation. ---- The books say that a major cause of the seismic background (microseisms) is ocean waves breaking on the shore. I had a brief discussion with Paul Richards of Lamont obs. and he says that the only way to reduce this problem is to locate away from any ocean. They have the use of a Russian site in the middle of Siberia which is the farthest from an ocean of any place on earth. This suggests that I should move back to my home town, Wichita, but it probably won't happen. When the nor-easter of 10/19 went up the east coast and dumped 7.23" of rain on me, my noise level was high. I hope to try to correlate my noise level with wave height on the Jersey shore more quantitatively . If someone could suggest an internet source of daily wave height data, I would appreciate it. I have a vague impression that ocean storms are more frequent during the change of seasons, e.g., fall to winter. This may account for some to the reports of higher noise at these times. Bob Barns Berk. Hts., NJ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lyzenga@................. (Greg Lyzenga) Subject: Lehmans and thermal noise, etc. Date: Tue, 29 Oct 1996 08:40:31 -0800 Well, it is with a mixture of satisfaction and some embarrassment that I report, thanks to all the good discussion on this list, the problem I said had stumped me for years is solved. After some experiments over the weekend, I am convinced now that it *is* indeed due to air convection when the air temperature drops below the concrete slab's temperature. The reason I feel sort of sheepish about this is that the idea had occurred to me a long time ago, only I had it backwards! I figured at the time that maybe the concrete needed to be heated, so I got an electric blanket and put it on the bottom of the enclosure. The problem only got worse (duh!). Now if I'd only stopped to think for two seconds about it, I'd have realized I wanted the warm air on *top* for stable stratification! Wow, and to think I call myself a physicist! This is much more embarrassing than always forgetting where you put your glasses... 8-) Anyway, installing a couple of light bulbs in the *top* of the box immediately and dramatically improves the thermal noise situation for me, although the bulbs do introduce a certain amount of their own turbulence. Now that I seem to have a handle on the problem, I think the next step will be to experiment with some of the styrofoam insulation ideas that you all have been discussing and really put this to rest. Thanks to everybody for the great ideas! - Greg |Gregory A. Lyzenga *** (909) 621-8378 |Dept. of Physics, Harvey Mudd College *** fax (909) 621-8887 |Claremont, CA 91711-5990 |http://www.physics.hmc.edu/profs/lyzenga.html _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: mgray1@................ (Mike Gray) Subject: Re: Reduce convection near seismometers Date: Tue, 29 Oct 1996 12:02:28 -0600 >Hi, > There has been a lot of traffic about the source of noise with Lehman and >other seismometers. I think that there is general agreement that air currents >can be a source of noise (but obviously not the only source). I can offer a >little quantitative data which may help thinking about this. > ............ >Bob Barns >Berk. Hts., NJ > Thanks, Bob for some interesting data. In regard to my previous posting about thermal lag, certainly thermal breaks reduce that effect. Could you elaborate on how you got a good base connection with your thermal break? Perhaps that small connection is not enough to cause a problem. The thermal break over the rest of the floor area in addition to the heat source is apparently enough to temper the environment. I agree that ocean waves breaking on shore and reefs can contribute to the noise but I always thought that they were much more pronounced at high tides and/or certain lunar phases. I may have been thinking that most of what has been discussed here referred to more constant increased noise, even during low tides. My first impression is that the rainy seasons (spring and fall) would affect the ocean wave situation, as you indicate. My second impression is that if we are dealing primarily with ocean waves, tides/lunar phases should provide the proof of that. Anybody care to look at a possible correlation? Mike Gray MO Bureau of Emergency Medical Services (Dept of Health) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Dan Dzurisin Subject: Status of Mount Rainier Date: Tue, 29 Oct 1996 09:33:52 -0800 There is no truth to the story being circulated by some radio and television stations in the Pacific Northwest, as reported on the Public Seismic Network email list server, that Mount Rainier is at orange alert. In fact, activity at the volcano is at a normal, background level. The root of the erroneous reports may be the fact that this month marks the tenth anniversary of the last dome-building eruption at Mount St. Helens. This was reported by Oregon Public Broadcasting yesterday in a story that also mentioned that scientists now regard Mount Rainier as the most dangerous volcano in the Cascades. The U.S. Geological Survey has documented the hazards posed by long-travelled debris flows at Mount Rainier, and the USGS and University of Washington monitor seismic activity at Mount Rainier continuously. Future eruptions or debris flows at Mount Rainier may threaten communities in the area, but for now the volcano remains quiet. ====================================================================== Dan Dzurisin U.S. Geological Survey dzurisin@.................. Volcano Observatory 360-696-7826 (office) 5400 MacArthur Blvd. 360-696-7610 (fax) Vancouver, Washington 98661 ====================================================================== _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: JAMES CRISTIANO Subject: QuakeAlert Date: Tue, 29 Oct 1996 13:06:10 -0800 Dr. John Lahr, re: QuakeAlert Thanks for your response. I just got a copy of your e mail today. Seems that the boss thought it was junk mail. I find it hard to believe that it can distinguish between seismic and other generated vibrations. On the other hand, I remember watching a show on earthquakes a while back and it showed a segment on a city in Japan where they installed "P" wave detectors that were up-linked to an early warning system. I can't remember the name of the city. Anyone remember the show or know who to get in touch with in Japan who might have information on this? I think the system was in a test phase. Might be interesting to find out if it would work or not. Jim Cristiano weitech@.......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@................. (Dr. John Lahr (USGS-GI Seismologist)) Subject: Re: QuakeAlert Date: Tue, 29 Oct 1996 14:07:26 -0900 Jim, The only "early warning" system that I am aware of involves rapidly locating an earthquake with the P phases from stations near the epicenter and then broadcasting an alert to more distant locations. Depending on the speed of the location process and the distance of the "more distant" location, there can be a warning a few seconds prior to the arrival of the S phase. This system was implemented on a temporary basis to warn workers at Oakland highway collapse of aftershocks from the Loma Prieta earthquake. JCLahr _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie & Terri Thompson -- Buda MicroRanch ) Subject: Re: Lehmans and thermal noise, etc. Date: Tue, 29 Oct 1996 21:51:44 -0600 Well I've been waiting on the Texas weather to verify the thermal noise theory and apply the heater solution. Tonight when the sun went down the air temp finally dipped below the slab temp: 70 degrees for the slab and 67.9 degrees for the air. I have a nice 3 hour WinQuake plot of the noise level rising. After this posting I will turn on the light bulb and record the noise (hopefully) going down. I'll be happy to share the expected plots with everyone. Thanks to all who shared their thoughts on this....I learned something! -Charlie Thompson Buda, Texas ct@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert Avakian Subject: Re: EARTHQUAKE TIMING Date: Tue, 29 Oct 1996 21:57:14 -0800 RON WW025 wrote: > > DUE TO THE INACCURACY OF THE REAL TIME CLOCK IN THE IBM PC. I HAVE > CONSTRUCTED A HOME MADE CLOCK USING A 10 MHZ CRYSTAL CONTROLLED CLOCK IN > A OVEN THIS IS PHASE LOCKED TO A RUBIDIUM STANDARD AT TWO OF OUR FIVE > TELEVISION STATIONS WHICH USE A RUBIDIUM STANDARD. THE CLOCK HAS A > DIGITAL READ OUT IN THE CONVENTIONAL MANNER BUT ALSO OUTPUTS OF 10 MHZ > DOWN TO 1 HZ. I WISH TO FEED THIS INTO THE COMPUTER TO EITHER CORRECT > THE REAL TIME CLOCK OR NOT USE THE REAL TIME CLOCK AT ALL AND USE A > SOFTWARE CLOCK STILL LOCKED TO MY OWN CLOCK. ANY IDEAS ON HOW TO GO > ABOUT THIS? > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > I just recieved a catalog from Parson's Technologies which includes a progarm to link the computer to any one of several "atomic clocks". That might fit your needs and costs a princely $19. It could obviate the need for a separate clock. Avakian Midland Texas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: mgray1@................ (Mike Gray) Subject: Re: QuakeAlert Date: Wed, 30 Oct 1996 09:21:07 -0600 >The correct URL is http://www.gsi-mc.go.jp/YOCHIREN/ccephome.e.html >Larry > >At 11:22 AM 10/30/96 +1200, you wrote: > >>>Jim, try the email address at the bottom of >>>http://www.gsi-mc.go.ip/YOCHIREN/ccephone.e.html >>>The link works. >>> >> THE Link Didn't Work........ not to worry Dave N. Was too late in a hectic day to read my printing when I was seeing double and cross-eyed at that! At least I got everything right except for one letter. Mike Gray MO Bureau of Emergency Medical Services (Dept of Health) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: Re: Reduce convection near seismometers Date: 30 Oct 96 10:24:30 EST Mike Gray, I don't understand your terms "thermal break" and "base connection". Upon further reflection, I'll bet that the whole subject of microseims has been studied to a fare-thee-well and there must be dozens of papers in the seismological literature. What we need is for someone familiar with this literature to point us at a good review article. Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Mike Stickney Subject: microseisms Date: Wed, 30 Oct 96 09:15:17 MST I have been lurking in the background for several weeks and have followed your discussions with interest. Perhaps I can offer a little information about microseisms. As the operator of a regional seismograph network in western Montana, I have recorded thousands of hours of microseisms. They are always present at some level but periodically, their amplitude increases dramatically. These periods of increased microseism amplitude typically last from 12-36 hours and almost always occur from October through April. I was told in school (and believe) that these episodes of increased microseism amplitude correspond to low pressure weather systems moving onto the Pacific coast, although I have never taken the time to make a careful study of the correlation. There have been published studies of microseisms. A quick search of the Cumulative Index of the Bulletin of the Seismological Society of America lists a paper by Webb and Constable (1986, Microseism propagation between two sites on the deep seafloor; v. 76, pp.1433-1445) as the most recent BSSA publication that may answer some of the questions raised in the discussion group. In this paper, the statement "The peak near 0.08 Hz is caused by seismic waves forced by the steepening and breaking of surface gravity waves (swell) along the coast" is attributed to Hasselmann (1963, A statistical analysis of the generation of microseisms; Rev. Geophys. Space Phys., v. 1, p.177-210). The article goes on to say that "This is a "primary" frequency peak because the seismic waves are predominately at frequencies near the primary swell frequency." -Mike Stickney Montana Bureau of Mines and Geology _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: QuakeAlert Date: Wed, 30 Oct 1996 08:32:40 -0800 Please be aware of the Guerreo Project along the central Mexican coast which has successfully warned Mexico City of very large earthquakes along the central American subduction zone from 30 -90 seconds prior to S-wave arrival. When a potentially damaging quake occurs along the Guerrero segment, the coastal accelerograph network trips, implimenting a warning systems in Mexico City which alerts the people of the impending shaking. The large distance proves an advantage for these types of distant early warning arrays. Once the distance early warning system is perfected, similar arrays could be deployed for other regions of the world as well. I strongly believe any warning is an advantage to saving lives and several creative systems could be designed around this concept to impliment life-saving devices (ie; waring lights on bridge or overpass approaches, sirens in areas of high liquefaction risk, automatic shut-off of critical pipeline utilities, etc). Sounds like a nitch market to capitalize on, eh? --- Charles P. Watson, Consulting Geologist Advanced Geologic Exploration Seismo-Watch / Earthquake Information Services Voice: 702-852-0992 / Fax: 702-852-3226 watson@................ http://www.seismo-watch.com _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie Thompson) Subject: Convection Currents in Lehman sensor housing Date: Wed, 30 Oct 1996 11:57:25 -0600 Using a nifty digital timer I set up my box heater to come ON at exactly 5:00 am this morning... as predicted I have a nice SDR record of the noise going DOWN fairly quickly starting at 5:00 am. It only took about 5 minutes for the noise to drop and level off. ....more observations and expriments to follow. -Charlie Thompson Buda, Texas PS. My guess is that insulating the BOTTOM of the housing might obviate the need for a heater. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie Thompson) Subject: Seismic warning and gas shutoff systems Date: Wed, 30 Oct 1996 12:04:09 -0600 > >Once the distance early warning system is perfected, similar arrays could be >deployed for other regions of the world as well. I strongly believe any warning >is an advantage to saving lives and several creative systems could be designed >around this concept to impliment life-saving devices (ie; waring lights on >bridge or overpass approaches, sirens in areas of high liquefaction risk, >automatic shut-off of critical pipeline utilities, etc). > >Sounds like a nitch market to capitalize on, eh? If you do a US Patent search on keyword "seismic" you will find that there are a couple of patents by individuals pertaining to automatic shutoff of gas/utilites during a seismic events. I think the individual inventors were in SF and LA areas of California. The CNIDR patent search engine on the Web is a great way to find related seismic stuff. -Charlie Thompson Buda, Texas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: microseisms Date: Wed, 30 Oct 1996 09:20:05 -0800 Seismo-Watch is geared to report activity from the established monitoring networks in the United States and the world. The former Seismo-Watch Newsletter tracked the weekly activity from these networks and displayed it in a high quality graphic format with bullet text descriptions During the early Spring of 1996, two pulse of increased microseismic activity affected nearly every network in North America. Coined "The Spring Push", it began with a significant increase in activity in Southern California during the first two weeks of April. In subsequent weeks, other networks reported elevated activity. Even the Southeastern Canadian network reported an increase in activity during late April and early May. The only region that did not report elevated seismic activity was the New Madrid-SE networks. Has anyone else tracked similar continental seismic pulses? Charlie --- Charles P. Watson, Consulting Geologist Advanced Geologic Exploration Seismo-Watch / Earthquake Information Services Voice: 702-852-0992 / Fax: 702-852-3226 watson@................ http://www.seismo-watch.com _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: Seismic warning and gas shutoff systems Date: Wed, 30 Oct 1996 09:30:11 -0800 Charlie Thompson wrote: > > > If you do a US Patent search on keyword "seismic" you will find > that there are a couple of patents by individuals pertaining to > automatic shutoff of gas/utilites during a seismic events. But what about the large picture of regional warning arrays and warning devices? John Larr's recall of the rescue workers on the Embarcadero Freeway is a great example how these systems could be employed. Imagin a 7+ earthquake along the Point Rayes segment of the San Andreas. It would take several 10s of seconds for the seismic waves to reach the high liquefaction risk regions around the South Bay. Deployment of early warning systems could be designed to facilitate life saving procedures there. Charlie --- Charles P. Watson, Consulting Geologist Advanced Geologic Exploration Seismo-Watch / Earthquake Information Services Voice: 702-852-0992 / Fax: 702-852-3226 watson@................ http://www.seismo-watch.com _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: Seismic warning and gas shutoff systems Date: Wed, 30 Oct 1996 13:43:42 -0700 Charles Watson wrote: > But what about the large picture of regional warning arrays and warning > devices? John Larr's recall of the rescue workers on the Embarcadero Freeway > is a great example how these systems could be employed. > > Imagin a 7+ earthquake along the Point Rayes segment of the San Andreas. It > would take several 10s of seconds for the seismic waves to reach the high > liquefaction risk regions around the South Bay. Deployment of early warning > systems could be designed to facilitate life saving procedures there. Except that if the last +7 M earthquake had been 20 years before, one might not know what the alarm was all about and it would take some time, several seconds at least, to get one's act together. -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: JAMES CRISTIANO Subject: Hall Effect, again Date: Wed, 30 Oct 1996 12:47:18 -0800 To Al and all, I just got a sample of Allegros high sensitivity Hall effect sensor UGN3507L-U. Its sensitivity is .0025V/Gauss. With the magnet setup described before, I get a .021V/mil signal (8.44 X .0025V = .021V). With a X100 amplifier its 2.1V/mil. Thats 2.1V for each .001" of boom movement! Sounds like a lot to me. With a capacitor the displacement/time signal can be changed to acceleration/time. The Earths magnetic field has a minimal effect on the Hall sensor. Just so I can compare apples to apples, can anyone tell me what the sensitivity of thier coil/magnet setup is? In Volts @ 1mm @ say 5Hz? Before I start winding 1000' of #36AWG wire on a bobbin, I want to make sure I'm not passing anything up. Thanks, Jim Cristiano weitech@.......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: mgray1@................ (Mike Gray) Subject: Re: Seismic warning and gas shutoff systems Date: Wed, 30 Oct 1996 16:01:03 -0600 >If you do a US Patent search on keyword "seismic" you will find >that there are a couple of patents by individuals pertaining to >automatic shutoff of gas/utilites during a seismic events. I think >the individual inventors were in SF and LA areas of California. >The CNIDR patent search engine on the Web is a great way to find >related seismic stuff. > >-Charlie Thompson >Buda, Texas > Charlie, do you have a specific URL or URL's for patent searches? Is there any cost for use? Mike Gray MO Bureau of Emergency Medical Services (Dept of Health) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bob@................. (Bob Hammond (USGS-AVO Geophysicist)) Subject: Re: Seismic warning and gas shutoff systems Date: Wed, 30 Oct 1996 11:59:28 -0900 I maintain (and others do as well) that preparedness is the best way to go for quake hazard mitigation. I agree with Ed Cranswick that our collective memory will fail us with an alarm system that is only triggered once every 5 or 10 years. I'd rather be ready ALL the time than have 10-90 seconds to get ready. The gas shutoff device should be mandatory in high-risk areas. I cannot see alerting a whole city to the fact that a quake is coming in less than a minute. I think you'd have more deaths due to panic. that's my 2 cents! Bob. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie Thompson) Subject: Patent database URL Date: Wed, 30 Oct 1996 16:16:26 -0600 For those interested in US Patents the FREE searchable database is: http://patents.cnidr.org/patbib_index.html To download patents for $3.00 each (very good image quality) you can access: http://www.micropat.com/ You'll need to download their viewer and they take a $50 deposit via credit card. (don't send your cc# via email ..phone them with it instead to be secure). I've had good luck with Micropatent they are decent people. Regards, Charlie Thompson Buda, TX ct@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson Subject: speaking of micro seisms Date: Thu, 31 Oct 1996 09:18:17 +1200 I live only 3 km from the coast and last nite observed a classic case of watching a cold weather front arrive from the south onto my east coast of the South Is., NZ. The background noise initially in the mid evening was very quiet and the pen trace was almost " Flat Lining" ~ 2300 hrs loc. the noise began to slowly build as the heavy seas began arriving.... some 2-3 hours before the cloud and rain arrived overhead. The seismic noise consisted of ~ +_ 3-4 mm amplitude and ~ 2 sec period. the seismometer I am using is ' Marks Products' L15 BH 4-5 Hz horizontal Geophone... they are very small... 3 cm diam. and 4 cm long. it is potted in a 5cm dia piece of plastic pipe, buried in the ground and coax cable running some 30 metres back into the house to the recorder. Only just shifted to seismom. to the greater distance as I have finally had enough of the man-made noise coming from the neighbour's house.... the hi freq vibrations from their washing machine in spin mode and the clothes drier caused havoc. I've been following the thermal noise prob. with interest as when I fire up the commercial L.P. seismom. I suspect that I will strike similar hassles. thanks for all the input Cheers all Dave Dave A. Nelson Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) When All Else Fails...... READ THE INSTRUCTIONS A SMITH and WESSON Beats Four Aces _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: mgray1@................ (Mike Gray) Subject: Re: Reduce convection near seismometers Date: Wed, 30 Oct 1996 15:07:42 -0600 >Mike Gray, > I don't understand your terms "thermal break" and "base connection". > Upon further reflection, I'll bet that the whole subject of microseims has >been studied to a fare-thee-well and there must be dozens of papers in the >seismological literature. What we need is for someone familiar with this >literature to point us at a good review article. >Bob Barns > A thermal break is a method of stopping the flow of heat from something warmer to something colder. The method generally involves using an insulating material. In its most common forms, thermal breaks are used on window and door installations and insulated basements. An additional benefit is the reduction of air infiltration to areas one does not want it in. Caulking is not a very good thermal break, but it is a good way to reduce air infiltration. My reference to the "base connection" was referring to however the seismic sensor is attached to the concrete or rock slab. If those connection points are small in size, I wouldn't see a need for a thermal break at the points. This is because the slab's thermal lag (release of stored latent heat to a colder area, usually the air above a horizontal surface) surface is greater than the mounting point(s). That greater surface area has more of an effect than possibly even the sum of the mounting points. If one were to compensate for the effect of thermal lag by using heaters to make the ambient temperature more stable, there probably isn't any need for a thermal break. A thermal break, if done properly, would eliminate the need for the heaters. Heaters, from what I'm hearing on this list, seem to more than make up for the thermal lag effects. Without knowing precisely how the Lehman or other sensors are mounted, I would say a thermal break is best installed between the areas of most concern (the sensor and what's below it). If the thermal break is below the slab, it would seem that the slab "connection" to the earth would not be as "stiff" as it needs to be. (Excuse my low tech descriptions - I may be trying too hard to simplify.) I don't have a sensor (yet!). But if were to have one and wanted to try a thermal break, I would start with ceiling insulation, foam insulation, or even layers of newspaper if rodents, bugs, and/or moisture are not a problem. The insulating material would be placed directly on the slab and go to the edges of the box cover. I would probably use as much as I could stuff in there without affecting mechanical movements. By the way, I've seen many seismic sensors buried in the ground, which stays at a relatively constant temperature (thermal lag imakes the ground temperature opposite to what the season and atmospheric temperature is). Thus sensor the is not as affected by thermal problems. Since I don't think any of this discussion has appeared in seismology, the best place to steer everyone desiring more info is to building contruction folks or window and door manufacturers. My offering is in the low tech, low cost vein. There may be other, more complex and costly solutions. Mike Gray MO Bureau of Emergency Medical Services (Dept of Health) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@................. (Dr. John Lahr (USGS-GI Seismologist)) Subject: Re: Hall Effect, again Date: Wed, 30 Oct 1996 13:24:20 -0900 Jim Cristiano writes "Can anyone tell me what the sensitivity of thier coil/magnet setup is?" For comparison, the L4C geophone has a velocity sensitivity (motor constant) of .17 volts per mm/s If you're interested in the output for a given amplitude and frequency, first convert to velocity and then apply the scaling factor above. If the amplitude (A) of the moving coil within the geophone is 1 mm zero to peak @ f=5Hz, then A = sin(2 pi f t) mm Then the velocity, V, of the coil is: V = 2 pi f cos(2 pi f t) V = 31.4 cos(2 pi f t) mm/s The output of the geophone would be: ..17*31.4 = 5.34 volts zero to peak JCLahr ################################# John C. Lahr ################################ U.S. Geological Survey ############################### c/o Geophysical Institute ############################## 903 Koyukuk Drive ########################################################### ########################################################### P.O. Box 757320 ################################ Fairbanks, AK 99775 ################################# Phone: (907) 474-7997 ################################## Fax: (907) 474-5618 ################################### lahr@........ #################################### _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson Subject: Marks Products seismometers Date: Thu, 31 Oct 1996 14:23:43 +1200 Specifically to Jim Forbes also to those others interested, Jim, the 3 Marks Products seismometers (2 x Horiz. and 1 x Vert.) I have were purchased second hand from the Seismological Obs. here in New Zealand. I was offered them when a seismologist have finished his studys and had no more need for them. The 3 cost me NZ$200.00 apparently they are approx US$75.00 new each. here is the blurp from Marks :: (quote) MARK's L-15 subminiature, digital grade, dual coil geophone has the HIGHEST OUTPUT per unit weight of OF ANY COMPARABLY PRICED GEOPHONE. It has an improved coil-magnet structure which makes this high OUTPUT feature CONSISTANT FROM GEOPHONE TO GEOPHONE, an absolute factor of efficient multiple geophone usage. The L - 15 is housed in a Super - Tuf case assuring the user of a FIELD PROVEN CABLE ANCHOR AND CASE SEAL. MARSH cases are also available for SHALLOW WATER applications. L - 15B Standard freq. range, Hz 4.5-10 Hz Freq toler. + - 0.5 Hz Standard coil resistance, Ohms 150/240/380 Resistance Toler. 5 5 5 Max. Distortion @ 0.7 in/sec @ 12 Hz or Resonance 0.2 % Transconduction Const. V/in/sec + - 10% 0.047 x sqr root Rc Open cct Damp, + - 10% 1.253 / f Coil cct Damp., 11.84 Rc / f(Rc + Rs) Suspended mass, Grams 23.00 Power Sens., mW/in/sec 2.21 Case-to-coil Motion, in p - p 0.080 Basic Unit Height, inches 1.4 Basic Unit diam., inches 1.25 Basic Unit Weight, oz 5.0 MARK PRODUCTS, U.S. INC. Area 713/498-0600 10507 Kinghurst Dr. Houston, Texas 77099 (end quote) address is as of ~ 5 years ago as in their spec sheets PS additional to my earlier comments I have approx a 2 kg cylindrical mass of lead sticking out of the bottom end of the section of pipe that the unit is potted in to give the system sensitivity for recording distant events. am able to record M3.5's up to 300 km 4.5's " 600 km 5.5's " 1000 km although not really designed for L.P. recording it has detected > 6.5 events all around the western South Pacific Hope that is of interest to some Cheers Dave Dave A. Nelson Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) When All Else Fails...... READ THE INSTRUCTIONS A SMITH and WESSON Beats Four Aces _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bfryer@............ (Bob Fryer) Subject: Re: QuakeAlert Date: Wed, 30 Oct 1996 19:08:37 -0800 Hello Mike, As a retired firefighter (35 years service), I'm always trying to stir up people in Emergency Services. Do you know anyone who would care to comment on the content of my WWW page? It will be upgraded in a couple of weeks. Thanks and take care.... Bob Fryer -- Beaverton, OR (Cascadia Subduction Zone) >>The correct URL is http://www.gsi-mc.go.jp/YOCHIREN/ccephome.e.html >>Larry >> >>At 11:22 AM 10/30/96 +1200, you wrote: >> >>>>Jim, try the email address at the bottom of >>>>http://www.gsi-mc.go.ip/YOCHIREN/ccephone.e.html >>>>The link works. >>>> >>> THE Link Didn't Work........ not to worry Dave N. > >Was too late in a hectic day to read my printing when I was seeing double >and cross-eyed at that! At least I got everything right except for one letter. > >Mike Gray >MO Bureau of Emergency Medical Services (Dept of Health) >_____________________________________________________________________ ----- earthquake WARNING research ----- --- http://www.teleport.com/~bfryer --- -- Animals, people, scientific evidence -- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: New WinQuake Release Version 2.3 Date: Wed, 30 Oct 1996 22:47:26 -0700 Greetings, Some great stuff on the list lately... I just finished a new release of my WinQuake program. The new features are: WinQuake can now process event files greater the 65000 samples. The maximum number of samples WinQuake can handle for all formats (PSN, SAC Binary and PEPP) is now 250,000. Added a dialog box to correct the start time of the event file. This can be used to correct the time of the event file if the system time of the data logging system is off by a known amount. The event display now shows the lock status of SDR at the time the event file was saved. If SDR was locked to WWV (or using the serial port connected to some other reference) you will see a (L) or (?) by the start time display at the top of the screen. The (?) indicates that SDR was locked at sometime but has had no new WWV locks within 24 hours. And as usual, fixed several bug. You can download the new version using the following URL: 16 bit version for MS Windows 3.1 ftp://ftp.seismicnet.com/users/psn/software/wq16v23.zip or http://psn.quake.net/software/wq16v23.zip 32 bit version for MS Win95 and NT: ftp://ftp.seismicnet.com/users/psn/software/wq32v23.zip or http://psn.quake.net/software/wq16v23.zip Please try to use the ftp.seismicnet.com address for downloads. This system is connected to a faster link into the net so downloads should be faster then my system at psn.quake.net. For WinQuake and SDR to read/write PSN format files greater then 65000 samples I had to modify the PSN format a little. For more information on the changes to the PSN format please read the format.txt file at http://psn.quake.net/info/format.txt. Note to SDR users: The next release of SDR (Seismic Data Recorder) will allow the user to save the larger then 65000 sample event files. I should have a new release ready in a few days. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Al Allworth Subject: Re: Thermal Effects on the Long Period Lehman Date: Wed, 30 Oct 1996 22:48:24 -0800 At 05:45 AM 10/30/96 -0800, you wrote: >Al, where did you pick up your L-4 sensor? I and a friend found some at a surplus sale in Portland, OR last year. No, there aren't any left. We bought all that were left. They had 12 when he first saw them and bought one, not knowing what they were. He knew I had built a seismograph so when I visited in the area he told me about them not thinking they could possibly be of any use. He and I went back to see if any were left. We found them but some had been bought in the 2 weeks since he had been there. Between the two of us , we bought the rest. They are the 1 Hz varity, and I was able to find connectors at a local surplus store. I have one installed with double stick foam tape to my garage floor under the workbench. My electronics got zapped in that big power outage a few months back and I haven't had time to fix it yet. I hope to soon. My friend is now getting more interested in getting his running. It is interesting how the discovery of a major component stirs up the enthusiasm. When I move next year I hope to have enough room to set up an array to try to explore directional effects. Al ____________________________________________________________________________ _____ Al Allworth. Pasadena,CA aallworth@........ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bfryer@............ (Bob Fryer) Subject: Re: speaking of micro seisms Date: Wed, 30 Oct 1996 23:09:16 -0800 Hi folks, From my _earthquake WARNING research_ bibliography: Bath, Marcus, Introduction to Seismology, New York: John Wiley, 1973. Geology, geophysics, seismology, microseisms. 3.7 (Microseisms) p97: "During World War II, the Americans were able to trace tropical cyclones in the Caribbean Sea and the Pacific Ocean by means of the microseisms which originated from the cyclones." Take care, Bob Fryer ----- earthquake WARNING research ----- --- http://www.teleport.com/~bfryer --- -- Animals, people, scientific evidence -- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jeff Batten Subject: How are quakes located on a Global Scale? Date: Thu, 31 Oct 1996 13:43:57 -0800 Looking at the Earthquake Information Messages, I notice that P wave arrival times are listed for about 100 stations. Can someone give me some references, that would describe how quakes are located on a global scale using the P-wave arrival times. What software does the USGS use? If us amateurs had the same software could we not locate the quakes ourselves? Jeff Jeff Batten - Research Engineer Caltech Seismo Lab 818-395-6965 Fax-818-564-0715 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Leigh House" Subject: Re: How are quakes located on a Global Scale? Date: Fri, 1 Nov 1996 10:26:23 -0700 To Jeff: I had thought that someone from the U.S. Geological Survey, perhaps Edward Cranswick, would have responded to this by now, but since I haven't seen a response, I'll try to shame one of them by putting my 2 cents in. Yes, certainly you (or anyone else) could locate earthquakes yourselves, given the arrival time information that is in the earthquake information messages that the Nat'l Earthquake Information Center sends out. The procedure for locating earthquakes is fairly straightforward, but the details of computing teleseismic travel times correctly can be a bit complicated. Nevertheless, since the earthquake seismology community has been locating earthquakes for many years, starting with computers that were far less capable than the slowest PC's now available, the computations can be done on basically any PC that anyone has (yes, even the slow, old original IBM PC should work!). I have a teleseismic earthquake location program, but it is fairly old, and since I did not write it, I can not pass out copies of it. I would assume that, since you are at the Seismo Lab at Cal Tech, you could walk down the hall and find a colleague who has a comparable program. You might even be able to get them to agree to making it available to others. I would be happy to assist with adapting it to a PC if necessary, or with putting a test data set together. I may even be able to persuade a colleague here to assist with adapting the program to a Mac, if necessary. If you cannot find a sympathetic colleague at the Seismo Lab, I can help with contacts there or elsewhere to find a program that can be made available via PSN. Regards, Leigh House On Oct 31, 1:43pm, Jeff Batten wrote: > Subject: How are quakes located on a Global Scale? > > > Looking at the Earthquake Information Messages, I notice that P wave > arrival times are listed for about 100 stations. > Can someone give me some references, that would describe how quakes are > located on a global scale using the P-wave arrival times. > What software does the USGS use? > If us amateurs had the same software could we not locate the quakes ourselves? > > Jeff > Jeff Batten - Research Engineer > Caltech Seismo Lab > 818-395-6965 > Fax-818-564-0715 > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L >-- End of excerpt from Jeff Batten -- ------------------ Leigh House MS D-443 Los Alamos National Laboratory Los Alamos, NM 87545 (email: house@......... Tel: 505-667-1912; FAX 505-667-8487) ------------------ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: mgray1@................ (Mike Gray) Subject: Wierd booms Date: Fri, 01 Nov 1996 14:42:31 -0600 Anybody pick up on their sensors the wierd booms (sonic boom- like) being heard and felt around the Florida panhandle? If so, please upload a file of same somewhere (not to the list!!!!) and post an email to this list as to the location and format of the file. Thanks!!! Georgia monitor(s), please make a special effort to look for things out of the ordinary, possibly making changes to try to capture the data. Thanks!!! Mike Gray MO Bureau of Emergency Medical Services (Dept of Health) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jeff Batten Subject: Global Location of epicenters Date: Fri, 01 Nov 1996 14:14:00 -0800 >To Jeff: >I had thought that someone from the U.S. Geological Survey, perhaps >Edward Cranswick, would have responded to this by now, but since I >haven't seen a response, I'll try to shame one of them by putting my 2 >cents in. >Yes, certainly you (or anyone else) could locate earthquakes >yourselves, given the arrival time information that is in the >earthquake information messages that the Nat'l Earthquake Information >Center sends out. The procedure for locating earthquakes is fairly >straightforward, but the details of computing teleseismic travel times >correctly can be a bit complicated. Nevertheless, since the earthquake >seismology community has been locating earthquakes for many years, >starting with computers that were far less capable than the slowest >PC's now available, the computations can be done on basically any PC >that anyone has (yes, even the slow, old original IBM PC should work!). >I have a teleseismic earthquake location program, but it is fairly old, >and since I did not write it, I can not pass out copies of it. I would >.assume that, since you are at the Seismo Lab at Cal Tech, you could >walk down the hall and find a colleague who has a comparable program. Actually I would have to take the elevator up two floors. Working as a mechanical engineer supporting the shock wave lab, I do not directly interface with the scientists working on earthquakes. Since they are very busy most of the time I try not to disturb them. I though someone here on the list might have the answer. I will have to track down a grad student. Most people do not know that bellow the seismo lab at caltech is a gaint light gas gun that can fire projectiles at up to 7 kilometers per second. This allows the equation of state to be determined for many different minerals. >You might even be able to get them to agree to making it available to >others. If I can get a program I will make it available. I belike that the number of amateurs running long period and short period instruments will allow fairly accurate location of global epicenters. All they need is a accurate clock to record the p-wave arrival time. We could all email the p-wave arrival times to a central site that could calculate the location. Jeff Jeff Batten - Research Engineer Caltech Seismo Lab 818-395-6965 Fax-818-564-0715 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bob@................. (Bob Hammond (USGS-AVO Geophysicist)) Subject: Re: Global Location of epicenters Date: Fri, 1 Nov 1996 14:36:22 -0900 It takes more than this to shame me! :^) Most of the location programs I'm aware of at the USGS are either mainframe programs or PC programs for local and regional locations which don't lend themselves to global locations very nicely. I know global solutions can be done on a PC because one of the guys I worked for at the Alaska Tsunami Warning Center wrote a BASIC program on the original IBM PC to perform earthquake locations. He spent quite a bit of time entering all the data for the J-B travel- time tables. The input to his program was the arrival times of identifiable phases such as P, S, pP, PP, etc. Since we all use Larry's J-B travel-time tables in WinQuake, I don't think it would be too hard to implement something. Heck, we used to use a globe, string, and J-B tables to measure off distances from stations to epicenters when all we got were phase readings over the teletype. I'll see what I can find out. Bob _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: How are quakes located on a Global Scale? Date: Sun, 03 Nov 1996 20:45:34 -0700 > I had thought that someone from the U.S. Geological Survey, perhaps > Edward Cranswick, would have responded to this by now, but since I > haven't seen a response, I'll try to shame one of them by putting my 2 > cents in. Leigh- I couldn't have said it better myself. I am glad that some US government agencies are willing to help the public. Thank you. -Edward -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: How are quakes located on a Global Scale? Date: Sun, 03 Nov 1996 21:07:46 -0700 Jeff Batten wrote: > > Looking at the Earthquake Information Messages, I notice that P wave > arrival times are listed for about 100 stations. > Can someone give me some references, that would describe how quakes are > located on a global scale using the P-wave arrival times. > What software does the USGS use? > If us amateurs had the same software could we not locate the quakes ourselves? > > Jeff > Jeff Batten - Research Engineer > Caltech Seismo Lab > 818-395-6965 > Fax-818-564-0715 > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L Jeff- >I had thought that someone from the U.S. Geological Survey, perhaps >Edward Cranswick, would have responded to this by now, but since I >haven't seen a response, I'll try to shame one of them by putting my 2 >cents in. (Leigh House) I have forwarded your request to the NEIC staff. As noted by Bob Hammand, the location programs we use (my group that chases aftershocks with portable autonomous digital seismographs, PADS, see http://geohazards.cr.usgs.gov/engnseis/chase_eq.html ), when we must locate earthquakes, are for locating local events. Shamed but unbowed, -Edward -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Cristiano Subject: SSS Date: Wed, 06 Nov 1996 08:35:19 -0700 Hi all, OK OK OK, I'll put my Linear Hall Sensor where my boom is. I wrote a proposal to the local high school on installing and maintaining a seismic station as a school project. The location is Sisters, Oregon. We are in the high desert, just East of the Cascade Mountains. We have active faults, subduction zones and volcanoes. Might be inter- esting. The project could be called the Sisters Seismic Station (SSS). Started scraping up the parts for a horizontal swinging boom type. Picked up two 5 pound barbell weights for $3.00 each at the sporting goods store. They already have a hole for mounting. Got a piece of 5/8" Dia. X 36" threaded rod with nuts and washers from the hardware store. For the boom hinge point, I drilled a 1/8" Dia. X 1/2" deep hole in one end of the rod and glued in a 3/4" long piece of nail with the head cut off. The point of the nail will seat into a shallow " V " drilled into the frame cross piece. Neat and easy. I'll keep ya posted on progress. Jim Cristiano cristiano@........... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: [Fwd: Availability of HYPOCENTER] Date: Wed, 06 Nov 1996 13:55:32 -0700 -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". Barry- I saw your article in SRL, "A Computer Program for Locating Earthquakes Both Locally and Globally" (Lienert and Havskov, 1995; Seismological Research Letters, v. 66, no. 5, Sep/Oct 1995, pp. 26-35.), and I thought that it would be a useful program with respect to the request below. Do you have a Web site? Is the program still available via FTP (elepaio.soest.hawaii.edu, anonymous login, ftp/pub/lienert)? -Edward ----------------------------------------------------------------------- Subject: How are quakes located on a Global Scale? Date: Thu, 31 Oct 1996 13:43:57 -0800 From: Jeff Batten Reply-To: PSN-L Mailing List To: PSN-L@............. Looking at the Earthquake Information Messages, I notice that P wave arrival times are listed for about 100 stations. Can someone give me some references, that would describe how quakes are located on a global scale using the P-wave arrival times. What software does the USGS use? If us amateurs had the same software could we not locate the quakes ourselves? Jeff Jeff Batten - Research Engineer Caltech Seismo Lab 818-395-6965 Fax-818-564-0715 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". From: Robert L Barns <75612.2635@..............> Subject: Re: SSS Date: 06 Nov 96 21:27:15 EST Jim, You may already know about this, but if not:The PEPP (Princeton Earth Physics Project) has a bunch of NSF money to set up seismographs in high schools. They have several already running. You can inquire at wanat@................. Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: SEED data file reader Date: 06 Nov 96 22:06:43 EST Hi gang, Paul Richards of Lamont-Doehrty tells me that I can get their quake data by FTP from lamont.ldeo.columbia.edu Sure enough, I download a 491k file called 96090.134524.seed (this is day 090 of 1996 at 13:45:24) with no problem. He sez that these require a SEED (Standard Exchange of Earthquake Data) reader program and sugggested ftp from dmc.iris.washington.edu as a source. I don't see anything there which will run on a PC. Can anyone suggest where to find such a reader? Bob Barns Berkeley Hts., NJ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: SEED data file reader Date: Wed, 06 Nov 1996 19:43:41 -0700 Hi, What you really need is a program that can convert the waveforms in the seed file to SAC binary files. You can then view them with WinQuake. Unfortunately I don't know of a PC based program to do this. I'm sure there's a UNIX program that can do the conversion. If you have access to a unix system you could convert the file to SAC files and then download then to your PC. I did convert one unix conversion program (I found it the DMC Iris site) called csstosac. This program converts CSS waveform files into SAC binary ones. I ported it over to a 32 bit command line program for WIN95 or NT. Because of the long file names used by unix systems it would not work very well with the old 8.3 format. Event files in this format can be found at the International Data Center (http://www.cdidc.org:65120/). They deal with the comprehensive test ban treaty. Some of the EQ events have waveforms. If anyone would like a copy of my version of csstosac drop me a line and I will send you a copy. You will also need a copy to TAR.EXE and GUNZIP.EXE to extract the waveforms. If anyone finds some "C" code to work with SEED files please drop me a line. I can try and see if I can port it over to the PC, if it hasn't been done yet. Regards, Larry Cochrane Redwood City, PSN At 10:06 PM 11/6/96 EST, you wrote: >Hi gang, > Paul Richards of Lamont-Doehrty tells me that I can get their quake data by >FTP from lamont.ldeo.columbia.edu > Sure enough, I download a 491k file called 96090.134524.seed (this is day 090 >of 1996 at 13:45:24) with no problem. He sez that these require a SEED >(Standard Exchange of Earthquake Data) reader program and sugggested ftp from >dmc.iris.washington.edu as a source. I don't see anything there which will >run on a PC. > Can anyone suggest where to find such a reader? >Bob Barns >Berkeley Hts., NJ > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: [Fwd: Re: Availability of HYPOCENTER] Date: Thu, 07 Nov 1996 10:57:29 -0700 -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". Edward, Yes, all the necessary software, including FORTRAN sources, a manual, a PC executable (386 or better) are on our elepaio ftp server. You are welcome to download them. >From an internet connected SUN, PC or MAC: 1. ftp elepaio.soest.hawaii.edu 2. login as anonymous 3. give your e-mail address as a password 4. cd ~ftp/pub/lienert 5. lcd the directory in which you want the files (e.g. c:\hypo) 6. mget * Please let me know if you have any difficulty in getting them to run. I strongly recommend Microsoft Powerstation Fortran as the best way to compile it, although it has been successfully compiled on SUN's with small modifications to the subdirectory structure portions. It will not run on the older 16-bit Fortran compilers such as MS Fortran 5.1. I was recently informed by Jens Havskov that the latest version of the ISC global arrival time CD-ROM, which will be released sometime next year, will contain HYPOCENTER. The present software package includes a program (ISCNOR) that will quickly convert travel times from the existing NEIC/ISC CD-ROM (containing all globally recorded arrival times from 1964-87: a goldmine of information!), to HYPOCENTER format, allowing their parent events to be relocated using HYPOCENTER and IASP91 travel times (rather than the JB times used by the ISC). In its present form, HYPOCENTER does allow the user to interactively select events to locate, with on-screen display of residuals, etc. However, it does not have any graphical interface, although I have included a rather basic plot program utilizing the PLOT88 library (which you have to buy). I would like to write a nice Windows version of HYPOCENTER in C/C++, as it is presently very UNIX-like in its organization. I considered a proposal to NSF to do this, but they didn't seem very receptive to the idea, despite all their hoohah about making the results of science available to the general public. I have also had all my time taken up recently constructing and programming Hawaii's first scanning LIDAR. From: Jim Cristiano Subject: Re: SSS Instrument Date: Thu, 07 Nov 1996 11:18:07 -0700 Darrell Collins wrote: > > Hi, > I too have a school project like yours. > Let me know if you need any small machining work done ( like > for bushings for the weight holes to 5/8 rod, etc ). Darrell, Your'e right! I do need bushings to fit the weight with a ~1-1/16" hole onto a 5/8" threaded rod. If I can't find something that will do the job from the hardware store, I'll measure the hole and let you know what size it is for sure so that you could make a couple. Thanks for the offer. Bob Barns, Thanks for the tip on the Princeton PEPP info. I'll submit this along with my proposal. Re: QuakeAlert Just received my sample QuakeAlert from Tectonics, Inc. I'll let you all know what happens. Thanks, Jim Cristiano cristiano@........... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond Subject: Re: Convection Currents in Lehman sensor housing Date: Fri, 8 Nov 1996 02:56:34 -0800 (PST) On Wed, 30 Oct 1996, Charlie Thompson wrote: >>more experiments So Charlie, how goes the experiment? I was wondering why the Lehmans here were no having problems as the temps started to drop and I realize that the two of them are in wood boxes that are not totally air tight so the temp from top to bottom is the same. Did you happen to try some kind of vent that would allow the heat to keep flowing up-up-and-away? The two here are outside in a wooden 4x8 shed next to the side of the house on a cement slab and each has its own wooden 2x2x4 wooden box covering it. The air escapes via small gaps in the plastic windows in the top of the boxes that allow me to see and access to the devices without removing the covers. I also have another general question for all... The first 3/4 inch of rain took place last week in the bay area. As it does each year, the ground tilt put the Lehman to the side stop on both and I had to re-center each. My question is this: anybody that has dry summer and wet winters, did you notice a shift in the natural frequency of a fixed microseismic source? I have the San Jose lightrail at one end of my block and the 85 freeway, yes-- the joys of urban seismology, and the SP train tracks 1.6km the other way, The FFT of the coda made by the lightrail going down the tracks shifted just as it has done each year starting in 1990 from 11Hz to 8Hz. I've talked to Ed Cranswick about this and think that he will agree that it's kind of an intersting thing to look at. I'm looking for other examples in different area of San Francisco/San Jose and the world to see how they might be effected. I've noticed a couple of things that go along with it. (a) a lot of higher frequency short period noise seems to get filtered out after the rain. (B) Coda data of any kind of wheels passing by the location is much more harmonic than it had been late into the dry summer. I think the effects of this might be to actually have two different levels of site response given different times of the year and weather conditions, which could result in different damage patterns in an earthquake. So if you have data around that exhibits what I describe, please let me know. Regards, Steve Hammond PSN BBS San Jose 408-226-0675 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond Subject: PSN BBS San Jose 408-226-0675 is once again on-line Date: Fri, 8 Nov 1996 03:02:12 -0800 (PST) I fixed the bad hard drive and the San Jose BBS is back on line. There is several years of earthquake data stored on it. There is also some free software. Regards, Steve Hammond PSN BBS San Jose, CA 408-226-0675 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: toddm@........... (Todd Miller) Subject: A cry for help Date: Fri, 8 Nov 1996 09:12:24 +0100 I am building my seismograph and the mechanical parts are straightforward. However, I haven't built anything electronic since the seventies when I assembled vacumn tube Heathkits. My power supply and amplifier don't work and my question is how easy is it to fry the IC's specifically op-amp 941's when I solder them? Are you supposed to solder them in fact, or is there a socket kit to use? What do you all recommend? Thanks in advance- Todd Miller _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond Subject: Re: A cry for help Date: Fri, 8 Nov 1996 10:26:49 -0800 (PST) There is a socket kit to plug IC's in to. Is there a Radio Shack store near you? IF there is you want the 8-pin DIP socket. There is also nice perf hoards with holes to align to the pins for mounting. Where are you located? Maybe we can get you some help. Regards, Steve Hammond PSN BBS San Jose 408-226-0675 On Fri, 8 Nov 1996, Todd Miller wrote: > I am building my seismograph and the mechanical parts are straightforward. > However, I haven't built anything electronic since the seventies when I > assembled vacumn tube Heathkits. My power supply and amplifier don't work > and my question is how easy is it to fry the IC's specifically op-amp 941's > when I solder them? Are you supposed to solder them in fact, or is there a > socket kit to use? What do you all recommend? > > Thanks in advance- Todd Miller > > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ron Westfall Subject: Re: A cry for help Date: Fri, 08 Nov 1996 10:33:53 -0800 Todd Miller wrote: > > and my question is how easy is it to fry the IC's specifically op-amp 941's > when I solder them? Are you supposed to solder them in fact, or is there a > socket kit to use? What do you all recommend? > It is fairly easy to fry most ICs. It is just a matter of how long the heat has been applied to the chip, and how much heat has accumulated in the chip. The secret to soldering ICs is speed. Speed will come with practice. If necessary, wait between pins to allow accumulated heat to disperse. The other trick is to clamp something metallic (not always possible) to the exposed part of the pins on the top side of the board. This will take heat away from the pins and the chip. Another danger of too much heat is that the solder pads on the printed circuit board will eventually lift off the board. Socketing is much better than soldering. There should be a socket for just about any chip on the market. For small quantities, reasonable prices, and good selection, try: Digi-Key http://www.digikey.com/ 1-800-344-4539 (1-800-DIG-IKEY) The advantage of sockets is that a bad chip can be easily replaced. Whether you solder or socket, it is important to deal with electrostatic discharge (ESD)(static electricity). Many modern ICs can be easily destroyed by the static electricity that builds up on your body. They must be grounded until they are connected into a circuit board. The board should be grounded until it is installed and attached to a ground. While some chips will not be damaged, most electronics shops just treat all chips as if they will blow so that proper handling becomes second nature. The proper technique is to keep all chips in an ESD bag (commonly appears to be a dark translucent smoky green colour with a slight metallic reflectivity) until they are needed. Ground yourself using a proper electrostatic wrist strap and do your work on an electrostatic mat. Both the wrist strap and the mat must be grounded to be effective. Make sure you buy a proper wrist strap, rather than cobble something up yourself. They are pretty cheap, work well, and may save your life. They incorporate a 10 Megohm resistor between your wrist and ground to ensure that you are not electrocuted if you inadvertantly come in contact with a power source. Hope this helps, Ron Westfall westfall@...... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: mgray1@................ (Mike Gray) Subject: Re: A cry for help Date: Fri, 08 Nov 1996 15:09:45 -0600 >Todd Miller wrote: >> >> and my question is how easy is it to fry the IC's specifically op-amp 941's >> when I solder them? Are you supposed to solder them in fact, or is there a >> socket kit to use? What do you all recommend? If you used a soldering GUN, as many of us used back in the vacuum tube (valve) days, you probably literally fried the IC's. Even if you use a socket, you should use a small wattage soldering iron. Many members of this list are now groaning "duh!!!" However, from my experiences with dealing with people getting back in the hobby, one can not make basic assumptions. Mike Gray MO Bureau of Emergency Medical Services (Dept of Health) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie Thompson) Subject: Re: Convection Currents in Lehman sensor housing Date: Fri, 08 Nov 1996 17:41:50 -0600 I promised to report on my Lehman convection current problems here goes: The solution for me was actually quite simple (almost!). A small light bulb in the top of the box nails the problem completely! Only one additional small problem: Light escapes from the small cracks in my styrofoam box...flying insects...namely moths...home in on the light during the night. They get inside the box and start bumping the sensor. The result is magnitude 10 moth-induced events. My EVENTS directory has about 20 moth-induced events per night! Now I have to seal ALL cracks to keep the bugs out...not the air! I am optimistic that sealing the box with the bulb inside will bring the job to completion. I have a nice plot of the noise level changing as the bulb is turned on for 1 hour and then off again. Slowly but surely I'm getting there! My advice to all Lehman sensor owners would be USE A HEATER unless you have your sensor indoors in a controlled climate. -Charlie Thompson ct@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ken Navarre Subject: 12 bit A/D Date: Sat, 9 Nov 1996 07:54:48 -0800 (PST) Saw this on the newsgroups today. Just thought I'd pass it along. Haven't heard of these guys before so... Ken. Newsgroups: sci.geo.earthquakes Subject: $59 12-bit A/D for Seismometer Date: Fri, 08 Nov 1996 22:54:38 -0600 Organization: ADNAV Electronics The seismometer described in the April 1996 Scientific American "Amateur Scientist"