From: Edward Cranswick Subject: Re: Thrust animation Date: Mon, 31 Mar 1997 13:50:08 -0700 Charles > Gosh, this animation stuff has a lot of potential. The graphics are cool, but you have the fault displacing at the surface before any seismic waves, indicated by the expanding concentric circles, get there -- which they never do anyway. Seismic waves are the way the that information about the state -- stress and strain -- of the Earth is propagated, and there can be no deformation prior to propagation. -Edward -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: Thrust animation Date: Mon, 31 Mar 1997 14:16:05 -0700 Charles- Notwithstanding my previous comment, I think that the break off of the thrust block with attendant trees down the scarp is a nice touch. It is very realistic and an appropriate reminder to geophysicists that the Earth is more than a homogeneous halfspace or a sphere. -Edward > I used the new Macromedia Freehand 7.0 to make the graphic and just > nudged the hanging wall block up a few knotches before saving it each > time as a tiff file. Had to throw a few white blocks in blot out the > background behind the trees and to size the top of the graphic. And just > for fun, I had the nose of the thrust block break off and send tree and > a bunch of dirt down the scarp for the final frame. -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@................. (Dr. John Lahr (USGS-GI Seismologist)) Subject: Re: Thrust animation Date: Mon, 31 Mar 1997 12:39:37 -0900 Charlie, I like the animation. Check out the EQ animation of Tau Rho that I converted to quick time at: http://www.giseis.alaska.edu/Input/lahr/taurho/eqeffects/introduction.html I would like to have an animation that shows the elastic rebound: slow bending followed by rupture. I've tried a bit on this but my artwork is not very good. JCLahr ################################## John C. Lahr ################################# Seismologist ################################ U.S. Geological Survey ############################### c/o Geophysical Institute ############################## 903 Koyukuk Drive ~~~~~~~~~~~~~~ Get ~~~~~~~~~~ ############################# ########################################################### P.O. Box 757320 ################################ Fairbanks, AK 99775 ################################# Phone: (907) 474-7997 ################################## Fax: (907) 474-5618 ~~~~~~~~ the thrust? ~~~~~~~~~~~~~~ lahr@........ #################################### http://www.aeic.alaska.edu/Input/lahr/ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@................. (Dr. John Lahr (USGS-GI Seismologist)) Subject: Correction Correction!!!! Date: Mon, 31 Mar 1997 13:57:50 -0900 I've been looking at the location of the recent earthquakes incorrectly! They are East and not West longitude, so occur within the eastern end of the 1965 Rat Islands earthquake zone, not within the western end of the 1957 break. Sorry for the confusion on my part. I've made some corrections below. > > The continuing activity in the Rat Islands is quite interesting. > > This portion of the arc was ruptured by an MW 8.6 earthquake in 1957 > which allowed a 900 km-wide portion of the Pacific plate to subduct > a bit deeper beneath the Bearing Sea, which is part of the North > American Plate. > > In 1986 a 225-km wide portion of the 1957 zone located south and east > of Adak Island broke again in a magnitude MW 8.0 event. This > left two portions of the 1957 break still unbroken: a 175-km wide > zone on the west and a 500-km wide zone on the east. > > On June 10, 1996, a magnitude MW 7.9 earthquake extended the > reruptured portion of the 1957 break another 125-km to the west, > possibly falling short by about 50 km from rupturing all the way to > the western limit of the 1957 break. > The recent MW 6.6 event on March 26 at 02:08 UT and its aftershocks are located very near the eastern limit of the 1965 rupture zone, which is the next large break (MW 8.7) west of the 1957 zone. What does this portend for rerupture of the 1965 zone? What about rerupture of the eastern portion of the 1957 zone? Stay tuned to see what happens. (To be continued, on a geologic time scale.) JCLahr _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: Rat Islands Earthquakes Date: Mon, 31 Mar 1997 04:47:13 -0800 John, It was my understanding the 1957 Mw 9.1 earthquake ruptured the Andreanof and the western Fox Islands segemnts and the 1965 M8.2 earthquake ruptured the Rat and Near Islands segments. By looking at the aftershock pattern from the June 10 Mw 7.9 and Mw 7.2 earthquakes ruptured the western portion of the Andreanof segment from 174W-179W (central Atka Is. to just west of Amatignak Island) (See Seismo-Watch Newsletter Vol. 4 No. 25. The aftershocks suggest the 1957 rupture extended at least to Amatignak Island and more likely past Amchitka Passage to Amchitka Island. The 1965 Rat Islands earthquake was centered pretty darn close to Amchitka Island and part of it may have extended eastward into Amchitka passage and into the 1957 rupture zone. The recent Mw 6.6 earthquake was centered about 12 miles east of a M6.4 event a year and two days ago. What is interesting is the Komdandorsky segment which has not ruptured in historic times. Every now and again it releases a M5 and creates a stir amoung the Seismo betting tables - an in house thing here at Seismo-Watch. -- ---/---- Charles P. Watson, Consulting Geologist Advanced Geologic Exploration Seismo-Watch / Earthquake Information Services Voice: 702-852-0992 / Fax: 702-852-3226 mailto:watson@................ http://www.seismo-watch.com Dr. John Lahr (USGS-GI Seismologist) wrote: > > The continuing activity in the Rat Islands is quite interesting. > > This portion of the arc was ruptured by an MW 8.6 earthquake in 1957 > which allowed a 900 km-wide portion of the Pacific plate to subduct > a bit deeper beneath the Bearing Sea, which is part of the North > American Plate. > > In 1986 a 225-km wide portion of the 1957 zone located south and east > of Adak Island broke again in a magnitude MW 8.0 event. This > left two portions of the 1957 break still unbroken: a 175-km wide > zone on the west and a 500-km wide zone on the east. > > On June 10, 1996, a magnitude MW 7.9 earthquake extended the > reruptured portion of the 1957 break another 125-km to the west, > possibly falling short by about 50 km from rupturing all the way to > the western limit of the 1957 break. > > The recent MW 6.6 event on March 26 at 02:08 UT and its aftershocks > are located very near the western limit of the 1957 rupture zone. > Is this it for the western end of the 1957 break, or will there > be more action in the near future? What about rerupture of > the eastern portion of the 1957 zone? Stay tuned to see what > happens. > > (To be continued, on a geologic time scale.) > > JCLahr > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: Thrust animation Date: Mon, 31 Mar 1997 20:49:46 -0700 John- > I like the animation. Check out the EQ animation of Tau Rho that > I converted to quick time at: I downloaded your file and the Quicktime plug-in for Win 95/NT for the Netscape 3.0 browser I use, but the graphics were wierd -- coarse and black -- though there was some heavy duty sounds ... I don't know whether that was live or Memorex, i.e., my machine or your file or both. -Edward -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: more Grizzly Island swarm Date: Wed, 02 Apr 1997 10:00:12 -0800 ....and the Grizzly Island swarm in the San Francisco Delta continues. Five M2+ events in the last two days, including a pair of M3s. The largest registered M3.4. ...and just when your thought it had gone away... 4 guines for a M4+? Ante up! -- ---/---- Charles P. Watson, Consulting Geologist Advanced Geologic Exploration Seismo-Watch / Earthquake Information Services Voice: 702-852-0992 / Fax: 702-852-3226 mailto:watson@................ http://www.seismo-watch.com _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Dennis Leatart Subject: large quake? Date: Fri, 04 Apr 1997 11:36:30 -0800 Hi to all!!! Did any of you pick up a quake about 9:30 UT on 4/4/97 (1:30PST)?? I have a large classic trace at that time, but it does not correspond to the 5.0 or 4.9 in Central America-- this was the only match I could find on the net?? -- _____ __ | \.-----.-----.-----.|__|.-----. | -- | -__| | || ||__ --| |_____/|_____|__|__|__|__||__||_____| _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: large quake? Date: Fri, 04 Apr 1997 12:58:03 -0800 At 11:36 AM 4/4/97 -0800, Dennis Leatart wrote: >Did any of you pick up a quake about 9:30 UT on 4/4/97 (1:30PST)?? I >have a large classic trace at that time, but it does not correspond to >the 5.0 or 4.9 in Central America-- this was the only match I could find >on the net?? Hi Dennis -- I saw it too. It was a ML3.3 in Inglewood, CA... The following is from http://scec.gps.caltech.edu/cgi-bin/finger?quake, the Southern California Earthquake Report. 97/04/04 09:26:24 33.98N 118.35W 4.2 3.3MLG A 1 mi. N of INGLEWOOD Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz Subject: Re: geophones Date: Mon, 07 Apr 1997 22:12:33 -0700 David A Nelson wrote: > > hi all, > below is a reply I received from the Geo Space Corp. It may be > of general interest > Their homepages at http://www.geospacecorp.com/ have photos of the > GS-20DX geophone > > At a resonance of 8Hz I wonder if the info that it would give for > regional quakes US$22.00 is a great price worth the experimentation I > think ??? > > the other unit (GS-11D) is not listed on their pages only in the e-mail > to me at 4.5Hz it is the same as the ones I am using at home in Dunedin > and at US$60 is a good option for a precision short period seismometer. > > for your thoughts Dave > Hi Dave- I have also inquired about freq. response and cost. Normally if you are measuring displacement you want the natural freq of the sensor to be lower than the lowest freq monitored. If you are measuring acceleration you want the sensors natural freq to be higher than the highest freq measured. I'm not sure if these sensors are force balance or not. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson Subject: Re: geophones Date: Tue, 08 Apr 1997 19:44:45 +1200 Barry,.... ok on your thoughts, I am already using 4.5 Hz geophones at home and as a short period seismometer they are perfect with excellent detection of regional events. I have recorded many large events in the 1500 km + (eventually when my LP unit is working the distant events will be recorded much better) Since posting the original mail I have placed an order with Geo Space Corp. for 1 x GS20-DX, 8 Hz unit and 3 x GS11-D, 4.5 Hz units. This company's prices were better than any other quotes that I received, for a virtually identical unit. It will be interesting to see the response of the 8 Hz seismometer when recording regional events. I don't know if they are forced balanced or not either as I don't really know the definition of what is meant by forced balance????. Dave Barry, you wrote >Hi Dave- > I have also inquired about freq. response and cost. Normally if you >are measuring displacement you want the natural freq of the sensor to be >lower than the lowest freq monitored. If you are measuring acceleration >you want the sensors natural freq to be higher than the highest freq >measured. I'm not sure if these sensors are force balance or not. > Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'SLAW-- When Something Does Go Wrong, There Is Sod All You Can Do AboutIt When The Last Of Ten Screws Has Been Removed From A Cover, It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: geophones Date: Tue, 08 Apr 1997 20:52:29 -0600 A velocity sensor (a geophone, i.e., a damped harmonic oscillator with a velocity transducer sensing pendulum motion) will have a flat frequency response to (output voltage will be proportional to) ground velocity above the natural frequency, and its response will decay (decrease) at 12 dB per octave (2-pole; proportional to frequency squared: 1/f^2) below the natural frequency, i.e., it acts as a high-pass filter. By the same token, the pendulum motion will have the same response to acceleration and displacement, i.e., the acceleration and displacement responses of the pendulum (assuming one has a way of sensing the acceleration or displacement motion of the pendulum directly) will be flat above the natural frequency and equivalently decay below the natural frequency. Actually, a velocity sensor exhibits a higher, or upper, resonant frequency caused by the inductance response of the velocity sensor coil interacting with the magnetic field. This produces a 6 dB per octave (1-pole) decay above the upper resonant frequency, i.e., it acts like a low-pass filter, that is characteristically one to orders of magnitude above the natural freqency. For example, the Marks Products L-22 geophone has a 2.0 Hz natural frequency and an 85.0 Hz upper frequency. Barry Lotz wrote: > > David A Nelson wrote: > > > > hi all, > > below is a reply I received from the Geo Space Corp. It may be > > of general interest > > Their homepages at http://www.geospacecorp.com/ have photos of the > > GS-20DX geophone > > > > At a resonance of 8Hz I wonder if the info that it would give for > > regional quakes US$22.00 is a great price worth the experimentation I > > think ??? > > > > the other unit (GS-11D) is not listed on their pages only in the e-mail > > to me at 4.5Hz it is the same as the ones I am using at home in Dunedin > > and at US$60 is a good option for a precision short period seismometer. > > > > for your thoughts Dave > > > Hi Dave- > I have also inquired about freq. response and cost. Normally if you > are measuring displacement you want the natural freq of the sensor to be > lower than the lowest freq monitored. If you are measuring acceleration > you want the sensors natural freq to be higher than the highest freq > measured. I'm not sure if these sensors are force balance or not. -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Fox Island Event(?) Date: Tue, 08 Apr 1997 20:26:21 -0700 Hi Everyone, I just uploaded to Larry's machine an event I recorded at about 15:20 UT today (4/8/97). I think it must be the Fox Island event, but nothing seems to quite match the USGS report. -- The time, distance, and magnitude don't seem quite right. Anyone else see this event, and do your numbers match the USGS's better than mine? Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie & Terri Thompson -- @MicroRanch ) Subject: Re: Fox Island Event(?) Date: Tue, 08 Apr 1997 23:02:28 -0500 I have an un-matched event estimated origin time of 15:24 UTC 4/8. Fox Island seems too far away. If I ID'ed the P and S correctly it's less than 1000 miles from Buda, Texas..probably Mexico.. shallow quake with large surface wave estimated Ms5.5. Anybody else bag this event? -Charlie Thompson Buda, Texas >Hi Everyone, > >I just uploaded to Larry's machine an event I recorded at about 15:20 UT >today (4/8/97). I think it must be the Fox Island event, but nothing seems >to quite match the USGS report. -- The time, distance, and magnitude don't >seem quite right. > >Anyone else see this event, and do your numbers match the USGS's better >than mine? > > >Karl Cunningham >La Mesa, CA. >karlc@......... > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz Subject: Re: geophones Date: Tue, 08 Apr 1997 21:20:18 -0700 Edward Cranswick wrote: > > A velocity sensor (a geophone, i.e., a damped harmonic oscillator with a > velocity transducer sensing pendulum motion) will have a flat frequency > response to (output voltage will be proportional to) ground velocity > above the natural frequency, and its response will decay (decrease) at > 12 dB per octave (2-pole; proportional to frequency squared: 1/f^2) > below the natural frequency, i.e., it acts as a high-pass filter. By > the same token, the pendulum motion will have the same response to > acceleration and displacement, i.e., the acceleration and displacement > responses of the pendulum (assuming one has a way of sensing the > acceleration or displacement motion of the pendulum directly) will be > flat above the natural frequency and equivalently decay below the > natural frequency. Actually, a velocity sensor exhibits a higher, or > upper, resonant frequency caused by the inductance response of the > velocity sensor coil interacting with the magnetic field. This produces > a 6 dB per octave (1-pole) decay above the upper resonant frequency, > i.e., it acts like a low-pass filter, that is characteristically one to > orders of magnitude above the natural freqency. For example, the Marks > Products L-22 geophone has a 2.0 Hz natural frequency and an 85.0 Hz > upper frequency Put another way: What I was refering to was(For damping around 0.7): For long period sensors, the deflection of the sensor would measure the ground deflection and be flat for frequencies above the sensor's natural frequency and decay for frequencies lower. For short period sensors, the sensor's deflection would represent the ground acceleration and would be flat for frequencies below the sensor's natural frequency and decay for frequencies above the sensors natural frequency; ie, turning a acceleromometer on it side(low frequency) induces a 1G acceleration but is evidenced by the sensor deflecting. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@................. (Dr. John Lahr (USGS-GI Seismologist)) Subject: Exploration Geophones Date: Wed, 9 Apr 1997 12:17:16 -0800 Arlen, Here's the revised text from http://www.giseis.alaska.edu/Input/lahr/web.sites.html: "Arlen Juels of Seistex '86, Inc. has a number of used seismic refraction geophones that he is willing to provide to teachers for the cost of shipping. He can be contacted at AJuels@......... These are relatively high frequency phones (mostly 8 to 14 Hz vertical) that are small and well suited to "table-top" seismology. Due to their poor response to frequencies below 8 Hz, these phones are not ideally suited for earthquake monitoring, but would respond to very nearby earthquakes." I'll cc this message to the amateur seismologists of the Public Seismic Network to let them know of your offer, so you may get some requests from them too. Thanks again for you generousity, JCLahr ################################## John C. Lahr ################################# Seismologist ################################ U.S. Geological Survey ############################### c/o Geophysical Institute ############################## 903 Koyukuk Drive ~~~~~~~~~~~~~~ Get ~~~~~~~~~~ ############################# ########################################################### P.O. Box 757320 ################################ Fairbanks, AK 99775 ################################# Phone: (907) 474-7997 ################################## Fax: (907) 474-5618 ~~~~~~~~ the thrust? ~~~~~~~~~~~~~~ lahr@........ #################################### http://www.aeic.alaska.edu/Input/lahr/ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: geophones Date: Wed, 09 Apr 1997 15:45:01 -0600 Barry- I completely with you agree that the displacement response, i.e., the deflection, is proportional to ground acceleration for frequencies below the natural frequency and to ground displacement above the natural frequency. -Edward Barry Lotz wrote: > What I was refering to was(For damping around 0.7): For long period > sensors, the deflection of the sensor would measure the ground > deflection and be flat for frequencies above the sensor's natural > frequency and decay for frequencies lower. For short period sensors, the > sensor's deflection would represent the ground acceleration and would be > flat for frequencies below the sensor's natural frequency and decay for > frequencies above the sensors natural frequency; ie, turning a > acceleromometer on it side(low frequency) induces a 1G acceleration but > is evidenced by the sensor deflecting. -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: geophones Date: Wed, 09 Apr 1997 15:55:50 -0600 George- Though I am not very familiar with the Lehmans used by many of the PSN, I think you have raised an excellent point, or rather, have made a very insightful inference. In 1975, when I was in graduate school for seismology, I read an interesting paper for an instrumentation seminar that described various cross-coupling phenomena, including the tilt effect you surmise, that long-period seismometers are subject to. I do not have the reference to the paper handy, but it should be out there somewhere. -Edward George A. Harris wrote: > > Ed, > I have been monitoring the PSN newsgroup for some time, and have been > running a displacement seismometer during the quakes in Russia and > the far east last year. I have a question. > > My seismometer was a displacement unit which caught the 16 second > period signals from the distant quakes. Since the natural mechanical > frequency of the unit was near 1 hz., I have become suspicous that > the unit is actually measuring tilts rather than lateral accelerations. > Do you agree? If so it might be useful to discuss this on the > mailgroup. > > George Harris > > -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: owl@............ Subject: Is Your Web Site A Secret? Date: Thu, 10 Apr 1997 07:14:59 -0400 (EDT) Is your web site the best kept secret on the Internet? We'll promote it to 50 search engines and indexes for $85 and complete the job in 2 business days. Satisfaction is guaranteed! If you have a great product, but are not getting many inquiries from your Web site, you may not be adequately listed on the Web's search engines and indexes. Millions of viewers daily use these facilities to find the products and services they are looking for. But if your site is not listed, no one will see it. Listings on most of these services are free. However, locating and filling out the forms required to get a listing can take several days, and most people just don't have the time to do it. That is why we offer a web site promotion service. WHAT'S THE DEAL? We will submit your site to 50 indexes and search engines for $85. We will accept the return of this E-mail, with the form below filled out, as an order. We will bill you upon completion of the promotion. Our terms are net 15 days from date of invoice. Satisfaction guaranteed! HOW LONG WILL IT TAKE? Generally, we complete the submissions within 48 hours of receiving your order. It can take any individual search engine or index up to three weeks to process your submission, although most are much faster. WHAT SEARCH ENGINES AND INDEXES ARE INCLUDED IN THE PROMOTION? The list changes from time to time. This is our current list: Abaweb!, Alta Vista, Been There, BizWeb, Central Source Yellow Pages, Enterpreneurs on the Web, Excite, Four11, Galaxy, I-Network I-Systems Spiral Business Directory, I-World Web Pointer, Infoseek, Inktomi, Innovator's Network Yellow Pages, Internet Mall, Jayde Online Directory, Jumpcity, Jumper Hot Links, Linkmaster, Lycos, Magellan, Mega Mall, Net-Happenings, Net Navigator, Net Mall, NTG's List, NYNEX Big Yellow, One World Plaza, OnLine's WWWeb Index, Rex, Starting Point, Truenorth, URL Tree, Virtual Lynx, Web Point, WebCentral, Web Venture Hotlist, Webcrawler, Websurf, Win Mag/NetGuide Hotspots, WhatUSeek, Worldwide Announce Archive, WWW Business Yellow Pages, World Wide Yellow Pages, WWW Worm, YelloWWWeb. HOW WILL I KNOW THAT YOU HAVE PROMOTED MY SITE? When we have completed the promotion, we will send you an HTML file as an attachment to your E-mail bill. Save this file to your disk, and view it through your Web browser. It provides links to the search engine we submitted your site to, plus any comments we received from them when we did it. ARE THERE ANY GUARANTEES? We do not require prepayment. Your satisfaction is guaranteed or you don't pay the bill. WHO IS OWL'S EYE PRODUCTIONS? We are a web site promotion company located at: Owl's Eye Productions, Inc. 260 E. Main Street Brewster, NY 10509 Phone: (914) 278-4933 Fax: (914) 278-4507 Email: owl@............ HOW DO I ORDER? The easiest way to order is by e-mail. Just hit the REPLY button on your e-mail program and fill out the following information. (This information will be posted to the search engines/indexes): Your name: Company Name: Address: City: State/Prov: Zip/Postal Code: Telephone: Fax: Email address: URL: http:// Site Title: Description (about 25 words): Key words (maximum of 25, in descending order of importance): Proofs (Where shall we e-mail proofs): If billing a different address, please complete the following: Addressee: Company Name: Address: City: State/Prov: Zip/Postal Code: Telephone: Fax: Email address: We will bill via Email. (7310) Terms: By returning this document via Email, you agree as follows: You have the authority to purchase this service on behalf of your company. Terms are net 15 days. Accounts sent to collections will be liable for collection costs. You agree to protect and indemnify Owl's Eye Productions, Inc. in any claim for libel, copyright violations, plagiarism, or privacy and other suits or claims based on the content or subject matter of your site. WHAT HAPPENS NEXT? When we receive your order, we will input the information into our system, and send you a proof. After we process any corrections, we will run your promotion, capturing any comments from search engines as we go. We will incorporate these into an HTML-formatted report to you, which we will attach to your bill. ===Web Promotions=====Press Releases=====Link Exchanges========= Owl's Eye Productions, Inc. 260 E. Main Street Brewster, NY 10509 Ph: 914-278-4933 Fx: 914-278-4507 E-mail: owlseye@............ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: owl@............ Subject: Is Your Web Site A Secret? Date: Thu, 10 Apr 1997 07:14:54 -0400 (EDT) Is your web site the best kept secret on the Internet? We'll promote it to 50 search engines and indexes for $85 and complete the job in 2 business days. Satisfaction is guaranteed! If you have a great product, but are not getting many inquiries from your Web site, you may not be adequately listed on the Web's search engines and indexes. Millions of viewers daily use these facilities to find the products and services they are looking for. But if your site is not listed, no one will see it. Listings on most of these services are free. However, locating and filling out the forms required to get a listing can take several days, and most people just don't have the time to do it. That is why we offer a web site promotion service. WHAT'S THE DEAL? We will submit your site to 50 indexes and search engines for $85. We will accept the return of this E-mail, with the form below filled out, as an order. We will bill you upon completion of the promotion. Our terms are net 15 days from date of invoice. Satisfaction guaranteed! HOW LONG WILL IT TAKE? Generally, we complete the submissions within 48 hours of receiving your order. It can take any individual search engine or index up to three weeks to process your submission, although most are much faster. WHAT SEARCH ENGINES AND INDEXES ARE INCLUDED IN THE PROMOTION? The list changes from time to time. This is our current list: Abaweb!, Alta Vista, Been There, BizWeb, Central Source Yellow Pages, Enterpreneurs on the Web, Excite, Four11, Galaxy, I-Network I-Systems Spiral Business Directory, I-World Web Pointer, Infoseek, Inktomi, Innovator's Network Yellow Pages, Internet Mall, Jayde Online Directory, Jumpcity, Jumper Hot Links, Linkmaster, Lycos, Magellan, Mega Mall, Net-Happenings, Net Navigator, Net Mall, NTG's List, NYNEX Big Yellow, One World Plaza, OnLine's WWWeb Index, Rex, Starting Point, Truenorth, URL Tree, Virtual Lynx, Web Point, WebCentral, Web Venture Hotlist, Webcrawler, Websurf, Win Mag/NetGuide Hotspots, WhatUSeek, Worldwide Announce Archive, WWW Business Yellow Pages, World Wide Yellow Pages, WWW Worm, YelloWWWeb. HOW WILL I KNOW THAT YOU HAVE PROMOTED MY SITE? When we have completed the promotion, we will send you an HTML file as an attachment to your E-mail bill. Save this file to your disk, and view it through your Web browser. It provides links to the search engine we submitted your site to, plus any comments we received from them when we did it. ARE THERE ANY GUARANTEES? We do not require prepayment. Your satisfaction is guaranteed or you don't pay the bill. WHO IS OWL'S EYE PRODUCTIONS? We are a web site promotion company located at: Owl's Eye Productions, Inc. 260 E. Main Street Brewster, NY 10509 Phone: (914) 278-4933 Fax: (914) 278-4507 Email: owl@............ HOW DO I ORDER? The easiest way to order is by e-mail. Just hit the REPLY button on your e-mail program and fill out the following information. (This information will be posted to the search engines/indexes): Your name: Company Name: Address: City: State/Prov: Zip/Postal Code: Telephone: Fax: Email address: URL: http:// Site Title: Description (about 25 words): Key words (maximum of 25, in descending order of importance): Proofs (Where shall we e-mail proofs): If billing a different address, please complete the following: Addressee: Company Name: Address: City: State/Prov: Zip/Postal Code: Telephone: Fax: Email address: We will bill via Email. (7310) Terms: By returning this document via Email, you agree as follows: You have the authority to purchase this service on behalf of your company. Terms are net 15 days. Accounts sent to collections will be liable for collection costs. You agree to protect and indemnify Owl's Eye Productions, Inc. in any claim for libel, copyright violations, plagiarism, or privacy and other suits or claims based on the content or subject matter of your site. WHAT HAPPENS NEXT? When we receive your order, we will input the information into our system, and send you a proof. After we process any corrections, we will run your promotion, capturing any comments from search engines as we go. We will incorporate these into an HTML-formatted report to you, which we will attach to your bill. ===Web Promotions=====Press Releases=====Link Exchanges========= Owl's Eye Productions, Inc. 260 E. Main Street Brewster, NY 10509 Ph: 914-278-4933 Fx: 914-278-4507 E-mail: owlseye@............ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Michael J. Roseberry" Subject: Re: Is Your Web Site A Secret? Date: Thu, 10 Apr 1997 11:10:57 -0500 owl@............ wrote: > > Is your web site the best kept secret on the Internet? > > We'll promote it to 50 search engines and indexes for $85 > and complete the job in 2 business days. Satisfaction is > guaranteed! > > snip ... Have we been invaded? :-| Michael J. Roseberry -- _____________________ roseberry@........... mjr@........ "There is no good substitute for understanding." -- mjr _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@................. (Dr. John Lahr (USGS-GI Seismologist)) Subject: Re: arrival time calculator Date: Thu, 10 Apr 1997 11:54:58 -0800 Charlie, Thank you for pointing out that my arrival time calculator page (http://www.giseis.alaska.edu/Input/lahr/artim.html) was not working for NEIC finger events. I found a bug I had introduced the other day when I added spyder events, neic accumulated events, etc. Everything worked except the standard NEIC finger! Reload and try it again now. Write back if you stop any other problems. Microsoft isn't the only one that depends on user feedback. Cheers, JCLahr _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: Is Your Web Site A Secret? Date: Thu, 10 Apr 1997 12:57:51 -0700 At 11:10 AM 4/10/97 -0500, you wrote: >owl@............ wrote: >> >> Is your web site the best kept secret on the Internet? >> >> We'll promote it to 50 search engines and indexes for $85 >> and complete the job in 2 business days. Satisfaction is >> guaranteed! >> >> snip ... > > >Have we been invaded? :-| Sure have, I sent a nasty note to owl@. I also did a whois and found the contact person for the domain so I also sent the note to john@............. Feel free to write your own note to the email spammers letting them know what you think of them. Make sure and send the message directly to them and not the list. I also contacted there ISP at postmaster@....... letting them know one of there accounts is spamming email. Later tonight I will call the number at the bottom of the message and leave a nasty voice mail message. I will also make a change to my mail server so email from olwsnest.com will not go out. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Lucas Haag Subject: Re: Is Your Web Site A Secret? Date: Thu, 10 Apr 97 16:09:41 CDT THANK YOU LARRY! I'm sure that you efforts are appricated by all of the members of the mailing list. At 12:57 PM 4/10/97 -0700, you wrote: >At 11:10 AM 4/10/97 -0500, you wrote: >>owl@............ wrote: >>> >>> Is your web site the best kept secret on the Internet? >>> >>> We'll promote it to 50 search engines and indexes for $85 >>> and complete the job in 2 business days. Satisfaction is >>> guaranteed! >>> >>> snip ... >> >> >>Have we been invaded? :-| > >Sure have, I sent a nasty note to owl@. I also did a whois and found the >contact person for the domain so I also sent the note to john@............. >Feel free to write your own note to the email spammers letting them know >what you think of them. Make sure and send the message directly to them and >not the list. I also contacted there ISP at postmaster@....... letting them >know one of there accounts is spamming email. Later tonight I will call the >number at the bottom of the message and leave a nasty voice mail message. > >I will also make a change to my mail server so email from olwsnest.com will >not go out. > >Regards, >Larry Cochrane >Redwood City, PSN > > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > ************************************************* Lucas Haag HCR 66 Box 25A Bartley, Nebraska 69020-9717 lhaag@.............. http://www.swnebr.net/~lhaag "Through da keyboard, into the chips, over the copper, through the fiber, back through the copper into the chips, to the screen... NOTHING BUT NET!" ************************************************* _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie & Terri Thompson -- @MicroRanch ) Subject: Jalisco Event Date: Thu, 10 Apr 1997 19:40:45 -0500 My uploaded Jalisco event has a date error...the date should be 4/8/97 NOT 4/9/97....daylight savings time caused me to foul up the date on my computer...the date has been corrected for all subsequent uploads to PSN. Additionally, the USGS was LATE is posting this event and many people could not find it...here's the USGS data: 97/04/08 15:23:43 18.55N 106.38W 33.0 4.9Ms B OFF COAST OF JALISCO, MEXICO ....better late than never! -Charlie Thompson Buda, Texas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson Subject: for something totally different Date: Fri, 11 Apr 1997 20:20:17 +1200 hi all, for those of you in the northern states, canada, alaska ie above 45 deg Nth keep an eye on the sky for some good auroral activity. A major to severe geomagnetic storm started 7 hrs ago and is still in progress. dave Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'SLAW-- When Something Does Go Wrong, There Is Sod All You Can Do AboutIt When The Last Of Ten Screws Has Been Removed From A Cover, It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: Ground tilt and acceleration Date: 11 Apr 97 12:56:30 EDT Hi gang, Harris and Cranswick recently discussed the response of a horizontal long-period seismometer to horizontal acceleration and tilt. Aki & Richards, "Quantitative Seismology", vol 1, 1980, p 485 sez " For almost all designs of pendulum seismometers, it is not possible to distinguish between a horizontal acceleration of the ground and a contribution from gravity due to tilt." "...most seismologists have been content with the rather arbitrary assumption that either acceleration or tilt dominates a particular signal." A mathematical analysis (which is over my head) follows. Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: Ground tilt and acceleration Date: Fri, 11 Apr 1997 12:06:18 -0600 While Paul Richards and Keiti Aki were writing Aki&Richards, Paul gave a seminar on seismic instrumentation, partly as preparation for writing the book. I was a graduate student and took the seminar and had to present the paper about cross-coupling of tilt and inertial response, the subject George Harris raised. The mathematics were over my head as well, but I suddenly realized how a long-period "swinging gate" seismometer would respond to the dynamic variations of tilt produced by the passage of surface waves. During my presentation, I demonstrated this truth with considerable literal "arm waving", rather than writing equations on the board, and Paul, the consummate mathematician, told me that he had not understood that implication from the equations. My failure as a mathematician has always kept me relatively close to the Earth. Robert L Barns wrote: > > Hi gang, > Harris and Cranswick recently discussed the response of a horizontal > long-period seismometer to horizontal acceleration and tilt. Aki & Richards, > "Quantitative Seismology", vol 1, 1980, p 485 sez " For almost all designs of > pendulum seismometers, it is not possible to distinguish between a horizontal > acceleration of the ground and a contribution from gravity due to tilt." > "...most seismologists have been content with the rather arbitrary assumption > that either acceleration or tilt dominates a particular signal." A mathematical > analysis (which is over my head) follows. > Bob Barns > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@................. (Dr. John Lahr (USGS-GI Seismologist)) Subject: Re: Ground tilt and acceleration Date: Fri, 11 Apr 1997 13:24:31 -0800 Ed C. is "close to the earth." Is that like "down and dirty?" :-) JCLahr PS. Thanks for the insight into tilt vs horizontal motion. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@................. (Dr. John Lahr (USGS-GI Seismologist)) Subject: Arrival Time Calculator Date: Mon, 14 Apr 1997 10:55:58 -0800 I modified the arrival time calculator (http://www.giseis.alaska.edu/Input/lahr/artim.html) this weekend so that you can store your station coordinates on your disk for repeated use with the web page. This is done through the use of "cookies." This works with the Netscape browser, but I'm not sure about others. If the cookies don't work for you, coordinates can be still be entered each time as usual. JCLahr ################################## John C. Lahr ################################# Seismologist ################################ U.S. Geological Survey ############################### c/o Geophysical Institute ############################## 903 Koyukuk Drive ~~~~~~~~~~~~~~ Get ~~~~~~~~~~ ############################# ########################################################### P.O. Box 757320 ################################ Fairbanks, AK 99775 ################################# Phone: (907) 474-7997 ################################## Fax: (907) 474-5618 ~~~~~~~~ the thrust? ~~~~~~~~~~~~~~ lahr@........ #################################### http://www.aeic.alaska.edu/Input/lahr/ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: Smaller Lehmans? Date: 14 Apr 97 15:23:34 EDT Hi gang, My Lehman has a boom about 30" long and it works fine. However, we have been in the 'age of miniaturization' for a long time and I am curious to hear of any experiences on the performance of smaller Lehmans. (Who has operated the worlds' smallest with a period of at least 16"?). I am aware that Cochrane finds that a Shackelford-Gunderson (which is much smaller) is a better instrument but I would still like to know about small Lehmans. I'm also aware that professional seismometers (e.g. Geotechs) have booms about a foot long. I can't see why a smaller Lehman (say with a 15" boom) should be inferior except that friction in the boom pivot would be more important. If this proves to be a problem, there seems to be a neat fix--the 'Zollner suspension (1869!)'. This is described in Aki & Richards, "Quantitative Seismology", 1980, vol 1, p 484. I built a very crude working model of this (with a 12" boom, 0.2kg mass and a period of 14 secs.) and it looks very practical. In fact, I may modify my Lehman to this design. Can anyone report experience with this suspension? To save you the trouble of looking up Aki & Richards (although this should be required reading for all of us), I'll take a stab at describing the Zollner-- Imagine a standard Lehman horizontal boom with the mass on the right end. The main suspension wire comes down from the upper support and attaches to the boom just to the left of the mass as per usual in a Lehman. Instead of a pivot on the left end of the boom, a wire (which can be very thin because it carries little load) is attached to the left end of the boom and this end of the boom extends an inch or two to the left of the lower 'support'. The lower 'support' is almost directly below the upper support. The wire on the left end of the boom is attached to the lower support and makes an angle of ~45 deg. to the boom. As usual, the period is determined by the angle from the vertical of the line connecting the upper and lower 'support'. Well, there's a whole bunch of questions for the group to munch on. Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie Thompson) Subject: Re: Arrival Time Calculator Date: Mon, 14 Apr 1997 16:29:11 -0500 Sounds like a nifty and useful addition...I'll give it a try. thanks, Charlie >I modified the arrival time calculator > >(http://www.giseis.alaska.edu/Input/lahr/artim.html) > >this weekend so that you can store your station coordinates on >your disk for repeated use with the web page. This is >done through the use of "cookies." This works with the >Netscape browser, but I'm not sure about others. If the >cookies don't work for you, coordinates can be still be >entered each time as usual. > >JCLahr >################################## John C. Lahr >################################# Seismologist >################################ U.S. Geological Survey >############################### c/o Geophysical Institute >############################## 903 Koyukuk Drive >~~~~~~~~~~~~~~ Get ~~~~~~~~~~ ############################# >########################################################### > P.O. Box 757320 ################################ > Fairbanks, AK 99775 ################################# > Phone: (907) 474-7997 ################################## > Fax: (907) 474-5618 ~~~~~~~~ the thrust? ~~~~~~~~~~~~~~ > lahr@........ #################################### > http://www.aeic.alaska.edu/Input/lahr/ > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie Thompson) Subject: Re: Smaller Lehmans? Date: Mon, 14 Apr 1997 16:39:12 -0500 Speaking of smaller Lehmans...I have a "mini-Lehman" that I designed to fit under a 10-gallion aquarium..available for about $10 at Petsmart. The glass allows you to show off your sensor as well. I have the thing levelled up in my garage and it's been stable for about 1 month now. Period is about 6 seconds. I don't have it wired up yet but plan to do so soon. Aquarium dimensions are about 15w"x12h"x8d" It will take up MUCH LESS room than my full-sized Lehaman w/box. So much less that I can place two of the smaller mini-Lehmans in the foot print of the single larger Lehman. FFT's show that P and S waves have frequencies above 6 seconds so I feel that the P and S waves will not be degraded by the use of a higher natural frequency. Since L waves "tilt" the unit I believe that it may prove sensitive enough for L waves regardless of period. I'd like to hear everyone's thoughts on this ....maybe P and S are different at different locations but my Texas data shows the P and S are almost always higher than 6 seconds in frequency. This is how I distinguish small quakes from 6-second background noise. Regards, Charlie Thompson Buda, Texas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jeff Batten Subject: Smaller Lehmans Date: Mon, 14 Apr 1997 16:50:26 -0700 Speaking of smaller Lehmans...I have a "mini-Lehman" that I designed to fit under a 10-gallion aquarium..available for about $10 at Petsmart. The glass allows you to show off your sensor as well. I have the thing levelled up in my garage and it's been stable for about 1 month now. Period is about 6 seconds. I don't have it wired up yet but plan to do so soon. Aquarium dimensions are about 15w"x12h"x8d" It will take up MUCH LESS room than my full-sized Lehaman w/box. So much less that I can place two of the smaller mini-Lehmans in the foot print of the single larger Lehman. FFT's show that P and S waves have frequencies above 6 seconds so I feel that the P and S waves will not be degraded by the use of a higher natural frequency. Since L waves "tilt" the unit I believe that it may prove sensitive enough for L waves regardless of period. What you can do is crank up the gain, and add a 20 sec low pass filter, you will have no problem recording 20 second surface waves. Have different stages in the amplifier. One for low, and one for high frequencies, then sum them. Totally filter out the 6 second garbage. There really is not a need for a horizontal with a period longer than 6 seconds with todays electronics. With a shaped response one can have the best of both worlds. Recorded a nice mammoth lakes trace today on my AS1. Jeff _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: SCEC Date: Tue, 15 Apr 1997 08:19:36 -0700 Hi -- The finger server at the Southern California Earthquake Center (quake@..................... hasn't reported any events since 4/12 at 17:36UTC. I've seen two ~M3 events local to Southern California since then. Does anyone know the status of the finger server? Thanks, Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: SCEC Date: Tue, 15 Apr 1997 08:49:45 -0700 I called Nick Sheckley at Caltech. Although he was not in Debi said the system appears to be working fine. -- ---/---- Charles P. Watson, Consulting Geologist Advanced Geologic Exploration Seismo-Watch / Earthquake Information Services Voice: 702-852-0992 / Fax: 702-852-3226 mailto:watson@................ http://www.seismo-watch.com Karl Cunningham wrote: > > Hi -- > > The finger server at the Southern California Earthquake Center > (quake@..................... hasn't reported any events since 4/12 at > 17:36UTC. I've seen two ~M3 events local to Southern California since then. > > Does anyone know the status of the finger server? > > Thanks, > > Karl Cunningham > La Mesa, CA. > karlc@......... > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: Jalisco Event Date: Wed, 16 Apr 1997 16:11:58 -0700 Greetings -- My upload of this same event also has an error -- I incorrectly reported it as the Fox Island event, rather than as from Jalisco, MX. The two events were separated in time by only minutes, and with only the Fox Island event on the USGS list around that time, I made an assumption... I wonder if the proximity of these two events in time contributed to the tardy listing of the Jalisco event? Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Joe Irvine Subject: new address Date: Wed, 16 Apr 1997 15:20:49 Http://www.scec.gps.caltech.edu Joe Irvine _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "George A. Harris" Subject: Smaller Lehmans Date: Wed, 16 Apr 1997 20:07:07 -0700 (PDT) For some time I have been experimenting with a small Lehman with a 9 inch boom. The secret is to support it with very flexible pivots. Mine is an "L" shape with the short end pointing down. The support is by means of two pieces of thin plastic. A piece of 1/4 inch recording tape makes a good pair. The vertical part of the boom is about 3 inches long. At the bottom, a piece of tape pulls to the right toward the weight. At the upper part, and somewhat to the right of the vertical is another tape which pulls toward the upper left. The proper angle of the upper tape is that which would make the two pieces of tape meet at or above the center of gravity of the boom. My boom anly weighs a few ounces, but can easily be adjusted to a period of at least 8 seconds in air. It could be longer if it is covered but the adjustment is very critical, and the unit seems to become very temperature sensative. It is imporant that the stationary ends of the tape pivots be capable of being adjusted to be in a vertical line. Also, if the beam is allowed to move too much (like more than a quarter inch) it tends to become unstable due to the geometry. My present conclusion is that the only really useful long period small unit should be a feedback one. My present model has two magnets at the end of the boom (1/2 dia by 1/4 thick magnets) which are above the two sides of a two inch coil. An EO sensor is amplified and fed back to the coil. It is very sensitive, but I am trying for a two axis model now. George Harris _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: [Fwd: Letter from Alan Hale] Date: Thu, 17 Apr 1997 09:01:51 -0700 This letter was forwarded to me and I am passing it on to other groups that would benefit from its content. -- ---/---- Charles P. Watson, Consulting Geologist Advanced Geologic Exploration Seismo-Watch / Earthquake Information Services Voice: 702-852-0992 / Fax: 702-852-3226 mailto:watson@................ http://www.seismo-watch.com From: Karl Cunningham Subject: Force Balance Idea Date: Thu, 17 Apr 1997 16:13:07 -0700 Hi All -- A while back I had another idea for a force-balance seismometer... Fantasy mode on... Imagine a superconducting coil sitting on a table, with the ends shorted together. Then place a magnet above it ... the magnet should be levitated by the current induced in the superconducting coil. If one could measure the current in the coil (without introducing loss), it would be a measure of vertical acceleration on the magnet (including a dc current equivalent to 1g). Even if there was some loss in the current measurement system, it probably would be good enough to measure dynamic acceleration on the magnet but certainly not keep it levitated. The force coil I used in my FB seismometer has pretty good coupling to its magnet, and a dc resistance of about 7 ohms. Thinking for a moment that if the equivalent circuit of the force coil is an ideal coil with a 7-ohm resistor in series with it, I reasoned that if I connected a NEGATIVE 7-ohm resistor in series with the positive 7-ohm resistor, the whole thing would simulate a superconducting coil. Shorting the ends of the simulated superconducting coil together would yield the situation in the above paragraph. Back to the real world... There is such a thing as a "negative impedance convertor" (NIC), which is a circuit composed of an op-amp and a handful of resistors. It provides a terminal that has all the characteristics of a negative resistance with respect to ground. By adjusting the values of the resistors, the value of the negative resistance can be adjusted. I built one of these circuits, adjusted it for about negative 7 ohms, and connected it to my coil, which was set up on my Lehman mechanical system (horizontal). To my astonishment, it worked. It resisted movement very well (balancing the force), and the current in the coil was proportional to the force (acceleration on the mass). As a test, I un-leveled the base of the Lehman a bit and pulled the mass to the upper stop. When I let it go without the NIC connected the mass fell to the other side in 1/2 second or less. With the NIC connected, it took more than 20 MINUTES for the mass to fall to the other stop! Elecronically, this is a very simple system. It is a force-balance accelerometer with only one coil, no separate position detector, and only a very small number of components to do the feedback. Now for the problem. (There's always a catch) When it is just balancing the resistance of the force coil, the NIC becomes unstable (oscillates). Adjusting it to just shy of that point stops the oscillation, but the stability of that adjustment is poor. The coil is copper (~0.3%/deg C resistance tempco), and not matched by the fixed resistors I used. Also, near the critical adjustment, drift of the op-amp is multiplied by something akin to the reciprocal of the match in resistances -- it gets pretty bad. Looking at noise, it was still far above the 6-second background noise. I moved on to other ideas. Anyway, I thought I'd throw it out to the group. Maybe some of you out there have ideas that will overcome the problems. Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Greg Lyzenga Subject: Force Balance article Date: Fri, 18 Apr 1997 09:12:35 -0700 Hi folks: Sorry to bother you with a rehash of something discussed earlier -- I couldn't seem to find it in my archives of old messages. Some months ago, somebody mentioned a journal article that had been published describing the design and construction of a force balance seismometer system. I think this might be a good project to turn loose some of my students on. Could somebody please refresh my memory on the citation I'm thinking of? Thanks x 10^6 ! - Greg |Gregory A. Lyzenga *** (909) 621-8378 |Dept. of Physics, Harvey Mudd College *** fax (909) 621-8887 |Claremont, CA 91711-5990 http://www.physics.hmc.edu/profs/lyzenga.html _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ron Westfall Subject: Re: Force Balance article Date: Fri, 18 Apr 1997 11:38:56 -0700 Greg Lyzenga wrote: > Some months ago, somebody mentioned a journal article that had been > published describing the design and construction of a force balance > seismometer system. I think this might be a good project to turn > loose some of my students on. Could somebody please refresh my > memory on the citation I'm thinking of? The reference you might be thinking of was: A miniature wide band horizontal-component feedback seismometer. Journal of Physics E: Scientific Instruments 1977 Ovulate 10 I found the article in our local university library. The design (especially the controlling electronics) is not fully specified in the article, but enough clues are provided that the details can probably be worked out. The only other issue was that the mechanical design called for some materials I had never heard of (Ni-Span I think it was). Good Luck Ron Westfall westfall@...... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jeff Batten Subject: FBS stuff Date: Fri, 18 Apr 1997 13:42:36 -0700 If you are trying to build your own force balance seismometer you should check out A miniature wide band horizontal-component feedback seismometer. Journal of Physics E: Scientific Instruments 1977 Ovulate 10 It has a pretty good description of a FBS. I think that a lot of readers of this group have the skills to construct the seismometer. The article has a good drawing and photos. If you have a milling machine and lathe, give it a try. Another good reference. The design of miniature wide band seismometers M. J. Usher and C Guralp Geophysical Journal of the Royal Astronomical Society 1978 (55), 605-613 M J usher I W Buckner R F Burch If you like seeing a lot of unique designs for seismometers check out old Bull. Seismol. Soc. Am. The BSSA has a few hundred articles on seismometer design back to 1906. You will probably have to visit a university library to find the above references. Jeff Batten - Research Engineer Caltech Seismo Lab 818-395-6965 Fax-818-564-0715 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) Jeff Batten - Research Engineer Caltech Seismo Lab 1200 E. California Bl. Pasadena, Ca. 91125 818-395-6965 Fax-818-564-0715 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz Subject: Re: Force Balance article Date: Fri, 18 Apr 1997 18:02:36 -0700 Greg Lyzenga wrote: > > Hi folks: > Sorry to bother you with a rehash of something discussed earlier -- I > couldn't seem to find it in my archives of old messages. > > Some months ago, somebody mentioned a journal article that had been > published describing the design and construction of a force balance > seismometer system. I think this might be a good project to turn loose > some of my students on. Could somebody please refresh my memory on the > citation I'm thinking of? > > Thanks x 10^6 ! > > - Greg > > |Gregory A. Lyzenga *** (909) 621-8378 > |Dept. of Physics, Harvey Mudd College *** fax (909) 621-8887 > |Claremont, CA 91711-5990 > http://www.physics.hmc.edu/profs/lyzenga.html > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L Hi You might also try Sientific American Sept 1975 Amateur Scientist. I think you could call it a force balance seismometer. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: Force Balance article Date: Sun, 20 Apr 1997 14:54:28 -0700 At 06:02 PM 4/18/97 -0700, Barry Lotz wrote: >Hi > You might also try Sientific American Sept 1975 Amateur Scientist. >I think you could call it a force balance seismometer. > This is the Shackleford-Gundersen Seismometer article. It's not really a FB sensor because the feedback to the coil is AC coupled. I think that it can be turned into a FB sensor by adding a resistor where the DC block capacitor goes. You need to add some capacitance across the resistor so the sensor won't oscillate. I think this makes a lead circuit. I played around with this a few months ago. By DC coupling the feedback coil you now get a DC signal that changes with the tilt of the sensor. As you increase the feedback you need to tilt the sensor more to get the same output. This has the same effect as my two other FB sensors (the ADX05 and the FBA-31). As you tilt the sensor, using the 1g force of mother earth, you get a DC output that increases until the sensor is straight up and down. I was unable to get my SG sensor to go that far because of the weight of the pendulum and the amount of current I could supply to the coil. I have the SA Sept 1975 article on my Website at http://psn.quake.net/sgsendor.html. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: Re: Force Balance article Date: 20 Apr 97 20:21:18 EDT Greg, I can't answer your question about the article reference but I have a few of my own. Somewhere I read that the Harvey Mudd Coll. uses a mercury tiltmeter as a seismometer. If so: 1. Is this a commercial device? If so, who made it? 2. Could you tell us about it--size, period, performance, stability, etc. etc.? One of these is described in great detail in Sci. Am. mag., Nov. 1973 p124... and sounds easy to make and capable of good performance. Is your sensor like this one? I am also interested in your opinion of this article. Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson Subject: ALERT MONSTER QUAKE !!!!!! Date: Tue, 22 Apr 1997 00:32:11 +1200 HI ALL, Just recorded a large event here in New Zealand still waiting for a report on the NEIC page No S-P but it is the largest amplitude lower freq. waves that I have ever recorded LP waves still coming in 20 minutes after the original arrival original arrival 1212:10 UTC Mon 21 Apr 97 Dave Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'SLAW-- When Something Does Go Wrong, There Is Sod All You Can Do AboutIt When The Last Of Ten Screws Has Been Removed From A Cover, It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bzimmerman@............ Subject: Re: ALERT MONSTER QUAKE !!!!!! Date: Mon, 21 Apr 1997 08:44:46 -0500 (EST) Thanks for the warning Dave. I ran down to check and watched what look like surface waves rolling in. Brian S. Zimmerman Department of Geosciences Edinboro University of Pennsylvania Edinboro, PA 16444 Phone: (814) 732-2207 Email: BZimmerman@............ On Tue, 22 Apr 1997, David A Nelson wrote: > HI ALL, > Just recorded a large event here in New Zealand still > waiting for a report on the NEIC page > No S-P but it is the largest amplitude lower freq. waves that I have > ever recorded > > LP waves still coming in 20 minutes after the original arrival > > original arrival 1212:10 UTC Mon 21 Apr 97 > > > > Dave > Dave A. Nelson > > 24 Jensen St., > Green Is., Dunedin, > South Is.. New Zealand. > > http://psn.quake.net/dave/home.htm ( world wide access ) > http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) > > SOD'SLAW-- > When Something Does Go Wrong, There Is Sod All You Can Do AboutIt > > > When The Last Of Ten Screws Has Been Removed From A Cover, It Will Be > Discovered That The Wrong Cover Has Been Removed > > When The Last Of Ten Screws Has Been fitted back Into A Cover, It Will Be > Discovered That The gasket Has Been Left Out > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bob@................. (Bob Hammond (USGS-AVO Geophysicist)) Subject: Re: ALERT MONSTER QUAKE !!!!!! Date: Mon, 21 Apr 1997 04:51:14 -0800 I got the surface waves here too on my home seismograph. And got roused out of bed by a quake alarm for work. The borehole broadband seismograph is going strong. It's not in Alaska. Bob Hammond Fairbanks _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson Subject: Re: ALERT MONSTER QUAKE !!!!!! Date: Tue, 22 Apr 1997 00:58:42 +1200 good one Brian, still waiting for one of the data centres to show some info it is shown in Larry's event list on his page just downloaded his ..LC1 file but it is not shown too well will try some of his other sensor files I will put my one up there soon. dave At 08:44 AM 4/21/97 -0500, you wrote: > >Thanks for the warning Dave. I ran down to check and watched what look >like surface waves rolling in. > >Brian S. Zimmerman >Department of Geosciences >Edinboro University of Pennsylvania >Edinboro, PA 16444 > >Phone: (814) 732-2207 >Email: BZimmerman@............ > Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'SLAW-- When Something Does Go Wrong, There Is Sod All You Can Do AboutIt When The Last Of Ten Screws Has Been Removed From A Cover, It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson Subject: Re: ALERT MONSTER QUAKE !!!!!! Date: Tue, 22 Apr 1997 01:04:22 +1200 ok Bob No, by the amplitude that it has on my short period sensors it has to be in the sth Pacific either to the south of me in the Macquarie Ridge area or to the north inthe Fiji - Tonga area and I am picking M8 + dave At 04:51 AM 4/21/97 -0800, you wrote: >I got the surface waves here too on my home seismograph. And got roused out of bed by a quake alarm for work. >The borehole broadband seismograph is going strong. > >It's not in Alaska. > >Bob Hammond >Fairbanks > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'SLAW-- When Something Does Go Wrong, There Is Sod All You Can Do AboutIt When The Last Of Ten Screws Has Been Removed From A Cover, It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: ALERT MONSTER QUAKE !!!!!! Date: Mon, 21 Apr 1997 05:08:36 -0700 Hi, The event was around 9200 to 9500km from me. My SG sensors is giving me a Ms7.9 to Ms8.0! I don't know if it's really that large, will see when USGS reports something. Regards, Larry Cochrane Redwood City, PSN At 12:32 AM 4/22/97 +1200, you wrote: >HI ALL, > Just recorded a large event here in New Zealand still >waiting for a report on the NEIC page > No S-P but it is the largest amplitude lower freq. waves that I have >ever recorded > > LP waves still coming in 20 minutes after the original arrival > > original arrival 1212:10 UTC Mon 21 Apr 97 > > > > Dave > Dave A. Nelson _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bob@................. (Bob Hammond (USGS-AVO Geophysicist)) Subject: Re: ALERT MONSTER QUAKE !!!!!! Date: Mon, 21 Apr 1997 05:16:59 -0800 preliminary location is 7.6S, 166.3E, 7.5mw Bob Hammond Fairbanks _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson Subject: Re: ALERT MONSTER QUAKE !!!!!! Date: Tue, 22 Apr 1997 01:19:21 +1200 gidday Larry, just looked at your uploaded event looks impressive Dave Now 01:18 Local At 05:08 AM 4/21/97 -0700, you wrote: >Hi, > >The event was around 9200 to 9500km from me. My SG sensors is giving me a >Ms7.9 to Ms8.0! I don't know if it's really that large, will see when USGS >reports something. > >Regards, >Larry Cochrane >Redwood City, PSN > > Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'SLAW-- When Something Does Go Wrong, There Is Sod All You Can Do AboutIt When The Last Of Ten Screws Has Been Removed From A Cover, It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz Subject: Re: ALERT MONSTER QUAKE !!!!!! Date: Mon, 21 Apr 1997 05:32:04 -0700 David A Nelson wrote: > > HI ALL, > Just recorded a large event here in New Zealand still > waiting for a report on the NEIC page > No S-P but it is the largest amplitude lower freq. waves that I have > ever recorded > > LP waves still coming in 20 minutes after the original arrival > > original arrival 1212:10 UTC Mon 21 Apr 97 > > > > Dave > Dave A. Nelson > Hi all- I got it all here also. Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Dennis Leatart Subject: Re: ALERT MONSTER QUAKE !!!!!! Date: Mon, 21 Apr 1997 07:13:32 -0700 Hi Everyone!! I picked it up also--woke me up (my alarm that is!!). I am still picking up what looks like Rayleigh waves one hour after the event!!! -- _____ __ | \.-----.-----.-----.|__|.-----. | -- | -__| | || ||__ --| |_____/|_____|__|__|__|__||__||_____| _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie & Terri Thompson -- @MicroRanch ) Subject: Murphy's Law and Monster Quakes Date: Mon, 21 Apr 1997 09:12:30 -0500 Last night I powered everything down due to a violent electrical storm. This morning I powered up the machine in the middle of giant L-waves! If I had gotten out of bed 10 minutes earlier I would have bagged the complete event! I don't know where the quake is but it must have been the Mag 7+ that we record about once a month. Murphy's Law... -Charlie _ ________________________________________________ _ / ) | | ( \ / / | Charlie Thompson WB4HVD | \ \ _( (_ | _ e-mail: ct@....... _ | _) )_ (((\ \> |/ ) http://www.onr.com/user/ct/ct.html ( \| Subject: NEIC report Date: Tue, 22 Apr 1997 02:17:27 +1200 97/04/21 12:02:25 12.47S 166.21E 33.0 7.9Ms B SANTA CRUZ ISLANDS origin 12:02:25 arrival here 12:09:07 travel time ~ 7 minutes 18 sec the second arrival on my 15 min. file at ~ 12:18 could be this event 97/04/21 12:11:28 13.11S 166.24E 33.0 6.1Mb C VANUATU ISLANDS Dave Keen to see the Mw for this one I have recorded Ms 7.7-7.9 up here before but NEVER with this sort of amplitude Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'SLAW-- When Something Does Go Wrong, There Is Sod All You Can Do AboutIt When The Last Of Ten Screws Has Been Removed From A Cover, It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Dennis Leatart Subject: Monster Quake!!! Date: Mon, 21 Apr 1997 07:26:31 -0700 Hi!! The quake was located in the Santa Cruz Islands--Northeast of Australia and appears to have taken place in the ocean. Tidal wave alert??? Dave-- you are closests to this event -- did you feel it?? 12.47S and 166.21E--- Mag.7.9 ee-gad!!! -- _____ __ | \.-----.-----.-----.|__|.-----. | -- | -__| | || ||__ --| |_____/|_____|__|__|__|__||__||_____| _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson Subject: Re: Murphy's Law and Monster Quakes Date: Tue, 22 Apr 1997 02:29:07 +1200 check my last psn posting Charlie there is the NEIC report within. dave At 09:12 AM 4/21/97 -0500, you wrote: >Last night I powered everything down due to a violent electrical storm. > >This morning I powered up the machine in the middle of giant L-waves! >If I had gotten out of bed 10 minutes earlier I would have bagged the >complete event! > >I don't know where the quake is but it must have been the Mag 7+ >that we record about once a month. > >Murphy's Law... > >-Charlie > _ ________________________________________________ _ > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'SLAW-- When Something Does Go Wrong, There Is Sod All You Can Do AboutIt When The Last Of Ten Screws Has Been Removed From A Cover, It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson Subject: Re: Monster Quake!!! Date: Tue, 22 Apr 1997 02:37:08 +1200 Dennis, It was ~ 6-7000 Km to the NNW of me to be felt a M8 would have to be within 1000km like the M8.2 near Macquarie Is. ~900 km SW of me in the late 1980's 1988 I think Dave At 07:26 AM 4/21/97 -0700, you wrote: >Hi!! > >The quake was located in the Santa Cruz Islands--Northeast of Australia >and appears to have taken place in the ocean. Tidal wave alert??? >Dave-- you are closests to this event -- did you feel it?? > >12.47S and 166.21E--- Mag.7.9 ee-gad!!! >-- Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'SLAW-- When Something Does Go Wrong, There Is Sod All You Can Do AboutIt When The Last Of Ten Screws Has Been Removed From A Cover, It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: ALERT MONSTER QUAKE !!!!!! Date: Mon, 21 Apr 1997 11:49:47 -0600 Coming in to find this great flurry of PSN email after Dave Nelson's post, I figured I would try a find out something upstairs at NEIC. The only things that Waverly Person told me that you may not know is that there have been no reports of a tsunami and no reports damage of damage as yet. -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: ALERT MONSTER QUAKE !!!!!! Date: Mon, 21 Apr 1997 12:12:13 -0600 Larry's .LC3 made a very nice record, both in velocity and integrated to displacement, that makes me interested in teleseismic long-period seismology again. -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: [Fwd: Tsunami Bulletin (fwd)] Re: ALERT MONSTER QUAKE !!!!!! Date: Mon, 21 Apr 1997 13:30:16 -0600 -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". Gee, for a minute when I saw the name "Santa Cruz Island" I thought we were going to get our California tsunami, but the lat/long put this in the southwest Pacific... oh well... a later report cancelled the tsunami alert, already. Gotta go teach class, talk to you later.... JB ---------- Forwarded message ---------- Date: Mon, 21 Apr 1997 12:57:59 GMT From: Alaska Tsunami Warning Center To: TSUNAMI@............. Subject: Tsunami Bulletin TSUNAMI BULLETIN NUMBER 1 ALASKA TSUNAMI WARNING CENTER/NOAA/NWS ISSUED APR 21 AT 1253 UTC ....THIS IS A TSUNAMI ADVISORY BULLETIN FOR ALASKA, BRITISH COLUMBIA, WASHINGTON, OREGON, AND CALIFORNIA ONLY... NO, REPEAT NO, WATCH OR WARNING IS IN EFFECT. AN EARTHQUAKE, PRELIMINARY MAGNITUDE 7.7, OCCURRED AT 0402 ADT ON APR 21, OR 0502 PDT ON APR 21, OR 1202 UTC ON APR 21. THE EARTHQUAKE WAS LOCATED IN THE GENERAL AREA OF: SANTA CRUZ IS. NEAR 12.2S, 166.3E. THE PACIFIC TSUNAMI WARNING CENTER AT EWA BEACH, HAWAII WILL ISSUE BULLETINS FOR OTHER AREAS OF THE PACIFIC. EVALUATION: BASED ON THE LOCATION, MAGNITUDE AND HISTORICAL RECORDS, THE EARTHQUAKE WAS NOT SUFFICIENT TO GENERATE A TSUNAMI DAMAGING TO CALIFORNIA, OREGON, WASHINGTON, BRITISH COLUMBIA OR ALASKA. SOME AREAS MAY EXPERIENCE SMALL SEA LEVEL CHANGES. A FEW SELECTED ETA'S FOLLOW FOR INFORMATION AND REFERENCE: LA JOLLA, CA 1744 PDT APR 21 TOFINO, BC 1812 PDT APR 21 SAN FRANCISCO,CA 1748 PDT APR 21 SITKA, AK 1655 ADT APR 21 CRESCENT CITY,CA 1730 PDT APR 21 KODIAK, AK 1628 ADT APR 21 NEAH BAY, WA 1816 PDT APR 21 SHEMYA, AK 1357 ADT APR 21 BULLETINS WILL BE ISSUED HOURLY TO KEEP YOU INFORMED OF THE PROGRESS OF THIS EVENT UNTIL THE PACIFIC TSUNAMI WARNING CENTER ISSUES A CANCELLATION OR FINAL BULLETIN. From: Karl Cunningham Subject: Unknown Quake Date: Mon, 21 Apr 1997 22:15:08 -0700 Hi Folks -- Did anyone get an earthquake at about 00:44:50 UTC 4/22? I saw a ~M3.9 about 350KM from here (San Diego, CA area), likely in Mexico. I don't see it on any of the lists yet. Thanks. Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson Subject: Trinidad Mw6.5 Date: Tue, 22 Apr 1997 23:41:09 +1200 Charlie, hope you had the recorder going for the Trinidad event looking forward to seeing a winquake posted from you. Dave N Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'SLAW-- When Something Does Go Wrong, There Is Sod All You Can Do AboutIt When The Last Of Ten Screws Has Been Removed From A Cover, It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Tony Carrasco Subject: Re: Unknown Quake Date: Tue, 22 Apr 1997 09:03:17 -0700 (PDT) Karl, We also received a quake around that time. I'm not sure of the epicenter or magnitude, but it was stronger on our Barrett Dam Station then our Vista and Palomar Stations. I also noticed a similar quake this morning, perhaps a small aftershock. TONY SDSU >Hi Folks -- > >Did anyone get an earthquake at about 00:44:50 UTC 4/22? I saw a ~M3.9 >about 350KM from here (San Diego, CA area), likely in Mexico. I don't see >it on any of the lists yet. > >Thanks. > > >Karl Cunningham >La Mesa, CA. >karlc@......... > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: roger baker Subject: micromanometers, etc Date: Tue, 22 Apr 1997 12:12:23 -0500 (CDT) Friends, I just stumbled onto your group by accident while surfing the topic of microbarometers. It turns out I know Jack Herron well since I write a Science Hacker column for the Society for Amateur Scientists Bulletin which he edits. But anyhow, I thought I would pass along a nice little design for a sensitive-as-all-get-out little micromanometer. My specialty is cheap home brew instrumentation. Incidently, I also have a homebrew design for a sensitive vertical seismometer that you can build for $20 or so and which is sensitive enough so that it is constantly recording background noise here in Austin, Texas and has a period of ten seconds or so (dont really remember exactly). It was really designed as a tidal gravimeter and all tidal gravimeters are also thermometers. Without temperature buffering, it was never stable enough to see daily gravity fluctuations, but a bad gravimeter can easily be a good seismometer if the temperature variations are long compared to the seismic disturbances being monitored, as is generally the case. If I got some of the addresses wrong and you think others might be interested in this stuff, could someone be so kind as to repost? --Yours, Roger Baker (Science Hacker) 1303 bentwood, Austin, Texas A Supersensitive Micromanometer and the Uses Thereof There are many reasons that one might want to accurately measure the volume of a gas. Of course one might choose to buy a silicon diaphragm pressure sensor, but these have the disadvantage of being less sensitive, more expensive and not nearly as fun to build. Here is a relatively cheap easy way to build a simple pressure guage for between $10 and $20 that is sensitive to nanoliter changes in volume in a gas or liquid, and which therefore allows one to build many sort of scientific instruments. Some examples might be a tiltmeter, a carbon dioxide measuring device, a microbarovariometer (essentially a detector for subsonic air pressure waves that can be used to detect nuclear explosions as well as nearby weather disturbances). Other uses for such a device might be an infrared thermometer, a flowmeter, a micropipette calibrator, a tactile pressure sensor for a robot hand, as well as many other kinds of instruments. Due to the easy compressibility of gases, measuring either very slight pressure changes in the volume or the pressure of a gas near atmospheric pressure amount to much the same thing. Experience building such a sensor develops easily transferrable knowledge useful for building many other types of sensitive instruments and detectors requiring optical detection and electronic amplification. A scrap of glass tubing, a little silicone rubber, a little glycerine and blue food coloring and a few scraps of aluminum and a nut and bolt comprise the sensor. The associated electronics can be nothing much more than a 324 op amp and battery power supply. In principle my instrument is very easy to understand. One simply creates a short column perhaps one millimeter in diameter of food coloring and glycerine in a constriction in a small glass tube. Then one measures the variation in light absorption caused by a slight movement of the column. The column responds to any very slight change in external gas pressure, causing it to intercept to a variable degree an optical light beam transversing the tube. This is my own version of the old fashioned manometer that in its classic version used the motion of a column of mercury or other liquid trapped in the low curved portion of a U-tube to measure relative pressure changes between the two vertical arms. However, my version uses a short section of a horizontal tube and has various advantages. For one thing, it is very small and cheap to set up and the use of solid state optics makes it very sensitive. The basic principle of the gadget is that the short column of liquid tends to center itself in the narrowest part of the glass tube due to surface tension. If too much air pressure forces the column over to one side of the constricted tube, the column merely becomes unstable, breaks (since pure glycerine does not form stable bubbles), and the surface tension of the liquid regenerates the column near the center of the tube. One can zero the column in relation to the optical detectors by tilting the glass tube very slightly so that one edge of the nearly horizontal fluid column shifts position slightly due to the combination of the forces of surface tension and gravity until it is properly positioned to partially intersect the light beam. I use two super-bright red LEDs from Radio Shack for less than $2 apiece as both the detector and the emitter. These LEDs make wonderful emitter and detector combinations since the red light is very bright and adjustments are easily made by sight. The second LED being used as a detector is operated in the zero bias voltage mode. In other words, it is allowed to function like a tiny solar battery short-circuited with an external resistor. A one meg resistor loads it enough to make its output linear without reducing the output voltage too much. Under these conditions, the second LED becomes a very linear red light detector in its voltage output, which can be easily measured with any of a number of high impedence voltmeter or op amp circuits. Each LED has its focusing lens ground off flat and is then glued behind a small hole in a small aluminum plate. The two plates are bolted together so they grip the constriction in the glass tube from opposite sides. Silicone rubber is used to make little depressed pads on the aluminum plates that cradle the tube in the proper adjustable position so that the light beam from the LEDs just intersects the edge of the blue column of glycerine. The output voltage of such a sensor can easily be made to have a range of 100 to one with movement of the column. This output is probably responsive to a few nanoliters of volumetric change at near atmospheric pressure. A voltage controlled oscillator from a one dollar 4066 CMOS phase locked loop chip and small piezo speaker are useful to give the experimenter an audible indication of small changes during the initial setup and experimentation stages. The day I first built such a device, I found it interesting to use such a setup to audibly monitor the frequent barometric pressure swings associated with a passing storm front. I believe such a device could probably be modified to total the number and intensity of changes in atmospheric pressure to warn of nearby weather disturbances In this latter application of my sensor, I used a very slow air leak in parallel with my micromanometer and attached them both to a large reservoir of air in the form of a one gallon glass jug. In this way the instrument responds to rapid atmospheric pressure changes acting on the air in the jug. Roughly speaking, the device might respond to pressure changes ranging from perhaps one second to 10 minutes, whereas very gradual changes in absolute barometric pressure are automatically eliminated by the slow bypass air leak. Not having a two hole stopper handy, I drilled two holes in a small aluminum plate and sealed this plate directly to the mouth of the jug with silicone. Then I sealed two short lengths of vinyl aquarium tubing in the plate with more silicone. One of the tubes is attached to the micromanometer, which is clamped in an adjustable position nearby, and the other tube has a little piece of cotton or paper in the end. It is then clamped shut with a bulldog paper clip so that the cotton or paper prevents it from closing completely and generates the slow leak that allows the manometer to follow very slow changes in atmospheric pressure while retaining high sensitivity to rapid fluctuations, Once the mechanical elements are working properly, a chart recorder or computer data link can be used for quantitiative work. For about $125, one can get a nice LCD digital multimeter from Radio Shack that includes software and a serial port connector to turn almost any PC into a chart recorder. (thanks for this latter tip from someone in the quake discussion group; I just ran out and got one yesterday) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: Santa Cruz boomer Date: 22 Apr 97 14:02:47 EDT Re:4/21 12:2:25 Santa Cruz Is.!!! A winner! I turned on the monitor yesterday morning and it had been coming in for about 15 mins so I saw most of it in real time. It was a rather quiet day here and it was above background for more than 4 hrs. No P or S identifiable--from here it is 120 deg (8320 mi) so just out of range of the tables. The surface waves arrived about 48 mins after the P (calc.). The surface waves had a max. p-p velocity of 168,000 nm/sec or almost 0.2mm/sec. The FFT of these peaked rather sharply at 0.04Hz. The sig/noise ratio was about 240. The coda seems to me to be remarkably complex--I'll be interested to download some other 'grams to see how they compare. I'll send my record (970412B.RLB) to the archives soon. Bob Barns in far away Berk. Hts., NJ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jeff Batten Subject: Re: Unknown Quake Date: Tue, 22 Apr 1997 11:27:52 -0700 At 09:03 AM 4/22/97 -0700, you wrote: >Karl, > >We also received a quake around that time. I'm not sure of the epicenter or >magnitude, but it was stronger on our Barrett Dam Station then our Vista >and Palomar Stations. I also noticed a similar quake this morning, perhaps >a small aftershock. > I installed that Palomar Station two weeks ago. Nice to see that puppy works. It is a STS-2 with a Quanterra Data Logger, Frame relay data transmission, GPS Clock. A typical Trinet Station. Located just across from the 18" schmidt of Shoemaker-Levy fame. What was nice about installing the Palamar station was getting a one hour tour of the 200" scope. Jeff Batten - Research Engineer Caltech Seismo Lab 1200 E. California Bl. Pasadena, Ca. 91125 818-395-6965 Fax-818-564-0715 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: roger baker Subject: Re: micromanometers, etc Date: Tue, 22 Apr 1997 13:50:36 -0500 (CDT) To Dennis and other interested parties: In essence, my seismometer/gravimeter is a horizontal glass filament with a tiny lens and a little chunk of iron mounted near the free end, and carefully mounted in a little glass case. A magnet is adjustably mounted nearby so that it very nearly balances the weight of the free end and relatively heavy of the filament, greatly magnifying the force of gravity. The lens is actually the tip of the filament fused into a glass bead. This free end swings up and down past a light emitter and detector behind little slits in aluminum foil. Therefore only a few microns of vertical motion are easily registered with a circuit similar to that used with my micromanometer. Of course, one can also use a phototransistor as a detector for the narrowest light beams and best sensitivity. The glass bead acts as an optical element to make the light emerging from one slit converge back into the other slit; the two straddling the swinging filament with its bead lens. The Society for Amateur Scientists does have a web page but unfortunately, it doesn't get updated very often. Check with Jack Herron, who is probably also on this list. Sorry I don't have a web page yet. --Yours, Roger Baker _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@................. (Dr. John Lahr (USGS-GI Seismologist)) Subject: Re: micromanometers, etc Date: Tue, 22 Apr 1997 12:35:51 -0800 Roger, Welcome to the PSN! I hope you will join in the discussion. I'm having some difficulty visualizing the glass tube used for the pressure sensor. What is the inside diameter, away from the 1 mm diameter constriction? How wide is the constricted area? A diagram would help a lot! I guess that the diameter tapers down to 1 mm and then back again. Does the rate of taper matter much? The fluid is only located in the tapered region, and centers itself at the narrowest point. Then the led's sense the position of one of the two ends of the fluid. Sounds like a fun experiment. Is this on the Amateur Scientist web site? Thanks, JCLahr ################################## John C. Lahr ################################# Seismologist ################################ U.S. Geological Survey ############################### c/o Geophysical Institute ############################## 903 Koyukuk Drive ~~~~~~~~~~~~~~ Get ~~~~~~~~~~ ############################# ########################################################### P.O. Box 757320 ################################ Fairbanks, AK 99775 ################################# Phone: (907) 474-7997 ################################## Fax: (907) 474-5618 ~~~~~~~~ the thrust? ~~~~~~~~~~~~~~ lahr@........ #################################### http://www.aeic.alaska.edu/Input/lahr/ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: roger baker Subject: Re: micromanometers, etc Date: Tue, 22 Apr 1997 19:09:30 -0500 (CDT) Dear Dr. Lahr, The tube was 4mm pyrex heated in a propane torch and pulled out from an initial 3 inches to 3 1/2 inches when soft to give a constricted central portion that tapers to an internal bore of about 1 mm. Nothing is very critical, but you might have to tinker around a bit. One thing I did not mention is that you may have to mask the light source and detector with black masking tape to exclude light that could circumvent the liquid column. You can run the LED in series with about 200 ohms and at 12 volts, which is also used to power the 324 op amp.The midpoint between two similar resistors used with a voltage follower config that ties to one leg of the detector (LED and 1 meg in parallel). The other terminal of the detector is tied to a second voltage follower. Since this only uses two of the op amps on the chip, you have two left over to amplify the signal or filter it. Even the unamplified output signal might be 100 millivolts due to the brightness of the LED so excessive signal noise should not be a problem compared to temperature drift. the sensor should be mounted on some type of swivel mount so it can be tilted to fine tune the column after rough adjustments have been made via the aluminum plates. More than this I cannot say, having just built the first version only a few days ago. Actually this micromanometer was designed for another purpose entirely: to make rapid accurate measurements in the field of the carbon dioxide content of air. The principle here is to trap air in two identical flat chambers, one of which has a CO2 absorbant in its wall. Obviously one chamber will start to develop a slight vacuum as the CO2 disappears from that chamber, all other factors like temperature being equal. The challenge is to devise a simple manometer that will respond to one part per four thousand change in the volume of two small chambers of air of capacity circa 1 cc each. This is response to comments below). --Roger On Tu, 22 Apr 1997, Dr. John Lahr (USGS-GI Seismologist) wrote: > > Roger, > > Welcome to the PSN! I hope you will join in the > discussion. > > I'm having some difficulty visualizing the glass tube > used for the pressure sensor. What is the inside > diameter, away from the 1 mm diameter constriction? > How wide is the constricted area? A diagram would > help a lot! I guess that the diameter tapers down > to 1 mm and then back again. Does the rate of taper > matter much? The fluid is only located > in the tapered region, and centers itself at the > narrowest point. Then the led's sense the position of > one of the two ends of the fluid. > > Sounds like a fun experiment. Is this on the Amateur > Scientist web site? > > Thanks, > JCLahr > ################################## John C. Lahr > ################################# Seismologist > ################################ U.S. Geological Survey > ############################### c/o Geophysical Institute > ############################## 903 Koyukuk Drive > ~~~~~~~~~~~~~~ Get ~~~~~~~~~~ ############################# > ########################################################### > P.O. Box 757320 ################################ > Fairbanks, AK 99775 ################################# > Phone: (907) 474-7997 ################################## > Fax: (907) 474-5618 ~~~~~~~~ the thrust? ~~~~~~~~~~~~~~ > lahr@........ #################################### > http://www.aeic.alaska.edu/Input/lahr/ > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@................. (Dr. John Lahr (USGS-GI Seismologist)) Subject: Re: micromanometers, etc Date: Tue, 22 Apr 1997 17:58:44 -0800 Roger, Thanks for the further details. Don't know how soon I'll be able to play around with this, but it sounds interesting. Let me know if you get your CO2 detector working. Seems like a clever plan to me. Is there a substance that will absorb CO2 but not other gases? Would it also absorb CO? JCLahr _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: FYI: Santa Cruz Islands Quake Update Date: Wed, 23 Apr 1997 11:35:29 -0700 FYI Discovered some new information regarding damage and tsunamis from the recent Santa Cruz Ms 7.9 earthquake and posted it in a Seismo-Watch E-mail Alert Bulletin you can see here: http://www.seismo-watch.com/EQS/AB/9704/970423-101.SC6.1.html The archive for past Alert Bulletins is here: http://www.seismo-watch.com/EQS/AB/ABA.html -- ---/---- Charles P. Watson, Consulting Geologist Advanced Geologic Exploration Seismo-Watch / Earthquake Information Services Voice: 702-852-0992 / Fax: 702-852-3226 mailto:watson@................ http://www.seismo-watch.com _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Dennis Leatart Subject: Mariana's Event (6.3) Date: Wed, 23 Apr 1997 15:30:49 -0700 Hello everyone!!! Did anyone else pick up the Mariana's Event --Mag. 6.3- today 4/23/97? I have what appears to be two events separated by about 8 minutes apart?? Thanks!!! -- _____ __ | \.-----.-----.-----.|__|.-----. | -- | -__| | || ||__ --| |_____/|_____|__|__|__|__||__||_____| _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson Subject: Santa Cruz Is. events map Date: Thu, 24 Apr 1997 19:25:03 +1200 hi ya all, for those interested, at the top of my quakes page, I have added for a short period of time a regional map showing the Ms 7.9 and aftershocks cheers Dave Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'SLAW-- When Something Does Go Wrong, There Is Sod All You Can Do AboutIt When The Last Of Ten Screws Has Been Removed From A Cover, It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: roger baker Subject: Seismometer design Date: Thu, 24 Apr 1997 11:11:45 -0500 (CDT) Zero Motion Feedback Principle for Seismometers? While pondering seismometer design over the last couple of days, it occurs to me that there might be great instrumental advantages to introducing a mass position resoration feedback loop into the design. This would give the result that the moving mass usually associated with seismometers is kept stationary by imposing a force, especially an opposing magnetic force, generated with a sensitive motion detector and an amplified feedback loop. I initially thought of this interesting concept many years ago in association with accelerometer design and later heard that it has been used for accelerometers. A lot of money and brainpower went into rocket and missile technology a few decades ago. This discussion may be old stuff to seismometer designers for all I know, but maybe not. The reason it may not be used is that most seismometers are designed to have long natural periods of natural oscillation, which means that they have heavy masses which are hard to stabilize with a practical feedback force. However, if a mass reacting to seismic motion is made small, say on the order a gram, then positional feedback becomes much simpler. But if the mass does not actually move, then all sorts of non-linearities can be eliminated from the instrument. The mass would actually still move of course but maybe only a micron before the optical feedback loop forces it back into place, whereas a more conventional instrument would let the mass swing millimeters and then measure the swings. Another advantage of a positional resoration feedback seismometer (if I might call it that) is that the natural period of the seismometer would no longer matter, since the mass would not be permitted to travel much more than a distance equal to the noise limit of the mass position detector. This consideration would be conducive to the construction of physically small and cheap seismometers with admirable insensitivity to the period of the seismic disturbance, if my analysis is correct. Am I out to lunch? Comments please: Yours, Roger Baker _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: Seismometer design Date: Thu, 24 Apr 1997 10:00:59 -0700 At 11:11 AM 4/24/97 -0500, you wrote: > Zero Motion Feedback Principle for Seismometers? > >While pondering seismometer design over the last couple of days, it >occurs to me that there might be great instrumental advantages to >introducing a mass position resoration feedback loop into the design. I agree. This is the principle used in the force-balance seismometers that several people on the list either have or are building. It is also used by many commercial seismometers in use today. BTW, this is also the principle of operation of many digital scales used for weighing. >Another advantage of >a positional resoration feedback seismometer (if I might call it that) is >that the natural period of the seismometer would no longer matter, since >the mass would not be permitted to travel much more than a distance equal >to the noise limit of the mass position detector. My background on this part is a bit weak, but I believe the period actually still does matter; but only with respect to the design of the feedback loop. But, at least in my experience, this is an important consideration. In a few days I'll be finished with details of my design of a similar instrument. I'll let you know when it's done. Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@................. (Dr. John Lahr (USGS-GI Seismologist)) Subject: Re: Santa Cruz Is. events map Date: Thu, 24 Apr 1997 11:24:03 -0800 Dave, I like the way** you are collecting felt information via the web, and may do something similar here in Alaska. I hadn't realized that a form could generate an Email message. **(http://psn.quake.net/dave/qu_form.htm) JCLahr ################################## John C. Lahr ################################# Seismologist ################################ U.S. Geological Survey ############################### c/o Geophysical Institute ############################## 903 Koyukuk Drive ~~~~~~~~~~~~~~ Get ~~~~~~~~~~ ############################# ########################################################### P.O. Box 757320 ################################ Fairbanks, AK 99775 ################################# Phone: (907) 474-7997 ################################## Fax: (907) 474-5618 ~~~~~~~~ the thrust? ~~~~~~~~~~~~~~ lahr@........ #################################### http://www.aeic.alaska.edu/Input/lahr/ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: [Fwd: Re: VOLCANO Disaster movie number reviews] Date: Thu, 24 Apr 1997 12:45:15 -0700 Too funny not to pass on... -- ---/---- cpw As a fan of the old Star Trek I have only three grades for volcano/geology movies/episodes. The geologist survives B The geologist survives and gets the girl (boy) A All other outcomes (usually death) F Michael J. Carr Geological Sciences Rutgers University New Brunswick, NJ 08903 phone 908-445-3619 fax 908-445-3374 carr@............... From: watson@................ (Charles Watson) Subject: Re: Santa Cruz Is. events map Date: Thu, 24 Apr 1997 12:53:39 -0700 I was cruising around Dave's site this morning. He has a lot of neat web tricks. Fun to check out -- ---/---- cpw Dr. John Lahr (USGS-GI Seismologist) wrote: > > Dave, > > I like the way** you are collecting felt information via the web, and > may do something similar here in Alaska. I hadn't realized that > a form could generate an Email message. > > **(http://psn.quake.net/dave/qu_form.htm) > > JCLahr message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Francesco Nucera" Subject: about QUAKE_L Date: Fri, 25 Apr 1997 01:57:16 +0200 Please, could anybody give me the address to subscrive on "QUAKE-L Earthquake Discussion List"? Best regards Francesco Nucera -Italy- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: about QUAKE_L Date: Thu, 24 Apr 1997 17:09:24 -0700 QUAKE-L Earthquake Discussion List -- ---/---- cpw _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson Subject: Re: Santa Cruz Is. events map Date: Fri, 25 Apr 1997 13:36:57 +1200 John, I originally tried playing with CGI script to make the form more like most that are on the web. But I could not get it to work. and then one nite it struck me .....why not just have the form e-mail the results to me. It does not have the nice laid out look of the from instead it is in one long string but is not too bad to read the inputted data. Unfortunately not one yet has made genuine use of the form to mail me a felt report..... maybe one day Html writing for web pages is great fun it is so versatile, but I DON'T claim to be an expert. Cheers Dave PS you are welcome to use my html file and just change the headers etc to suit your location.... no point re-inventing the wheel At 11:24 AM 4/24/97 -0800, you wrote: >Dave, >I like the way** you are collecting felt information via the web, and >may do something similar here in Alaska. I hadn't realized that >a form could generate an Email message. >**(http://psn.quake.net/dave/qu_form.htm) > >JCLahr Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'SLAW-- When Something Does Go Wrong, There Is Sod All You Can Do AboutIt When The Last Of Ten Screws Has Been Removed From A Cover, It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Stephen Paul Subject: Re: Seismometer design Date: Fri, 25 Apr 1997 05:05:23 -0700 roger baker wrote: > > Zero Motion Feedback Principle for Seismometers? > > While pondering seismometer design over the last couple of days, it > occurs to me that there might be great instrumental advantages to > introducing a mass position resoration feedback loop into the design. > This would give the result that the moving mass usually associated with > seismometers is kept stationary by imposing a force, especially an > opposing magnetic force, generated with a sensitive motion detector and > an amplified feedback loop. > > Am I out to lunch? Comments please: Yours, Roger Baker > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L No, Rog, You are not out of your mind (on this subject, at any rate IMO ). I think your best bet would be to use some form of ring laser gyro or RLG which is now a common part in what used to be mechanical inertial guidance platforms, (a little gizmo with gyros and a ball and stuff like what we like to play with,) formerly used on commercial airlines and missile systems to position the projectile from an initial fixed point, which, after much swearing and calibration ( though not neccessarily in that order, ) the IGP would be closed up, and from then on, any further change in the platform's position would be logged and compared to the original cal. and from this, precession would be errored out as much as possible, and the other various resulting errors, leaving, By the Grace of God, the position. (Hopefully not a bogey at 9 o' up your tail...) Flaws: gyroscopic precession possible and probable miscalibration only good for so many hours before cumulative errors become uncorrectable The RLG (Ring Laser Gyro) solved many of these problems by minimizing moving parts and computing the phase-shift of a pair of lasers fed through glass fibres in the form of a ring within a black triangle. Any such shift would then represent to a fine degree (the 1/2 wavelength of the laser frequency, I would imagine, (red from a He-Ne or the average visible-light semiconductor laers, especially back then....being about 615-632 nM then just /2 and stir lightly, or, say 309 nM, which is pretty fine... visible light ends for us in the 350 or 325 range, I think) and finding an old one of these might not be as hard as you think considering the missile failure rates and surplus prices on stuff like that these days. I've been out of it for awhile, but I would think these days that LAN and various other GPS (Global Position Systems) now have accuracy and cal's. that far exceed even the pretty solid interial stability of a RLG. That's about all I can say or type... but I think that obviously some kind of electronic stabilizing loop in a servo-feedback configuration to create a perfectly servo'd out platform in the field would be very desirable. 1. Various filters could be applied as windows through the electro-mechanical servo i.e. 2. Hanning, Hammimg, etc. windows coupled through FFT systems on VLSI DSP's could give resonance info as well as align the ETC or Energy Time Curve to more precisely self-align even during the event... 3. Little bitty micros could compare the phase and and energy of various waves by sampling before, after, (and if desired with all post-processing completed by the time the signal reaches the gadg. through the mechanical delay lines) 4. Just about anything else you might want to look at, basically. 5. You're probably wondering "good talk muh man, but kin you walk it?" Soitenly... f'rinstance, For a quick example: you couple your gadg, to a platform which is coupled to the earth through a set of acoustical delay lines consisting of spring systems, -well- damped and *timed*. of course, which are the only non acousstical coupling to the earth. You then take a set of small, powerful electric, geared motors, which could be charged by day with a batt. and solar-cell system, and at night by batt., then align the servo phase-lock-loops running the motors to the light-weight platform delays from the tip of the spring systems to the first gadg. sensor lines. That way, any vibration coming from the earth has a slight delay mechanically, which can be selectively left in, or eliminated completely, so that only the convolution you wish to apply has plenty of time to do it's thing before it hits your gadg. either right out of Mama Earth (somewhat impractical) or through the platform totally servo'd out of the picture, (IOW the platform and its attendant resonances and errors leading from it's design, materials and so forth will generate a signature which can be electrically stored and nulled, and all that comes through are the movements of your gadg...) leaving only the pure resonances of the roundish, ringing bell of our poor, beleagured wanderer, (for those who may feel this is an obscure reference, the Greek of couse -planet- means wanderer.) Forgive me, I have never written to this group before and I may sound as if I'm telling cows how to moo. If so, I apologize and risk your enmity in my desire to be understood . I'll bet you feel sane -now- dontcha?? -- Stephen :^) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: Mercury tiltmeter Date: 25 Apr 97 11:13:20 EDT Hi gang, Greg Lyzenga sent me a description of the mercury tiltmeter at Harvey Mudd Coll. I found it very interesting and am forwarding it to the net. I recorded a nice quake--4/23 with the LQ here at 1:06 UTC. It has a sig/noise of about 5 and the surface waves were above bg for about 25 mins. Bill Scolnik in Oakland NJ also got it. It would be pretty exciting if this turned out to be local but the only reports I know of from LaMont are at least 6 months late. Does anyone know of a source of up-to-date reports about the northeast US and adjacent Canada? Bob Barns Berk. Hts., NJ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: Mercury tiltmeter Date: 25 Apr 97 11:13:24 EDT FROM: Greg Lyzenga, INTERNET:lyzenga@................. TO: Robert L Barns, 75612,2635 DATE: 4/21/97 12:19 PM Re: Re: Force Balance article Sender: lyzenga@................. Received: from Thuban.AC.HMC.Edu (Thuban.AC.HMC.Edu [134.173.53.8]) by dub-img-2.compuserve.com (8.6.10/5.950515) id MAA13872; Mon, 21 Apr 1997 12:20:41 -0400 Re