Parts List for the APM-2
Four 1N34 germanium diodes (Radio shack #276-1123) ~ Figure 1,
X1, X2, X3, & X4
Two 0.2 mfd 50 V ceramic capacitors ~ Figure 1, C1 & C2
Two 100 mfd 50V electrolytic capacitors (Radio Shack #272-1016)
~ Figure 1, C3 & C4
Copper wire for antenna & ground connections
The Ambient Power Module (APM) is a simple electronic circuit
which, when connected to antenna and earth ground, will deliver
low voltage up to several milliwatts. The amount of voltage and
power will be determined by local radio noise levels and antenna
Generally a long wire antenna about 100' long and elevated in a
horizontal position about 30' above ground works best. A longer
antenna may be required in some locations. Any type copper wire,
insulated or not, may be used for the antenna. More details
about the antenna and ground will be discussed further on.
The actual circuit consists of two oppositely polarized voltage
doublers (Figure 1). The DC output of each doubler is connected
in series with the other to maximize voltage without using
transformers. Single voltage doublers were often found in older
TV sets for converting 120 VAC to 240 VDC. In the TV circuit the
operating frequency is 60 Hz.
The APM operates at radio frequencies, receiving most of its
power from below 1 MHz. The basic circuit may be combined with a
variety of voltage regulation schemes, some of which are shown
in Figure 2. Using the APM-2 to charge small NiCad batteries
provides effective voltage regulation as well as convenient
electrical storage. This is accomplished by connecting the APM-2
as shown in Figure 2B.
Charging lead acid batteries is not practical because their
internal leakage is too high for the APM to keep up with.
Similarly, this system will not provide enough power for
incandescent lights except in areas of very high radio noise.
It can be used to power small electronic devices with CMOS
circuitry, like clocks and calculators. Smoke alarms and low
voltage LEDs also can be powered by the APM.
Figure 3 is a characteristic APM power curve measured using
various loads from 0-19 kOhm. This unit was operating from a
100' horizontal wire about 25' high in Sausalito CA. As can be
seen from the plot, power drops rapidly as the load resistance
decrease from 2 kOhm. This means that low voltage, high
impedance devices, like digital clocks, calculators and smoke
alarms are the most likely applications for this power source.
Some applications are shown in Figures 4 through 7.
Figure 4 ~ A digital clock is shown powered by the APM-2. The
1.5 volt clock draws 28 microamps. Its position on the power
envelope curve would be off the scale to the right and almost on
the bottom line, dissipating only 42 microwatts.
Figure 6 shows a clock which has the APM-2 built into it so it
is only necessary to connect the antenna and ground wires
directly to the clock. The antenna for this clock, which is a
low frequency marine type, is shown in Figure 7.These antenna
are expensive, not generally available, and usually don't work
any better than the long wire mentioned above. But it may be
necessary to use them in urban areas where space is limited and
radio noise is high.
Building the Module
The builder has a choice of wiring techniques which may be used
to construct the module. It may be hand wired onto a terminal
strip, laid out on a bread board, experiment board, or printed
circuit. Figure 8 shows some of the different ways of
constructing the APM-2.
Figure 8A is constructed on a screw strip terminal; Figure 8B
is constructed on a perforated breadboard; Figure 8C is built on
a standard experiment board; Figures 8D, 8E, and 8F are all
printed circuits; Figure 8F is made up on a solder strip
If you wish to make only one or two units, hand wiring will be
most practical, either on a terminal strip or breadboard.
Assembly on the terminal strip (Figure 8A) can be done easily
and without soldering. It is important to get the polarity
correct on the electrolytic capacitor. The arrow printed on the
side of the capacitor points to negative.
Figure 9 is a closer view of the terminal strip with an
illustration of the components and how they are connected.
The breadboard unit is shown in Figure 10 with all components
on one side and all connections on the other. All you need is a
2" x 2" piece of perforated breadboard (Radio Shack #276-1395)
and the components on the parts list. Push component wires
through the holes and twist them together on the other side.
Just follow the pattern in the photo, making sure to observe the
correct polarity on the electrolytic capacitors and the diodes.
The ceramic capacitors may be inserted in either direction.
The experiment board unit is assembled by simply pushing the
component leads into the board as shown in Figure 11. This unit
is powering a small red LED indicated by the arrow.
The solder strip unit is made up on a five terminal strip. The
antenna connection is made to the twisted ends of the ceramic
capacitors. When soldering the leads of the 1N34 diodes, care
must be taken to avoid overheating. Clip a heat sink onto the
lead between the diode and the terminal as shown in Figure 12.
It is beyond the scope of this pamphlet to show how to make
printed circuits, but the layout of the board is provided in
Figure 14 shows the front and back view of the completed
A small switch may be installed on the board to activate the
zener regulator (Figure 15). This board was designed for use in
The antenna needs to be of sufficient size to supply the APM
with enough RF current to cause conduction in the germanium
diodes and charge the ground coupling capacitors. It has been
found that a long horizontal wire works best. It will work
better when raised higher. Usually 20-30 feet is required. Lower
elevations will work, but a longer wire may be necessary.
In most location, possible supporting structures already exist.
The wire may be stretched between the top of a building and some
nearby tree or telephone pole. If live wires are present on the
building or pole, care should be taken to keep your antenna and
body well clear of these hazards.
To mount the wire, standard commercial insulators may be sued
as well as homemade devices. Plastic pipe makes an excellent
antenna insulator. Synthetic rope also works very well, and has
the advantage of being secured simply by tying a knot. It is
convenient to mount a pulley at some elevated point so the
antenna wire may be pulled up to it using the rope which doubles
as an insulator (Figure 16).
Figure 17 is an illustration of a horizontal wire antenna using
a building and tree for supports.
Usually a good ground can be established by connecting a wire
to the water or gas pipes of a building. Solder or screw the
wire to the APM-2 ground terminal. In buildings with plastic
pipes or joints, some other hookup must be used. A metal rod or
pipe may be driven into the ground in a shady location where the
earth usually is damper. Special copper coated steel rods are
made for grounds which have the advantage of good bonding to
copper wire. A ground of this type usually is found within the
electrical system of most buildings.
Conduit is a convenient ground provided that the conduit is
properly grounded. This may be checked with an ohmmeter by
testing continuity between the conduit and system ground (ground
rod). Just as with the antenna, keep the ground wire away form
the hot wires. The APM's ground wire may pass through conduit
with other wires but should only be installed by qualified
Grounding in extremely dry ground can be enhanced by burying
some salts around the rod. The slats will increase the
conductivity of the ground and also help retain water. More
information on this subject may be found in an antenna handbook.
Good luck getting your Ambient Power Module working. It is our
hope that experimenters will find new applications and improve
the power capabilities of the APM.
Science News [date unknown]
Radio Waves Signal
From the bright flashes reported to appear in the sky during
strong earthquakes to computer breakdowns during severe tremors,
scientists have long suspected that seismic activity is
associated with a variety of electrical effects. Recently
researchers have been taking a careful look at this link, with
an eye toward using it to predict earthquakes.
One such study is being conducted by Joseph Tate of Ambient
Research in Sausalito, CA, and William Daily at Lawrence
Livermore National Laboratory in Livermore, CA. With a system of
radio wave monitors distributed along California's San Andreas
fault, the researchers have recorded two kinds of changes in
atmospheric radio waves prior to earthquakes that occurred
between 1983 and 1986.
The most common change is a drop in the radio signals that
normally pervade the air as a result of lightning and human
sources such as car ignition systems and electric power grids.
This reduction typically occurs one to six days before an
earthquake and can last for many hours. For example, a magnitude
6.2 earthquake that shook Hollister CA in April 1984 was
preceded six days earlier by a 24-hour drop in radio signals
being monitored 30 miles from the quake's epicenter. Tate and
Daily have found that the larger the earthquake, the longer the
time between the radio wave depression and the quake.
Laboratory studies have shown that the electrical conductivity
of rocks increases as they are stressed. Based on this and their
electrical modeling of the ground, Tate and Daily think the
increased conductivity of stressed rocks near the fault causes
more radio waves to be absorbed by the ground rather than their
traveling through the air. They also plan to test a possible
link between radio wave drops and the emission of radon gas,
which itself is thought to be a quake precursor. The radon may
ionize the air, making it temporarily more absorptive than the
The researchers have also found, in addition to these drops,
another prequake phenomenon in which short pulses of increased
radio wave activity are emitted. For example, five days before
the magnitude 6.5 earthquake hit palm Springs CA in July 1986, a
station 15 miles from the epicenter detected a rise in radio
signals. This sort of emission is consistent with laboratory
work showing that cracking rocks release electromagnetic
Tate says that in their first attempts at predicting
earthquakes in 1984 and 1985, they did not miss a single event,
so he his optimistic about using this technique for short-term
forecasting of San Andreas quakes. "In three to five years", he
says, "we should be able to issue [earthquake] warnings."
Whole Earth Review (Fall 1990, pp. 101-104)
Radio Earth: The
Since the earliest days of radio research, many people have
thought of these invisible waves as artificial, an effect
created solely by wizards in a laboratory. Later, in the 1930s,
Karl Jansky discovered radio emissions coming from the Milky
Way. Stars are now known to be giant transmitters, broadcasting
a spectrum of electromagnetism from low-frequency noise to gamma
rays. So much for the artificiality of radio.
Even in the 19th century, in the days of Tesla and Edison,
radio noise caused by lightning was known to have recognizable
propagation patterns. It was these patterns that Jansky was
measuring when he discovered cosmic radio.
Tesla actually calculated the resonant frequency of the Earth,
and proposed that electromagnetic waves of this frequency (6-8
Hz) should be generated by the planet from the action of
lightning. These "Schumann resonances", as they came to be
known, were finally detected in the 1960s.
Other strange radio emissions were noticed at about the same
time, a time when many new radio observatories were starting
operation at various places around the world. The observatories
could each detect and record a wide range and volume of
electromagnetic radiation (EMR). Before and during the great
Chilean earthquake of 1960, unusual strong signals were received
at six widely scattered radiotelescopes. The connection between
these radio signals and the earthquake was eventually shown by
James Warwick of the University of Colorado, who analyzed the
observatories' separately recorded data (Figure 1) [Not shown].
Earthquakes generate radio waves! But how?
Twenty-two years later, after performing a series of laboratory
experiments in which rocks were crushed in powerful presses and
the resulting electromagnetic emissions were measured, Warwick's
paper describing the phenomenon appeared in the April 1982 issue
of the Journal of Geophysical Research.
In the meantime, other experimenters had recorded similar
effects in Japan, France, the United States and the Soviet
Union. Several studies of satellite data revealed marked
increases in very-low-frequency (VLF) emissions from epicenter
regions before and during major earthquakes. In Greece,
researchers found that telluric currents (natural currents of
electricity flowing in the Earth) fluctuated prior to
In 1979, I was experimenting with methods of turning radio
energy in the air into usable electric power. I developed a
clock which drew its power from an antenna that was just a long
piece of wire stretched out horizontally about 20 feet above the
The power supply for the clock worked something like an
old-style crystal radio, except that it did not have a tuning
circuit. Because of this, the Crystal Clock (as I called it) was
able to absorb a wide spectrum of radio noise from the antenna
and yield electric power. The power supply was able to deliver
much more current than was developed in a crystal radio,
although its output was still just a few millivolts.
In the early 80s I demonstrated the clock to the late Frank
Oppenheimer, then director of San Francisco's Exploratorium,
where I worked in the exhibit repair shop. Oppenheimer suggested
recording the power supply's output over a long period of time
to determine its dependability. After all, the device relied
completely on whatever stray signals happened to be in the air.
Using an Atari computer which had been donated to themuseum,
the oputput of the clock's power supply was measured
continuously and recorded on floppy disk. This was done by
feeding the unregulated voltage output direcly into the
coputer's joystick port.
I began calling this power supply the "Ambient Power Module"
(APM) because it extracted power from ambient background radio
noise. This small circuit, when connected to antenna and ground,
used the potential difference between air and ground to generate
a small direct current continuously.
As we studied the recorded data, mild fluctuations were noted
in a daily cycle. The patterns were consistent over long periods
of time, though they differed in different locations. Aside form
that, the APM looked like a very dependable source of power.
Until the spring of 1984.
On April 24, 1984, a 6.0 magnitude earthquake struck about 90
miles from the APM recording station in Sausalito. Days later,
while looking through the data, I noticed that the APM output
dropped to less than half its normal value for several hours
during the afternoon 6 days before the earthquake (Figure 2)
[Not shown] this was very peculiar, because most of the APM's
power came from broadcast signals, and broadcasting stations
hadn't done anything different that afternoon. Apparently
something had temporarily depressed the propagation of radio
waves. At high frequencies, such effects can be caused by
atmospheric conditions. But the lower frequencies involved here
are hardly affected, particularly not the signals from the
nearest stations, which account for most of the power received.
It was tempting to think this strange radio depression might
somehow have been a precursor to the earthquake.
Several smaller quakes had occurred in the area during the year
before. Perhaps these also were preceded by similar radio
anomalies. Looking back through the accumulated data on the
APM's power output, indeed, smaller, less obvious radio
depressions were found to occur prior to the lesser earthquakes.
I called the US Geologic Survey (USGS) office and told them
about these radio events. I learned from them that ham operators
in the area had also reported radio noises accompanying
earthquakes, but no one had recorded them. Jack Everenden, with
whom I was speaking, asked for copies of my data, which I sent.
Two weeks later, William Daily of Lawrence Livermore Labs
called, asking if I would like to work with him gathering
earthquake radio noise data under a grant from the USGS.
For the next three years we deployed monitoring/recording
devices along the San Andreas fault, from San Francisco to San
Diego. The units were battery-powered paper-chart recorders
which could hold one month's worth of data. They recorded radio
noise levels in three adjacent bands: 0.2-1, 1-10 and 10-100
kHz. In addition we continued using the APM recorders in two
locations, Sausalito and San Mateo.
During this period, some 46 earthquakes 4.0 and above occurred
within 120 miles of our stations. Of these, 32 quakes were
preceded by a radio anomaly. Only five quakes were not preceded
by radio precursors. These were also ten false positives (radio
events with no quakes following). These may have been caused by
earthquake prepartion forces which failed to mature. Either way,
our score was about 70%.
The results of our study were published in October 1989, just
as the Loma Prieta Earthquake struck northern California.
By this time we had dismantled our network of recording
stations. However, one of the original APM recorders was still
running at my lab in Sausalito. This instrument recorded the
largest radio depression I have ever seen, about 60 days prior
to the October 17 shocks (Figure 3) [Not shown]. I had reported
that event to Galilee Harbor's board of directors, but no action
In studying several smaller earthquakes from 1985-1987, it
appeared that the larger the earthquake, the larger and sooner
the precursors appeared. The 6.0 earthquake of April 24, 1984
was preceded by a radio depression 6 days before the shock. The
Loma Prieta Earthquake of about 7.0 magnitude was preceded by a
much greater radio depression 60 days before. A 7.0 magnitude
quake is 10 times greater than a 6.0. The 60-day precursor time
for the 7.0 earthquake was 10 times the precursor time for the
6.0 earthquake. More data is needed to clarify this
Warrick's lab showed that fracturing rocks generate radio
waves: when Westerly granite was crushed in a shielded space, a
receiving antenna detected broadband signals ranging from 500
kHz to 30 MHz. Most of the energy was concentrated at the lower
Other experimenters measured changes in the electrical
resistance of rocks under pressure. During the late 1970s,
William Brace of MIT compressed various rocks in a powerful
press while recording their resistance. He found that as rocks
approach fracture pressure, they become much more electrically
conductive. A related experiment by William Daily at Lawrence
Livermore Lab subjected rocks to evenly distributed pressure
while their electrical resistance was measured. Under uniform
pressure, the rocks did not show the changes in resistance
produced in Brace's press. That suggested it was stress caused
by force being applied unevenly which caused the observed
changes in resistivity.
Although Warwick's experiment proved rocks can emit radio waves
during crushing, calculations showed that any such waves
generated far underground would be absorbed by the earth, never
reaching the surface with enough energy to be detected in the
atmosphere. In addition, this effect could not explain the
decrease of ambient radio energy observed by us and others.
Takeo Yoshino, of the University of Electro-Communications in
Tokyo, has proposed that "resistance slots" form along a fault
line due to effects similar to those demonstrated by Brace.
Yoshino argues that if ground resistance becomes high enough in
these slots, then radio waves coming from below will pass
through them, rather than being absorbed, and enter the
atmosphere. It would also mean atmospheric radio energy could
pass into the earth through these slots. This could create
interesting resonant effects.
Does ground resistance actually reach the levels needed to
sustain such an effect? It is known that ground water enhances
ground conductivity. However, C.B. Raleigh of the USGS has
calculated that enough heat can be produced by friction during
the earthquake preparation process to boil the ground water out
of a rupture zone. Perhaps dehydration could combine with
stress-induced fluctuations in rock resistance to produce slots
of heightened electrical resistance in the earth's crust.
Based on this idea, it is my belief that the radio depressions
and emissions recorded by us and others are the result of
fluctuations in ground radio absorption.
Radio waves moving through the atmosphere are always being
partly absorbed into the ground. The absorption rate varies from
place to place, based on the ground's conductance and the
distribution of rocks and sediments. If anything alters this
equilibrium, the radio fields in the atmosphere should also be
affected. For instance, more ground absorption should result in
a lower intensity in the atmosphere. A loss of absorption would
produce increased intensity in the atmosphere. Seismic radio
events may be due to this effect.
As a model for explaining the observed radio anomalies, this
has appeal, since it can account for both radio emissions and
depressions. It could also explain the changes in telluric
currents recorded in Greece prior to earthquakes. As ground
conductance changes, currents flowing through the Earth may be
diverted to channels and zones of greater conductance.
As more data is gathered, we'll understand more about these
phenomena. In the meantime, though, we're on a slow learning
curve, limited by the frequency of large earthquakes. There is
really no way to speed up this process, and perhaps we don't
actually want to.
Brady, B.T. & Rowell, G.A.: "Laboratory investigation of
the electrodynamics of rock fracture", Nature (London)
321: 29, may 1986.
Dazey, M.H. & Koons, H.C.: "Characteristics of a power line
used as a VLF antenna", Radio Science 17(3): 589-597
Dmowska, R.: "Electromagnetic phenomena associated with
earthquakes", Geophys. Serv. 3: 157-174 (1977).
Fraser-Smith, A.C, et al.: "Low-frequency magnetic field
measurements near the epicenter of the Ms 7.1 Loma Prieta
earthquake", Geophysical Research Letters (submitted
Gokhberg, M., et al.: "Experimental measurements of
electromagnetic emissions possibly related to earthquakes in
Japan", J. of Geophys. Res. 87(B9): 7824-7828 (1982).
Gokhberg, M., et al.: "Seismic precursors in the ionosphere", Izvestia
Physics 19: 762-765 (1983).
Gokhberg, M., et al.: "Resonant phenomena accompanying
seismic-ionospheric interaction", Izvestia Earth Physics
Nitsan, U.: "Eletromagnetic emission accompanying fracture of
quartz-bearing rocks", Geophys. Res. 4: 333 (1977).
Parrot, M. & Lefeuvre, F.: "Correlation between GEOS VLF
emissions and earthquakes", Annales Geophysicae 3:
Remizov, L., & Oleynikova, I.: "Spectral characteristics of
the natural random Earth's field in the frequency band from a
few hertz to 50 kHz", UDC 525.2.047: 621.391.244.029.4
Sadovsky, M., et al.: "Variations of natural radiowave emission
of the Earth during severe earthquake in the Carpathians", Dokl.
Akad. Nauk. SSR 244(2): 316-319 (1984).
Tate, J. & Daily, W.: "Evidence of electro-seismic
phenomena", Physics of the Earth & Planetary Interiors
57: 1-10 (1989).
Tate, J: "Radio absorption and electrical conductance in the
earth's crust" (1990, publication pending).
Vorotsos, P. & Alexopoulos, K.: "Physical properties of the
variations of the electric field of the earth preceding
earthquakes", I. Tectonophysics 110: 73-98 (1984).
Warwick, J., et al.: "Radio emissions associated with rock
fracture", J. Geophys. Res. 87(84): 2851-2859 (1982).
US Patent #
Seismic Warning System Using RF Energy
Joe Tate, et al.
Abstract -- The ambient broadband radio frequency field
strength from broadcast stations is monitored (Figure 4) by
periodic sampling (50, 52). A warning indication is provided if
the field strength drops significantly. Drops in such field
strength have been correlated empirically with the occurrence of
seismic activity, usually several days later. Thus the
indication serves as an early warning of an impending
earthquake. In one preferred embodiment, a broadband,
horizontal, very long monopole antenna (40) was connected to a
rectifying and smoothing circuit (Figure 3) to provide a dc
output proportional to the ambient rf field. This voltage is
digitized (50), and using a suitably programmed computer (52),
the digital version of the field strength signal is sampled once
per minute (78). A cumulative or running average of the minute
samples is calculated (80) and held. Once per hour the latest
running average is stored (84) and a standard deviation (SD) of
the last 24 hourly stored running averages is calculated (88).
If the SD exceeds a predetermined value, 0.3 in one embodiment,
an alarm is triggered (92). The use of the SD eliminates the
effect of day-to-day changes in the amounts of the variations of
the ambient field strength, due to changes in tides and other
factors. Once per day the samples are written (96) to a
permanent storage file and a continuous plot of the field
strength is also made (14). Preferably the alarm is triggered
only if another detector also provides an indication (FIG. 6),
thereby to eliminate the effect of machine error.
Inventors: Tate; Joseph B. (Sausalito, CA); Brown; David
E. (Mill Valley, CA)
Assignee: Pressman; David (San Francisco, CA)
Appl. No.: 695632; Filed: January 28, 1985
Current U.S. Class: 340/540; 324/323; 324/344; 340/600; 340/690;
Intern'l Class: G08B 021/00
Field of Search: 340/540,600,690
U.S. Patent Documents
4,214,238, Jul., 1980, Adams et al. 340/540.
4,364,033, Dec., 1982, Tsay 340/540.
Background: Field of Invention
This invention relates to the prediction of the fugure
occurrence of seismic activity, particularly to the advance
notification of earthquakes through the monitoring of ambient
radio frequency (rf) energy.
Background: Description of Prior Art
Heretofore, insofar as we are aware, seismology, the science of
earthquakes, has not been able to make any near-term predictions
While scientists have known that certain animals may have had
some sort of advance knowledge of quakes, due to the fact that
they exhibited peculiar behavior before quakes, and not at other
times, this behavior has not been consistent and reliable enough
to be of practical use.
Also, while scientists have also been able to predict
thunderstorms in advance by monitoring the ambient electrostatic
field (see, e.g., US Pat. No. 3,611,365 to Husbyorg and Scuka,
1968; 3,790,884 to Kohl, 1974; and 4,095,221 to Slocum, 1978),
they have not been aware of any corresponding system for
Scientists have been able actually to detect earthquakes during
their occurrence by monitoring air pressure variations (e.g., as
described in US. Pat. No. 4,126,203 to Miller, 1978) and by
monitoring the earth's physical movement by seismographs but,
again, science has not been aware of any system for short-term
advance detection or prediction of quakes.
Due to the devastating effects of quakes to property, life, and
limb, public and governmental authorities would derive great
benefit from any system which could provide short-time advance
notification of great earthquakes. As it is now, except for
aftershocks, which seismologists know will occur after any large
quake, all great and small quakes occur without warning. Because
people in the vicinity of such quakes are unprepared, they often
are in places of great vulnerability, such as beside or inside
collapsible buildings, so that severe and human injury usually
occurs during a quake. Also, property itself is left vulnerable,
e.g., by leaving automobiles in or near collapsible buildings,
leaving gas and electricity connected such that disruption of
these facilities causes fires, and leaving other valuable
property in vulnerable areas. If advance notification of a large
quake could be provided to the public and civil authorities,
people and valuable property could be evacuated and protected,
thereby preventing deaths, injuries, and greatly reducing
property damage. Further, advance notification of quakes would
eliminate the severe psychological trauma which often affects
large segments of the populace due to the surprise occurrence of
Objects & Advantages
Accordingly several objects and advantages of the invention are
to provide a reliable and effective method of earthquake
prediction, to provide a method of preventing death, injuries,
and reducing property damage in earthquakes, and to provide a
method of reducing the psychological trauma which often
accompanies quakes due to their surprise occurrence. Additional
objects are to provide such a system which is easy to use,
economical, reliable, and portable. Further objects will become
apparent from a consideration of the ensuing description, taken
in conjunction with the accompanying drawings.
Background: Theory of Invention
The following is a discussion of the background theory of the
invention. While we believe it to be technically accurate, we do
not wish to be limited by this theory since the operability of
the invention has been empirically verified, as will be apparent
from the later discussion.
We have recently worked work with the reception and utilization
of broadband radio-frequency reception, e.g., for low-power
utilization applications, as discussed in the copending
application Ser. No. 06/539,223 of Joseph B. Tate, filed Oct. 6,
1983. While doing this work, we have noted that the antenna's
output voltage fluctuated with time due to certain, known
First, we noted that the higher we placed an antenna above the
ground, the the greater the output signal it provided. We have
observed this by raising the physical height of an antenna and
observing an increase in power output, and also by observing
variations in the output of a fixed antenna near a body of ocean
water as a function of the tides: the antenna's output was
greatest at low tide and lowest at high tide. We believe that
the change in water level, which serves as a ground plane,
effectively lowers or raises the height of the antenna above the
We also noted that the antenna's output was affected by solar
flares to a limited extent; these caused the antenna to produce
a higher output voltage during their occurrence. We believe this
phenomena is caused by an increase in the level of ambient
ionization due to the flares.
Further, we noted that the antenna's output dropped at certain
irregular times; at first we would not attribute any cause to
these drops. However investigation enabled us to correlate these
drops with the subsequent occurrence of seismic activity. We
found that the magnitude of the drop was proportional to the
size of the subsequent earthquake.
Certain phenomena have been discovered to precede earthquakes.
These include an anomalous uplift of the ground, changes in the
electrical conductivity of rock, changes in the isotopic
composition of deep well water, changes in the nature of small
earthquake activity (e.g., bunching of small foreshocks),
anomalous ground tilt or strain changes, changes in physical
properties, such as porosity, electrical conductivity, and
elastic velocity in the hypocentral region. Earthquake,
McGraw-Hill Encyclopedia of Science And Technology, 1960;
Earth by F. Press, W. H. Freeman & Co., 1974.
Phenomena associated with rocks have attracted much recent
attention. Wm. Brace of the Mass. Inst. of Technology has found
that when rocks were squeezed or compressed, just before they
fractured, they tended to develop hairline cracks, swell or
dilate (dilatancy), become more porous and electrically
conductive, and transmitted high frequency seismic-like waves
more slowly. Two of Brace's former students, Amos Nur of
Stanford University and Christopher Scholz of Lamont-Doherty
furthered Brace's work, connecting the dilatancy theory with
seismic P-wave velocity shifts and rock resistivity changes as a
precursor for earthquakes. See. e.g., Brace, Orange, and Madden,
J. Geophys. Res., 70(22), 5669, 1965; A. Nur, Bull.
Seis. Soc. of Amer., V 62, Nr. 5, pp. 1217-1222, 1972
Oct.; Earthquake by B. Walker, Time-Life Books, 1982.
Based upon the above background, we have developed a theory as
to the cause of this drop in antenna output as a precursor or
predictor of earthquakes. We believe that before a quake occurs,
the pressure within underground rock bodies temporarily
increases greatly, causing the rocks to dilate and become
conductive, in accordance with the works of Brace, Nur, and
Scholz. This increase in conductivity effectively raises the
ground plane, thereby causing the antenna's output to decrease
Thus before the occurrence of a quake, the underground pressure
increases greatly temporarily, causing underground rock bodies
to swell and become more conductive, thereby raising the ground
plane, which in turn causes the voltaic output of nearby
antennas to drop.
We accordingly constructed an apparatus to automatically
monitor antenna output and provide a suitable indication if the
output level dropped significantly. The indication was
calibrated empirically after much experimentation so as to
filter out the effects of solar- and tide-caused variations. We
did this by arranging the apparatus so that an output indication
was provided only if the antenna output dropped a predetermined
degree beyond its average level; we utilized statistical
filtering techniques to accomplish this.
Figure 1 shows the front panel of a
Seismic Early Warning (SEW) apparatus according to the
Figure 2 is a plot of voltage
(representing ambient rf level) v. time as measured by the
apparatus of Figure 1.
Figure 3 is a schematic diagram of an
ambient power module circuit (used in the SEW apparatus) for
producing a DC output voltage proportional to the ambient rf
Figure 4 is a block diagram of a computer
in the apparatus of Figure 1.
Figure 5 is a flowchart which depicts the
operation of the SEW system.
Figure 6 is a flowchart which depicts the
operation of an optional alarm trigger system useable with the
Figure 1: Seismic Early Warning
In accordance with the invention, a seismic early warning
apparatus is provided as shown in FIG. 1. The apparatus consists
of a housing containing a general purpose computer (not shown),
a disc drive 10, an analog system comprising a microampere meter
12 arranged to monitor direct current (which is proportional to
the ambient rf energy), and a direct current strip chart
recorder 14 arranged to provide a continuous indication of the
current antenna output, which will be called the ambient power
level. A hexidecimal keypad 16 is provided to enter data, such
as time, for entering programs and changes and for operating the
system according to preset codes. The time, date, and voltaic
level of the antenna's output are continuously indicated by
digital readouts 18, 20, and 22, respectively. A screen display
24 is provided to display graphic and alphanumeric information
of the current status of the apparatus and previous data
Lastly the apparatus includes four status-indicating lamps,
which preferably are LEDs (light-emitting diodes) as follows: A
green LED 26 indicates that the system is on and functioning
normally. A yellow LED 28 indicates that the system has detected
an event, namely the occurrence of a drop in ambient power below
the preset level, which would be the prediction of an impending
earthquake. A red LED 30 is provided as backup confirmation of
the occurrence of the event; LED 30 is illuminated when a
duplicate receiving system also detects an event. A blue LED 32
indicates initiation of operation of an automatic telephone
dialer within the system, which has been preprogrammed to dial a
predetermined number and provide a warning in the event of an
occurrence of an alarm condition. Lastly the apparatus includes
a hard copy output port 33 for providing printed graphic and
numeric outputs of all system data.
Figure 2: Ambient RF Level vs Time
Figure 2 illustrates a reproduction of an actual plot of a
voltage as a function of time, which voltage was proportional to
the ambient RF (radio frequency) level, from the period from
before to after a relatively large earthquake. This plot, which
is typical of many we have observed before a quake, was made by
deriving the voltage with a 30-meter, long-wire monopole antenna
(not shown) which was mounted horizontally and which extended
over San Francisco (Richardson) Bay easterly from Sausalito,
California, 9 meters above sea level. The antenna thus
intercepted and converted to an RF voltage the ambient RF
energy, mainly from local (San Francisco area) AM radio
stations. We rectified and filtered the output of the antenna
using one-half of the circuit of FIG. 3 (described below) to
provide a DC voltage which was plotted on a conventional
ink-on-paper plotter. Note that on the section of the chart for
Apr. 19 (1984), which begins at time 0:00 (midnight) and ends at
24:00, the voltage or ambient RF power level at the antenna
increased and fell and then increased slightly in the 24-hour
period. This wavelike variation typically occurs on a daily
basis and is caused by tides: the peaks occurring at low tide
when the effective ground plane provided by the water drops and
the troughs occurring at high tide when the ground plane rises.
On Apr. 20, from about 8:00 to about 12:00, a sharp and
constant-level dip in the ambient rf power occurred, as
indicated. The magnitude of this pronounced dip is far greater
than the normal tide-caused variations, as is its beginning and
Thereafter, from Apr. 20 to Apr. 23, the plot (not shown)
continued unremarkably, albeit with a slight variation from
The same occurred on Apr. 24, with the plot actually being
generally similar to a normal day. However at 13:15 on Apr. 24,
as indicated, a large, Richter magnitude 6.0 quake occurred near
Hollister, Calif., about 340 km away from the antenna. No change
in the plot occurred at this time.
Correlation of this quake with the plot's marked dip of Apr. 20
was made by the repeated observation of dozens of similar dips
and subsequent quakes. Pronounced dips were always followed by a
quake several days later. Thus we have empirically established
causal and theoretical connections between pronounced dips of
the type shown and the occurrence of subsequent seismic
Figure 3: Ambient Power Module
The circuit of Figure 3 is used to convert the ambient RF
energy to a direct voltage which can be used and handled by data
processing equipment. Designated an ambient power module (APM),
it is connected to an antenna 40, preferably a broadband
monopole antenna of the type described in the preceeding
section. The distal end of the antenna is free and its proximal
end is connected to the circuit via two capacitors Cp1 and Cn1,
each being in series with the signal line for coupling and each
having a value of 0.047 microfarad. Taking the left or negative
side of the circuit first, it comprises two rectifiers (diodes)
Dn1 and Dn2 (1N34 type) and a filter capacitor Cn2 (40
microfarads). Rectifier Dn1 is connected in parallel to the
signal path and rectifier Dn2 is connected in series, in the
well known voltage multiplier arrangement. Capacitor Cn2 is
connected in parallel across the output of the APM to smooth the
rectified output. The right or positive side of the circuit is
similar, except for the polarity of the diodes.
In operation, an RF voltage is developed across antenna 40;
this voltage is voltage multiplied by the two rectifiers on each
side of the circuit. The resultant direct voltages are smoothed
or filtered by capacitors Cn1 and Cp2 and are supplied to output
terminals 42 and 44. A positive version of this direct voltage
is plotted in Figure 2, as described above.
Figure 4: Block Diagram of Computer
A computer for performing the monitoring and alarm functions of
the invention and which is provided within the apparatus of
Figure 1 is shown in Figure 4. The computer receives the
positive voltage from the APM (Figure 3) and processes this,
providing an alarm if the voltage dips a predetermined amount
from its recent average value.
The computer comprises an analog to digital converter (ADC) 50
which is arranged to convert the positive DC voltage from the
AAPM to digital form, preferably in the form of a parallel
signal at the output of ADC 50. The digitized voltage from ADC
50 is supplied to a central processing unit 52, which is a type
68000 microprocessor or computer on a chip. CPU 52 and ADC 50
are clocked by a clock 54 in conventional fashion.
CPU 52 operates on instructions from a program contained in an
electrically programmed read only memory (EPROM), the program
being listed later. CPU 52 temporarily stores data in a read and
write memory (RAM) 58. CPU 52 also supplies output data to
display screen 24, disc drive 10, and hard-copy printer 26',
each of which was already described in conjunction with Figure
CPU 52 can receive input data manually from hexidecimal keypad
16 (see FIG. 1) via a keyboard encoder 60.
CPU 52 can supply an alarm output to a radio transmitter or
automatic telephone dialer 62 via a modem
(modulator-demodulator) 64 for connecting the CPU to a phone
As also indicated in Figure 4, the negative output of the AAPM
of Figure 3 is connected to ammeter 12 and chart recorder 14.
Figure 5: Flowchart of Seismic Early
In operation, the system of Figure 4 operates under control of
the program in EPROM 56 in accordance with the flowchart of
Figure 5 as follows:
Startup: Blocks 70 and 72: An initialization and start-up
sequence is first initiated when the machine is turned on, as
indicated by block 70; this sets all registers and counters to
zero. The time and data are then set manually (using EPROM 56),
as indicated by block 72.
Clock Reading: Blocks 74 and 76: Next, under automatic program
control, the machine reads the elapsed time on its clock display
register, as indicated by block 74. If the "seconds" register
does not indicate the number one (#1), the machine continues to
read the clock, as indicated by the "no" output of decision
Minute Sample: Block 78: When second #1 appears, as it will
once per minute, the decision in block 76 will be "yes", so that
the machine will take one sample of the rectified, smoothed, and
digitized version of the antenna's output, i.e., the output of
ADC 50 of Figure 4, as indicated in block 78. This sample will
be taken once per minute, i.e., whenever second #1 is displayed.
Running Average: Block 80: Next, as indicated by block 80, a
running average of the samples taken in block 78 is calculated.
This is done by accumulating the samples to keep a running total
of their values, counting the number of samples accumulated, and
dividing the running total by the latest number of samples each
time a new sample is taken.
Store Hourly Average: Blocks 82 and 84: Next, as indicated in
block 82, a test is made to see if the time display register
indicates that minute number one (#1) has come up. If not, the
decision is "no" and the clock is read again (block 74). If the
decision is "yes", as it will be once per hour, the running
average in the accumulator will be stored (block 84) and the
accumulator will be cleared or reset to zero.
One Day Test: Block 86 ("No" decision) and Block 94: Next the
machine makes a test to see if 24 hours have passed. If not, the
machine will not be able to make any valid statistical
determinations. Thus it must run at least 24 hours before being
operative. Assuming the decision in block 86 is negative (24
hours have not yet elapsed) another test is made (block 94) to
see if hour zero is indicated, which will occur once per day. If
hour zero is not indicated, (decision in block 94 is negative),
the clock will be read again (block 74) in the usual loop.
Calculate SD: Block 86 ("Yes") and Block 88: If a full day has
elapsed, so that valid statistics can be calculated ("yes" from
block 86), the standard deviation (SD) of the last 24 hourly
averages is calculated, as indicated in block 88. This is done
once per hour. The calculation is made using the usual SD
where SDDEV=SD; SQR=the square root; sum=the sum of; x=the
individual hourly averages; X=the mean of the hourly averages;
and n=the number of individual hourly averages. Essentially the
SD is calculated by taking the mean of all of the hourly
averages, taking the difference or deviation of each hourly
average from the mean, squaring each deviation, taking the mean
of the squared deviations, and then taking the square root of
the mean of the squared deviations.
Evaluate SD: Block 90: The SD is then evaluated to see if it is
greater than 0.3. This value has been empirically determined to
be the level at which the present apparatus will provide a
reasonably positive indication that an earthquake will occur,
while neglecting the effects of non-seismic-caused variations.
If the SD is less than 0.3, (a "no" output from block 90), this
indicates that the last hourly average was not greatly different
from the average of the last 24 hourly samples, so that no alarm
need be indicated. I.e., the antenna's output did not drop
significantly to indicate an impending earthquake. Thereupon the
program moves to block 94, where a test is made for the
existence of hour zero, as described. If, however the SD exceeds
0.3 ("yes" output of block 90), this indicates that the
antenna's output has dropped significantly so as to affect the
last hourly average, thereby to indicate an impending
Alarm: Block 92: In response to the Yes output of block 92, an
alarm is triggered (block 94). The alarm may be a bell, the
dialing of a telephone to a location where personnel are present
if the apparatus is placed at a remote or non-manned location,
or the initiation of the further program of the Flowchart of
Figure 6, the alarm trigger sequence. To eliminate the
possibility of equipment failure and to provide confirmation
from another apparatus at another location, we prefer to provide
an alarm only upon confirmation from another apparatus, as
discussed in the description of Figure 6 below.
Make Record: Block 94 ("Yes") and Block 96: If hour zero is
being displayed when the operation of block 94 is performed,
which occurs once per day at midnight, the operation of block 96
will be performed, i.e., the data in the registers will be
stored to disc to create a permanent record and the registers
will be cleared to create new data for the next day. However the
previous 24 hourly averages are still stored at all times so
that a valid SD can be calculated and tested every hour. After
the operation of block 96, the clock is read again in accordance
with the regular program (block 74).
Figure 6: Alarm Trigger Flowchart
The sequence of Figure 6 is performed when the alarm is
triggered in block 92 of Figure 5 as an optional, but preferred
backup confirmation of an impending earthquake. The operations
in the backup confirmation system will be described briefly.
Beginning with blocks 100 and 102, the system is continually
tested (hourly) for the occurrence of a SD of the hourly
averages of greater than 0.3. If the SD is greater than 0.3, the
alert indicator (28 of Figure 1) is triggered (block 104) and
the program initiates a test (block 106) to see if a backup
apparatus (not shown) is present. If so (yes output of block
106) the backup apparatus is also checked (blocks 108 and 110).
If the backup does not indicate an excess SD, the indicators are
reset to normal (block 112), but if backup confirmation is
received, the alarm indicator (30 of Figure 1) is triggered per
block 114 and a preprogrammed telephone number is dialed and
indicator 32 is lit (block 116).
After the alarm condition is manually checked and the system is
reset, the output of block 120 will be a "yes" and the system
will be reset to normal (block 112). If a valid alarm condition
is indicated and confirmed, civil authorities will have time
(usually several days) to notify the populace, evacuate the
area, or take any other needed precautions, depending on the
size of the impending quake as indicated by the size of the
The attached computer programs will perform the calculations
and operations above described. These programs are written in
the BASIC programming language. Program "RECVOLT.AL" runs
continuously and writes the information to disc every 24 hours.
Program "GRASTAT.*" is manually run; it reads data from the disc
and plots it on the screen or printer, as desired.
While the above description contains many specifications, these
should not be construed as limitations on the scope of the
invention, but merely as an exemplification of one preferred
embodiment thereof. Many other variations are possible. For
example, the programming language can be changed, or the
calculations and operations can be performed with hard-wired
conventional circuitry in lieu of a programmed computer. More
than two corroboration receivers can be used, and these can be
placed at various locations. In lieu of testing the antenna's
output reception of the area's AM stations, a special, dedicated
transmitter with a special, dedicated frequency and a
specially-tuned matching receiver can be used to avoid
dependence on stations which are not under the control of the
earthquake prediction system and its personnel. The transmitter
and the receiver should be spaced apart geographically,
preferably by at least several km, so that the ground plane
conduction phenemonon can operate. Also the transmitted signal
can be a specially-coded or modulated signal, or it can be an
auxiliary signal of a regular transmitter, e.g., a SSB or SCA
signal, together with a matching receiver. In lieu of a test for
an excess SD, the apparatus can be arranged to test for a
predetermined drop in the value of the antenna output from its
immediately previous value or its average value over a
predetermined period, such as an hour or day, or for a drop
having greater than a predetermined slope. Accordingly the full
scope of the invention should be determined by the appended
claims and their legal equivalents, and not by the examples
Claims -- [ Not included here ]
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