Subject: Re: Big Quake From: twleiper@........ Date: Sat, 1 Apr 2000 11:48:17 -0500 Did anybody get a good trace on the mag 8.9 KERMADEC ISLANDS REGION event this morning? __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: R: Big Quake From: "Francesco" franuc@...... Date: Sat, 1 Apr 2000 19:23:05 +0200 Kermadec big quake? 1st April fish..............? ehehehe __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Big Quake From: John Hernlund hernlund@....... Date: Sat, 01 Apr 2000 12:24:01 -0700 (MST) On Sat, 1 Apr 2000 twleiper@........ wrote: > Did anybody get a good trace on the mag 8.9 KERMADEC ISLANDS REGION event > this morning? I haven't checked anything yet, but I was unable to find any reference to this event on the web. An 8.9 will be picked up by EVERYONE on the entire planet very strongly. In fact, the Earth would be oscillating for days after such a strong event in the low frequency modes. You might also expect strong tsunamis and other damage. Are you certain it was 8.9??? Where can I find more info??? John Hernlund E-mail: hernlund@....... WWW: http://www.public.asu.edu/~hernlund/ ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Big Quake From: meredith lamb mlamb1@.......... Date: Sat, 01 Apr 2000 14:54:54 -0800 John Hernlund wrote: > On Sat, 1 Apr 2000 twleiper@........ wrote: > > Did anybody get a good trace on the mag 8.9 KERMADEC ISLANDS REGION event > > this morning? > > I haven't checked anything yet, but I was unable to find any reference to this > event on the web. An 8.9 will be picked up by EVERYONE on the entire planet > very strongly. In fact, the Earth would be oscillating for days after such a > strong event in the low frequency modes. You might also expect strong > tsunamis and other damage. Are you certain it was 8.9??? Where can I find > more info??? > > John Hernlund > E-mail: hernlund@....... > WWW: http://www.public.asu.edu/~hernlund/ > Well.....I certainly did....on my new "black hole seismograph". Unfortunately, its all theoretical as informatiion can't be retrieved.....but you can trust me here..... Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Big Quake From: Edward Cranswick cranswick@........ Date: Sat, 01 Apr 2000 15:06:22 -0700 Meredith- I understand you also recorded the recent M6.7 Parkfield earthquake on the same instrument. Would you like a job at the USGS? -Edward > Well.....I certainly did....on my new "black hole seismograph". > Unfortunately, its all theoretical as informatiion can't be > retrieved.....but you can trust me here..... > > Meredith Lamb -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Big Quake From: twleiper@........ Date: Sat, 1 Apr 2000 17:38:17 -0500 John - I believe it was very nearly identical in magnitude and location to a similar event last April 1st. On Sat, 01 Apr 2000 12:24:01 -0700 (MST) John Hernlund writes: > On Sat, 1 Apr 2000 twleiper@........ wrote: > > Did anybody get a good trace on the mag 8.9 KERMADEC ISLANDS > REGION event > > this morning? > > I haven't checked anything yet, but I was unable to find any > reference to this > event on the web. An 8.9 will be picked up by EVERYONE on the > entire planet > very strongly. In fact, the Earth would be oscillating for days > after such a > strong event in the low frequency modes. You might also expect > strong > tsunamis and other damage. Are you certain it was 8.9??? Where can > I find > more info??? > > John Hernlund > E-mail: hernlund@....... > WWW: http://www.public.asu.edu/~hernlund/ > > ************************************************************************* ***** > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Big Quake From: ChrisAtUpw@....... Date: Sat, 1 Apr 2000 18:18:54 EST Tom, You really will have to get something done about that Beech Tree of yours. Chris __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Big Quake From: meredith lamb mlamb1@.......... Date: Sat, 01 Apr 2000 20:39:08 -0800 Edward Cranswick wrote: > Meredith- > I understand you also recorded the recent M6.7 Parkfield earthquake on the same > instrument. Would you like a job at the USGS? > -Edward > > > Well.....I certainly did....on my new "black hole seismograph". > > Unfortunately, its all theoretical as informatiion can't be > > retrieved.....but you can trust me here..... > > > > Meredith Lamb > Edward, Hey thanks Edward! Have my own job ideas with Ur Seismic Guessing Service (USGS). Figure I could start my own department called JIVE; Just Invalid Variable Entrys. Good thing too.....its hell standing on a streetcorner with a placard. :) Meredith __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Big Quake From: John Hernlund hernlund@....... Date: Mon, 03 Apr 2000 02:22:37 -0700 (MST) On Sat, 1 Apr 2000 twleiper@........ wrote: > John - I believe it was very nearly identical in magnitude and location > to a similar event last April 1st. Yes, and I probably fell for that one too!!! And will again next year of course. Ever Gullible, John Hernlund E-mail: hernlund@....... WWW: http://www.public.asu.edu/~hernlund/ ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Cal Day at Berkeley University on 4/15/00 From: Larry Cochrane cochrane@.............. Date: Mon, 03 Apr 2000 13:25:28 -0700 Greeting, If you are in the SF Bay Area you might be interested in the open house at Berkeley Univ. The Seismo Lab will be open for tours and Professor Bruce Bolt will be giving a talk on "What Have the 1999 Earthquakes in Taiwan and Turkey Taught Us?". For more information see http://www.seismo.berkeley.edu/seismo/seismo.calday.html. Regards, Larry Cochrane Redwood City, PSN __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Geophone layout From: "Robert W. Avakian" ravakian@............ Date: Mon, 03 Apr 2000 19:00:56 -0500 So, how did things work out?? Bob Avakian Thomas wrote: > > Hi everyone, > > I am 4th year student working a project using geophones to measure ice > thicknes. Is there a special method to layout the geophones to get an > accurate profile an induced vibration? The purposal is to generate an > acoustic pulse through possibly several kilometers of ice and have the > geophones detect this pulse and derive the ice thickness. Would anyone have > suggestions on a detonation mechanism? I've heard people use 1 kg of > dynamite for 1 km of ice. > > As you can see, I am not too familiar with geophones but I do know they work > like an accelerator. If anyone knows of a good book, please suggest it > because none of our group members are geology people. > > Thanks alot for your time. > > Thomas Looi > Aerospace Engineering > University of Toronto > > _____________________________________________________________________ > > 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) Subject: Article on gravimeters From: George Bush gbush@....... Date: Tue, 04 Apr 2000 09:44:57 -0700 I just discovered an interesting article on the development of an absolute differential gravimeter that appeared in an unusual place. As a ametuer seismometer builder, I found the article fascinating to see what the big boys do. The article appeared in the March 2000 issue of "Laser Focus World," on pp20-24. For you non-subscribers the article can be seen on the web at: http://lfw.pennwellnet.com/home/articles.cfm?ARTICLE_ID=66006&VERSION_NUM=1& PUBLICATION_ID=12&Section=CurrentIssue Now I have had trouble emailing long URL's before, so if this isn't clickable, try to copy and paste it into the address box of your browser. And if that doesn't work you can go the the magazine's main web address http://lfw.pennwellnet.com/home/home.cfm and then select "current Issue" then World News" then the article "Interferometry, Fiber Coupling improves Gravimeters" George Bush Sea Ranch, CA, USA 38.74N, 123.5W __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Fwd: USGS: Geomagnetic Storm Alert From: The Lahrs JohnJan@........ Date: Thu, 06 Apr 2000 17:46:16 -0600 >------------- Begin Forwarded Message ------------- > >Date: Thu, 6 Apr 2000 18:01:09 -0400 >From: tharlow@........ >To: outreach@...................... >Subject: USGS: Geomagnetic Storm Alert > > >Media Advisory Address >U.S. Department of the Interior PO Box 25046, MS 150 >U.S. Geological Survey Denver, CO 80225 > > >Release Contact Phone E-mail >April 6, 2000 Don Herzog 303-273-8487 >herzog@........ >Geomagnetic Storm Alert > >The U.S. Geological Survey (USGS) reports a sudden increase in geomagnetic >activity that may signal the onset of a geomagnetic storm. While it is >geomagnetic storms that give rise to the beautiful Northern lights, they >can also pose a serious threat for commercial and military satellite >operators, power companies, astronauts, and they can even shorten the life >of oil pipelines in Alaska by increasing pipeline corrosion. > >A significant increase in geomagnetic activity was observed at about 12:45 >p.m. (E.T) on Thursday, April 6, 2000. Space Weather sources at NOAA & >NASA indicate that the likely cause of this increased activity is due to an >interplanetary shock wave that was detected by the ACE satellite at about >12:30 p.m. (E.T) today. Magnetic activity increased at all USGS magnetic >observatories about 15 minutes later and could be significant over the next >24-48 hours. If this geomagnetic activity continues, there is the >possibility for visible aurora at mid-latitudes. Plots of the data from >these observatories can be seen on-line at: >http://geomag.usgs.gov/frames/plots.htm > >Geomagnetic storms occur when plasma, a hot ionized gas of charged >particles produced by eruptions on the Sun, impacts the Earth's magnetic >field causing it to fluctuate wildly. These fluctuations cause currents to >flow in conductors on the ground and in space. Solar eruptions can produce >billions of tons of plasma traveling at speeds in excess of a million miles >an hour. > >The USGS provides valuable geomagnetic data to a wide variety of users and >organizations that are affected by geomagnetic storms. The agency operates >a network of 14 magnetic observatories that continuously monitor the >Earth's magnetic field. The data are collected in near-real time via >satellite to a downlink center located in Golden, Colo., and provided to >numerous customers including NOAA's Space Environment Center and the U.S. >Air Force Space Command Center. > >As the nation's largest water, earth and biological science, and civilian >mapping agency, the USGS works in cooperation with more than 2000 >organizations across the country to provide reliable, impartial, scientific >information to resource managers, planners, and other customers. This >information is gathered in every state by USGS scientists to minimize the >loss of life and property from natural disasters, to contribute to the >conservation and the sound economic and physical development of the >nation's natural resources, and to enhance the quality of life by >monitoring water, biological, energy, and mineral resources. > ### USGS ### > >This press release and in-depth information about USGS programs may be >found on the USGS home page: http://www.usgs.gov . To receive the latest >USGS news releases automatically by email, send a request to >listproc@................... . Specify the listserver(s) of interest from >the following names: water-pr; geologic-hazards-pr; biological-pr; >mapping-pr; products-pr; lecture-pr. In the body of the message write: >subscribe (name of listserver) (your name). Example: subscribe water-pr joe >smith. > > > >------------- End Forwarded Message ------------- * John C. and Jan H. Lahr * JohnJan@........ * 1925 Foothills Road * Golden, Colorado 80401-1718 * (303) 215-9913 * http://lahr.org/john-jan __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Fwd: Geomagnetic activity From: The Lahrs JohnJan@........ Date: Thu, 06 Apr 2000 17:47:27 -0600 >------------- Begin Forwarded Message ------------- >Date: Thu, 06 Apr 2000 16:22:41 -0600 >From: "Donald C. Herzog" >Subject: Geomagnetic activity > >April 6,2000 > >Team members: > >Sorry for the late notice, but we had a interplanetary shock wave hit late >this morning with an accompanying sharp increase in the solar wind >velocity, and a corresponding sharp increase in geomagnetic activity. The >magnetic field continues to be disturbed, and there could be aurora visible >at mid-latitudes tonight. > >Attached is a graphic showing the location of the aurora as of about 4 pm >local (Denver) time today. Red indicates intense auroral displays. You can >see that northern Russia and the Scandinavian countries are having auroral >sightings right now, and as it stands, it is likely that this will expand >into the northern US as we pass into the night. The best time for viewing >is around midnight, and look to the northern horizon. > >Don >------------- End Forwarded Message ------------- > >Content-Type: IMAGE/gif; name="aurora_040600.gif" >Content-Description: aurora_040600.gif >Content-MD5: EyEtFmyTyfY63dY31rP0lQ== > >Content-Type: TEXT/plain; name=NoName; charset=us-ascii >Content-Description: NoName >Content-MD5: oxOYuLYLDvySc7SuTsOAyg== > > >------------------------------------------------------- >Donald C. Herzog TEL: 303.273.8487 >U.S. Geological Survey FAX: 303.273.8600 >Box 25046 MS 966 herzog@................... >Denver Federal Center http://geomag.usgs.gov >Denver, CO 80225-0046 >USA * John C. and Jan H. Lahr * JohnJan@........ * 1925 Foothills Road * Golden, Colorado 80401-1718 * (303) 215-9913 * http://lahr.org/john-jan __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Wavelength of Surface Waves From: Paul Jebb pfjebb@.............. Date: Fri, 07 Apr 2000 15:00:58 -0400 Dear Members, I am trying to getting a feeling for the S- waves that our Lehman seismometer will detect. If the period of the boom must be adjusted to around 20 seconds or greater, what is the wavelength of these waves. My back-of-an-envelope estimate (v=fl) is in the order of 100 km. Is that reasonable? What is a typical amplitude for such a wave? Paul Jebb Newcomb Central School Dear Members,
I am trying to getting a feeling for the  S- waves that our Lehman seismometer will detect.  If the period of the boom must be adjusted to around 20 seconds or greater, what is the wavelength of these waves.  My back-of-an-envelope estimate (v=fl) is in the order of 100 km.  Is that reasonable?  What is a typical amplitude for such a wave?
Paul Jebb
Newcomb Central School Subject: Lehman Construction Questions... From: Brad Rogers rogers_psn@............. Date: 9 Apr 2000 07:23:30 -0700 I'm in the early stages of constructing a Lehman type seimometer, and have a few questions for the list.... Can anyone give me a good explaination of the tradeoffs involved between: 1) strength of the magnet used in the pickup on a Lehman seismometer, 2) the number of windings in the pickup coil, 3) the bit resolution of my A->D board? I have a 12 bit A->D board, and live in central New York state. Will I gain additional sensitivity by increasing the strength of the magnet used in the pickup? If I use a stronger magnet do I need to increase the number of windings in the coil? I have a couple magnet options, with one being a 24 pound pull, and the second being a 30 pound pull. The difference in cost is not great, but do I gain anything by using a stronger magnet? My second line of questioning is the construction of the boom. For teleseismic events I obviously want the longest period poss ible. Certainly the period can be lengthened by careful adjustment of the boom balance. But I'm also assuming that this delic ate balancing act can be simplified by: 1) slightly lengthening the boom, 2) getting the lead mass as close to the outside end of the boom as possible, and 3) putting the attachment point for the suspending wire as close to the outside end of the boom as possible. 4) I'm also assuming that I want to get the pickup coil as far out on the boom as possible, in order to increase its range of m otion. At least these things would seem to be intuitively true. Are they? Or am I missing something. Thanks, --Brad Rogers ____________________________________________________________________ For the largest MP3 index on the Web, go to http://mp3.altavista.com ____________________________________________________________________ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Lehman Construction Questions... From: Brad Rogers rogers_psn@............. Date: 9 Apr 2000 07:23:30 -0700 I'm in the early stages of constructing a Lehman type seimometer, and have a few questions for the list.... Can anyone give me a good explaination of the tradeoffs involved between: 1) strength of the magnet used in the pickup on a Lehman seismometer, 2) the number of windings in the pickup coil, 3) the bit resolution of my A->D board? I have a 12 bit A->D board, and live in central New York state. Will I gain additional sensitivity by increasing the strength of the magnet used in the pickup? If I use a stronger magnet do I need to increase the number of windings in the coil? I have a couple magnet options, with one being a 24 pound pull, and the second being a 30 pound pull. The difference in cost is not great, but do I gain anything by using a stronger magnet? My second line of questioning is the construction of the boom. For teleseismic events I obviously want the longest period poss ible. Certainly the period can be lengthened by careful adjustment of the boom balance. But I'm also assuming that this delic ate balancing act can be simplified by: 1) slightly lengthening the boom, 2) getting the lead mass as close to the outside end of the boom as possible, and 3) putting the attachment point for the suspending wire as close to the outside end of the boom as possible. 4) I'm also assuming that I want to get the pickup coil as far out on the boom as possible, in order to increase its range of m otion. At least these things would seem to be intuitively true. Are they? Or am I missing something. Thanks, --Brad Rogers ____________________________________________________________________ For the largest MP3 index on the Web, go to http://mp3.altavista.com ____________________________________________________________________ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: seis dynamic range From: S-T Morrissey sean@........... Date: Sun, 9 Apr 2000 14:56:04 -0500 (CDT) Paul, You correctly estimate of the wavelength of surface waves for a 20 second wave (0.05hz) with a velocity of 5 km/second as 100 km. (using v = f * l; or wavelength = velocity * period) Most people don't realize this. The longest waves seen are the fundamental free oscillations of the earth at 51 minutes, where the wavelength is the earths' circumference. Even near field P waves of 15 hz at 7.5 km/sec have wavelenghts of half a kilometer. You also asked about the dynamic range required of seismometers. Here is a repeat of a previous discussion on the subject. (August 99) The range of ground motions expected from earthquakes as recorded by a seismometer is hugh. Obviously if "you are there" at the fault scarp, you will need an accelerometer with a range up to 2gs. But most instrumental seismology follows general magnitude formulas of the classic form: M = log(A/T) + 1.66*log(distance) + constant. The constant is a regional variable, usually about -0.18. The distance is degrees (111 km per), A is the ground amplitude in nanometers, (a nanometer = 10^-9 meter; in older data it was called a millimicron.) and T is the period of the wave in seconds. For Ms calculations, A is the sustained peak-peak surface wave amplitude. You can plug in numbers for various scenarios. To answer your question about what will happen in the seismometer, solve for A: log(A/T) = Ms - 1.66*log(distance) + 0.18 A = T*log^-1(Ms -1.66*log(d) + 0.18.) The first step though is to convert the velocity output of the seismometer to displacement by dividing by omega, w = 2*pi/period. For the Turkey quake: the record here (St. Louis) was 150 microns/second at 24 seconds. 24 seconds is an w (omega) of 2*pi/24 = 0.262radian/sec. The velocity is converted to displacement by dividing by w, so 150/0.262 = 573 microns or 5.73x10^5 nanometers. (0.573 millimeters) (Every seismometer should have recorded this, and many clipped). So Ms = log(5.73x10^5/24) + 1.66*log(81deg) -0.18 = 7.37 (solving for A for a maximum magnitude of 8.0 at that distance would cause 2.46 millimeters of motion at St. Louis) But what did I record for the Ms = 5.8 aftershock? A = 24[log^-1(5.8 - 3.17 + 0.18) = 15 564 nanometers. (15.5 microns) This is a velocity (at 24 seconds) of 4.07 microns/second. With an output of 5.3mv/micron/sec, the record here was about 22 millivolts p-p, (or about 10 times the 6-second microseisms; at 0.5 microns p-p; at the time they were running more than 10 times that due to the hurricane). But what about a nearby quake? Say a Ms 4.0 in the next state? Putting numbers in the formula with distance = 3 degrees (200 miles) and T = 0.3 second, the seismometer will record 0.81 microns. For a magnitude 3, it will only sense 0.081 microns or 81 nanometers. (using the more accurate local Mblg(3hz) formula gives 43 nanometers) If M = 4 and is 1000km away, the motion at 1 second will be 398 nanometers. If M = 3 and is 1000km away, the motion at 1 second will be 40 nanometers. For a threshold event, say a 2.5 at 110 km with T = 0.22 sec (4.5hz), (this magnitude formula is revised for such local events, but we'll use it anyhow) the amplitude is 105 nanometers. (using the local Mblg formula gives 56 nanometers). To record these with useful signal-to-noise ratio requires a resolution of 1 nanometer from the seismometer. SO.... we need a displacement dynamic range of 1 nanometer to 1 millimeter, or 10^6. This is one reason seismometers prefer a velocity output. Looking at such numbers:. At 10 hz, 1 nanometer is 63nm/sec. At 1 hz, it is 6.3nm/sec. At 20 seconds (a broadband instrument) 1 millimeter is 314 microns/second. This is a velocity range of about 50 000 to 1, which is the same as the voltage output range. Until recently this range was difficult to handle with analog electronics, so multi-level recording was used. A 16-bit digitizer can realize this if noise is ignored. Providing for noise and instrumental drift increases the required range by a factor of 100 to 1000. So modern broadband stations use 24-bit digitizers with a resolution of 1 part on 16 777 216 with a least count value of 1.2 microvolts. For a seismometer with a VBB velocity output of 2000 volts/meter/second, the LSB represents 1.67 nanometers/sec. The maximum value is 10 millimeters/second p-p. Regards, Sean-Thomas __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: seis dynamic range From: "Kareem Lanier" kareemjupiter@............. Date: Sun, 9 Apr 2000 13:36:10 -0700 Paul, How do you get rid of all the local high-frequency noise? (My delimma) -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of S-T Morrissey Sent: Sunday, April 09, 2000 12:56 PM To: psn-l@.............. Subject: seis dynamic range Paul, You correctly estimate of the wavelength of surface waves for a 20 second wave (0.05hz) with a velocity of 5 km/second as 100 km. (using v = f * l; or wavelength = velocity * period) Most people don't realize this. The longest waves seen are the fundamental free oscillations of the earth at 51 minutes, where the wavelength is the earths' circumference. Even near field P waves of 15 hz at 7.5 km/sec have wavelenghts of half a kilometer. You also asked about the dynamic range required of seismometers. Here is a repeat of a previous discussion on the subject. (August 99) The range of ground motions expected from earthquakes as recorded by a seismometer is hugh. Obviously if "you are there" at the fault scarp, you will need an accelerometer with a range up to 2gs. But most instrumental seismology follows general magnitude formulas of the classic form: M = log(A/T) + 1.66*log(distance) + constant. The constant is a regional variable, usually about -0.18. The distance is degrees (111 km per), A is the ground amplitude in nanometers, (a nanometer = 10^-9 meter; in older data it was called a millimicron.) and T is the period of the wave in seconds. For Ms calculations, A is the sustained peak-peak surface wave amplitude. You can plug in numbers for various scenarios. To answer your question about what will happen in the seismometer, solve for A: log(A/T) = Ms - 1.66*log(distance) + 0.18 A = T*log^-1(Ms -1.66*log(d) + 0.18.) The first step though is to convert the velocity output of the seismometer to displacement by dividing by omega, w = 2*pi/period. For the Turkey quake: the record here (St. Louis) was 150 microns/second at 24 seconds. 24 seconds is an w (omega) of 2*pi/24 = 0.262radian/sec. The velocity is converted to displacement by dividing by w, so 150/0.262 = 573 microns or 5.73x10^5 nanometers. (0.573 millimeters) (Every seismometer should have recorded this, and many clipped). So Ms = log(5.73x10^5/24) + 1.66*log(81deg) -0.18 = 7.37 (solving for A for a maximum magnitude of 8.0 at that distance would cause 2.46 millimeters of motion at St. Louis) But what did I record for the Ms = 5.8 aftershock? A = 24[log^-1(5.8 - 3.17 + 0.18) = 15 564 nanometers. (15.5 microns) This is a velocity (at 24 seconds) of 4.07 microns/second. With an output of 5.3mv/micron/sec, the record here was about 22 millivolts p-p, (or about 10 times the 6-second microseisms; at 0.5 microns p-p; at the time they were running more than 10 times that due to the hurricane). But what about a nearby quake? Say a Ms 4.0 in the next state? Putting numbers in the formula with distance = 3 degrees (200 miles) and T = 0.3 second, the seismometer will record 0.81 microns. For a magnitude 3, it will only sense 0.081 microns or 81 nanometers. (using the more accurate local Mblg(3hz) formula gives 43 nanometers) If M = 4 and is 1000km away, the motion at 1 second will be 398 nanometers. If M = 3 and is 1000km away, the motion at 1 second will be 40 nanometers. For a threshold event, say a 2.5 at 110 km with T = 0.22 sec (4.5hz), (this magnitude formula is revised for such local events, but we'll use it anyhow) the amplitude is 105 nanometers. (using the local Mblg formula gives 56 nanometers). To record these with useful signal-to-noise ratio requires a resolution of 1 nanometer from the seismometer. SO.... we need a displacement dynamic range of 1 nanometer to 1 millimeter, or 10^6. This is one reason seismometers prefer a velocity output. Looking at such numbers:. At 10 hz, 1 nanometer is 63nm/sec. At 1 hz, it is 6.3nm/sec. At 20 seconds (a broadband instrument) 1 millimeter is 314 microns/second. This is a velocity range of about 50 000 to 1, which is the same as the voltage output range. Until recently this range was difficult to handle with analog electronics, so multi-level recording was used. A 16-bit digitizer can realize this if noise is ignored. Providing for noise and instrumental drift increases the required range by a factor of 100 to 1000. So modern broadband stations use 24-bit digitizers with a resolution of 1 part on 16 777 216 with a least count value of 1.2 microvolts. For a seismometer with a VBB velocity output of 2000 volts/meter/second, the LSB represents 1.67 nanometers/sec. The maximum value is 10 millimeters/second p-p. Regards, Sean-Thomas __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Lehman Construction Questions... From: BOB BARNS roybar@........ Date: Mon, 10 Apr 2000 10:39:43 -0400 Brad, About your questions about a Lehman: 1. The magnet-coil properties are not related to bit resolution. 16 bit resolution is better than 12 bit because of the greater dynamic range achieved. See Sean-Thomas discussion of the last few days about dynamic range. 2. The output of the coil is directly proportional to the strength of the magnet and the number of turns of the coil if the geometry is the same. Since gain in the amplifier is cheap, getting enough signal from the coil is rather easy if the geometry of the coil is appropriate for the magnet. 10,000 turns (pretty easy if #40 or finer wire is used) should be enough with a reasonable horse-shoe magnet. 3. There is no reason to balance the boom-the balance does not affect the period. The length of the period depends only on the geometry of the boom and its pivot points. Call the point of emergence of the suspension wire from the top support A and the pivot point at the end of the boom (the end opposite from the magnet or coil) B. The boom should be reasonably horizontal-say within +/- 10 deg. The period is determined by the angle between the vertical and the line between A and B. If the line A-B is vertical, the period is infinite, that is, there is no stable position for the boom. The period will be long (say 24 sec.) if the line A-B is slightly (say 0.25 deg.) inclined toward the far end of the boom. Since you are 'in central New York state', I am reasonably close-in Berkeley Heights, NJ, which is about 25 miles due west of Manhattan. You are welcome to come see my Lehman. If the above is not clear, I would be happy to discuss this on the 'phone 908-464-6785 any time. Bob Barns __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Wavelength of Surface Waves From: John Hernlund hernlund@....... Date: Mon, 10 Apr 2000 10:08:35 -0700 (MST) On Fri, 7 Apr 2000, Paul Jebb wrote: > Dear Members, > I am trying to getting a feeling for the S- waves that our Lehman > seismometer will detect. Do you mean surface waves or do you mean S-waves? These are two different concepts in that an S wave travels through the interior of a body while a surface wave travels along the surface of a body because of the way it snaps back when waves arrive at the edge. When an earthquake source occurs, waves are given off at many different frequencies and different amplitudes corresponding to each frequency. If you made a plot of the amplitude vs. the frequency of the source (the fourier transform) then you would see some type of specific shape. As the distance these waves travel increases, the amplitude vs. frequency plotted at each distance will begin to keel over to the right so that higher frequencies get lower and lower faster than lower frequencies do. If you use a logarithmic scale this tilt to the right should be like tilting a straight line. As the distance from the source increases then the straight line has a more negative slope. The shape of the initial amplitude vs. frequency plot is not know in general from the earthquake source. To simplify matters a little, we often use "impulse" sources in time. This is like a sharp hammer strike with a very short duration. So the activity on the fault itself would only have a spike if you looked at displacement vs. time. It turns out that the amplitude vs. frequency plot of an impulse source is a flat line where all the frequencies have the same amplitude. This means that the straight line will begin to tilt to the right as the waves travel away as described above. Now this scenario is simplified too much to account for everything that is seen in seismograms. So instead of using a single impulse, we can approximate the true source by adding a bunch of impulses that occur in different locations and at different times along the fault. In this way, a very accurate model can be made. So since we can model this source with a bunch of spikes, and we know how the magnitude vs. frequency changes over the distance travelled, you might have guessed that we can get a pretty accurate idea of what the actual seismogram should look like at any sight along the wave path. Because the amplitude-frequency is a fourier spectrum, you can perform an inverse fourier transform on it to see how the amplitude changes with time, which is what a seismogram is. These records are called synthetic seismograms, and can be used to compare with actual records to see how accurate your estimates for the source really are. There will be some variations in the real seismogram that cannot be accounted for by the source. These variations give you specific information about the material the waves travelled through. Also, the amount that the spectrum tilts to the right over a given distance is a measure of the "attenuation" of the wave. As you can imagine, people have come up with all kinds of line fitting methods to measure how much tilt has occurred. This is another way of mapping out the material the waves are passing through. Generally, hot materials attenuate more (tilt the frequency spectrum more per a given distance) than cool materials. This is because hot materials deform inelastically more easily than cool ones and take energy away from the seismic waves passing through them by rearranging some of their atoms. If you look in the literature, you can find a lot of interesting studies on this topic as well as maps of attenuation (also referred to a Q or quality factor, though high Q implies low attenuation). Indeed, you can take real seismograms and back up time to the initial source to get an estimate of what the real source actually looks like. This is a wonderful way to study active faults. You can tell where the most slip has occurred and even when it occurred. This has been done beautifully for the Taiwan earthquake. > If the period of the boom must be adjusted to around 20 seconds or greater, > what is the wavelength of these waves. My back-of-an-envelope estimate > (v=fl) is in the order of 100 km. Is that reasonable? Yes, this estimate always works, provided you know the velocity well enough. Mostly though, the velocity changes quite a bit in the intervening material, but again, this can also be measured by compiling many records from different locations. An interesting thing to think about is the way in which waves with different wavelength interact with objects they are passing through when the objects diameter is around the wavelength of the wave. If the diameter is much smaller, than the wave does not "see" the object other than its contribution to the mechanics of the whole interval. Higher frequencies can then see smaller objects, because the wavelength is shorter. But as waves travel, we have seen that the high frequencies die out. So what if this wave has travelled through the core? Then the shortest detectable wavelength is hundreds of kilometers, and no object smaller than that will be very detectable. This is a challenge for studying the structure and properties of the region just outside of the liquid outer core (also called D"). > What is a typical amplitude for such a wave? > Paul Jebb > Newcomb Central School Depends on the frequency... You get a blast of various frequencies, but the lower ones become most dominant as the distance travelled increases. This is probably more info than you needed, but perhaps it can explain how complicated the real world actually is and how we can use seismograms to explain it. John Hernlund E-mail: hernlund@....... WWW: http://www.public.asu.edu/~hernlund/ ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: seis dynamic range From: Karl Cunningham karlc@....... Date: Mon, 10 Apr 2000 22:40:32 -0700 Sean-Thomas -- Thanks for the repeat and your great description of displacement and velocity vs distance and magnitude. Do these equations still hold in the very near field? My reason for asking is that there is some blasting going on about 1/4 mile away and about 200 feet higher in elevation from here, and I would like to be able to take advantage of what I record to the greatest extent I can. I am recording in both velocity and acceleration, and I am going to increase the digitizing rate to 100sps. I can appreciate that the coefficients of the equations probably depend on what's below the surface (in this case granite, hence the blasting). Would I be able to see echos from nearby discontinuities? All comments are welcome. Karl __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: seis dynamic range From: Paul Jebb pfjebb@.............. Date: Tue, 11 Apr 2000 10:42:17 -0400 Thanks for that note Sean, Wow! A wavelength the size of the earth. Paul S-T Morrissey wrote: > Paul, > > You correctly estimate of the wavelength of surface waves for a > 20 second wave (0.05hz) with a velocity of 5 km/second as 100 km. > (using v = f * l; or wavelength = velocity * period) > Most people don't realize this. The longest waves seen are the > fundamental free oscillations of the earth at 51 minutes, where the > wavelength is the earths' circumference. Even near field P waves > of 15 hz at 7.5 km/sec have wavelenghts of half a kilometer. > > You also asked about the dynamic range required of seismometers. > Here is a repeat of a previous discussion on the subject. (August 99) > > The range of ground motions expected from earthquakes as recorded > by a seismometer is hugh. Obviously if "you are there" at the fault > scarp, you will need an accelerometer with a range up to 2gs. > > But most instrumental seismology follows general magnitude formulas > of the classic form: > M = log(A/T) + 1.66*log(distance) + constant. > The constant is a regional variable, usually about -0.18. The distance > is degrees (111 km per), A is the ground amplitude in nanometers, > (a nanometer = 10^-9 meter; in older data it was called a millimicron.) > and T is the period of the wave in seconds. For Ms calculations, > A is the sustained peak-peak surface wave amplitude. > > You can plug in numbers for various scenarios. To answer your question > about what will happen in the seismometer, solve for A: > log(A/T) = Ms - 1.66*log(distance) + 0.18 > A = T*log^-1(Ms -1.66*log(d) + 0.18.) > > The first step though is to convert the velocity output of the seismometer > to displacement by dividing by omega, w = 2*pi/period. > > For the Turkey quake: the record here (St. Louis) was 150 microns/second > at 24 seconds. 24 seconds is an w (omega) of 2*pi/24 = 0.262radian/sec. > The velocity is converted to displacement by dividing by w, so > 150/0.262 = 573 microns or 5.73x10^5 nanometers. (0.573 millimeters) > (Every seismometer should have recorded this, and many clipped). > > So Ms = log(5.73x10^5/24) + 1.66*log(81deg) -0.18 = 7.37 > > (solving for A for a maximum magnitude of 8.0 at that distance would > cause 2.46 millimeters of motion at St. Louis) > > But what did I record for the Ms = 5.8 aftershock? > > A = 24[log^-1(5.8 - 3.17 + 0.18) = 15 564 nanometers. (15.5 microns) > > This is a velocity (at 24 seconds) of 4.07 microns/second. > With an output of 5.3mv/micron/sec, the record here was about 22 > millivolts p-p, (or about 10 times the 6-second microseisms; at 0.5 > microns p-p; at the time they were running more than 10 times that due to > the hurricane). > > But what about a nearby quake? Say a Ms 4.0 in the next state? Putting > numbers in the formula with distance = 3 degrees (200 miles) and > T = 0.3 second, the seismometer will record 0.81 microns. For a > magnitude 3, it will only sense 0.081 microns or 81 nanometers. > (using the more accurate local Mblg(3hz) formula gives 43 nanometers) > > If M = 4 and is 1000km away, the motion at 1 second will be 398 nanometers. > If M = 3 and is 1000km away, the motion at 1 second will be 40 nanometers. > > For a threshold event, say a 2.5 at 110 km with T = 0.22 sec (4.5hz), > (this magnitude formula is revised for such local events, but we'll > use it anyhow) the amplitude is 105 nanometers. (using the local > Mblg formula gives 56 nanometers). To record these with useful > signal-to-noise ratio requires a resolution of 1 nanometer from > the seismometer. > > SO.... we need a displacement dynamic range of 1 nanometer to 1 > millimeter, or 10^6. This is one reason seismometers prefer a velocity > output. Looking at such numbers:. > At 10 hz, 1 nanometer is 63nm/sec. At 1 hz, it is 6.3nm/sec. At 20 > seconds (a broadband instrument) 1 millimeter is 314 microns/second. > This is a velocity range of about 50 000 to 1, which is the same as > the voltage output range. > > Until recently this range was difficult to handle with analog > electronics, so multi-level recording was used. A 16-bit digitizer > can realize this if noise is ignored. Providing for noise and > instrumental drift increases the required range by a factor of > 100 to 1000. So modern broadband stations use 24-bit digitizers > with a resolution of 1 part on 16 777 216 with a least count value > of 1.2 microvolts. For a seismometer with a VBB velocity output of > 2000 volts/meter/second, the LSB represents 1.67 nanometers/sec. > The maximum value is 10 millimeters/second p-p. > > Regards, > Sean-Thomas > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: seis dynamic range From: Paul Jebb pfjebb@.............. Date: Tue, 11 Apr 2000 10:51:52 -0400 Kareem, I'm not sure, but I have a game plan for my set-up. We are still making mechanical adjustments. Larry Cochrane suggested that I control the time for the boom to die-back after a disturbance (move the boom 1 cm by hand or blowing on the boom) by changing the volume of oil surrounding the damper. A wave should die-out within a second (Larry Cochrane). I also have a gain control on my amplifier that we have to fiddle with. If you get any insights, please let me know Kareem. Paul Kareem Lanier wrote: > Paul, > How do you get rid of all the local high-frequency noise? (My delimma) > > -----Original Message----- > From: psn-l-request@.............. [mailto:psn-l-request@............... > On Behalf Of S-T Morrissey > Sent: Sunday, April 09, 2000 12:56 PM > To: psn-l@.............. > Subject: seis dynamic range > > Paul, > > You correctly estimate of the wavelength of surface waves for a > 20 second wave (0.05hz) with a velocity of 5 km/second as 100 km. > (using v = f * l; or wavelength = velocity * period) > Most people don't realize this. The longest waves seen are the > fundamental free oscillations of the earth at 51 minutes, where the > wavelength is the earths' circumference. Even near field P waves > of 15 hz at 7.5 km/sec have wavelenghts of half a kilometer. > > You also asked about the dynamic range required of seismometers. > Here is a repeat of a previous discussion on the subject. (August 99) > > The range of ground motions expected from earthquakes as recorded > by a seismometer is hugh. Obviously if "you are there" at the fault > scarp, you will need an accelerometer with a range up to 2gs. > > But most instrumental seismology follows general magnitude formulas > of the classic form: > M = log(A/T) + 1.66*log(distance) + constant. > The constant is a regional variable, usually about -0.18. The distance > is degrees (111 km per), A is the ground amplitude in nanometers, > (a nanometer = 10^-9 meter; in older data it was called a millimicron.) > and T is the period of the wave in seconds. For Ms calculations, > A is the sustained peak-peak surface wave amplitude. > > You can plug in numbers for various scenarios. To answer your question > about what will happen in the seismometer, solve for A: > log(A/T) = Ms - 1.66*log(distance) + 0.18 > A = T*log^-1(Ms -1.66*log(d) + 0.18.) > > The first step though is to convert the velocity output of the seismometer > to displacement by dividing by omega, w = 2*pi/period. > > For the Turkey quake: the record here (St. Louis) was 150 microns/second > at 24 seconds. 24 seconds is an w (omega) of 2*pi/24 = 0.262radian/sec. > The velocity is converted to displacement by dividing by w, so > 150/0.262 = 573 microns or 5.73x10^5 nanometers. (0.573 millimeters) > (Every seismometer should have recorded this, and many clipped). > > So Ms = log(5.73x10^5/24) + 1.66*log(81deg) -0.18 = 7.37 > > (solving for A for a maximum magnitude of 8.0 at that distance would > cause 2.46 millimeters of motion at St. Louis) > > But what did I record for the Ms = 5.8 aftershock? > > A = 24[log^-1(5.8 - 3.17 + 0.18) = 15 564 nanometers. (15.5 microns) > > This is a velocity (at 24 seconds) of 4.07 microns/second. > With an output of 5.3mv/micron/sec, the record here was about 22 > millivolts p-p, (or about 10 times the 6-second microseisms; at 0.5 > microns p-p; at the time they were running more than 10 times that due to > the hurricane). > > But what about a nearby quake? Say a Ms 4.0 in the next state? Putting > numbers in the formula with distance = 3 degrees (200 miles) and > T = 0.3 second, the seismometer will record 0.81 microns. For a > magnitude 3, it will only sense 0.081 microns or 81 nanometers. > (using the more accurate local Mblg(3hz) formula gives 43 nanometers) > > If M = 4 and is 1000km away, the motion at 1 second will be 398 nanometers. > If M = 3 and is 1000km away, the motion at 1 second will be 40 nanometers. > > For a threshold event, say a 2.5 at 110 km with T = 0.22 sec (4.5hz), > (this magnitude formula is revised for such local events, but we'll > use it anyhow) the amplitude is 105 nanometers. (using the local > Mblg formula gives 56 nanometers). To record these with useful > signal-to-noise ratio requires a resolution of 1 nanometer from > the seismometer. > > SO.... we need a displacement dynamic range of 1 nanometer to 1 > millimeter, or 10^6. This is one reason seismometers prefer a velocity > output. Looking at such numbers:. > At 10 hz, 1 nanometer is 63nm/sec. At 1 hz, it is 6.3nm/sec. At 20 > seconds (a broadband instrument) 1 millimeter is 314 microns/second. > This is a velocity range of about 50 000 to 1, which is the same as > the voltage output range. > > Until recently this range was difficult to handle with analog > electronics, so multi-level recording was used. A 16-bit digitizer > can realize this if noise is ignored. Providing for noise and > instrumental drift increases the required range by a factor of > 100 to 1000. So modern broadband stations use 24-bit digitizers > with a resolution of 1 part on 16 777 216 with a least count value > of 1.2 microvolts. For a seismometer with a VBB velocity output of > 2000 volts/meter/second, the LSB represents 1.67 nanometers/sec. > The maximum value is 10 millimeters/second p-p. > > Regards, > Sean-Thomas > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: My Seismometer From: "Darren Lamison-White" DLamisonWhite@............. Date: Tue, 11 Apr 2000 11:18:05 -0400 Hello My name is Darren Lamison-White. I am in the 8th grade my = seismometer has won first place in the junior division of the County = Science Fair=20 If you have anything else to say E-mail me at DLamisonWhite@.............
Hello My name is = Darren=20 Lamison-White. I am in the 8th grade my seismometer has won first place = in the=20 junior division of the County Science Fair
If you have = anything else to=20 say E-mail me at
DLamisonWhite@.............
Subject: Re: My Seismometer From: Paul Jebb pfjebb@.............. Date: Tue, 11 Apr 2000 11:44:43 -0400 Hey Darren, Congratulations! Good job on the first place finish! We are building a seismic station at our school here in the Adirondack mountains in central New York state. We haven't caught any quakes yet, but we will. Cheers, Paul Jebb Newcomb Central School Science Teacher Darren Lamison-White wrote: > Part 1.1 Type: Plain Text (text/plain) > Encoding: quoted-printable __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Filtering local noise From: S-T Morrissey sean@........... Date: Tue, 11 Apr 2000 22:20:45 -0500 (CDT) Paul and Kareem have brought up a question that has not been explicitly discussed, namely what to do about short period local or "cultural" noise. Seismology would be a lot easier sport if we didn't have to put up with ourselves and the noises of civilization. This includes everything from the dogs romping through the house, the school bus or Mack trucks on the street, and the freeway a kilometer away. This is why professional seismic stations are hidden in remote underground vaults rather than basements. Such noise has generally been dealt with by using low-pass active analog filters in the output of the seismometer. If a digitizer is used, its input circuitry probably includes a measure of "anti-aliasing" filtering, where the filter period is set to twice the sample interval. (A 10 hz waveform is minimally sampled by a 20 hz digitizer, which would then require a 10 hz low pass anti-alias filter.) For analog recording, the cosmetic appearance of the record becomes the determining factor. You cannot see the small P-wave if the record is full of noise bursts from passing cars. So the idea is to try to reduce the cultural noise to about the same level as longer period noises such as from tilting of the base of a horizontal or atmospheric pressure (vertical). Some amount of short period noise assures that the instrument is working. Also, the 6-second microseisms should be present. (this is true even for a long period sensor, not necessarily a broadband) So it is a matter of customizing the filters to the site. For my monitor here of the leaf spring vertical operating at 90 seconds, I use a 6-second passive notch filter to reduce the microseisms by about 100, and about 6 poles of low pass filtering the cut the traffic noise. I set the gain so I still see the local traffic noise at peaks of about a mm, the microseisms when there is a storm, and barometric noise of storms of 10 minutes period or more, while not having a record that is too messy. For utilizing low pass filters, simple one pole series resistor, shunt capacitor combinations can be used prior to almost any amplifier stage. More formal 2 and 4 pole active filters are generally employed. The preferred response is the uniform phase delay of the Bessel configuration. In a typical seismic system, the pre-amplifier at the seismometer usually has two two-pole filters at a net cutoff of about 20 hz, which is more than adequate for local short period instruments. The schematic of this preamplifier is on the web site. The filter is easily changed form 20 hz to 2 hz by using 10x the values of 4 resistors for use with broader response long period sensors. (This filter can be built with regular amplifiers like the LM308 if it doesn't have to be battery powered.) Additional filtering is found in the output of the telemetry discriminator (if used) and the digitizer input. Again, a phase linear response is used at about 20 hz for short period sensors like the L4-C, and 2 hz for a long period sensor. Most analog recorders provide several poles of additional, often switch selectable, filtering. Here one can play the tradeoffs of increasing the gain while lowering the frequency response to make the best of the cultural noise problem. I have seen some of the schematics suggested for use with the Lehman and SG designs, and they do include a measure of low pass filtering, even if it is scattered about. A more focused filter arrangement would be preferable. On the other hand, I see a number of amplifiers with a high value feedback resistor (for high gain) that is not bypassed with a capacitor to limit the gain at the noise frequencies. Since all our amplifiers operate at frequencies from DC to a few hz at most, we should be careful that higher frequencies, which are still sub-audio, are not amplified. Regards, Sean-Thomas __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: My Seismometer From: "steve hammond" shammon1@............. Date: Wed, 12 Apr 2000 22:47:00 -0700 Way to go Darren-- If you have a digital picture and more details, I = would be honored to post the information on the PSN web site in San = Jose, California http://pw2.netcom.com/~shammon1/psnsj.htm with other = PSN related information. Regards, Steve Hammond PSN San Jose, Aptos, California=20 -----Original Message----- From: Darren Lamison-White To: psn-l@.............. Date: Tuesday, April 11, 2000 8:19 AM Subject: My Seismometer =20 =20 Hello My name is Darren Lamison-White. I am in the 8th grade my = seismometer has won first place in the junior division of the County = Science Fair=20 If you have anything else to say E-mail me at DLamisonWhite@.............
Way to = go Darren-- If=20 you have a digital picture and more details, I would be honored to post = the=20 information on the PSN web site in San Jose, California http://pw2.netcom.com/= ~shammon1/psnsj.htm=20 with other PSN related information.
Regards, = Steve Hammond=20 PSN San Jose, Aptos, California 
-----Original = Message-----
From:=20 Darren Lamison-White <DLamisonWhite@.............>
To:=20 psn-l@.............. = <psn-l@..............>
D= ate:=20 Tuesday, April 11, 2000 8:19 AM
Subject: My=20 Seismometer

Hello My name = is Darren=20 Lamison-White. I am in the 8th grade my seismometer has won first = place in=20 the junior division of the County Science Fair
If you have = anything else=20 to say E-mail me at
DLamisonWhite@.............
Subject: mail From: john c cole johnccole@........ Date: Tue, 18 Apr 2000 06:15:16 -0500 Gentlemen For some reason I no longer get mail . I recently upgraded Juno . Could you put me back on? Thanks -- johnccole@........ ________________________________________________________________ YOU'RE PAYING TOO MUCH FOR THE INTERNET! Juno now offers FREE Internet Access! Try it today - there's no risk! For your FREE software, visit: http://dl.www.juno.com/get/tagj. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Filtering local noise From: "Tom Schmitt" tschmitt@.............. Date: Tue, 18 Apr 2000 08:46:38 -0400 This is a very late comment on the local noise question. In exploration seismic work geophone arrays were used to filter local noise. The signals from several geophnes would be summed. The noise would be out of phase at the geophones but the signal would be in phase. In reflection work that assumption is more justified than in earthquake or refraction seismology as in reflection the signal is coming more or less straight up. Has this ever been used in earthquake seismology? The usual answer to noise is a quiet location but with educational seismometers rather than research seismometers, location near the classroom is important. Second. There is a new chip that is up to a 6 pole analog filter. The configuration of the filter is set in a device similar to an EPROM burner. The software that comes with it has full design features such as simulation of amplitude and phase. Unfortunately I threw the flier away but I am trying to find the manufacturer through other channels. This could be helpful in designing filters for local noise. If anyone knows the web site of the manufacturer please let me know. I will continue to try to find it by other sources, Tom Schmitt tschmitt@.............. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Filtering local noise From: Karl Cunningham karlc@....... Date: Tue, 18 Apr 2000 08:19:24 -0700 Tom -- My $0.02... I don't think this is the filter you were using, but Maxim has a family of filters that don't need to be programmed but use an external clock to set the cutoff frequency. Often, the cutoff is 100:1 lower in frequency than the clock. There is very little attenuation at the clock frequency, so a simple analog filter is needed too. See http://dbserv.maxim-ic.com/pl_list.cfm?filter=f I can say about the ones you were using, but one problem with integrated filters such as Maxim's is drift and low-frequency noise. In these filters, the signal path goes through the IC. Some integrated filters are designed so that they are in parallel with and shunt a signal source to effect the desired filtering. That takes care of the drift problem but not the low-frequency noise. Karl At 08:46 AM 4/18/2000 -0400, you wrote: >Second. There is a new chip that is up to a 6 pole analog filter. The >configuration of the filter is set in a device similar to an EPROM burner. >The software that comes with it has full design features such as simulation >of amplitude and phase. Unfortunately I threw the flier away but I am >trying to find the manufacturer through other channels. This could be >helpful in designing filters for local noise. If anyone knows the web site >of the manufacturer please let me know. I will continue to try to find it >by other sources, __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: filter on ebay From: BOB BARNS roybar@........ Date: Wed, 19 Apr 2000 09:43:03 -0400 Hi gang, ebay (#308130108) has a Rockland Model 452 Dual Hi/Lo filter. The auction ends 4/20 and the current bid is $39. I don't know what frequency range this model covers. Bob Barns __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: preamplifier filter From: S-T Morrissey sean@........... Date: Thu, 20 Apr 2000 02:02:22 -0500 (CDT) To Cap and others who asked: The schematic of the seismic preamplifier with the 4-pole low pass Bessel filter can be found at: http://www.eas.slu.edu/People/STMorrissey/index.html under the section: stmmisc.html "PSN INFO ... SLU Seismic Network" I had previously posted the old 1980 pencil drawing, but about a year ago I redrew it and updated some details. I just got around to scanning the new drawing to the web page. regards, Sean-Thomas __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Filtering local noise From: ChrisAtUpw@....... Date: Thu, 20 Apr 2000 20:04:18 EDT Dear Tom Schmitt, You wrote :- > In exploration seismic work geophone arrays were used to filter local noise. > The signals from several geophones would be summed. The noise would be out > of phase at the geophones but the signal would be in phase. In reflection > work that assumption is more justified than in earthquake or refraction > seismology as in reflection the signal is coming more or less straight up. > Has this ever been used in earthquake seismology? Your letter raises several questions. How many and how widely spaced locations were you proposing for your recording stations? The wavelength of earthquake waves is likely to be VERY long when compared to explosive sounding signals / environmental noise and what you actually record at a particular site is effected by the wave path, which may have different properties from different directions. > The usual answer to noise is a quiet location but with > educational seismometers rather than research > seismometers, location near the classroom is important. If you can use your many observers to identify the various man made noise sources, there is no reason in principle why you should not place an auxiliary sensor(s) closer to sources and feed the relatively strong interfering signals back to provide compensation, but don't expect a perfect match. It is easier to do this using digital delays, rather than analogue delay lines. Can you record an environmental noise channel to help in identification and the seismograph channel? Could the identification / characterisation / avoidance of local sources be a worthwhile project? If the local noise is terrible, could you get on line data from some quiet location for your 'real earthquakes' and use your local set-up as a teaching / backup aid? > Second. There is a new chip that is up to a 6 pole analogue filter. The > configuration of the filter is set in a device similar to an EPROM burner. > The software that comes with it has full design features such as simulation > of amplitude and phase. Filters of this type are produced for use in hearing aids, to vary the audio characteristics over a wide band. In your application, it is probably better to use four pole Bessel filters, which are relatively easy and cheap to make with a couple of OPAs. When you go to six pole filters, the delay can get rather long. You may find that shifting the corner frequency downwards just a bit is actually preferable to adding more filter stages. If you have a two channel recording system, could you use it to compare the simultaneous results of various filter choices? If you initially use 'plug in' breadboard (with silver plated contacts), you can easily change the filter characteristics. Regards, Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Filtering local noise From: "Tom Schmitt" tschmitt@.............. Date: Fri, 21 Apr 2000 09:00:22 -0400 ----- Original Message ----- From: To: Sent: Thursday, April 20, 2000 8:04 PM Subject: Re: Filtering local noise Dear Chris Thank you for your comments. I have left my original and your comments in this to make it easier to read. It is thus long and I apologize for that. > Dear Tom Schmitt, > > You wrote :- > > > In exploration seismic work geophone arrays were used to filter local > noise. > > The signals from several geophones would be summed. The noise would be out > > of phase at the geophones but the signal would be in phase. In reflection > > work that assumption is more justified than in earthquake or refraction > > seismology as in reflection the signal is coming more or less straight up. > > Has this ever been used in earthquake seismology? > > Your letter raises several questions. How many and how widely spaced > locations were you proposing for your recording stations? The wavelength of > earthquake waves is likely to be VERY long when compared to explosive > sounding signals / environmental noise and what you actually record at a > particular site is effected by the wave path, which may have different > properties from different directions. Well first I was hoping that one of the academic seismologists would answer with (1) that's impossable or (2) here is how to do it. Lacking that clear guidance :-) I will attempt some speculations. The period of the earthuakes is very long but the period of local noise is very short. If I remember Sean-Thomas was talking about 100 HZ notch filters to remove the local noise. At 5 km/sec for surface material and a frequency of 100hz the wavelength is 50 meters. Considering a wave propigating only in the x-z plane, and a seismometer located at 0,0 a second seismometer located at 25,0 would be 180 degrees out of phase for a 100 hz signal. Summing the two signals would result in zero ( minus the attenuation over 25 meters and local effects). > > > The usual answer to noise is a quiet location but with > > educational seismometers rather than research > > seismometers, location near the classroom is important. > > If you can use your many observers to identify the various man made noise > sources, there is no reason in principle why you should not place an > auxiliary sensor(s) closer to sources and feed the relatively strong > interfering signals back to provide compensation, but don't expect a perfect > match. It is easier to do this using digital delays, rather than analogue > delay lines. Can you record an environmental noise channel to help in > identification and the seismograph channel? Could the identification / > characterisation / avoidance of local sources be a worthwhile project? If the > local noise is terrible, could you get on line data from some quiet location > for your 'real earthquakes' and use your local set-up as a teaching / backup > aid? > The noise is usually diffuse in origin, thus having sensor near the noise probably will not work. The idea is to have enough sesors out there that the sum of them at any given time covers an intergal number of wave lengths of the noise. The sum is then zero. Since the signal is a much longer wave length it is not reduced by the summing. It would be prohibitively expensive to do this with long periond seismometers but your idea of noise monitors is good. One might be able to use exploration geopones to get the "noise", high pass those signals and sum them with the seismometer and reduce the noise. The news broadcsasters often use a second noise canceling microphone in noisey environments. The only reason for this is cosmetic or to look at local events. Also exploration work is much simpler in that one knows the source and noise characteristics better. Also that was an old technique in exploration, with vibroseis@ they may not have to do it any more. Also a quiet beats filtering any day. > > Second. There is a new chip that is up to a 6 pole analogue filter. The > > configuration of the filter is set in a device similar to an EPROM burner. > > The software that comes with it has full design features such as simulation > > of amplitude and phase. > > Filters of this type are produced for use in hearing aids, to vary the > audio characteristics over a wide band. In your application, it is probably > better to use four pole Bessel filters, which are relatively easy and cheap > to make with a couple of OPAs. When you go to six pole filters, the delay can > get rather long. You may find that shifting the corner frequency downwards > just a bit is actually preferable to adding more filter stages. If you have a > two channel recording system, could you use it to compare the simultaneous > results of various filter choices? If you initially use 'plug in' breadboard > (with silver plated contacts), you can easily change the filter > characteristics. > > Regards, > > Chris Chapman > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. I am going to send this whole thing to one of my academic friends to see what he says. I suspect some of these tricks might have been used in the good old days when we were monitoring the nuclear detonations of the former Soviet Union. There were some very long dedicated arrays focused to specific points in Asia. I do not have a machine right now, I hope to have one by the end of the Summer as I want that as a Summer science project for my daughters. I am working on a computer interface now. We live in a noisy environment which is why Sean Thomas' comments hit home. Thank you Tom Schmitt tschmitt@.............. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: seismic arrays From: S-T Morrissey sean@........... Date: Fri, 21 Apr 2000 15:03:35 -0500 (CDT) Tom, Chris, and company, You are quite correct in surmising that very sensitive arrays were deployed during the cold war to monitor Soviet nuclear tests. These had as many as 100 sensors in deep boreholes, with sensor spacings of kilometers or more. They could "beam" their sensitivity by summing the output of sensors with a time delay appropriate to the velocity of the propagation of the seismic wave across the array. Most of the science was top secret, run by the Air Force Geophysics Program (AFTAC), with the university involvement through ARPA (Advanced Research Projects Agency of DOD), and AFOSR (Air Force Office of Scientific Research). Some known installations were in Montana (the LASA: Large Aperture Seismic Array), at Yellowknife in central Canada, Grafenburg in Germany, and NORSAR in Norway. In a minimal example of how they worked, three sensors are aligned north , middle, and south , and a suspected test site in Kazakhstan is the source of a 1-second seismic pulse. The wavefront is lost in the noise as it passes the north sensor, but the array sensitivity is "tuned" to a velocity of a 1-second compressional wave (8 km/sec) propagating from the north. So the data from the north sensor is delayed by the appropriate time and then summed with the center seismometer data. This is repeated for the south sensor. Since the noise of each site is random, the summed signals increase the seismic wave amplitude by three times over the noise. Obviously much more improvement is made as more sensors are summed. And sensors along an arc at a constant radial distance from the source can be summed without any delays. So array geometry became a hot topic. Fortunately nuclear tests sites are difficult to move around or hide completely from satellites. This method makes many assumptions about wave paths, etc., and in the early '70s days of analog tape recorders, filters, and oscilloscopes, it was difficult to work with delays as large as a second. Digital analysis with analog triggers followed, and of course it is all digital now. As the arrays have been upgraded, the surplus scene has been flooded with used HS-10 seismometers, which were originally installed in 30 to 100 meter boreholes. Now the whole world is an array with the installation of several hundred broadband digital stations, with the focus of a major part of the newest instrumentation being verification of compliance with the CTBT (Comprehensive Test Ban Treaty). So arrays are not everyman's way to improve the signal to noise ratio. But, as they say, location is everything. Short period noise, like traffic, is generally outside our interest (is above 10hz), or attenuates rapidly, so 100 meters can make a big difference. But cultural noise generally does not interfere with 1 second and longer waves, so sharp filtering at the seismometer and/or at the recorder is very beneficial. From the VBB vertical seis in the basement here, I routinely see the 20 to 40 second surface waves of anything above a 5.5 that NEIS lists. But even with considerable filtering at 10 hz, I still recorded the Mblg 3.7 near Indianapolis on April 14, a distance of about 300 km from St. Louis. It did help that it was at night, after the local noise subsided. Regards, Sean-Thomas __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: seismic arrays From: Tobin Fricke tobin@....... Date: Fri, 21 Apr 2000 13:26:12 -0700 (PDT) My summer project last summer concerned seismic arrays in Alaska. As part of my project I wrote a program that takes the data from array stations and performs the "beamforming" process, outputting a slowness vector for the incident wavefield. If anyone's interested.. talk to me. Tobin __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Filtering local noise From: John Hernlund hernlund@....... Date: Sun, 23 Apr 2000 01:45:07 -0700 (MST) On Fri, 21 Apr 2000, Tom Schmitt wrote: > > > In exploration seismic work geophone arrays were used to filter local > > noise. > > > The signals from several geophones would be summed. The noise would be > out > > > of phase at the geophones but the signal would be in phase. In > reflection > > > work that assumption is more justified than in earthquake or refraction > > > seismology as in reflection the signal is coming more or less straight > up. > > > Has this ever been used in earthquake seismology? This technique is used in many variations. The buzz word for these types of techniques is "stacking" the data. For data on a single phase for many records you can average them, and because the noise is random it will be reduced. According to the mean value theorem of statistics, the noise should totally disappear as you average an infinite number of records. This is not, of course, possible, but the more the better. One of the cool things being done with stacking these days is to measure PP and SS precursors. These are the small reflections off the discontinuities in the Earth occurring at 670, 500 and 410 km depths which are interesting to study in terms of mineral phase transitions. A small part of the energy of the waves is reflected off these before the PP hits the surface, which is almost precisely between the quake location and the seismograph station. The result is a little wiggle one the seismogram just before the arrival of the main SS or PP phase. These are often too small to be seen for an individual event. By stacking enough seismograms for given "bounce points" the topography of these features can be mapped out really well. Also, the amplitude of the bumps tells you about the impedance of the boundary, which is useful in finding out what material change is occurring to produce it. > > Your letter raises several questions. How many and how widely spaced > > locations were you proposing for your recording stations? The wavelength > of > > earthquake waves is likely to be VERY long when compared to explosive > > sounding signals / environmental noise and what you actually record at a > > particular site is effected by the wave path, which may have different > > properties from different directions. > > Well first I was hoping that one of the academic seismologists would answer > with (1) that's impossable > or (2) here is how to do it. Lacking that clear guidance :-) I will attempt > some speculations. > > The period of the earthuakes is very long but the period of local noise is > very short. If I remember Sean-Thomas was talking about 100 HZ notch > filters to remove the local noise. At 5 km/sec for surface material and a > frequency of 100hz the wavelength is 50 meters. Considering a wave > propigating only in the x-z plane, and a seismometer located at 0,0 a second > seismometer located at 25,0 would be 180 degrees out of phase for a 100 hz > signal. Summing the two signals would result in zero ( minus the > attenuation over 25 meters and local effects). Correct, but you have many different frequencies to deal with. If the stations get too far apart, then the seismic waves will hit each one at a generally different time and phase. This can be dealt with using some fairly simple mathematics... The bottom line is that the detail of an object or structure you want to look at is never greater than the station spacing for a single teleseismic earthquake. Many earthquakes increase the resolution with all of the paths, but the rays that hit the seismometer are still travelling at a nearly vertical angle and the stations are far apart. Recent work has begun to develop using noise more creatively. For instance, atmospheric noise excites some of the Earth's free modes, and this can be very useful for some types of work. There are all kinds of cool numerical tricks for playing with this stuff. But if you just want a decent-looking seismogram for a teleseismic event then simply low-pass it... > > > The usual answer to noise is a quiet location but with > > > educational seismometers rather than research > > > seismometers, location near the classroom is important. > > > > If you can use your many observers to identify the various man made > noise > > sources, there is no reason in principle why you should not place an > > auxiliary sensor(s) closer to sources and feed the relatively strong > > interfering signals back to provide compensation, but don't expect a > perfect > > match. It is easier to do this using digital delays, rather than analogue > > delay lines. Can you record an environmental noise channel to help in > > identification and the seismograph channel? Could the identification / > > characterisation / avoidance of local sources be a worthwhile project? If > the > > local noise is terrible, could you get on line data from some quiet > location > > for your 'real earthquakes' and use your local set-up as a teaching / > backup > > aid? > > > > The noise is usually diffuse in origin, thus having sensor near the noise > probably will not work. The idea is to have enough sesors out there that > the sum of them at any given time covers an intergal number of wave lengths > of the noise. The sum is then zero. Since the signal is a much longer wave > length it is not reduced by the summing. No it is more complicated than that. One of the theories for dealing with noise uses the definition that noise is not correlated with itself. By removing the uncorrelated part of the seismogram, I think you can reduce some of the noise by up to a maximum estimate of 1/sqrt(2) (don't quote me on this value). Anyways, you can use a large array, and see the phase move across it. This is similar in principle to the new binocular telescopes being implemented around the world. In this scenario you assume that the noise at each location is completely random and different from the others. Then you can easily remove it. It is not about averaging necessarily, it is more about finding phases that cross the array which can be easily correlated. > It would be prohibitively expensive to do this with long periond > seismometers but your idea of noise monitors is good. One might be able to > use exploration geopones to get the "noise", high pass those signals and > sum them with the seismometer and reduce the noise. The news broadcsasters > often use a second noise canceling microphone in noisey environments. > > The only reason for this is cosmetic or to look at local events. Also > exploration work is much simpler in that one knows the source and noise > characteristics better. Also that was an old technique in exploration, > with vibroseis@ they may not have to do it any more. Also a quiet beats > filtering any day. Yikes, I think it is difficult and nearly impossible to extrapolate records over from a high frequency geophone to a low frequency instrument...better to just low pass and focus on distant events whose frequencies are lower than the poles on you filter. I don't think anybody learns much about the earth by putting a sophisticated broad band instrument right next to the earthquake source; this is where strong motion instruments are used instead. And when it is strong motion you are recording, the local noise is going to be small compared to recording distant events. > > > Second. There is a new chip that is up to a 6 pole analogue filter. > The > > > configuration of the filter is set in a device similar to an EPROM > burner. > > > The software that comes with it has full design features such as > simulation > > > of amplitude and phase. > > > > Filters of this type are produced for use in hearing aids, to vary the > > audio characteristics over a wide band. In your application, it is > probably > > better to use four pole Bessel filters, which are relatively easy and > cheap > > to make with a couple of OPAs. When you go to six pole filters, the delay > can > > get rather long. You may find that shifting the corner frequency downwards > > just a bit is actually preferable to adding more filter stages. If you > have a > > two channel recording system, could you use it to compare the simultaneous > > results of various filter choices? If you initially use 'plug in' > breadboard > > (with silver plated contacts), you can easily change the filter > > characteristics. > I am going to send this whole thing to one of my academic friends to see > what he says. > > I suspect some of these tricks might have been used in the good old days > when we were monitoring the nuclear detonations of the former Soviet Union. > There were some very long dedicated arrays focused to specific points in > Asia. > > I do not have a machine right now, I hope to have one by the end of the > Summer as I want that as a Summer science project for my daughters. I am > working on a computer interface now. We live in a noisy environment which > is why Sean Thomas' comments hit home. > Thank you > Tom Schmitt > tschmitt@.............. Tom, One sure way to test if something is noise or not, like a nuclear explosion is to forward model it. You then predict the groundmotion at each station where you can get records. This can be done fairly accurately by using either the travel-time tables or some mathematical model. You can either look directly at the seismograms or you can try and do a convolution of your predicted data with the actual records for each station. If the correlation is high for most of the records, then you can test it by using a given confidence interval (e.g. 95%). The more records you have, of course, the better you can decide. Many times, you add records and can correspondingly increase your confidence level. Also, you may want to statistically weight stations closer to the event more than ones further if it is a weak source. John Hernlund E-mail: hernlund@....... WWW: http://www.public.asu.edu/~hernlund/ ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Anatomy of Seismograms From: Amy pstimson@......... Date: Sun, 23 Apr 2000 09:18:17 -0700 Anyone have a copy for sale or know of a link to same? Thanks, Paul Stimson __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Newcomb, NY Earthquake From: Paul Jebb pfjebb@.............. Date: Mon, 24 Apr 2000 11:43:02 -0400 Dear Members, On April 20th there was a 3.7 event here in Newcomb, almost directly below our school. In an unbeliveably bad stroke of luck, we were on vacation here and our seismometer totally missed the whole thing. If you have access to any seismic recordings for this event, I would love to get them. Can you help? Yours truly, Paul Jebb NCS __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Newcomb, NY Earthquake From: Paul Jebb pfjebb@.............. Date: Mon, 24 Apr 2000 13:23:41 -0400 Dear John, Thanks for that start. I took a cursory run to the IRIS site and at least got the depth down. I want to get a look at the actual seismograph output for this quake if I can. I'll run around there some more and see what I come up with. As for the local geology, Newcomb is located in the Adirondack mountains which is an anorthositic plug contiguous with the Canadian Shield. We do have a couple of faults running through Town but I am not sure of the exact layout. Yours truly, Paul Jebb John Hernlund wrote: > On Mon, 24 Apr 2000, Paul Jebb wrote: > > Dear Members, > > On April 20th there was a 3.7 event here in Newcomb, almost directly > > below our school. In an unbeliveably bad stroke of luck, we were on > > vacation here and our seismometer totally missed the whole thing. If > > you have access to any seismic recordings for this event, I would love > > to get them. > > Can you help? > > Yours truly, > > Paul Jebb > > NCS > > Paul, > What a bummer! These NE quakes are always quite interesting to see. What > is your geological setting there in Newcomb? I'd be interested to here more > about this (you can post to the list, because I am sure they are interested > too). As you may or may not know, all of the records of earthquake data from > the global seismic network are available for free on the web. I believe there > are quite a few stations around some of the ivy league schools in New England, > and you could probably get some of those. To obtain any record from any of > these stations, go to the site: http://www.iris.edu. IRIS is a university > consortium funded by NSF to study global seismology. They have quite a few > member institutions (including ASU, where I am). These seismograms are > recorded on the best, state-of-the-art equipment available today. > > John Hernlund > E-mail: hernlund@....... > WWW: http://www.public.asu.edu/~hernlund/ > > ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Newcomb, NY Earthquake From: "Kareem Lanier" kareemjupiter@............. Date: Mon, 24 Apr 2000 21:16:13 -0700 Does anyone monitor telemetry signals coming from remote seismic stations? I need help doing this. I currently have a drum recorder and need either a discriminator or A to D card. -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Paul Jebb Sent: Monday, April 24, 2000 10:24 AM To: John Hernlund; Seismic Network Subject: Re: Newcomb, NY Earthquake Dear John, Thanks for that start. I took a cursory run to the IRIS site and at least got the depth down. I want to get a look at the actual seismograph output for this quake if I can. I'll run around there some more and see what I come up with. As for the local geology, Newcomb is located in the Adirondack mountains which is an anorthositic plug contiguous with the Canadian Shield. We do have a couple of faults running through Town but I am not sure of the exact layout. Yours truly, Paul Jebb John Hernlund wrote: > On Mon, 24 Apr 2000, Paul Jebb wrote: > > Dear Members, > > On April 20th there was a 3.7 event here in Newcomb, almost directly > > below our school. In an unbeliveably bad stroke of luck, we were on > > vacation here and our seismometer totally missed the whole thing. If > > you have access to any seismic recordings for this event, I would love > > to get them. > > Can you help? > > Yours truly, > > Paul Jebb > > NCS > > Paul, > What a bummer! These NE quakes are always quite interesting to see. What > is your geological setting there in Newcomb? I'd be interested to here more > about this (you can post to the list, because I am sure they are interested > too). As you may or may not know, all of the records of earthquake data from > the global seismic network are available for free on the web. I believe there > are quite a few stations around some of the ivy league schools in New England, > and you could probably get some of those. To obtain any record from any of > these stations, go to the site: http://www.iris.edu. IRIS is a university > consortium funded by NSF to study global seismology. They have quite a few > member institutions (including ASU, where I am). These seismograms are > recorded on the best, state-of-the-art equipment available today. > > John Hernlund > E-mail: hernlund@....... > WWW: http://www.public.asu.edu/~hernlund/ > > **************************************************************************** ** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Monitoring telemetry signals From: Larry Cochrane cochrane@.............. Date: Mon, 24 Apr 2000 22:13:05 -0700 Kareem, I and a few other PSN members monitor telemetry from remote sensors using my demodulator (discriminator) board. See http://www.seismicnet.com/telebrd.html for more information.The output of the demod board can drive a drum recorder or A/D card. Currently the *.CNI and *.CGP event files on my system (http://www.seismicnet.com) come from remote USGS sensors. At one point I had up to 5 channels recording remote senors. The problem is the USGS is slowly going digital around here (N. California) making my board obsolete. My board only works with the analog system commonly used to send analog data using a phone line or audio RF line. Regards, Larry Cochrane Redwood City, PSN At 09:16 PM 4/24/00 -0700, Kareem Lanier wrote: >Does anyone monitor telemetry signals coming from remote seismic stations? I >need help doing this. I currently have a drum recorder and need either a >discriminator or A to D card. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: SDR & Windows98 From: "Rex Klopfenstein, Jr." rklopfen@......... Date: Tue, 25 Apr 2000 19:40:24 -0400 Has anybody used SDR with Windows98? Specifically can SDR & Win98 be used with network like Windows 95? -- Rex Klopfenstein, Jr. Bowling Green, OH rklopfen@......... http://www.wcnet.org/~rklopfen __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: SDR & Windows98 From: Larry Cochrane cochrane@.............. Date: Tue, 25 Apr 2000 16:55:17 -0700 Rex, Yes, you can use Win98 to run SDR with networking. As with 95, you do need to boot to the DOS only mode. If you have the network properly installed under Win98, the DOS only mode should be able to connect to your other Windows system(s) using the NET command. -Larry Cochrane Redwood City, PSN At 07:40 PM 4/25/00 -0400, you wrote: >Has anybody used SDR with Windows98? Specifically can SDR & Win98 be >used with network like Windows 95? > >-- >Rex Klopfenstein, Jr. >Bowling Green, OH >rklopfen@......... >http://www.wcnet.org/~rklopfen > > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: SDR & Windows98 From: angel rodriguez angel@............ Date: Wed, 26 Apr 2000 16:11:49 -0500 Hello Rex, Tuesday, April 25, 2000, 6:40:24 PM, you wrote: RKJ> Has anybody used SDR with Windows98? Specifically can SDR & Win98 be RKJ> used with network like Windows 95? RKJ> -- RKJ> Rex Klopfenstein, Jr. RKJ> Bowling Green, OH RKJ> rklopfen@......... RKJ> http://www.wcnet.org/~rklopfen RKJ> __________________________________________________________ RKJ> Public Seismic Network Mailing List (PSN-L) RKJ> To leave this list email PSN-L-REQUEST@.............. with RKJ> the body of the message (first line only): unsubscribe RKJ> See http://www.seismicnet.com/maillist.html for more information. Hi, Yes, I use a das box to run SDR and the data and event files are sent to the W98 box. I do that cause the DOS box has very little memory and disk space. Both boxes are battery powered and off the grid. Best regards, angel mailto:angel@............ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Newcomb, NY Earthquake From: Bill Scolnik wls@......... Date: Thu, 27 Apr 2000 12:01:41 -0400 Paul, I checked my seismometer records this evening for April 20 and I show a trace at the right time for that quake. It's pretty deep in the noise, but with a little filtering the vertical trace is quite readable. I'd be happy to send you the file. Bill S At 11:43 AM 04/24/2000 , you wrote: >Dear Members, >On April 20th there was a 3.7 event here in Newcomb, almost directly >below our school. In an unbeliveably bad stroke of luck, we were on >vacation here and our seismometer totally missed the whole thing. If >you have access to any seismic recordings for this event, I would love >to get them. > >Can you help? > >Yours truly, >Paul Jebb >NCS > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: [Fwd: Geology Labs On-Line, Virtual River Beta Release] From: Steve Hammond Shammon1@............. Date: Thu, 27 Apr 2000 10:31:44 -0700 FYI, if you do not already know, this is a high quality educational web site. Regards, Steve Hammond PSN Aptos California Colleagues, This is to notify you of the BETA release of a new activity for the Geology Labs On-Line project. VirtualRiver-Discharge. http://vcourseware.calstatela.edu/GeoLabs/ Follow the link to Virtual River. (You received this email because your address is in my database of people who may be interested in the "Virtual Labs" of the Geology Labs On-line project. If you received this email in error, please accept my apology and let me know so I can remove your address from the database.) I hope you will take a look at VirtualRiver and provide some feedback to me. It's designed as an interactive Web-based lab for introductory earth or environmental science courses at the university level. It may also be appropriate for some high school or middle school earth science classes. If you do review the activity, please note that there is a DEMONSTRATION version available (a link can be found on the first page) that gives you the opportunity for a quick overview. Can you use it? Did you find any bugs? Do you have any suggestions to improve it? VirtualRiver-Discharge and is one of three virtual labs we hope to eventually have available on the Web about rivers. It focuses on the determination of a stream's discharge using the "method of verticals." The next activity will be about flooding, hydrographs, flood recurrence intervals and flood probability. The final one will be concerned with erosion, load transport, and sediment deposition. VirtualRiver-Discharge, similar to previous virtual labs (Virtual Earthquake and Virtual Dating), requires students to interact with the content of a Web page (through Java Applets, JavaScripts, Dynamic HTML, and Shockwave Animations) in order to make careful observations and measurements, do simple calculations, and answer questions about their work. If the student correctly completes all aspects of the activity, a personalized "Certificate of Completion" is awarded to him/her. The certificate is proof positive that the student has completed the lab. Warning: Because VirtualRiver contains numerous Java Applets, there are certain "Technical Considerations and System Requirements" that need to be addressed. The site's first page contains a statement about these requirements. Thank you very much for your assistance in testing this activity. Gary Novak Department of Geological Sciences California State University at Los Angeles gnovak@..............
Colleagues,
This is to notify you of the BETA release of a new activity for the Geology Labs On-Line project. VirtualRiver-Discharge.
http://vcourseware.calstatela.ed u/GeoLabs/ Follow the link to Virtual River.

(You received this email because your address is in my database of people who may be interested in the "Virtual Labs" of the Geology Labs On-line project. If you received this email in error, please accept my apology and let me know so I can re move your address from the database.)

I hope you will take a look at VirtualRiver and provide some feedback to me. It's designed as an interactive Web-based l ab for introductory earth or environmental science courses at the university level. It may also be appropriate for some high sc hool or middle school earth science classes. If you do review the activity, please note that there is a DEMONSTRATION version a vailable (a link can be found on the first page) that gives you the opportunity for a quick overview.

Can you use it? Did you find any bugs? Do you have any suggestions to improve it?

VirtualRiver-Discharge and is one of three virtual labs we hope to eventually have available on the Web about riv ers. It focuses on the determination of a stream's discharge using the "method of verticals." The next activity will be about flooding, hydrographs, flood recurrence intervals and flood probability. The final one will be concerned with erosion, load transport, and sediment deposition.

VirtualRiver-Discharge, similar to previous virtual labs (Virtual Earthquake and Virtual Dating), r equires students to interact with the content of a Web page (through Java Applets, JavaScripts, Dynamic HTML, and Shockwave Ani mations) in order to make careful observations and measurements, do simple calculations, and answer questions about their work. If the student correctly completes all aspects of the activity, a personalized "Certificate of Completion" is awarde d to him/her. The certificate is proof positive that the student has completed the lab.

Warning: Because VirtualRiver contains numerous Java Applets, there are certain "Technical Considerations an d System Requirements" that need to be addressed. The site's first page contains a statement about these requirements.

Thank you very much for your assistance in testing this activity.

Gary Novak
Department of Geological Sciences
California State University at Los Angeles
gnovak@..............





Subject: Nerdess's in the PSN From: Edward Cranswick cranswick@........ Date: Fri, 28 Apr 2000 04:11:44 -0600 Kathy- When I made that remark about the members of the Public Seismic Network (PSN; see, e.g., ) largely consisting of men escaping into the garage from their wives, children, and families (an observation originally made by my friend, Benjamin Gardner, a USGS Volunteer for Science who did alot of work with the PSN in the early 1990's), I was not being mindlessly sexist. Over the last decade, I have kept my eye out for the appearance of women in the international group of amateur and not-so-amateur seismologists which now numbers over 300 members worldwide; but, unfortunately, most of them so far have been nerds, not nerdess's. -Edward -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Nordic's in the PSN From: "Taylor, Victor" Victor.Taylor@......... Date: Fri, 28 Apr 2000 08:54:11 -0400 Go fishing, camping and trekking for your private time....Victoria > -----Original Message----- > From: cranswick@........ [SMTP:cranswick@......... > Sent: Friday, April 28, 2000 6:12 AM > To: haller@........ > Cc: sbohlen@......... bpgetcetc@.......... psn-l@.............. > Subject: Nerdess's in the PSN > > Kathy- > When I made that remark about the members of the Public Seismic > Network (PSN; see, e.g., ) largely consisting of > men escaping into the garage from their wives, children, and families > (an observation originally made by my friend, Benjamin Gardner, a USGS > Volunteer for Science who did alot of work with the PSN in the early > 1990's), I was not being mindlessly sexist. Over the last decade, I have > kept my eye out for the appearance of women in the international group > of amateur and not-so-amateur seismologists which now numbers over 300 > members worldwide; but, unfortunately, most of them so far have been > nerds, not nerdess's. > -Edward > > -- > Edward Cranswick Tel: 303-273-8609 > US Geological Survey, MS 966 Fax: 303-273-8600 > PO Box 25046, Federal Center cranswick@........ > Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Anatomy of Seismograms From: ted@.......... Date: Fri, 28 Apr 2000 09:29:04 -0700 E-bay had a copy of "Principles Underlying the Interpretation of Seismograms", U.S. Dept. of Commerce Special Publication 254 (revised 1966 edition) for sale a few months ago. I think it went for about $65. However since the publication is out of print, the winning bidder was kind enough to send me a xerox copy of the book. If anyone on our list would like a copy of this document (about 50 pages), send me $5 to cover copying and shipping costs and I'll be glad to make you a copy. Address is 238 Highland St., Portsmouth, NH 03801. Regards, Ted __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Nordic's in the PSN From: ted@.......... Date: Fri, 28 Apr 2000 15:12:55 -0400 For years my plan has been that when the seismic station is online, recording and stable I will be able to leave the basement and go off to the mountains to fish, camp and trek, knowing that I'll capture any quakes that happen while I'm out there in the countryside doing healthy things. Unfortunately these three characteristics have never occured at the same time. :-( However I am now offering at a reduced rate to PSN members large lithographs of natural scenes to place in your basement or garage. Throw in a StairMaster and you won't hardly know the difference. Regards, Ted __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Nordic's in the PSN From: Steve Hammond Shammon1@............. Date: Fri, 28 Apr 2000 12:22:16 -0700 Hi Ed, -- sorry, but I think we had some really excellent Nerdess's in the group in the early days. While Ben was correct, the original six (Bruce, Al, Pete, Jan, Dick, and myself) consisted largely of men escaping into the garage to hack on their seismographs… it would be incorrect to represent the PSN as being void of women involvement during the first few years of existence. Need I remind you of the role that Dorothy Darby played in getting the PSN in Pasadena up and running or the results her actions had after relaying critical life saving information by radio during the early hours of the Northridge earthquake. Also, remember that in 1992 Carol Taylor at Anderson Elementary in San Jose had her fifth grade class on-line daily to the BBS in San Jose as they studied seismology and plate tectonics. Carol spent many of her own hours getting prepared to tech that initial group of students. Regards, Steve Hammond PSN Aptos, California Taylor, Victor wrote: > > Go fishing, camping and trekking for your private time....Victoria > > > -----Original Message----- > > From: cranswick@........ [SMTP:cranswick@......... > > Sent: Friday, April 28, 2000 6:12 AM > > To: haller@........ > > Cc: sbohlen@......... bpgetcetc@.......... psn-l@.............. > > Subject: Nerdess's in the PSN > > > > Kathy- > > When I made that remark about the members of the Public Seismic > > Network (PSN; see, e.g., ) largely consisting of > > men escaping into the garage from their wives, children, and families > > (an observation originally made by my friend, Benjamin Gardner, a USGS > > Volunteer for Science who did alot of work with the PSN in the early > > 1990's), I was not being mindlessly sexist. Over the last decade, I have > > kept my eye out for the appearance of women in the international group > > of amateur and not-so-amateur seismologists which now numbers over 300 > > members worldwide; but, unfortunately, most of them so far have been > > nerds, not nerdess's. > > -Edward > > > > -- > > Edward Cranswick Tel: 303-273-8609 > > US Geological Survey, MS 966 Fax: 303-273-8600 > > PO Box 25046, Federal Center cranswick@........ > > Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". > > > > > > __________________________________________________________ > > > > Public Seismic Network Mailing List (PSN-L) > > > > To leave this list email PSN-L-REQUEST@.............. with > > the body of the message (first line only): unsubscribe > > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Nordic's in the PSN From: "Taylor, Victor" Victor.Taylor@......... Date: Fri, 28 Apr 2000 15:49:25 -0400 Ted, I have found in my seismic studies that a very stable power supply, coupled to a battery bank, and utilizing a sola ac power line regulator leads to stability in the calibration, and operation of the system. It provides on line time during power outages. RF shielding around the seismic sensors removes transient EMF impulses. Computers are noisy and produce various intensities of RF noise depending on how hard they are running, more input and computing time means more RF noise. Optical fiber line with Photo Electronic coupling is useful over long runs. Build a system like this, install the sensors in a RF screen room, calibrate and collect data. Justify the expense as a tornado shelter. Buy a new fly rod and go fishing, camping and trekking with the whole household. > -----Original Message----- > From: ted@.......... [SMTP:ted@........... > Sent: Friday, April 28, 2000 3:13 PM > To: psn-l@.............. > Subject: RE: Nordic's in the PSN > > > > For years my plan has been that when the seismic station is online, > recording and stable I will be able to leave the basement and go off to > the > mountains to fish, camp and trek, knowing that I'll capture any quakes > that > happen while I'm out there in the countryside doing healthy things. > Unfortunately these three characteristics have never occured at the same > time. :-( > > However I am now offering at a reduced rate to PSN members large > lithographs of natural scenes to place in your basement or garage. Throw > in a StairMaster and you won't hardly know the difference. > > Regards, Ted > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Fwd: New web page to look at! From: The Lahrs JohnJan@........ Date: Fri, 28 Apr 2000 17:56:43 -0600 Interesting site from the USGS Menlo Park. John >------------- Begin Forwarded Message ------------- > >X-Sender: reasen@................... >Date: Fri, 28 Apr 2000 14:02:44 -0700 >To: wehz@........................ >From: Paul Reasenberg >Subject: New web page to look at! > > >Hello All, > >There's a new web page I think you'll like! It presents Jim Luetgert's >real-time display of seismograms from our network in the "Helicorder" >format. Jim did a masterful job of writing the programs that keep these >displays fresh automatically. Some of you have seen these displays, but >most of you haven't yet. > >When you have a minute or two, take a look at > >http://quake.wr.usgs.gov/helicorders > >Both Jim (who did all the hard work) and I (who developed the web page) >would like your comments. I think Jim deserves a lot of credit for >creating this! > >Cheers, >Paul > > >-------------------------------------------------------------------- > >Paul A. Reasenberg Tel: 650-329-5002 >U.S. Geological Survey Fax: 650-329-5143 >345 Middlefield Road email: reasen@........ >Menlo Park, California 94025 > >Please note NEW EMAIL ADDRESS: reasen@........ > >Visit our website at http://quake.wr.usgs.gov/ > > > > >------------- End Forwarded Message ------------- John C. Lahr 1925 Foothills Road Golden, CO 80402 (303) 215-9913 http://lahr.org/john-jan/science.html __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Anatomy of Seismograms From: mbrewer mbrewer@...... Date: Fri, 28 Apr 2000 22:54:52 -0300 Ted, I would love to have a copy, but how do I get the $5 to you. It will cost me $4 to buy a bank draft. It is still a LOT less than $65. Would you happen to be coming to Bermuda soon? Regards, Martin -----Original Message----- From: ted@.......... [SMTP:ted@........... Sent: Friday, April 28, 2000 1:29 PM To: psn-l@.............. Subject: Re: Anatomy of Seismograms E-bay had a copy of "Principles Underlying the Interpretation of Seismograms", U.S. Dept. of Commerce Special Publication 254 (revised 1966 edition) for sale a few months ago. I think it went for about $65. However since the publication is out of print, the winning bidder was kind enough to send me a xerox copy of the book. If anyone on our list would like a copy of this document (about 50 pages), send me $5 to cover copying and shipping costs and I'll be glad to make you a copy. Address is 238 Highland St., Portsmouth, NH 03801. Regards, Ted __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Anatomy of Seismograms / Postage From: "Erich Kern" ekern@......... Date: Fri, 28 Apr 2000 19:38:24 -0700 Guys, The postage to Bermuda from the US at the "printed matter" air rate for 50 single sided pages (9 oz. with envelope) is $3.63. If it was going to Australia or NZ it would be $5.95 postage. If you do 50 pages with double sided copies, this still is 5 ounces with the envelope. The printed matter airmail postage to Bermuda is $2.35 or to Aus/ NZ would be $3.75 My guess is that Ted didn't include postage beyond US borders when he made the offer. Five bucks is a bargain any way you look at it. Regards, Erich Kern -----Original Message----- From: mbrewer To: 'psn-l@............... Date: Friday, April 28, 2000 7:24 PM Subject: RE: Anatomy of Seismograms Ted, I would love to have a copy, but how do I get the $5 to you. It will cost me $4 to buy a bank draft. It is still a LOT less than $65. Would you happen to be coming to Bermuda soon? Regards, Martin __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Article on gravimeters From: George Bush gbush@....... Date: Sat, 29 Apr 2000 09:42:15 -0700 I just discovered an interesting article on the development of an absolute differential gravimeter that appeared in an unusual place. As a ametuer seismometer builder, I found the article fascinating to see what the big boys do. The article appeared in the March 2000 issue of "Laser Focus World," on pp20-24. For you non-subscribers the article can be seen on the web at: http://lfw.pennwellnet.com/home/articles.cfm?ARTICLE_ID=66006&VERSION_NUM=1& PUBLICATION_ID=12&Section=CurrentIssue Now I have had trouble emailing long URL's before, so if this isn't clickable, try to copy and paste it into the address box of your browser. And if that doesn't work you can go the the magazine's main web address http://lfw.pennwellnet.com/home/home.cfm and then select "current Issue" then World News" then the article "Interferometry, Fiber Coupling improves Gravimeters" George Bush Sea Ranch, CA, USA 38.74N, 123.5W __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Anatomy of Seismograms / Postage From: ted@.......... Date: Sat, 29 Apr 2000 13:29:03 -0400 Erich is correct, that was USD 2.50 for copying and USD 2.50 for postage within US. Let's amend the offer to USD 5.00 for US addresses and USD 10.00 for outside the US. Any leftover money I will donate to Larry. Gee, if I had an e-business site you could all use your charge cards... Ted Blank (for those who want to write checks) "Erich Kern" @.............. on 04/28/2000 10:38:24 PM Please respond to psn-l@.............. Sent by: psn-l-request@.............. To: cc: Subject: Re: Anatomy of Seismograms / Postage Guys, The postage to Bermuda from the US at the "printed matter" air rate for 50 single sided pages (9 oz. with envelope) is $3.63. If it was going to Australia or NZ it would be $5.95 postage. If you do 50 pages with double sided copies, this still is 5 ounces with the envelope. The printed matter airmail postage to Bermuda is $2.35 or to Aus/ NZ would be $3.75 My guess is that Ted didn't include postage beyond US borders when he made the offer. Five bucks is a bargain any way you look at it. Regards, Erich Kern -----Original Message----- From: mbrewer To: 'psn-l@............... Date: Friday, April 28, 2000 7:24 PM Subject: RE: Anatomy of Seismograms Ted, I would love to have a copy, but how do I get the $5 to you. It will cost me $4 to buy a bank draft. It is still a LOT less than $65. Would you happen to be coming to Bermuda soon? Regards, Martin __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Seismogram Analysis From: meredith lamb mlamb1@.......... Date: Sat, 29 Apr 2000 11:57:21 -0700 Dennis Recla has sent a email, which he wishes forwarded to the PSN: I have copied the document Seismogram Analysis (Training Outline), 32 pages, which was prepared by the Laramie Analysis Facility Personnel as part of some government contracts to a PDF format file. Its old, vintage 1960, but a very basic description of examining seismograms to determine epicenters and travel times. Its about 1.3 mbyte, and I can email them to anyone who would like it, drop me a note, and I'll send out the copies. Don't want to put it out as a general post because of the size. I also have alot of the old Geotech/Geotechnical Corp manuals and such, which I can now covert to PDF formats. (depends on what is and what is not copyright protected). Reply to: recla@.......... Regards, Dennis Recla __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Nordic's in the PSN From: Edward Cranswick cranswick@........ Date: Sat, 29 Apr 2000 15:25:50 -0600 Victoria & Steve- I acknowledge your corrections. Of course, I see that the Earth, Gaia, is feminine, so that women tend to know what's going on anyway -- while men are busy putting instruments together to try and find out. -Edward Steve Hammond wrote: > Hi Ed, -- sorry, but I think we had some really excellent Nerdess's in > the group in the early days. While Ben was correct, the original six > (Bruce, Al, Pete, Jan, Dick, and myself) consisted largely of men > escaping into the garage to hack on their seismographs… it would be > incorrect to represent the PSN as being void of women involvement during > the first few years of existence. Need I remind you of the role that > Dorothy Darby played in getting the PSN in Pasadena up and running or > the results her actions had after relaying critical life saving > information by radio during the early hours of the Northridge > earthquake. Also, remember that in 1992 Carol Taylor at Anderson > Elementary in San Jose had her fifth grade class on-line daily to the > BBS in San Jose as they studied seismology and plate tectonics. Carol > spent many of her own hours getting prepared to tech that initial group > of students. > > Regards, Steve Hammond PSN Aptos, California > > Taylor, Victor wrote: > > > > Go fishing, camping and trekking for your private time....Victoria -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Anatomy of Seismograms / Postage From: "Rex Klopfenstein, Jr." rklopfen@......... Date: Sat, 29 Apr 2000 18:02:35 -0400 I you send me your mailing address via private mail, I will be forwarding you a check! ted@.......... wrote: > Erich is correct, that was USD 2.50 for copying and USD 2.50 for postage > within US. > > Let's amend the offer to USD 5.00 for US addresses and USD 10.00 for > outside the US. Any leftover money I will donate to Larry. Gee, if I had > an e-business site you could all use your charge cards... > > Ted Blank (for those who want to write checks) > -- Rex Klopfenstein, Jr. Bowling Green, OH rklopfen@......... http://www.wcnet.org/~rklopfen __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Seismogram Analysis From: "Rex Klopfenstein, Jr." rklopfen@......... Date: Sat, 29 Apr 2000 18:05:41 -0400 Send me a copy!! Thanks meredith lamb wrote: > Dennis Recla has sent a email, which he wishes forwarded to > the PSN: > > I have copied the document Seismogram Analysis (Training > Outline), 32 pages, which was prepared by the Laramie > Analysis Facility Personnel as part of some government > contracts to a PDF format file. Its old, vintage 1960, but a > very basic description of examining seismograms to determine > epicenters and travel times. > > Its about 1.3 mbyte, and I can email them to anyone who > would like it, drop me a note, and I'll send out the copies. > Don't want to put it out as a general post because of the size. > > I also have alot of the old Geotech/Geotechnical Corp manuals > and such, which I can now covert to PDF formats. (depends > on what is and what is not copyright protected). > > Reply to: recla@.......... > > Regards, > > Dennis Recla > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. -- Rex Klopfenstein, Jr. Bowling Green, OH rklopfen@......... http://www.wcnet.org/~rklopfen __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Article on gravimeters From: John Hernlund hernlund@....... Date: Sat, 29 Apr 2000 19:58:10 -0700 (MST) On Sat, 29 Apr 2000, George Bush wrote: > I just discovered an interesting article on the development of an absolute > differential gravimeter that appeared in an unusual place. As a ametuer > seismometer builder, I found the article fascinating to see what the big > boys do. The article appeared in the March 2000 issue of "Laser Focus > World," on pp20-24. For you non-subscribers the article can be seen on the > web at: > http://lfw.pennwellnet.com/home/articles.cfm?ARTICLE_ID=66006&VERSION_NUM=1& > PUBLICATION_ID=12&Section=CurrentIssue > Now I have had trouble emailing long URL's before, so if this isn't > clickable, try to copy and paste it into the address box of your browser. > And if that doesn't work you can go the the magazine's main web address > http://lfw.pennwellnet.com/home/home.cfm > and then select "current Issue" then World News" then the article > "Interferometry, Fiber Coupling improves Gravimeters" > George Bush George, There was a horribly written article about an incredibly interesting subject a few years back in Scientific American. Even though the article did not belong in the magazine, you might be interested in reading it. It was about a gravity gradiometer that had been designed to help submarines "see" the topography on the ocean floor and avoid collision with sea mounts. They needed a passive method to see the ocean floor so that they would not be detected. Supposedly this thing worked great (too bad all the data they collected is classified). Anyways, the company that made it was allowed to contract its use out to some geophysical concerns, such as finding oil and natural gas resevoirs. The company takes a huge amount of money, throws this thing in a boat and drives around for a while. They take the data, reduce it, and then sell portions of it for commercial use. Nobody is allowed to buy one of these instrume