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Thesis and Dissertation Collection
1984
Design of a freestanding noise measurement and
recording system to predict the intensity and location
of electromagnetic radiation from earthquakes.
Ross, Mickey V.
http://hdl.handle.net/10945/19245
DUDLEY KNOX LIBRARY
NAVAL POSTGRADUATE SCHOOL
MONTERFY, CALIFORNIA 93943
NAVAL POSTGRADUATE SCHOOL
Monterey, California
THESIS
DESIGN OF A FREESTANDING NOISE MEASUREMENT
AND RECORDING SYSTEM TO PREDICT THE intensity!
AND LOCATION OF ELECTROMAGNETIC
RADIATION FROM EARTHQUAKES
|
by
Mickey V. Ross
December 1984
Thesis Advisor:
R.
W. Adler
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Master's Thesis;
Design of a Freestanding Noise Measurement and Recording System to Predict the December
Intensity and Location of Electromagnetic
PERFORMING ORG. REPORT
Radiation from Earthquakes
6.
7.
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Mickey V. Ross
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Naval Postgraduate School
Monterey, California 93943
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December 1984
Naval Postgraduate School
Monterey, California 93943
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Noise Measurement; Prediction; Electromagnetic Radiation from
Earthquakes
20,
ABSTRACT
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The design, construction, and testing of a freestanding
radio frequency (RF) noise measurement and recording system
Placement of
in the 30 MHz and 150 MHz range is presented.
the system along the San Andreas fault to permit the
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establishment of a correlation between increased
background RF noise to earthquake fault activity
for potential as an earthquake prediction tool is
described.
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Design of a Freestanding Noise Measurement and Recording System
to Predict the Intensity and location of Electromagnetic
Radiation from Earthquakes
by
Mickey V. Ross
Lieutenant, United States Navy
B.S., United States Naval Academy, 1977
Submitted in partial fulfillment of the
reguirements for the degree of
MASTER OF SCIENCE IN ELICTRICAL ENGINEERING
from the
NAVAL POSTGRADUATE SCHOOL
December 1984
ABSTEACT
The design, construction,
radio frequency
(RF)
in the 30 MHz and 150
and testing of a freestanding
noise measurement and recording system
MHz range is presented.
the system along the San Andreas
lishment of
a
correlation
to earthquake
Placement of
fault to permit the estab-
between increased
background RF
activity for potential
earthquake prediction tool is described.
noise
fault
as
an
TABLE OF CCNTENTS
I.
II.
INTEODUCTION
11
A.
EVOLUTION OF EARTHQUAKE PBEDICTION
11
B.
FOCUS OF STUDY
13
BACKGROUND
A.
B.
C.
14
EARTHQUAKE GROUND MOTION
SOURCES OF ELECTROMAGNETIC RADIATION IN
14
EARTHQUAKES
Insulators and Conductors
1.
15
20
2.
Contact Electrification
22
3.
Fracture of Quartz-bearinj Rocks
25
4.
Porous Rock
SOURCES OF ELECTROMAGNETIC PRECURSOR
27
EVENTS
32
1.
Electric Fields and Atmospheric
Electric Potential
2-
III.
Magnetic Fields and Animal Behavoir
...
33
ELECTROMAGNETIC PROPOGATION CRITERIA FOR
EARTHQUAKES
IV.
32
38
A.
THE ELECTRIC FIELD EQUATIONS
39
B.
SKIN DEPTH AND RADIATED FREQUENCIES
43
C.
THE PROPOGATION CRITERION
44
DESCRIPTION OF RESEARCH
46
A.
DESIGN GOALS
46
B-
SYSTEM COMPONENTS
49
1.
Receivers
49
2.
Recorders
52
3.
Interface Amplifiers
53
Timer
54
V.
PERFORMANCE OF SYSTEM
62
VI.
CONCLUSIONS AND EECOMMENIATIONS
4.
.
68
A.
CONCLUSIONS
68
B.
RECOMMENDATIONS
69
APPENDIX
A:
RECEIVER SENSITIVITY DATA AT VHF
FREQUENCIES
APPENDIX
B:
70
ELECTROMAGNETIC EMISSIONS FROM
EARTHQUAKES
73
A.
COALINGA
73
B.
RUSSIA
73
C.
JAPAN
74
LIST OF REFERENCES
79
INITIAL DISTRIBUTION LIST
81
LIST OF lABLES
I.
Time Variations in the Geomagnetic Field
II.
Order of Magnitude Estimates of the Various
34
Possible Physical Mechanisms for
Earthquake-Related Field Anomalies
36
III.
Chart Speed and Trace Density
54
IV.
Frequency 38.45 MHz RF Irput in uV and Signal
Output
V-
inmV
71
Frequency 150.75 MHz RF Input in uV and Signal
Output in mV
72
LIST OF FIGOBES
Elastic-Rebound Model of Zarthciuakes
Oblique View Across the San Andreas Fault Zone
Typical Right- Lateral Offset of Stream Offset
16
is About 450 Feet
17
2.3
Idealized Model of Earthquake Source
18
2.4
Double Couple Source Model of Fault Slippage
2.1
2.2
Similar to Spheres Pulled by Wire Through
2.5
Frictionless Tube
Shock-Induced Polarization Signals of Plexiglas
Below Transition Pressure
2.7
Shock-Induced Polarization Signals of Plexiglas
Above Transition Pressure
Shock-Induced Polarization Signals of
2.8
Polystyrene Above and Belcw Transition Pressure
Shock-Induced Polarization Signals of
2.6
Polystyrene and Plexiglas as a Function of
Shock Pressure
2.9
22
.
.
23
Spectral Content of Fracture-Related EM
26
Examples of EM Transients Accompanying Fracture
of Piezoelectric Specimens
2.11
21
24
Emission
2.10
19
Electric Double Layer and Velocity Profile in
28
a
Capillary
29
Spectrum of the Geomagnetic Field
35
3.1
Cross-Section of Earthquake Fault Line
39
3.2
Electromagnet Vectors at Fault Hypocenter
Position of Antennas Along the San Andreas
Fault
4
2.
4.
12
8
1
47
U.2
Block Diagram of Data Reception System
48
4.3
VHF Converter Schematic fcr 38.45 MHz
50
4.4
VHF Converter Schematic fcr 150.75 MHz
51
4.5
IF Audio Module Schematic
53
4.6
Eustrak Model 2146 Schematic
55
4.7
Rustrak Model 2146 with Signal Processor
Schematic
56
4.8
Single Channel Modificaticn (S-MOD)
57
4.9
Bias Stepper Demodif icaticn
58
4.10
Interface Amplifier with Voltage Generator
4.11
Time Tick Generator
5.
Signal Level Data from Noise Measurement System
.
.
63
5.2
Signal Level Data from Noise Measurement System
.
.
64
5.3
Signal Level Data from Noise Measurement System
.
.
65
5.4
Signal Level Data from Noise Measurement System
.
.
66
5.5
Signal Level Data from Noise Measurement System
.
.
67
B.I
Earthquake Epicenter and
B.2
Eseudo 3-D Plot of Doppler Disturbance Path
B.3
Electromagnetic Noise Levels at Caucasus
Electromagnetic Noise Levels at Sugadaira
Electromagnetic Noise Levels at Suginami
B.
B.
....
59
61
HF
Path Locations
....
....
74
75
76
77
78
ACKNOWLEDGEMENTS
The author
is indebted
to a
multitude of
persons for
their assistance and patience during the preparation of this
thesis.
Foremost,
I
wish to thank my Lord and Savior,
Jesus
Christ, whose grace I found sufficient.
I
and my
wish to
son,
express sincere gratitude to my wife,
Mary,
confidence and assurance
Timothy Joel,
for
throughout this endeavor.
W.
Adler, and Dr.
also wish to thank Dr.
Richard
Stephen Jauregui, Jr., whose guidance and
support were incessant.
Naval Postgraduate School
under,
I
thank all the
professors of whom I had classes
Finally,
CAPT Warren Averill,
and
their superb support.
10
I
wish to
the Bullard Hall gang for
^'
A.
INTRODCCTION
EVOLUTION OF EARTHQUAKE PREEICTION
The problem involving searching for a reliable precursor
luch attention throughout the
to earthquakes is being given
reality that within minutes
With the
world.
act of nature leaving
can trigger an incredibly disasterous
thousands and property damage in
death tolls in the tens of
the
anywhere
billions
an earthquake
world.
the
in
The
desire
for
prediction capabilities has evolved into an intense investi-
scientific
gative
activity
data was
undertaking.
collected
recently,
Until
to establish
only
earthquake has the greatest potential to occur.
potentially
destructive
because they occur
seismic
in remote,
shocks
seismic
where
an
Hundreds of
escape
sparsely populated
unnoticed
areas of
the earth.
The present
state of the
art in
earthquake prediction
may be compared to that of weather forecasting some 50 years
Seismological
data acquired
continuous and
detailed from every area of the world that is subject to
seismic disturbances.
Various experimental methods for
prediction of seismic activity are widely used such as electric and magnetic field,
tilt, creep,
and strain motion
measurements to establish a practical data base [Ref. 1].
ago.
Evidence of radio
(RF)
must be
emission associated with precur-
sors to earthquake activity is very sparse.
Electromagnetic
radiation associated with earthquakes appears impulsively
[Ref. 2],
which
suggests that these electromagnetic waves
are radiated in a wide range of radio frequencies. The characteristics of the electromagnetic radiation depend greatly,
however, on such factors as the magnitude of the earthquake.
11
the depth of
the earthquake region,
the geology of
focus,
the distance between epicenter and point of observation, the
condition of ionospheric propagation,
and others.
This is
possibly the reason why the intensity of the electromagnetic
radiation is different for different earthquakes,
with
values varying from tens or hundreds of microvolts per meter
up to tens of hundreds of volts per meter.
Measurements
possibility
being made
are presently
existence
of the
to explore
of electro-magnetic
the
fields.
However, there presently appears to be no directed research,
or a
plausible explanation
for,
reported
emission interference coinciding with
radio frequency
an increase in earth-
quake activity.
Derr noted an observation of noise on the FM
broadcast band
(88-108 MHz)
earthquake lights [Eef. 3].
MHz
radio noise by J-W.
with
The reception of earth-based 18
Warwick
of the
High
Altitude
at the time of the famous Chilean
Observatory, Boulder, Co,
has been
earthquake still
cccuring simultaneously
unanswered [Eef. 4].
Research
personnel involved in RF interference study, in interviewing
citizen band and amateur radio operators in the Hollister,
Caarea,
noted a consistent report of "increase in backnoise level
ground
preceding earthquake
frequency range of CB
bands
(50-54 MHz and
noticeable
(10
(27 MHz)
activity" in
the
and six and two meter amateur
144-148 MHz). Reports typically cited
increase in
dB)
background
noise
a
which
returning to
normal just before the tremors were felt
(one hour
to 1
(field
minutes)
Observations of the electrostatic field
mills)
have reported that diurnal variations at selected
an earthquake
preceded
by
12
to 24
hours,
.
sites are accompanied by "high frequency,
apparently have no explanation.
approached
boundary,
induced
on what
whether
is
actually
spiky noise" that
Various theories have been
occuring at
the
impact of dissimilar materials
polarization have
developed
12
the necessary
fissure
or shock
charge
density to produce
the electric field and
specific
area
surface
behaves
as
a
subsequently the
constant
current
generator.
B.
FOCOS OF STUDY
and testing of a freestanding
The design, construction,
radio frequency
(RF)
in the 30 MHz and
150
noise measurement and recording system
MHz range is presented.
the system along the San Andreas
lishment of
noise
a
correlation
to earthquake
fault
fault to permit the estab-
between increased
activity
background RF
for potential
earthquake prediction tool is described.
13
Placement of
as
an
BACKGfiOgND
II.
A.
EARTHQUAKE GROOND MOTION
predicting
important to
Equally
earthquake is determining which of
is
likely
the
an
the many ways the ground
the earthquake,
to shake during
and how long it will
shaking will be,
occurence of
how
last.
strong the
Knowledge of
ground motion can make it possible to understand the charac-
teristics of the earthquake source. Most measurements made
during actual earthquakes at seismological stations are some
distance from the source.
The localized source of an earthits significance until
not observed for
quake was
the San
Francisco earthquake of 1906.
recognized that
It was
earth's crust caused
rocks parallel
From the
elastic
Hopkins University
had been strained
to the fault
basis of
his geodetic
rocks are elastic,
fault
in the
study of
revealed that
or sheared.
observations eminated
of earthquakes
rebound theory
a
The classic
the earthquake.
Reid of John's
Harry F.
slippage along
which asserts
and mechanical energy can
blocks forming the
near the
opposite sides of
a
5]-
fault
the motion elastically strains the
move by a small amount,
rocks
that
be stored in
them just as it is stored in a compressed spring [fief.
When two
the
fault.
frictional bond
The
fails at
its
becomes large enough. That
point of initial rupture, called the hypocenter, may be near
the surface or deep below it. The seismic waves radiate from
weakest point
when the stress
the hypocenter in all
The point on
directions producing the earthquakes.
the surface of the earth
is the epicenter of the
an interval
of minutes,
earthquake.
days
14
above the hypocenter
The rocks rebound over
or even years.
The seismic
over ground
energy radiated
be quite
time may
at any one
small. This slow process is referred to as a seismic slip or
creep.
generated in zones where the huge
which make up the outer layer of
plates of the lithosphere,
earth's surface, as in Figure 2.1 and Figure 2,2
the
A conceptual model
[Bef. 6], are shearing past each other.
Most earthquakes are
process,
of the faulting
developed from
were largely
along the San Andreas fault.
than 20 severe
of
California,
meter to
investigations of
earthquakes
Over the past 137 years,
earthquakes have been recorded
to Cape
about
width from
almost vertically
and plunges
1.6 KM,
The San
of California in
extends from the Gulf
Mendocino varies in
more
in the state
mainly along the San Andreas fault.
Andreas fault which
the South
and Figure 2.4,
as in Figure 2.3
a
into the
earth for 15 to 20 KM. These are some of the reasons why the
San Andreas qualifies for conducting an intensive,
RF
noise
increases
measurement
in
show
anomalous
electromagnetic
radiation
investigation
the intensity
of
longterm
to
precursor to earthquakes,
B.
SOURCES OF ELECTBOHAGNETIC RADIATION IN EARTHQUAKES
The emissions
of RF are theorized
to be caused
by the
increasing of mechanical pressure at the fault causing shear
stresses that convert the insulating rock to
semiconductor)
by
reducing
the energy
a
gap
conductor
(or
between
the
valence and conduction bands.
During the stress increase,
microfractures cause shock waves that accelerate the electrons in the conducting bands to radiate both acoustic and
electromagnetic energy. If the mechanical forces increase to
the yield
point,
the
rock fails
in brittle
fracture and
causes a sudden decrease in the shear forces. The mechanical
motion is described by a stick-slip motion that has stable
15
Figure
2.
1
Elastic-Rebound Model of Earthquakes
16
Figure 2,2
Oblique View Across the San Andreas Fault Zone
Typical Right-Lateral Offset of Stream
Offset is About 4 50 Feet
17
Figure 2.3
Idealized Model of Earthquake Source
18
COUf LE
Figure 2.4
Doable Couple Source Model of Fault Slippage
Similar to Spheres Pulled by Bire Through Frictionless Tube
19
sliding during stress increases and stick-slip motion during
the stress release.
Ins ula tors and Conductors
1-
radio emission
The
theory rests
can be mechanically stressed
that an insulator
conductor or semiconductor with
to become
a
subsequent charge migration
conducting rocky material
from the
principle
on the
insulating rock
to the
equivalent electric field generated by a shock
during brittle fracture of the rock.
wave
Experimental
evidence from the Ballistic Eesearch Laboratory,
Aberdeen
Proving Ground, Maryland showed that shock-induced polarizaunder the
tion is an increasing function of pressure [Ref. 7].
low
At
pressures shock-induced
associated with
level
of both plexiglas and
Shock-induced polarization
polystyrene was observed at lower
pressures,
but the noise
experiments prevented
the
(Ps)
to approximately
is easily measured down
becomes small but
25 Kbar-
polarization
accurate
measurement. At high pressures data indicated transitions Ps
more rapid increase,
began a
state where the
suggesting transitions
to a
more easily
plexiglas and polystyrene were
polarized by the shock wave.
The dielectric constant of
the shocked medium,
was also an increasing function of pressure.
K'
were characterized by appreciable scatter,
K*
The values for
but indicated
gradual increase up to the transition pressure where a
more rapid increase was noted. The relaxation time, 0^ , was
a
characterized by appreciable scatter, but remained
between 0.5 and
1.5 usee
pressure,
up to
the transition
also
where
a
rapid decrease began.
zation is
caused by the motion
then the sudden
more
If it is
freely
decrease in
in the
transitions are to
a
high
more
'
i
of
atoms or
suggest that
pressure
phase,
fluid state.
20
assumed that polari-
atomic groups,
motion occurs
and
that
the
Greater freedom of
motion would result in
a
larger polarization of the material
forces in aggreement with
the phase
K» at
Ps and
by both mechanical and electrical
the
observed
increase in
both
212 kiloBarx
187 kilobori
^ 112 kiMort
0.2
0.3
0,4
0,S
TIMC -psec
Shock- Induced Polarization Signals
Figure 2.5
of Plexiglas Below Transition Pressure
Figures 2.5, 2.6, 2.7, and 2.8 show that over
the entire pressure range of the measurements, the polarizatransition.
by a physical model involving
tion signals can be described
three variables, Ps,
the computed
K'
curves are in
an
d^
It should be noted that
better agreement
21
with measured
33
3.2
20
MEASURfO SIGNAL
— o--C0M/»U7T0
POINTS
297
(iilobors
a.
E
o
I
i
1.0
u
0.3
2
0.4.
0.5
Shock- Induced Polarization Signals
Figure 2.6
of Plexiglas Above Transition Pressure
signals at
low pressures than
at high pressures
where the
ends of the measured signals are more distorted by curvature
and obliquity of the shock front.
2.
Contact El ec t rificat ion
Electrification
of
insulators
oil.
Slow
sliding
conductors
by
experiments conducted by Schnurmann
two metals separated by an insulating
jerks
can proceed by a series of
impact are described in
and Warlow-Davies of
and
22
0\4
Za7
012
Vitoosr^
'COM(»ur£D POINTS
1^
010
kitabari
I 009
a
I
»-
= 006
<r
U kidbarr
o
\
ac<
^e:
Shock-Induced Polarization Signals
Figure 2.7
of Polystyrene Above and Below Transition Pressure
exhibiting two characteristics,
tion.
The first
that of relaxation oscilla-
is a fixed amplitude and the
period determined by
second is a
relaxation time for the building up
of a limiting value. The experiments described the amplitude
of the
jerJcs was observed
to decrease when the dielectric
a
breakdown strength of
diminished, or when,
of
sliding
was
electrification show
a
lubricant was
with the same lubricant,
the velocity
the material used as
increased.
Observations
that an electrostatic
23
of
contact
force resisting
30
10
20
o
O-PtEVlGLAS
I
a -polysty<jcne
<
4
O
a.
I
u
iGO
;to
cc-o
300
PRCSSURE - Xbor
Shock-Indaced Polarization Signals of Polystyrene
and Plexiglas as a Function of Shock Pressure
Figure 2-8
sliding must exist if the boundary layer consists of dielecand this electrostatic compo-
tric or semiconducting matter
nent is an appreciable part of the force of sliding friction
[Ref. 8].
Active fault
lines move by
relaxation oscillations
and can be described by the nonlinear stick-slip motion that
is generated
than the
stress,
when the
static force
of friction
is larger
kinetic frictional value. During the increasing
the motion of the fault proceeds uniformly by creep
24
insulating
converts the
stress
the large
and
rock to
a
conductor or semiconductor. On reaching the brittle fracture
stress,
the material unloads and the stress is reduced and
results in
shock wave
retreating
a
shock vave has
The
with free electrons
conductor ahead of it
a
material.
in the
insulator conduction band behind the
that can fall into the
retreating shock front. The charges can accumulate by succesive creep-slip motions to cause the electronic charge to
produce an electrical field beyond the breakdown value in
an arc with the attendant
causing
the air or rock surface,
radio emissions.
Fracture of Quartz-bearing Rocks
3-
geological research
The
believed
Laboratory were
Scientific
group
the Los
at
to
Alamos
first
be the
to
detect radio frequencies when guartz-bearing rocks and other
hard piezoelectric
experiments.
Using
placed about
5
to
a
standard RF coil with
50 CM
from the
recorder it was found that small
transients with
shown
produce
single crystals
maline
in
a
fractured in
materials were
Figure 2-9
Rock
.
ferrite core
a
sample and
transient
a
cracks in quartz and tour-
exponentially decaying
constant of about
time
laboratory
10~5
samples were
seconds as
fractured
applying uniaxial load between two parallel steel
by pressing a small
sample.
RF
by
anvils or
steel ball against a flat surface of the
The signal developed on the coil was amplified by a
wideband amplifier and fed into one channel of the transient
recorder.
All measurements were performed under
ambient
conditions. Also the samples were not treated in any way
except for cutting or coring [Eef. 9].
The fact that the fracture related EM
observed
only in
guartz-bearing
quartz
rocks
(frictional electricity)
and
rules
emission was
tourmaline crystals
out
triboelectric
and
in
effects
as the source of this emission and
indicates that it is related to piezoelectricity.
25
The most
o
to
>-
q:
t-
a
or
<
a
3
a.
>
<
FREQUENCY (MMj)
Spectral content of fracture-related
Fig. 2.
EM enisKion from (mean grain size shown in
a. coarse-yrain granite (15 mn)
b.
brackets):
;
granodiorite (2 ran); c. fme-prain cranite
(from Westerly, R. I., 0.5 mm); d. fine-grain
quartzite (0.1 rcr.) e. a 2 x 1 x 0.5 cm
toui-maline single crystal cracked by applying
The curves show
pressure along the c axis.
averaRCS of 10 spectra for each sample.
;
Figure 2.9
Spectral Content of Fracture-Belated EM Emission
26
for this emission
probable mechanism
the piezoelectric
occurs as shown in Figure
hypothesis is supported
of the
since
regardless
experiments)
and
independent of load,
distribution within the
higher than the average
(much
the ampli-
the local stress exceeds a
sample fracture occurs only when
specific value
This
.
signal is
the stress
of
2.9
by the observation that
resulting RF
drop in
release of
field accompanying the sudden
stress when fracture
tude
is the rapid
therefore drop
in stress
stress in the
is essentially
independent of load.
compares the spectral content
Figure 2.10
of frac-
several samples,
obtained by
averaging 10 different spectra for each sample.
It is clear
ture related EM emission from
that a shift to higher frequency occurs as the grain size of
quart z- bearing rocks decrease.
Detection
and
analysis
signals was very difficult at
With regard to
RF emissions outside of
substantial increase
fracture-related
RF
distances greater than 50 cm.
conclusions could be made from
a
of
the laboratory,
no
the study concerning whether
in the size of
the fracture results
corresponding increase in the emitted RF energy,
thereby permitting detection at larger distances.
also in a
4.
Porous Rock
Electrokinet ic
phenomera
induced by
ground
water
flow associated with
earthquakes are believed to provide a
possible means of earthquake prediction.
Detectable variations of earth currents, electric potential and geomagnetic
field may be caused by diffusion of fluid into
a dilatant
(wider or larger) focal region- The electrokinetic phenomena
controlled by the processes of mineralized water migration
through microcapillary rock channels are an
source of charge separation
and
relaxation.
27
independent
The charge
S M**C
2
11
(«c
i^My>v-^
500u»tc
Fig. 1.
Examples of EM transients acco~panyinf,
fracture of piezoelectric spcci.-ier..s (tl'.e digital sampling interval is given in brackets): a.
small crack in a quartz single crystal (50 ns);
b. cr^ll crack in a tourmaline single crystal
(10 ns); c. failure of a specinen of fine grain
sandstone (200 ns) d. failure of a qu-irtzite
specinen, showing also the accoinpanyin?; crop
load (2C00 ns, see text).
Note the different
time scale for each transient.
;
m
Figure 2.10
Exao] lies of EH Transients Accompanying
Fracture oj Piezoelectric Specimens
;
28
separation is due
to the selective absorbtion
the solutions on the fracture
of ions from
surfaces and the formation of
double electric layers.
-Solid-Liquid Interface
Electric Ooubte Layer
Figure 2. 1 1
Electric Double Layer and
Velocity Profile in a Capillary
The double
layer is made
firmly held to
the solid,
up of a
layer of ions
and a more
which are
diffuse mobile layer
extending into the liquid phase- The resultant charge of the
diffuse layer is equal in magnitude but of opposite sign to
that
of the firmly held
A
layer.
simplified schematic
diagram of the structure of the double layer and profiles of
the electric potential and velocity of liquid in a capillary
shown in Figure 2.11 . Because of the electrical charges,
there is a difference of electrical potential between the
is
29
solid-liquid interface and the bulk
of
the liquid.
This is
When
called the electrokinetic potential or zeta potential.
electromotive force
(EMF)
is applied to an electric
an
double layer, there will be a displacement of the oppositely
If the solid cannot
charged layers relative to one another.
double layer also is unable to
move,
the fixed part of the
move;
the application of an EMP
will result in movement of
the diffuse layered ions and liquid [Ref.
10].
Applied EMF and viscous force is given by:
j
=
ie"^
where
j
//|
)
grad
(2.1)
is the fluid flow flux
the viscosity
of the
through a capillary
(volume)
and per unit area,
per unit time
is
E
"^
fluid,
is H the zeta potential,
and
^
is the
dielectric
constant of the fluid.
The streaming potential
difference when
potential
(E)
liquid
a
is
the production of a
is forced
through
a
porous medium or a capillary tube. It is given by
grad
where
E = -
and
(^^
P
/PjCT)
grad
(2.2)
E
are the electrical conductivity and the pres-
sure of the fluid,
respectively.
Since all electrokinetic processes are irreversible,
thermodynamics of an
irreversible process can be
applied.
most general relations between the electric
The
current i and the fluid flow j, and the forces of grad E and
the
grad
P
are
-i = 111
grad
E
+
L12
grad
P
(2.3)
-j = L21
grad E
+
L22
grad P
(2.4)
30
where Lij are constants. Explicit expressions of Lij's for
a
capillary tube are:
Cr
L11 =
(2.5)
L12 = 121 = L22 = k*
(f^
"^
/A
(2.6)
{2.1)
/f\
where k* is the specific permeatility of the capillary tube.
For porous media k is given by
k
= ^k*
where
(2.8)
is the porosity of the porous media.. The basic equa-
<^
tions of fluid flow in the porous medium are
-I =
<)>
-J = -
cr gr ad E -
{(^e
^
/
)
{^C^/f)
grad E
grad P
)
(k /.I
+
)
(2.9)
grad
P
that the electrical conductivity
It is assumed
substance is much smaller than ^cT
(2. 10)
of a matrix
.
The maximum magnitude of the current density associ-
ated with the water flow is obtained by setting grad
-I =
{(^6^ /
1)
)
grad P
E
=
;
(2. 11)
This shows the electric current
is proportional to the pore
pressure gradient (the pore pressure is assumed to change by
10 -
1000 bars
following the
in the dilatant
earthquake)
.
If
focal region
the mean
preceding or
gradient of
pore
pressure is approximated to be
grad
P =
1
'^
100 bar/Km
(2.12)
31
the electric current induced is
= 0.7 X
lli
(10^ -
A/m2
(2.13)
flow exists,
of detecting the water
If the capability
direction
10^)
of water
flow can
te
consequently
and
known,
the
The earth current
earthquake.
predict the epicenter of the
due
to electrokinetic effects yields variations of the
geomagnetic field on the surface.
horizontal
a
in
the current flows uniformly
If
the magnetic field caused by
circular cylinder of radius R,
the current is simply obtained by Biot and Savart's law,
H =
/ 2Ttr)
(I
•
TfrRS
(2. 14)
the distance from the center of
where r is
the cylinder to
the point at which the magnetic field is observed.
r
= R = L / 2
If
(2. 15)
then the field strength becomes
H
= 0.2
^
200
(2. 16)
y
where the field strength is independent
of R and L for this
Interestingly enough most observed magnitudes of magnetic anomalies associated with earthquakes are
assumed geometry.
almost all in the range estimated above.
C.
SODBCES OF ELECTBCMAGNETIC lEECORSOR EVENTS
'^
•
Electric
At
F
ie lds and Atmcspheric Elect ric Potential
the earthquake
moment and
just
before it
the
effects due to disturbances of natural electromagnetic earth
32
field
were observed
(NEMEF)
These
repeatedly.
effects
quasi-stationary disturbances of the atmospheric
at distances up to
electric potential (AEP) up to 1000 V/m,
some hundred kilometers from the epicenter. In the course of
observations the AEP perturbations were noted some
field
involve
or two hours
earthquake moment within one
hours before the
period [Bef . 11].
AEP disturbances
charged surface
estimated for the
are:
^
=
AEf
C-/
2
(2.17)
6k6^
where
Cr =
q
N
(2.18)
§
Under the assumptions that the linear charge density
q,
surface density N, and the dislocation path length
are:
q
=
N =
10-1* - 10-10
109
- 10*1
AEP disturbances
c/m
(2.19)
m2
of
the
(2. 20)
100 -
V/m can be expected
1000
in the
final stage of the earthquake precursor period.
2.
Magnetic Fields and Aniital Behayoir
The amplitude and time duration
of the most charac-
teristic time varying geomagnetic
disturbances occurring at
the earth's surface are listed in
Table
presenting the same data is in
total magnetic
2.12 [Bef.
12],
plotted as
a
field.
Such a
a
.
Another way of
plot of the spectrum of the
spectrum is shown
where skin depth
function of frequency
33
I
(Z =
f
500
in Figure
(c-f)"^'^)
and conductivity
cr
.
is
It
TABLE I
Time Variations in the Geomagnetic Field
Typical
Magnitude
Description of
Phenomena
Characteristic
Period
(gamma)
(sees)
10*2
Sub-audio frequency
fluctuations
Micro-pulsations
10°
0.0
sec~^
0.1
Giant pulsations
Sudden commencements
102
1
10
20
Crochets
20
Bay Phenomena
100
10*
Diurnal variation
30
106
Storm Time effects
10
Twenty-faeven day
recurrence effects
8
Annual variation
10^
10
Solar cycle secular
variations
is evident that
semi-diurnal,
sun)
the most dominant signals
25 year"*
are the diurnal,
the rotation of the
twenty-seven day (due to
and high frequency changes that are,
in general,
nons-
tationary, that is net frequency stable. This spectrum could
represent also a crude measure
of discrimination limits for
detection by animals. It is, of course, possible that
animals can somehow understand these variations well enough
to
detect changes
well
Schemes for doing this are
below
the background
variations.
necessary also for field experi-
ments presently in operation on the San Andreas Fault where
information on the large scale of these distrubances is used
to
enhance detection
capability for
34
local magnetic
field
SKIN DEPTH (km)
^
u
o
>-
o
UJ
IS
s
a
S
(yna^
Figure 2.12
^-mns)
asMOd
Spectrum of the Geomagnetic Field
35
If animals can detect effects occur-
variations [Ref- 13].
an earthquake,
ring days before
systematic charge
effects involve
spectrum over
a
possible that these
it is
which would
enhance the
critical frequency range.
There are a number of physical mechanisms that might
be
considered
sources
as
earthquake-related
for
animal
TABLE II
Order of Magnitude Estimates of the Various Possible
Physical Hechanisms for Earthquake-Related Field
Anomalies
L.
MAGNETO HYDRODYNAMIC
^^XNtvcEt, ~ Bo£r>v
(cr* =
conductivity,
D = length scale)
/•V
d
^=
B.
- 0.1
gamma
x
10"'',
^
v =
velocity,
TELLURIC CURRENTS
^^XNt^'cec^' cr^ / ^ ~ 0.01 gamma
(cr = conductivity, E = gecelectric field,
D = depth of current flow)
C.
PIEZO MAGNETIC EFFECT
AB
= 40 S I -
gamma
stress change, 1= magnetization)
(S =
D.
1
LOCALIZED CRACKS AND FRACTURES
AB
behavior.
=
?
Table
II lists several
order of magnitude estimates of
of these
together with
their amplitudes.
It would
appear that for these effects at least,
it is difficult to
generate source amplitudes of more than a few tens of
gammas.
The last
process
suggested which involves this
36
concerns
effects of
the
relatively unkno^jn
local surface
electrical
crac]<s and
possit3le exception to this.
37
and
magnetic
fractures might
be
a
III. ELECTBOHAGHETIC PROPOGATICN CRITEEIA POR EARTH^OAKES
fault line becomes
A geological
and electromagnetic
thermal
relative to
plates move
fault
shown
line,
Figure 3.1
in
than in the
source
radiations
each ether.
compressive stress and the
greater here
a
is
of acoustic,
when the
tectonic
The region
near the
in
both shear
and
relative permittivity, (c/--] ' ^^
unstressed region having permit-
tivity ^^ . The fault width of 2Yo is the region of uniform
stress and the regions beyond this point are unstressed,
When fault line motion commences,
causing
current
flow
across
voltage is generated
interface
an
The interface
different materials-
a
can be
between
two
formed by
the
following means:
a.
Forces near 100 Kbars can convert the insulating rock
to a semiconductor
(or conductor)
in solid form [Ref,
14] so
that charges can flow at the insulating-semiconductor inter-
also the voltage generating
the work functions differ in the two media.
face which
is
b. Forces above
produce
a
100
Kbars may cause plastic rock flew to
liquid-solid interface
work functions
mechanism since
[Ref.
causing current flow
15] with
and charge
differing
storage in
the solid portion having insulating properties.
c.
Shock waves can distort the dipole fields in the rock
to produce a
polarization in the material
and increase the
permittivity by nearly an order of magnitude [Ref. 16].
The
transient charge is stored on the lower permittivity regions
and accumulates with subsequent shocks.
38
E
FXELt
XV
Ari^
^.
\
Su/?FAc£
>
1
>
TO
fftuLT
(ZAjcrtEtJTj
Figure 3.1
Cross-Section of Earthquake Fault Line
39
THE ELECTRIC FIELD EQOATIONS
A.
The
source of
electromagnetic
the
radiations is
accumulated electrons that were
discharge of the
shock waves or increasing pressures on the fault.
uous corona discharge
can occur from the
formed by
A
contin-
nonuniform fields
the rock or a sudden discharge
that form on sharp points of
exceeds the breakdown strength of
can result when the field
the rocks in uniform or nonuniform fields.
If the breakdown
radio waves in the megahertz region
occurs in microseconds,
are radiated.
the
This increasing pressure
at
a
fault
can be
related to the strength and frequency spectrum of radiations
which can be correlated to the acoustic data presently being
recorded at the earthquake sites.
hypocenter,
shovin in
The fault
belov the surface
and is the source
radiation, shown as a point source.
ably elliptically polarized
depicted for clarity.
Figure 3.1
is usually
of the electromagnetic
The emissions are prob-
but only the parallel
Figure 3.2 shows the
field is
electric field
volts/meter in the incident X-Y plane and the
magnetic field vector,
H in amperes/meter,
normal to the
incident plane. The energy propagates on the transverse mode
vector,
(TEM)
E in
and the Poynting vector,
P in
watts/sguare meter,
on
the X axis.
The fault
location of
epicenter is shown in
the hypocenter at
Figure 3.1 and
the fault surface
is the
where the
electromagnetic radiations are a maximum.
The electromagnetic radiaticns can be obtained from the
retarded potential method but the objective is to only indicate the attenuation of the field with distance which can be
found from the Maxwellian equations:
VxH=CrE+6aE/at
(3.1)
V
(3.2)
X
E =
-/^^H / ^t
40
/N
X
-^y
Vbt-Ts
Figure 3.2
/merBt
Electromagnet Yectors at Fault Hypocenter
41
The parallel
vector mode,
E
where the
E
field is in the
incident plane, can tie obtained from the vector equations to
obtain the scalar differential equations:
aHz / ^x =
-
3Ey /
-
=
<3t
/at
e c?Ey
crEy
(3.3)
^^Hz /^t
(3.4)
Let the arc discharge have the spectrum
Oj = 2 T'
If E = Eo«
f-
/
3iEy
^x
-
e"^
,
^2 Ey (x,t)
f1
<
f < f2 and
the scalar field reduces to:
=
(3.5)
where
Y
.2
-j^^"
=
•
Assume
^ p6:
(3.6)
scalar solution with E
a
=
Eo« e
•
e
"^'^
This gives the phase shift and attenuation:
^
=
Kjjto)'^
= j(//^u)'5
(J
0-/^6 -1)
(3.7)
{1-jcr/,.,^),5
(3.8)
= j(/^) 'S(1-jcr/ 2a>6+ ...)
-
j(//^)
-
j(^^)'5
'5{l-j cr/ 2^e)
+
(3.9)
(3.10)
cr'/2 ^fc
(3-11)
The radiating field has the form:
,
E = Eo e
i
-^
'^e
..,
-^
^
,
(3.12)
e-"
42
SKIN DEPTH AND RADIATED FBECOENCIES
B-
Figure
In
3.1,
fault
the
line
region which
has
a
constant compressive and shear stress is region one, and the
designated region
away from fault line,
unstressed region,
and conductivities
permittivities
The
two.
in
the
two
regions are:
D7=Zri-
(3-14)
^;,=
^^^^^
(3.15)
ui
(3.16)
ir^=
Where
£,^
permittivity of free space
is the
are the relative permittivities.
and 6r
The skin depth, %,
and^^
is the
distance where the radiation is reduced by the factor of 1/e
from the initial value.
The skin depth can be obtained from
equations:
% =
2cjG^
/c- = 2^6f6/cr;
(3.17)
Using:
f =
SxlO'^ Hz,
6^ = 25.0,
^
e^=
S
Since the
skin
depth is
lOOTx
=
=
106
Hz,
/j;
=10-5^
(3. 18)
8.8 x10"i2
(3.19)
13.9 Km
(3.20)
San Andreas fault is
less than
this value
43
about
15 Km
deep,
which indicates
the
that
under the worst case of the hypccenter at the extreme depth,
the electrical field is reduced slightly more than 1/e,
but
easily measured at the epicenter.
The values
and conductivity
of permittivity
frequency and the
upper limit of propogating
be estimated from
the graph by Kraus
Using the worst case of urban
15 Km
frequency can
and Carver [Bef-
17].
ground at 100 megahertz,
the
and if the hypocenter is halfway
skin depth is about 0.8 Km
down the
vary with
the attenuation is
tectonic plates,
This limits the radiation to the range
X
5
10^ < f <
e"^.^.
lO^ Hz.
THE PEOPOGATION CBITEEION
C.
source at the hypocenter
Figure 3.1 shows the radiation
and the
parallel to
electric field,
the incident
plane,
makes an incident angle 9i with the normal to the fault. The
reflected
stressed
wave is
angle
at an
region has
a
width
Or with
and
2Yo
regions are insulating and lossless,
^r
the normal.
>
^r
•
^f
The
"tiie
the reflection coeffi-
cient is given by:
f*= Er / Ei
(3.21)
rr
The reflected wave,
when the
(3.22)
1
radical in the
Er,
equals the incident wave,
numerator vanishes.
Ei,
The critical
value of the incident angle for complete reflection is:
sin Gic = (^2/6,)
This
relation
'5
=
(3.23)
(6;3/^^^),5
obtains
for
either
perpendicular
or
parallel polarization of the electric field and for all <c >
^ic.
Using
^r ~ 25.0 for the stressed region and 6 r^ = 5.0
for
the unstressed portion,
gives
Oi = sin-i (0.2)
.5
= sin
"MO-
Since the critical angle is
^5)
-'"
26
small,
(3.24)
the majority of the
radio emissions are reflected from the unstressed region for
hypocenters deep in the fault.
emission may account for the
This wide region
abnormal human
of radio
and
animal
behavior distant from the fault line but within the stressed
fault region.
epicenter
When the
exceeds
confirms the
field in the
30 Kv/cm
,
reports of lightning
earthquakes.
45
the
air space
air breaks
before and
above the
down
and
during large
IV,
A-
DESCRIPTION OF EESEARCH
DESIGN GOALS
One of the most important problems associated with using
electromagnetic radiation as a precursor of earth quakes is
select the point of observation.
Placement of the
how to
system far from industrial areas, but near potential earthquake activity was
potential site
desired.
A
preliminary field
locations was conducted under
survey of
the direction
Geological
Survey. Site location along the San Andreas fault was chosen
of the United States Department of the Interior,
historically and recently
it being known
because of
The chcsen observation site is 1000
active earthquake area.
feet from the San Andreas Rift
23.5'
and 36° 45.5'
W
as an
N
Zone
which is
located at 121°
three miles east of San.
(fault)
Juan Bautista and seven miles scuth of Hollister.
It became very important to
the system
cies for
have any
United States identified
the Western
project
interference from
The Army Frequency Coordinator for
so not to
transmitted radio waves.
secure spot window frequen-
bands
VHF
frequencies,
(38.45 MHz
with a 50 KHz
and
and assigned
150.75
bandwidth,
Mhz)
to this
.
These
have been allocated
with exclusive use for a period of one year.
For observation of signal intensity and direction in the
VHF range,
a
sjstem was positioned with its
data recording
directional sensors (antennas)
fault as shown in Figure 4.1
detect both horizontally and
looking both up and down the
.
vertically polarized emissions
at both reserved frequencies.
(two)
are erected
The antennas (eight Yagi's)
The omnidirectional antennas
for detection at both
with vertical polarization.
connected to a detector
frequencies,
Each of the ten
antennas are
(communications receiver)
46
and
A,B,D, and E have 2 antennas each.
One is vertically
polarized and the other is horizontally polarized.
There are two omni antennas vertically polarized at C.
Figure 4.1
Position of Antennas Along the San Andreas Fault
47
I\N\
Tx.\sA^^
1
Figure 4.2
Block Diagram cf Data Reception Systea
43
Low cost
modularized receivers were procured
and modi-
assigned frequencies. The output of
noise level
the receiver
is offset to nullify any ambient
collect any
and is fed into slow speed chart recorder to
detected emissions as a function of time. A block diagram of
fied to receive at the
is illustrated in Figure
the measurement system
4.2
.
The
noise measurement system can operate from 12 volt DC storage
batteries or
a
power supply.
Electromagnetic
batteries have to be replaced periodically.
emission data collected through this
to
seismic
guake
provided
data
and storage
The chart paper
system will be related
the
by
Onited
States
Geological Survey Office, Palo Alto, Ca.
B.
SYSTEM COMPONENTS
gec eiv ers
1 .
The VHF Converter Module is
convert
the
specific
frequency to
converter is supplied with
(IF)
transformer for
a
designed to amplify and
the
HF
range.
10.7 MHz intermediate frequency
the mixer output circuit-
output circuit consists of
a
The
slug tuned coil,
The mixer
a
capacitive
voltage divider, and an RCA jack to provide a 50 ohm output.
Figures 4.3,4.4 show schematic diagrams of the VHF Converter
Modules.
The IF Audio Module comprises a highly sensitive and
selective IF amplifier,
squelch system for use
audio amplifier,
with the converter to
make a
communications receiver.
The selectivity of the unit
tailored to operate in the noise measurement system.
unit has automatic gain control (AGC)
of both IF and
AM detector,
with the EF AGC being delayed f cr best response.
log detector
provides drive
fcr the
Eustrak recorder) output.
49
"S" meter
and
VHF
was
The
EF,
An integral
(signal to
u.
-^yi>
t3.
Q
41-
-^-\w
'^
^^
**.
-'SN
SI
'Mnf-t>
Vi
Figure 4.3
VHP Converter Schematic for 38.45 MHz
50
2s
U
+
^
-1^
41-
[-?><n,
lJ:s^
-nnm_^
^^-i>
^
Ml-
^)-^
'^Ob^iA^
<
'-iKu^
—\)—^-l>
I
II
L
©
^UJUL/
^aM>
-J
Figure 4,4
7HF Converter Schematic for 150.75 MHz
51
amplified
three
fcy
converted to
signal is
10.7 MHz
The
stages.
transistors biased from an
455 KHz
Each stage consists
and
of several
integral zener regulated source.
coupled three stage IF filter provides selecFigure 4.5
tivity against adjacent channel interference.
shows a schematic diagram of the IF Audio Module.
Appendix
An optimally
A
Table IV and Table
contains
1,
signal input voltage at both
output voltages for a given RF
VHF assigned
receiver
S-meter
2
•
frequencies.
were
determined
receiver signal
data of
output capabilities
The
from
this
information
of the
on
the
(output signal to the chart recorder).
Recorders
The Rustrak DC recorder prints through the impinging
action
of its
stylus
pressure-sensitive
series of
driven ty
chart
paper.
dots appearing
as a
speed varies with motor speed.
depend on
the ratio of
couples the paper
the
chopper bar
against
presentation is a
continuous line.
Writing
Its
Chart speed and trace density
the interchangeable gear
drive to the motor.
chart speed and trace density.
Table
Figure 4.6 is
box which
III shows the
schematic of
a
the Model 2146 dual trace chart recorder and Figure 4.7 is a
schematic of the same model with a signal processor included
as shown. Both versions of Model 2146 had to be modified for
single channel use.
The single channel modification
involved bypassing a switch
(S-2)
by putting a small jumper
wire between the normally closed (N/C)
(N/0)
terminals
recorders have
as shown
in Figure
and the normally open
4.8
.
Three of
signal processors to desensitize
input to one volt per
division.
demodified by
rearranging the
the Jones plug making non-bias
(S-MOD)
the
the signal
The desensitizer board was
bias stepper
connections at
stepper connections as shown
in Figure 4.9
There were no modifications necessary for
.
the Model 388 chart recorder.
52
i
iTi^^
go
Q-~
—
-->
ih-^
:s^
I
^^.
I
T
-xD-y-t>
41—
u.
3
K>
-ff-
-1
IhqIt-J
J
>o
Figure 4.5
IF Audio Module Schematic
53
TABLE III
Chart Speed and Trace Density
Model Drive Writing
Motor Speed
2
6
30:1
10;
1
Gear Train No.
Gear Ratio
(RPM)
2194
1
1
4
388
2
1
2
strike/
seconds
strike/
seconds
Chart Speed
76 mm/hr Chart Speed
252 hrs
2
Paper Duration
Chart Speed
Chart Speed
Paper Duration
in/hr
50 mm/hr
378 hrs
Trace Density
3.
in/hr
3
900
300
Strikes/Inch
Interf ace Amplifiers
By design the receiver output voltages were approxi-
mately between 280 mV to 320 m7 with RF inputs from approximately 10 uV to 100 uV, Ideally this 40 mV range would drive
the recorder from zero to full
amp voltage offset
scale,
only 80 % scale
but because of an op
readings were achieved.
interface
amplifier was designed to set full scale
minimum and maximum needle movement in the chart recorder.
Calibration of the meter movement was accomplished by variable resistor settings as shown in the schematic of Figure
An
4.10
.
4
.
Timer
To compare
seismological disturbance data
with the
noise measurement site recordings accurate time needed to be
54
Figure 4.6
Bastrak Mcdel 2146 Schematic
55
Figure 4-7
Rustrak Model 2146 with Signal Processor Schematic
56
si^^xxc-H
[jNr^^oc^TFrE:b.
f-TO
^To TanjeS.
PXAi
&fi
vj^I-'/O
•-
.
WH//«£0-mx
— TO
i±
t*±
«
i
SW
N/C
^H/fLe^
n/o
j
t^fc
4^-^
COG
AS PAPE^
N/
/yXohZFTEh
\
'^yrrrc'r\
r T^ SW
4
— TO Toues
8^4.
Ptat i*4-
wH/«ECi
v^H/»t£^-*-ei.>c
(X
T^O GrAL'/O
Figure
t».8
Single Channel Modificatioa (S-MOD)
57
t/?/^i^
dm^ sra?o&Q^
XJJPor
I
II5^
'"^
•••.
*\^
y
,u
—
^
-•
y
>-
^!.'^
r-i
>•'
r-\
i_
"1 ""
I
-1^
Figure 4.9
Bias Stepper Demodification
58
CO
_!'
Figure 4.10
Interface Amplifier with Voltage Generator
59
Because of
indicated on the chart paper.
ultra-low dissipation and operation
a
CMOS
21
stage
conjunction with
counters (RCA
counter timer
CMOS
8
CD40103B)
(BCA
requirement for
a
using a battery source,
CD4045A)
was
used in
stage presettable
synchronous down
CMOS dual
J-K master-slave
and a
flip-flop (ECA CDa027B) to obtain the time. The 2.097152 MHz
crystal establishes the one second clock pulse as shown in
Figure 4.11
.
are set using
The time and the length of the pulse duration
8-bit down counters.
When
the timer pulses,
fifteen minute
pulse will last for six seconds. A one hour pulse will last
twenty-four hour pulse will last
for twelve seconds and a
Time can be initialized as necessary
for eighteen seconds.
the length of the pulse indicates the time.
by the reset switch.
60
A
Figure 4.11
Time Tick Generator
61
V.
PEHFORHANCE OF SYSTEM
The informational parameter of
is variations in the level
a
possible seismic event
of the electromagnetic radiation
envelope or in the number of radiation impulses whose ampliexceeds a
tude
noise
discrimination threshold.
pre-chosen
measurement system
range of 0.1 uV to 100 uV
is
designed
EF input.
with a
sensitivity
The system was given a
the roof of Spanagel Hall
"shakedown test" on
The
at the Naval
Postgraduate School to see if it was sensitive to variations
in the level of electromagnetic radiation based on a 24 hour
period.
Along the San Andreas Fault,
it is expected that varia-
tions in signal level will occur due to seasonal changes.
during autumn and winter the highest signal
For instance,
level
summer,
the 2U
falls into
the
sunless part
the day.
Spring,
autumn have two maxima during
and the beginning of
hour period,
of
the nightly
and the
post-noon ones.
Figures 5.1, 5.2,
and 5.5 are recordings which
5.3,
5.4,
show the noise levels over a 24 hour period.
62
I
I
^f;
;— --r-/
.1—
i
w>
,
Ifh,
;
!
:t:\/
-9^
PS"
>
\
I
i
r
T
I
h
y-
:
1
I
;
1
I
""
!
I
T
I
I
I
l -!-;
I
"rr'T-
15--:q
<
I
I
1;^
I
!
j
I
^^
M
)M:
)i
41
I
s.-:^
,_..-.^
I
4- I r
i---^--^
i
I
!
I
!
I
I
n:
^^
!'
i
c
1
!
I
I
!
U-.
I
\
til
ill
I
I
5^
-T-T-p-rTl
1
H
!
!
I
I
R
>
\
»t
I
—
n
->
I
i
Xr
T—
•I
t-
A
!
i
i"
'i
-If-
r
t
I
I
-r—ti
-r-
!
^
:
r^
-J,
:t
Figure 5-1
i
V
n
-f-9'c
u
"Y"
t
I
!
I
Signal Level Data from Noise Measurement System
63
Figure 5.2
Signal Level Data from Noise Measureaent System
64
1
1
'
!
1
!
!
n^:
1
•r
H
i
1
!
1
!
1
1
Figure 5.3
Signal Level Data from Noise Measurement System
65
"l ^1-
V
^
._r^
—p-^T-:
M
'
.
'
'
'I-
'I
cy
—•
i~~:
^%i
^
1^
'
-
I
'
I
!
I
J
I
:
'
I
r:
I
o
i
:-:-..:
^
'
— 1--or
I
!
I
4 --r-
:r^
I
I
.;
---]
t
-Tl
1
.L:.4..-.i.^-
!
•!
I
I
:
-I
i
-^-r
•>
;
o
I
I.'
I
-1
d
^
"^
i
I
^
I
^
I
I
T
«.
--4-
t~-r
— .r
I
I
I
>
%
-y-V
..-
,~>i
._^
V
N
O
I
J,
...
^
r
i
I
<-
Figure 5.4
'^
5
"VM
I
i
-
—-,-
!-"
-r-i-ri'-'' -T'T-^i
_u_j_4-'— -1-4.-1-
^
n
n
Signal Level Data from Noise Measurement System
66
Figure 5.5
Signal Level Data from Noise Measurement System
67
VI.
A.
CONCLDSIONS AND BECQMflENDATIQMS
CONCIOSIONS
The design,
construction,
and testing of an
RF noise
measurement and recording
system in the 30 MHz
range has been described.
Test results show that background
noise levels
can be
received and
microvolts
volts.
Theory has
to
recorded from
and 150 MHz
tenths of
shown that anomalous elec-
radiation levels from earthquakes can occur.
only detect the
The noise measurement system data will not
presence of increased background noise levels at the desigtromagnetic
nated frequencies, but it may also give an indication of the
direction of reception relative to the San Andreas Fault due
to the polarization of the antennas.
Besides
physically
erecting
fault, the most difficult problem
along the
was designing a receiver/
the
antennas
recorder system that would be sensitive to slight changes in
background noise level at frequencies near those of citizen
band and amateur radio operators.
The signal output of the
receiver was sent through an interface amplifier and the
chart recorders modified to accomplish thisAppendix B presents electromagnetic emissions and other
observations
possibly related
to earthquake
precusor
activity.
Measurements of electromagnetic radiation from
earthquakes
were detected
by changes
in background
noise
levels, but in the very low, low, and high frequency ranges.
The results
radiation
of this
research suggest
measurements
has
potential
prediction tool.
68
that electromagnetic
as
an
earthquake
B.
EICOMMENDATIONS
acquired from
Data
should be
noise
taken for
the
noise measurement
V EF
system
observing background
Since seismological data can be
at least
level variatiocs.
a
year
acquired from the Geological Survey Office, any significant
earthquake in the area of the noise measurement site should
be immediately
compared with the recorded
data.
Otherwise
periodic basis.
studies were presented
data can be examined on
a
concerning the
mechanism by which rocks emit radiowave energy when they are
crushed,
further investigation is needed in this area and
Although several
the following:
1.
The relation between the intensity of the background
noise
in the
epicenter.
The
VHF
range and
antennas of
location of the
the noise measurement
the
system are looking up and down the fault which makes
location probable.
2-
The relation between the
VHF radio
3.
intensity of the precursor
noise and the earthquake's
magnitude and
depth of focus.
The data obtained may show similar
variations in background noise levels at 38 MHz or
150 MHz or both for earthquakes of similar magnitude
and depth of focus,
Long term
data collection is needed
obtain
to
through order-of-magnitude calculations,
of VHF radio noise radiated
69
the amount
in these events.
APPENDIX A
EECEIVEB SENSITIVITY DATA AT VHF FBEQDENCIES
70
TABLE 17
Frequency 3 8.45 MHz
BF Input in uV ana Signal Output in mV
RF
S
RF
S
RF
S
RF-
S
IN
OUT
IN
OUT
IN
OUT
IN
OUT
0.0
0.268
1.8
0.227
3
0.306
300
0.327
0.
1
0.220
2.0
0.228
40
0.311
350
0.328
0.2
0.220
2.5
0.233
50
0.315
400
0.329
0.3
0.220
3.0
0.237
60
0.317
450
0.330
0.4
0.221
3.5
0.241
70
0.318
500
0.331
0.5
0.221
4.0
0.246
80
0.319
600
0.332
0.6
0.221
4.5
0.249
90
0.320
700
0.333
0.7
0.221
5.0
0.253
100
0.320
800
0.333
0.8
0.221
6.0
0.262
120
0.321
900
0.333
0.9
0. 221
7.0
0.267
140
0.321
1
.0
mV 0.334
1.0
0.222
8.0
0.271
160
0.322
1
.4
mV 0.334
.2
0.223
9.0
0.275
180
0.323
1
.6
mV 0.334
1.4
0.224
10
0.279
200
0.323
2
.0 mV
0.334
1.6
0.225
20
0.296
250
0.326
MAX
0.335
1
71
TABLE 7
Frequency 150.75 MHz
HF Input in a7 ana Signal Output in mV
RF
S
RF
S
RF
S
RF-
S
IN
OUT
IN
OUT
IN
OUT
IN
OUT
0.0
0.29
1
.8
0.296
30
0.322
300
0.342
0.
1
0.226
2.0
0.298
40
0.324
350
0.344
0.2
0.237
2.5
0.304
50
0.326
400
0.345
0.3
0.246
3.0
0.307
60
0.327
450
0.346
0.4
0.255
3.5
0.310
70
0.329
500
0.347
0.5
0.263
4.0
0.311
80
0,330
600
0.348
0.6
0.269
4.5
0.312
90
0.322
700
0.349
0.7
C.274
5.0
0.313
100
0.322
800
0.350
0.8
0.279
6.0
0.314
120
0.334
900
0.351
0.9
0.280
7.0
0.315
140
0.335
1
.0
mV
0.352
.0
0.284
8.0
0.315
160
0.336
1
.4
mV
0.355
.
6
1
:
'
:
!
•
1.2
0.287
9.0
0.316
180
0.337
1
mV
0.355
1.4
0.290
10
0.317
200
0.338
2.0 mV
0.356
.6
0.293
20
0.319
250
0.340
1
-
MAX
0.358
J
72
APPENDIX B
ELECTBOMAGNETIC EMISSIONS FROM EARTHQUAKES
A.
COALINGA
ionospheric perturbation
An
Coalinga
earthquake of
network
of
California.
These
by
a
northern
and 285 km
as shown in Figure
by a ground-motion-induced acoustic
in Figure B.2,
that
propagated to ionos-
observations appear to be
ionospheric disturbances
earthquake epicenter
in
the
regions of all five
from the epicenter,
were all affected
as shown
detected
at distances between 160
paths,
pheric heights.
B.
links
The ionospheric refraction
(horizontal range)
pulse,
was
1983,
radio
frequency
high
HF propagation
B.I,
May,
2
produced by
that was
to be
[fief.
reported this
the first
close to
an
18].
RUSSIA
Figure
B.3 illustrates
one
example
of the
anomalous
electromagnetic radiation possibly related to
earthquake activity on September 16, 1978. In this case, the
epicenter of earthquake was located in central Iran, and the
receiving equipment was set up in a tunnel 50 m below the
increase in
ground surface at
on-set time
Caucasus,
USSR,
1200
Km
of electromagnetic radiation at
distant.
The
frequencies of
KHz and 1.63 MHz was about 30 minutes before the main
shock with magnitude of 7.4, as shown in
Figure B.3
27
[Ref. 2].
73
Figure B.I
Earthquake Epicenter and HP Path Locations
74
souu3|v;s(ri
!.-
I
«-
^^^'A
s
2C;2 V-_1T^-
f\...
.
^v*Vy
<<^^??v^
"/;
"'
r'-.vir-';'—
''--
>
'v^
•*'--'-2 -^-'-i-i
/J-:/'''
>^'V
Mi
r
Figure B.2
Pseudo 3-D Plot
75
cf
Doppler Disturbance Path
CAUCASUS
SEPTEMBER
II.
H7«
J7KHI
l.llMHzt
^^^^rvn/^u-
H
SISKHzli-
±
28 5
^^=1
SEISMO-h
GRAPHtU:*SZ
is.'Daz
ii:zsz
"•"2
,^
= ,.4
1»:»»2
^
UT
t
Electromagnetic Noise Levels at Caucasus
Figure B-3
C.
JAPAH
On March 31,
Standard Time
1980,
(JST)
,
an earthquake occurred at
The magnitude was
7,
1633 Japan
and the epicenter
was located at 35.40 n and 135-30 E in the Kyoto prefectureThe focus of this earthquake was very deep, at approximately
U80 Km. The distance between the location of the station and
epicenter was around 250 Km.
about half an hour before
As shown in Figure B.4 [Ref. 2],
reception system recorded an
KHz data
the 81
the shock,
76
II
:
IKHl
M^»
SUGAOAIR*
>••?.
>1
1*-
==5=
1'««>
17 00
5f»TMs«tO<a
Electromagnetic Noise Levels at Sugadaira
Figure B.4
anomalous increase in the intensity.
the normal level
approximately
8
by more than
uV.
15
It can also
The amplitude exceeded
dB.
The
normal level was
be seen in Figure B.4 that
the intensity
dropped sharply back, to
exactly at the moment of the shock.
the previous
level
Another event occurred at 1247 JST on January 28,
1981, as
shown in Figure B.5 [Hef, 2].
The location of the epicenter
was in
the western Ibaragi
side of Tokyo^
prefecture on
and the distance between
77
the northeastern
the epicenter and
II.IKHt
li:}«
Figure B.5
g.ir..>i4MI
lANUARY. M.
It Jl
i:.ii
I
l»T
J»flO»
10«
M» JH
IJM
'I *>
"r
H»1
JJT
SO
Electromagnetic Noise Levels at Suginaai
the observation point was approximately 50 Km.
focus was 60 Km and the
magnitude was 5.0.
at 81 KHz increased to about
The depth of
The noise lovel
12 dB above the threshold level
about 45 minutes
Such a feature is
before the main shock.
quite similar to the typical events presented in Figure B.U,
78
LIST OF EEPEEENCES
1.
Friedlander, G.D., "Earthquake Prediction:
Sp ect rum, IEEE, pp. 46-57, September 1973.
2.
Morgounov,
V.A.,
Yoshino,
T.,
and
Measurement
"Experimental
of
Possibly
to
Emissions
Related
Electromagnetic
Japan," Journal
of
Geophysical
Earthquakes
in
78 27=7828';
TU
NoB^, "Pages
Research,
Vol.
87,
SepTemSer 19 82.
Gokhberg,
Tomizawa,
M. B.
A New
Art,"
,
I.,
3-
Review of
"Earthquake Lights:
A
Derr,
J. S. ,
Theories,"
Observations
and
Present
Bull .
Vol.
Seism olo qical Society of America,
63,
pp.
2177=2TH77"T^7 31
4-
"Radio
Stoker,
C. ,
and Meyer,
T.,
Warwick,
J.,
With Rock Fracture:
Possible
Emission Associated
Application to the Great Chilean Earthquake of May 22,
1950," Journal of Geophysical Research, Vol.
No.
87,
E4, AprII"T?F7.
5.
Boore,
"The
Kotion of
the
Ground
D.M.,
Earthquakes," Sci entific American, Vol.
No.
237,
pp.
68-7 8,
in
6,
197T:
6.
ed.,
Proceedinqs of
Dickinson, W.R., and Grantz. A.,
Conference on Geologic Problems of San ^nHreas Faul^
System, ^fanZord Univ.
PuEIicafion, Vol. TT, T^65.
7.
"Shock-Induced Polarization in Plastics.
II.
Experimental Study of Plexiglas and Polystyrene,"
J our nal of Applied Physics, Vol. 36, No. 7, July 1965.
8.
"
Schnurmann,
liarlow-Davies,
The
and
E. ,
E.,
Electrostatic Component of the
Sliding
Force of
Friction," Proceedings,
Physical Society of London,
Vol. 54, Sep Vernier "Tg^l.
9.
Nitsan,
"Electromagnetic Emission Accompanying
U.,
Fracture
of
Quartz-Bearing
Rocks,"
Ge oph y sica l
Research Letters, Vol. 4, No. 8, August 19 77.
10.
Mizutani, H. , Ishido^ T. , Yokokura,
T.,
and Ohnishi,
S,,
"Electrokinetic
Phenomena
Associated
With
Earthquakes," G eop hysical Research Letters,
Vol.
3,
No. 7, July 197^7^
11.
Gokhberg, M.B., Gufeld, I.L.,
and Dobrovolsky,
I. P.
"Sources of Electromagnetic Earthquake Precursors,"
Academy of Scien ces of the USSR,
Schmidt Institute of
PHysics ol fEe~IarTh7~VoTT 75D"7 No. 2, 19 80.
Hauver, G.E.,
79
12.
Bleaney,
B.I. ^
and Bleaney,
B.,
Electricity
Magnetism, p, bl5, Oxford, London, 19 57.
13.
M. ,
Smith,
B. E.,
and Mueller,
Johnston,
R.
"Tectono-magnetic Experiaents and
Observations in
Western U.S.A.," Geomaq. Geoelec.
pp. 28, 85-97 1976.
14.
C.W.,
and
Frank,
Electronic
Drickamer,
H-E. ,
Pressure Chemistry an3
Transitions and the High
VEys ics ol SolIHs, CEapman and Hall, lond'on, 1'973.
15.
Burke, J. J., Shock Haves and the Mexhanical Prope rtie s
of Solids, Syracuse Univ. Press, T5TT.
16.
Allen, F.E., "Shock Induced Polarization in Plastics,"
Journal of Applied Physics, Vol. 36, No.
2111,
7, p.
T^S57
17.
and Carver,
Kraus,
J.D.,
McGraw Hill, p. 402, 1973.
18.
Los Alamos
National Laboratory
Technical Report
83-3120,
Obser vat ions of an Ionospheric Perturbation
Arising from"THe CoaTInqa EartEgualce of"^ ^ay T?g3, by
J. FT TIolcoTr, and U.J. Slnions7 t^E3.
80
K.R.,
and
Electromagnetics,
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Library. Code 0142
Naval Postgraduate School
Monterey, California 93943
2
Richard W. Adler
Code 62
Naval Postgraduate School
Monterey, California 93943
6
Attn:
2-
Dr.
3.
Dr. Stephen Jauregui, Jr.
Code 62JA
Naval Postgraduate School
Monterey, California 93943
4.
Defense Technical Information Center
Cameron Station
Alexandria, Virginia 22314
2
5.
LT Mickey V.
Ross
Ross circle
North Little Rock, Arkansas 72114
2
CAPT Carl Mortensen
2
1
12
6.
MS
977
U.
S.
Geological Survey
345 Middlefield
Menlo Park, California 94025
81
/ff'V/y
—to xiwiae meaM
surement and
recording
J7ste«. to predict
the
intensity and
location
Of electromagnetic
Thesis
RTT568
c.l
Ross
Design of a freestanding noise measurement and recording
system to predict the
intensity and location
of electromagnetic
radiation from earthquakes
.