12 monthly issues for $20.00 in the USA or
$30.00 outside the USA.
Geo-Monitor: is published bi-monthly for the purpose of disseminating information on the science of earthquake prediction, to provide a forum for discussion, and to assist amateur scientists in geophysical monitoring. technical dialog, articles and experiments are welcome.
Back Issues: From July, 1991 through Sept. 197 are available from Vince T. Migliore for $2.00 each, or $20.00 for any 12 copies.
Photocopies from the Geo-Monitor bibliography -- posted on the Web page http://home.earthlink.net/-geomonitor/ -- are $1.00 per page. Send orders for these items to the address below.
65 Washington Street #400
Santa Clara, California USA 95050
(408) 749-6770
September 1992
Dear Inquirer,
Thank you for contacting me about earthquake prediction studies. I've always been
fascinated by the stories of amateur radio operators reporting strange signals on the
ham bands. Then, a team of Stanford scientists headed by Anthony Fraser-Smith
discovered some very distinctive signals in their low frequency equipment just prior
to the 1989 Loma Prieta earthquake. This was the beginning of popular interest in
modern earthquake precursor research, though there have been a number of other
investigations long before the Stanford report.
Geo-Monitor newsletter grew out of intense interest in earthquake signals by the
ranks of back-yard seismologists and electronics experimenters. Each month we include
a simple, low cost project that can be used to measure a variety of geophysical
processes that may be related to earthquakes. The biggest problem in this research is
that there are no established standards yet, and just the beginnings of solid evidence
to support the anecdotal claims of the past. This is a situation that is begging for
the participation of amateur scientists in on-going monitoring experiments. And, this
is the essence of the philosophy behind the newsletter.
We want to look at a broad spectrum of processes that might be correlated with
seismic activity. This includes many measures of geological processes agreed upon as
useful by geophysicists, such as gas emissions, tilt levels and ground resistivity.
It also includes some of the far out theories, such as runaway pets, solar activity
and psychic phenomena. The most powerful research however is possible by the use of
simple electronic instruments that can measure transients in the magnetic, electro-
agnetic and audio realms. Modern technology, in combination with the generous sharing
of schematics by other researchers, makes this an affordable hobby for the inquisitive
mind.
Let me summarize the electronic research. The electromagnetic spectrum is full of
transients, and God only knows which ones are related to earthquakes. There are a
number of untested stories of monitoring different frequencies forbroadband noise
changes and long bursts of static. From a review of the scientific literature, the
most promising for earthquake precursors are, in order of reliability:
1. Magnetic transients in the .01 to 10 Hz region, especially around 3 Hz.
2. Electromagnetic transients in the 10 kHz region.
3. Broadband noise level measurements in the 8 to 100 kHz region.
4. Noise and propagation studies in the 150 kHz to 2000 kHz region.
5. Noise and propagation studies over 2 megahertz.
Item 1 is difficult to work with because analog tuned circuits are bulky, awkward
and have low Q, while digital, PLL or FFT circuits are complicated. On the other
hand, this is the focus of much scientific study, and many experimenters love to make
30-pound coils and high Q filters. We are currently working on a low cost magnetic
transient circuit that will probably offered in kit form. This requires several more
months of preparation.
Items 2 and 3 are much easier to plan for with low frequency converters, but are
slightly less reliable as earthquake precursors. Several experimenters report a
hissing sound, rumbling noises, bursts of static over 1/2 second long and sudden
changes in noise level prior to quakes. This is certainly the easiest for amateur
radio operators and experimenters to get into, and would be a nice group experiment
for a network.
At least two manufacturers have now come out with commercial receivers for the
200 to 20 kHz range. These are the WR-3 from Conversion Research, P.0. Box 535,
Descanso, CA 91916, and the L-500 from LF Engineering, 17 Jeffry Road, East Haven,
CT. Since they are very low in cost ($50 and $100 respectively) this may prove to
be a usable standard for coordinated earthquake experiments.
Items 4 and 5 are even less reliable, but there are a number of experiments that
can be easily accomplished in these bands. Sudden noise level changes have been
reported at radio frequencies. These are often correlated with sunspot activity and
fluctuations in the solar wind. However, when there is a sudden enhancement of signal
(SES) without a solar flare, there is speculation that this anomaly is related to
earthquakes. The same is true for sudden drops. Much more experimentation is
needed. Generally, investigators monitor world-wide beacons on the ham bands and plot
signal strength. There are also some tinkerers that swear the received (perceived)
nominal frequency of AM broadcast stations exhibit a measurable drift prior to
quakes. This is not proven, but I have toyed with this myself and there do seem to be
changes in apparent frequency.
Besides the receiver, the data storage mode is another bottleneck. It becomes
quickly obvious when monitoring real-time transients that an automated display or
data capture mechanism is needed. A strip chart recorder or A/D converter to disk is
the preferred solution. The only caution is that most Geo-Monitor readers are on a
limited budget, so data storage must be low cost and efficient. Add to this the need
for standardization, and you begin to see the problem. I am working on several
fronts at once to solve this. It may be that with A/D cards coming down to less than
$100, and PC clones (8088s and 286's) appearing at flea markets for $100- $200, that
digital storage may be the answer. The only matter left to decide then would be
sampling rates and software.
The ULF pickup coil, again is another matter for standardization. Most ULF
experimenters that I've spoken with talk about "pounds of wire." They often use
anywhere from 7,000 to 45,000 turns of thin (#21 to #47 AWG) enameled wire on various
cores. Others use simple loops or longwires, but the 2 to 5 henry coils seem most
popular. Again, we are still working on defining a practical standard.
Geo-Monitor started in July of 1991 and has grown to over 1000 readers.
Subscriptions are $22.00 per year, 12 issues. Back issues are $2.00 each. Sample
projects include the following:
Pendulum seismometer - Vol. 2, #8, August '92
Magnetic transient detector - Vol. 2, #5, May '92
Radio propagation studies - Vol.2, #4, April '92.
Geo-Monitor works cooperatively with the Public Seismic Network. This group was
founded on the idea of linking backyard seismographs to a USGS computer network. It
has evolved into a wellspring of information for amateur scientists and professionals
alike. Lots of fantastic shareware and interesting dialogs. SysOp Steve Hammond:
voice (408) 365-9830; BBS Pasadena (818) 797-0536; BBS Menlo Park (415) 327-1517; BBS
San Jose (408) 226-0675. All are in California, using 2400 baud, 8-none-1 .
REFERENCES
1. Earthquake Prediction, Haroun Tazieff, McGraw-Hill 1992, NY.
2. Earthquakes: the Solar Connection, Patrick Huyghe, Science Digest, Oct. 1982.
3. Radio Earth: The Radio-Seismic Connection. Joe Tate, Whole Earth Review, Fall, 1990.
4. ULF, ELF and VLF Electromagnetic Field Observations Close to the Epicenter of the
7.1 Loma Prieta Earthquake: Possible ULF precursors. A.C. Fraser-Smith, A.
Bernardi, P.R. McGill, M.E. Ladd, R.A Heliwell, and O.G. Villard, Jr., STAR
Laboratory, Stanford University.
5. When the Snakes Awake, Helmut Tributsch, MIT Press 1984, Cambridge, MA.
Respectfully,
Vince T. Migliore, editor