EARTHQUAKE PREDICTION TECHNIQUES
INTRODUCTION
The devastating nature of earthquakes, scientists shows great interest in predicting
the location and time of large earthquakes. Earthquake prediction is still “ELUSIVE”.
Elaborate post-seismic event analysis exercise is in vogue and rampant rather than preseismic analysis in our country. The outcome is “impossible to predict”, implying that the
manifestations of the natural processes that are embedded in this system are most
intricate, complex, complicated, compounded etc. The scientists should overcome this
mental blockade and they should move on, otherwise their existence becomes
questionable.
REQUIRED PARAMETERS FOR SUCCESSFUL PREDICTION
The goal of earthquake prediction is to give warning of potentially damaging
earthquakes early enough to allow appropriate response to the disaster. For the following
fixing three parameters are important Latitude, longitude, magnitude of earthquake and
time of occurrence have to be fixed as early as possible.
THREE – TIER PREDICTION SYSTEM
In order to achieve the required parameters for successful prediction based on the
time span, three tire prediction systems can be devised.




Long Term Prediction: It is otherwise called Macro range. In such predictions the
time frame is usually a decade or more.
Midterm Prediction: It can be called as Meso range, with a time span two to three
years.
Short Term Prediction: Micro ranges can be used for the public warning. It gives
information on the time and location of an earthquake within months or weeks.
Immediate range: It is useful for the public and evacuation can be done, since it
gives specific information on the time and location of an earthquake within days.
Initially, the precursors identification should be focused as a matter of fact on routine
basis with the help of Long and Medium range predictive techniques, irrespective of
areas are seismic or aseismic. After identifying an area based on the long and medium
range, by using Short range techniques it possible to narrow down the impending event,
with required parameters such as location, magnitude and time with almost surgical
precision.
None may follow this ideally, but this is a logical sequence. It is more likelihood that
medium and short range could be in sequence; long range may or may not be an
indicator. The short-range tools must be in place and be activated and vigilant as and
when any indicator is obtained in the long and/or medium ranges. Long-term predictions
involve a time frame of a decade or more and can only in general and with very limited
usefulness for public safety. Statistical Methods and GPS [Geodesy & Geodetic
measurements] methods can be used for long term prediction.
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STATITICAL METHODS
The statistical methods normally based on the past earthquake history of a region.
Using modern computational facilities, model can be developed to analyse the paleo
earthquake data, which can be compared with current situation.
STATISTICAL
METHODS
Recurrence
Frequency
Seismic Gap Theory
Slip Rates
Using Trees to Date
Earthquakes And
Crustal Movements
CN AND M8
ALGORITHMS
Fig. 1: Various methodologies available in statistical methods
RECURRENCE FREQUENCY
Recurrence frequency is the relationship between magnitude and repetition of
earthquakes. Statistically speaking, recurrence rates of earthquakes of certain magnitude
can be determined by plotting magnitudes versus chronology of historical earthquakes.
Of course, the more historical data that is available, the more reliable the predictions of
the recurrence frequency will be, or the recurrence interval of a certain earthquake in a
certain area.
This is fairly simple to determine for smaller magnitude earthquakes for which
there is a wealth of recent historical data. It is much more difficult to determine for the
larger magnitude earthquakes for which no similarly abundant data exists. The basic
assumption is made that the recurrence frequency of earthquakes is a function of time and
that the same set of conditions leading to the occurrence of an earthquake.
The statistical approach usually ignores clustering of earthquakes in time, or
changes in geologic and tectonic conditions. However, there is evidence that in the last 25
million years of geologic time, the tectonic stresses of the fault systems have been very
similar. Therefore, it can be assumed that the present tectonic movements and release of
strain proceed at the same rate.
Although over the short term variations in the release of strain are possible, over
the longer term a consistency in the behavior of major faults can be expected. Also, we
can expect a relative uniformity in the geographic location of earthquakes and their time
of recurrence.
SEISMIC GAP THEORY
The focus of statistical earthquake prediction in the last few years has been on the
pattern of seismicity of a given region. Search for irregularities or deviations from this
pattern that might suggest a forthcoming earthquake. However, along some boundaries
there are regions that, in recent years, have not produced earthquakes.
These are nearly aseismic regions, or seismic gaps, and these could be the sites for
future large earthquakes. If a segment of a major seismic belt has not been broken for the
last 30 years, such a region can be considered as a seismic gap and a potential site for a
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future large event. Of course, identifying regions where large earthquakes are likely to
occur is useful, but more specific information is needed as to the time of its occurrence.
The 30-year time interval is considered as a minimum because, sometimes, great,
shallow earthquakes recur in the same location within several decades. Thus, by studying
the statistical recurrence of major earthquakes, we can identify not only the repeat cycle
of great earthquakes, but also the areas where these large earthquakes could occur.
For example, the Alaska earthquake of 1972, with a magnitude of 7.3, occurred
near Sitka. This was in a seismic gap area that had been identified as a likely place for an
earthquake. Based on seismic gap studies, the 19 September 1985 earthquake in Mexico
also occurred along a seismic gap and was predicted. However, the time of its occurrence
had not been pinpointed.
SLIP RATES
A different approach has been used in estimating the average recurrence intervals
of earthquakes along major faults. It is possible to examine the history of slip rates along
a fault as preserved in the geologic record and evidenced by offsets in sediments and in
the surface configuration of geo-morphological features. The advantage of this method is
that it utilizes data spanning a much longer period of time, thus getting better estimates of
the recurrence frequency of small earthquakes.
Using the variable rates of relative movements between two sides of a fault, the
basic average recurrence estimates can be obtained. It may be applied in understanding
future behavior of the different segments of a fault. The basic assumptions of this
approach are that slip on a fault is accomplished by the sudden strain released by the
rocks during earthquakes, by gradual slow tectonic aseismic creep, or by a combination
of the two processes. It also assumes that in areas of the fault where aseismic creep
occurs, strain energy is released gradually. In such areas large catastrophic earthquakes of
magnitudes 8 or greater cannot take place. However, along segments of the fault that
display little or no creep, very strong earthquakes can occur. This method used
effectively such methods for establishing slip rates along the San Andreas Fault, where an
empirical relationship between probable Richter magnitudes and creep rates has been
established. But this can be used for well understood faults.
USING TREES TO DATE EARTHQUAKES AND CRUSTAL MOVEMENTS
Earthquakes and surface movements along a fault can often be measured or dated
using trees as indicators. Trees growing on or near a surface rupture along a fault can
provide indirect evidence of historical fault disturbances that may have occurred up to
several hundred years ago. Direct evidence may be fracturing, tilting or twisting of trees
that grow on the surface break from the actual rupturing during an earthquake or the
movement due to aseismic creep.
On either side of the fault, trees may be topped as a result of surface seismic
motion. Indirect evidence may include tilting, topping, or burial of trees by earthquaketriggered landslides. Longer-term effects may include changes in growth rates due to
hydrologic and topographical changes. Often, scars on the trunks of trees, indicating an
earthquake event, can be dated using tree ring methods.
Tilting and fracturing of trees located directly over the fault can often be readily
observed and dated by cutting the surfaces of stumps left. By counting backward, one
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year increments from the outermost ring of a tree, which is representing most recent
growth, to a scar representing damage by an earthquake. It is possible to date past
earthquakes and estimate the recurrence of future events. Often, scars on the trunks of
trees, indicating an earthquake event, can be dated using tree ring methods.
Asymmetries in the cross-sections of tree trunks often indicate a differential rate
of growth which could be the result of tilting due to an earthquake or movement along a
fault. A systematic study of trees over a great distance along a fault can help. In
California, where many tree species like redwoods, can reach the ages of several hundred
years.
Prediction Algorithms
Prediction algorithms basically may predict by averaging the chaotic process with
some confinement. The approach of a strong earthquake may be indicated by certain
patterns in an earthquake sequence; they are called premonitory seismicity patterns.
Pattern recognition methods are able distinguish any repetitive patterns in seismic activity
that might be caused by precursory processes.
Algorithm CN
This algorithm is originally developed for the shallow seismicity of the California
– Nevada (CN) region, later applied to the other parts of the world.
Core of the Algorithm: After considering the spatial distribution of seismicity, an area
will be selected for further investigation. The average annual number of earthquakes (Ñ =
3) will be considered with in each area after removing aftershocks. Functions like number
of main shocks, concentration of the main shocks and maximal number of aftershocks are
used to identify the sequence of earthquakes.
In that sequence - share of relatively higher magnitudes, variations of this
sequence in time and average value of the source area with respect to the slip are also be
identified. Time of increased Probability (TIP) is determined from the recognized pattern.
Algorithm M8
From the analysis of seismicity past greatest earthquakes (M8+) the algorithm M8
was designed. It can be briefly described as follows:
 Overlapping circles with the diameter “D (M0)” scan the seismic territory.
 Within each circle the sequence of earthquakes is considered with aftershocks
removed.
 The sequence is normalized by the lower magnitude cut off Mmin (Ñ), where, Ñ is
the average annual number of earthquakes in the sequence.
 Seven functions like number of main shocks, the deviation from the long term
trend, concentration of the main shocks and the maximum number of aftershocks
are used to characterize the sequence.
 Each functions are calculated for Ñ = 20 and Ñ = 10.
 TIP is declared for 5 years, when 6 of 7 functions become very large within a
narrow time.
Example of CN and M8 Algorithms
Based on catalogues of historical seismicity developed prediction algorithms
designed to identify times of increased probability (TIPs) for a given region using
statistical methods. The CN and M8 algorithms are used to predict the October 17, 1989
Loma Prieta earthquake of Ms 7.1. CN algorithm was used for the prediction of a ≥M 6.4
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for the Northern California and Northern Nevada region. However, the prediction
encompassed a spatial window of 600 x 450 km and a time window of 4-year TIP starting
in mid-summer 1986.
On the other hand, their M8 algorithm predicted that an earthquake with ≥M 7.0
would occur within 5-7 years after 1985 in a spatial window of 800 x 560 km along the
coast of California.
Algorithm Mendocino Scenario (MSc)
This algorithm was originally designed for Mendocino region near California.
From the retrospective analysis of seismicity erstwhile to Eureka Earthquake occurred on
1980 with the magnitude of 7.2. This algorithm will help us to further reduce the spatial
area proposed by CN and M8 algorithms.
Basic Features: Given a TIP diagnosed for certain territory “U” at the moment “T”. The
objective of the algorithm is to find smaller area “V” within the main territory “U”, where
the impending earthquake may occur. The area of “V” is normally 4 to 14 times smaller
than main territory “U”. The main requirement of this algorithm is to collect complete
data of earthquakes with magnitudes M ≥ (Mo – 4), which is minimal threshold than the
algorithms CN and M8.
Pattern Informatics (PI)
The basis for this methodology is strong space-time correlations of seismicity,
which can be derived from the ideas of non-linear threshold dynamics and mean-field
long-range theory. This PI technique has thus been used to detect precursory seismic
activation and quiescence, so that forecasting can be made.
Applications of this methodology to the paleo earthquake records data from
southern California region shows that this method can be used as a powerful tool for
forecasting large events. Also it can provide earthquake forecasts on a worldwide basis.
Algorithm RI (Relative Intensity)
Another different approach in earthquake forecasting is Algorithm RI, which is in
simpler form. The name of the algorithm is abbreviation of “Relative Intensity”, since it
uses relative intensity of past seismicity, which is based on counting the number of
earthquakes that occurred in the past. The algorithm suggests the possibility of
occurrence of an earthquake depends on the historical seismicity. Higher the historical
seismicity increases the possibility future occurrences. The algorithm shows considerable
performance even though basis of the algorithm is very simple.
Outline of the Algorithm: The region selected will be divided into grid of boxes. The
number of earthquakes with M ≥ ML for the ith box, for a given period from t0 to t1,
which is represented by ni (t0, t1, ML) and this is repeated for all the boxes in the region.
Relative values of these numbers are found by the formula ni(t0,t1,ML)/Σj nj(t0,t1, ML).
Where, ‘j’ represents sum of values of all boxes. The box having higher relative value is
identified as having higher possibility of occurrence of large earthquake for a given
period.
MID - TERM AND SHORT TERM PRECURSORS
GEOPHYSICAL AND GEOCHEMICAL PRECURSORS
At present, statistical methods are interesting and informative. But they are not a
reliable way of predicting earthquakes. Therefore, scientists look for precursors and other
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physical geological changes that take place with consistency before an actual earthquake
occurs. Studies of earthquake precursory events require the complete and systematic
analysis of large volumes of seismic data. The complete interpretation of the physical and
geochemical changes occurring along a potential earthquake-prone area has to be
analysed by using of computers and other geophysical techniques. Seismographic
networks placed along major active faults can measure seismic precursors of earthquakes.
Therefore, a study of the seismicity of a region and an analysis of the smaller events can
lead to conclusions as to the time of occurrence of a major earthquake.
STUDY OF PRECURSORY EVENTS
• Increase in the rate of a seismic creep
• The slow movement along the fault
• Gradual tilting of the land near the fault zone
• Drop or rise in the water level of a well
• Increase of hydrogen gas in the soil
• Release of radon
• Decrease in the number of micro quakes
• Foreshocks
• Lessening of electrical resistance in the rocks
• Flashes and other lights in the sky
• Appearance of "Mogi's donut"
FAULT CREEP MEASUREMENTS
Fault creep is a gradual slip produced by the yielding of rocks along the weak
boundary of a fault. Creep is defined as an aseismic rupture process which occurs so
slowly that no detectable seismic waves are generated. Although creep occurs on normal
and thrust faults, it is predominantly observed on strike-slip faults with a steep slip
component. Mostly it is directly observed only at or near the Earth's surface. Also It
occurs at depth, since creep is the manifestation of aseismic slip movements of large
crustal blocks. Thus creep can occur at any fault depth although not necessarily with
uniform distribution. In fact, fault creep must be comparatively greater at depths of 12 to
15 kilometers below the surface on strike-slip faults and above the 2- or 3-km depth of
certain sections. There is a direct relationship between fault creep and earthquakes.
Along fault segments where strains are not released by slow fault creep
movements, large earthquakes of greater magnitude seem to occur. Conversely, high rates
of creep generally inhibit the generation of large magnitude earthquakes. Fault creep is
being extensively studied on the San Andreas fault system in California. Instruments
known as creep meters measure the changes in distance between markers set diagonally
across a fault. Such aseismic displacements known as creep events occur frequently on
the faults of the San Andreas Fault system. Often, some of these events begin suddenly
for a few minutes at rates on the order of 0.5 mm/min., and are followed by much longer
periods of gradually diminishing creep rate.
Thus, movement along a fault may be accommodated without an earthquake, as
creep, cannot produce detectable seismic waves. The significance of measuring present
creep is the following. In sections of the fault systems where displacements can be
accommodated by this aseismic rupture (creep), the occurrence of even minor
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earthquakes is comparatively rare. It is the sections of the fault system that are locked,
where creep does not occur steadily or periodically where larger destructive earthquakes
can occur. But even at the sites of larger earthquakes on such sections, creep events have
been observed immediately after a large earthquake has struck. In such instances, such
earthquake-creep event associations have been attributed to after slip effects. Although
rare, some creep events have also been recorded prior to the occurrence of a major
earthquake. Instrumentation, which has been developed recently, permits geodetic
measurements of surface changes near faults with remarkable precision.
For example, instruments such as geodimeters with laser beams can accurately
measure distances anywhere from one to 30 kilometers. These instruments are extremely
sensitive and have an accuracy of about 0.2 parts per million, which is equivalent to an
average error of less than five millimeters over a distance of 20 kilometers or more in
length. Any errors that are introduced in the measurement are not by the instrument itself
but from the meteorological conditions surrounding the instrument. For example,
atmospheric conditions such as temperature and the refractive index of the light along the
path of the laser beam can introduce errors, if not properly compensated. This capability
of precise distance measurements has been applied to earthquake studies and earthquake
prediction by using repeated distance measurements to determine any net movements
between monuments located on both sides of a major fault.
By making measurements over a number of years and by plotting the differences,
scientists find the average rate of change. Collection of data with a network of such
geodimeters provides information on the fault creep. For better accuracy, a small array of
such geodimeters is placed directly over a fault that has to be measured. Measurable
precursor movements occur within periods that range from approximately one month for
a magnitude 4.5 earthquake, to several years before a magnitude 6.5 occurs. Although the
surface changes are significant in earthquake prediction, scientists have to be careful not
to confuse anomalies and instrumental errors with the actual movements related to
earthquake activity along a fault.
STRAIN MEASUREMENTS
Strain meters are measuring instruments that record the motion of the ground as it
relates to a reference point. Usually, these measurements are made across an active fault
line, and several of these instruments can be placed to determine net movement along a
fault. The instruments record signals related to the failure behavior of the rocks preceding
an earthquake. In addition to actual movements, strain meters can measure other effects
such as earth tides and thermo - elastic changes. Thus, the behavior of the fault can be
measured continuously as active faults may generate precursory tectonic signals such as
creep and strain. Strain measurements have been used continuously to across major faults
before and after earthquakes. Of course, Strain signals are more evident in the vicinity of
the fault and closer to the epicenter, which is the area of greatest strain and potential
failure. Thus, strain meters more effectively record creep events of short duration
resulting from local, near surface failures.
That may be triggered by some kind of movement at a depth below the surface
and along the fault. Strain measurements can reveal surface fault creep, tilt, and strain,
but have to be recorded at distances of 500 feet from the fault or less, to be accurate.
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Water level changes in wells are often simultaneously measured, along with other surface
strain measurements.
MEASURING CHANGES IN SURFACE TILT
It is not known with certainty why the earth's surface deforms around active
faults, but often does. Tilt meters are instruments that measure vertical displacements or
local uplift of the crust near a potential site of an earthquake. It is observed by tilt meters,
along an 85-kilometer section of the San Andreas Fault in Central California, systematic
tilting of the surface occurs in a fixed direction during periods of low seismicity. Prior to
the occurrence of an earthquake, the direction of tilting begins to change dramatically,
and after the earthquake, the slow, systematic tilting of the surface again resumes. Thus,
tilt changes are precursory events to earthquakes and can help in understanding the cause
and prediction of earthquakes. Anomalous tilting of the earth's surface prior to
earthquakes has been reported from other countries including the Soviet Union, Japan,
and Italy. Factors that could influence the tilt measurements are meteorological loading
effects, thermal and mechanical instabilities. It is because of both in the instrument and in
the site, and the non-homogeneous nature of crustal rocks.
WATER LEVEL CHANGES
It has been demonstrated that seismic waves can induce large water level
fluctuations in wells. Larger in amplitude of surface seismic waves, such as "Raleigh
Waves”, force the particles of the rock near the surface to move in an elliptical orbit and
thus the aquifer layer also is affected, which in turn results in the water level fluctuation
in the well. Thus if appropriate measuring instruments are used, the water level in wells
can be used for recording distant earthquakes. In essence, a well can act as a seismograph
by recording the passage of the surface waves through the aquifer and amplifying the
amplitude of these waves, much like a seismograph does. Thus, many major earthquakes
throughout the world have produced water level changes. Not only do water level
changes occur following an earthquake, but they also precede most earthquakes. Water
wells are very sensitive to various earth processes such as earth tides, tilting of the crust,
and seismic creeping, particularly if these wells are in the close proximity to an active
fault. By drilling water wells at carefully selected sites and by measuring water level and
water quality, the information can be used for earthquake prediction, particularly if it is
used in conjunction with a dense network of other instruments such as tilt meters and
creep meters. Thus, actual pre-seismic processes and precursory fluctuations in water
levels, can give a clear indication of strain building up along a particular seismic fault.
HYDROGEN MONITORING
Geochemical measurements can also be used for earthquake prediction. For
example, Dr. Motoaki Sato, a scientist with the Geological Survey, and several of his
colleagues, began monitoring hydrogen along various faults in Central California,
including the San Andreas Fault, in 1980. In 1982, they found higher concentrations of
hydrogen along the fault, and those concentrations jumped from 20 parts per million to
over a 1,000 at some stations. Dispersion of hydrogen gas continued sporadically and
then increased sharply in April 1982. On 2 May 1983, a major earthquake of 6.5 occurred
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in Coalinga, an agricultural town north of Parkfield, and this earthquake coincided with
peaks in the hydrogen concentration. Similarly, the hydrogen concentration at one station
continued to rise immediately receding several of the aftershocks that hit the town, in the
subsequent months. The explanation for such a chemical precursor is not simple. It has
nothing to do with the earthquake process itself, but it appears to be a side effect of
chemical changes that occur in rocks before quakes. For example, stresses on the rocks
could be destroying a distinctive rock called serpentinite which lies along many faults of
California, as well as in Japan, and hydrogen is a by-product of the disintegration of
serpentinite. As the tectonic plates grind, the rock containing serpentinite at depths of six
to 10 miles below the surface is squeezed releasing gases until, finally, the fault ruptures.
MONITORING RADON EMISSIONS
Radon is a radioactive gas that is constantly emitted from the earth into the
atmosphere. The gas has a half-life of 3.8 days. By half-life, we mean the time required
for the substance to lose half of its radioactivity through decay. Thus, radon is a very
short-lived, radioactive substance. Studies in the concentration of radon, and its isotope
thoron, in the vicinity of faults, have been unusually high. Thus, a number of researchers
have monitored the radon content in deep wells, as a potential predictor of earthquake
activity. For example, they found a gradual increase in concentrations until the time of
the earthquake. After the earthquake occurs, radon emission decreases rapidly, although
some variation can be observed related to earthquake aftershocks. The radon content of
ground water used to determine increases in emission and to correlate the concentrations
to earthquake activity. The mechanism for radon generation can be easily explained.
Compression along a fault builds up prior to an earthquake and this stress squeezes radon
out of the rock and into the atmosphere at an increased rate. Since radon itself has a very
short half-life, it is known to move slowly in ground soils. Therefore, the detected radon
concentrations must be from earthquake sources several kilometers underneath the
surface.
HYDRO-GEOCHEMICAL CHANGES
Rapid 12%–19% increases in the concentrations of B, Ca, K, Li, Mo, Na, Rb, S,
Si, Sr, Cl, and SO4. Decreases in Na/Ca occurred 2–9 days after the earthquake. The
rapidity of these changes is consistent with time scales of fault sealing due to coupled
deformation and fluid flow. Variation in Na/Ca ratio appears to be sensitive to the
changing stress state associated with M 4.0 earthquakes. This study highlights the
potential of hydro-geochemical change in earthquake-prediction studies.
HYDRO-GEOLOGICAL CHANGES
To measure the hydrological variations, several data regarding groundwater level,
spring discharge and river flow rates are considered. The hydrological variations are
identified by a comparison with the average yearly regime, estimated from the data
referring to previous years with current year. The river gauge stations registered
anomalies several months before the crisis started, acting as earthquake precursors.
Events that involve a significant normal faulting component expel substantial quantities
of water, whereas reverse faulting events do not. Strike-slip events typically expel water
in more restricted regions but not in the quantity associated with normal faulting events.
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MONITORING OF ATMOSPHERIC METHANE CONCENTRATION
Before earthquakes, there is a significant increase of concentrations of various
gases in the atmosphere, such as CO2, CH4, and so on. Due to large quantity of gases
escaped from the crust in seismic areas, particularly, when the seismic areas are located
in oil and natural gas enrichment places. In 1991 in Chinese capital territory (38.5 N 41.0 N, 113.0 E - 120 E) there were four earthquakes with magnitudes of M 3.8 to M 5.1
occurred. The observational data shown that the CH4, concentrations in the surface
atmosphere could be about 0.7 to 5 times higher than the normal value in Beijing several
days to more than ten days before these earthquakes. So that the significant increase of
atmospheric methane concentration in seismic areas may also be considered as a kind of
earthquake precursor. Methane is an infrared absorbing gas, its concentration
variation may cause changes of outgoing radiation at the top of the atmosphere.
Hence, it may also be possible to monitor such phenomenon from satellite with some
properly selected channels and used as a possible precursor in earthquake prediction.
DILATANCY
Dilatancy occurs, when the rocks on a fault are stressed and the ground "dilates"
or swells. Symmetric tilting of the ground can be expected in a uniform pattern away
from the potential earthquake epicenter. Asymmetric tilting of the ground around the
earthquake source area can occur also from non-uniform stresses on the rocks, which
eventually result in rupturing of a fault. The theory of Dilatancy is complex and has not
been generally accepted. However, it has been used to predict and explain other
precursory phenomena such as variations in magnetic and electrical fields, changes in the
flow of ground water, and anomalous tilts and uplifts of the earth's surface. These are all
precursory effects that are presently being investigated and have been associated with
Dilatancy. All such studies are based on the concept of the Dilatancy of the rocks.
EARTHQUAKE EARLY WARNING (EEW)
EEW can be a useful tool for reducing earthquake hazards. The spatial relation
between cities and earthquake sources should be favorable for such warning and their
citizens are properly trained to respond to earthquake warning messages. An EEW
system forewarns an urban area of forthcoming strong shaking, normally with a few sec
to a few tens of sec of warning time. It warns before the arrival of the destructive S-wave
part of the strong ground motion.
Potential Use Even a few second of advanced warning time will be useful for preprogrammed emergency measures for various critical facilities, such as rapid-transit
vehicles and high-speed trains to avoid potential derailment; It will be also useful for
orderly shutoff of gas pipelines to minimize fire hazards, controlled shutdown of hightechnological manufacturing operations to reduce potential losses, and safe-guarding of
computer facilities to avoid loss of vital databases.
P – WAVE VELOCITY
An earthquake excites both P and S waves. The S wave carries the major
destructive energy. The smaller amplitude P wave arrives at a location first, before the S
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wave comes. By the time S – wave reaches, 70% of the P-wave already propagated
through the station. The initial portion of the P wave, despite its small and
nondestructive amplitude, carries the information of the earthquake size. Estimation of
the earthquake size from the P wave provides information about the strength of shaking
to be brought by the following S wave. Using P wave information to estimate the strength
of S wave destructive shaking is a principal concept of EEW. One of the major elements
of EEW is to determine the earthquake magnitude rapidly and reliably. To determine the
size of an earthquake, it is important to determine whether the earthquake rupture has
stopped or keeps growing which is generally reflected in the period of the initial motion.
Small and large events generally cause short and long period initial motions, respectively.
CHANGE IN P – WAVE VELOCITY
The change in the velocity of the P-wave is found by measuring the change in the
ratio of the P- wave velocity to the S- wave velocity (Vp/Vs). The Vp/Vs ratio is obtained
from an analysis of the travel times of P - waves and S - waves. By denoting the arrival
times of P- and S-waves by tp and ts respectively, the S - P time versus tp relation can be
expressed by a straight line on the “(ts - tp)” – “tp” graph.
The slope (k) of the line is given as:
k = (ts - tp) / tp ---------> (1)
If the propagation path for both waves is assumed to be identical, we obtain:
Vp. tp=Vs. ts ----------> (2)
Vp / Vs = ts / tp
So that we have:
k = (ts / tp) – (tp / tp)
k = (Vp / Vs) - 1 -----> (3)
Vp/Vs = 1 + k --------> (4)
Therefore, it is seen that the Vp/Vs ratio is obtained from k calculated on the basis
of travel-time analysis. Experiments have shown that the Vp/Vs ratio decreases at least
10%, a year before an earthquake. Then increases again months before and about to
normal just prior to an earthquake.
GRAVITY METHOD
When tectonic plates crushed against each other, they subjected to compressional
forces, suffer deformation or strain, before the rock fractures. In deformation zone, on
earth’s surface, the displacement or relative movement of the earth’s gravitational center,
a precursor in advance of an imminent EQ in 5 to 6 days. Given, at least 3 measuring
points of earth’s gravity force, a triangulation procedure allows locating the epicenter.
INFRASOUND WAVES [ISW]
Imminent EQ precursors are having abnormal infrasonic wave signals which are
measurable in 1 to 9 days in advance. ISW are longitudinal vibrations in the air, they
propagate very long distances, without significant attenuation and distortion. Since, they
are normal sound waves of longitudinal nature, there is no polarization. ISW wave length
ranges from 17 meters to thousands of kilometers. In nature strong ISW are produced by
meteors, volcanic eruptions [0.5-10 Hz]. EQ’s ISW frequency range is from 5 to 12 Hz,
but whereas, EQ’s precursor frequency range is < 1 Hz. Wind pressure variations and
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ISW are separable, in later case signals are coherent over several kilometers.
Atmospheric components are relatively dynamic than solid earth’s static nature. ISWs
released from fault fractures prior to large EQs at epicenter, the range being 0.004 to 0.1
Hz. A high value of 1.250 mV is a manifestation of an EQ’s magnitude of Ms >7 to 7.5.
GEOMAGNETIC FIELD CHANGE
The geomagnetic field starts changing 6 to 8 months and perceptible even just 10
to 20 hours before an EQ. The audio, video and EM spectral disturbances in TV
reception, wireless communications and shift in radio frequency could be felt. The longterm changes also can be seen on telecommunications. In Turkey, Japan and China,
mobile phones malfunctioned 50 to 100 minutes prior to an EQ. The Latur earthquake
occurred on 29th September 1993. On an average there were about 3000 complaints per
month for the period January to April. Since May, the number of complaints started
rising. The number of telephones was more or less unchanged.
Table 1: Showing numbers of complaints on telephone malfunction in Latur region prior
to 1993 earthquake.
It is observed that the rise in number of complaints during a span of about five
months is about 53 % of the original value. The process of stress building was accelerated
during May to September and the earthquake occurred on 29th September 1993. It was
found that a large number of persons have observed repeated disturbances on television.
These were of audio, visual and spectral type of disturbances.
ABNORMAL ANIMAL BEHAVIOUR
On a horizontal rod, a budgerigar [a kind of parrot] couple is caged and the cage
is connected with a sensor and a counter. The normal jump frequency of budgerigars is
around 600 to 700 p/day. But before an imminent EQ the jump frequency is more than
2000 p/day. This information is only about an imminent EQ and is a good EQ precursor.
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But no other information could be obtained on: direction, epicenter, magnitude
and time. Based on this method an EQ can be predicted before 7 to 13 days. In Kangra
EQ [1905], where the magnitude was >8, a day before, all zoo animals were highly
disturbed is a recorded fact.
Fig.2: The Budgerigar
Chinese began to study systematically on the unusual animal’s behavior. The
Haicheng earthquake of magnitude 7.3, on 4 February 1975 was predicted successfully as
early as in mid December of 1974. The most unusual circumstance of animal’s behavior
was that of snakes that came out of hibernation and froze on the surface of the earth.
Also a group of rats appeared. These events were succeeded by the swarm of earth of
earthquakes at the end of December 1974. In first three days in Feb the unusual behavior
of the larger animals such as cows, horses, dogs and pigs was reported. They successfully
evacuated Haicheng city several hours before an earthquake (M7.3) on February 4, 1975.
This earthquake caused considerable damage to existing structures and cultivated lands,
and the successful evacuation was thought to have saved more than 100,000 lives.
In Japan, unusual behavior of catfish before the 1855 Edo earthquake was
reported. Many fish jumping in a pond just one day before the great Kanto earthquake
occurred was reported. Aquatic animals are more sensitive to electric signals than other
animals. Some of them have special electro-sensory systems which are used to acquire
information for orientation and communication with each other. These systems may be
perturbed by electric field before earthquakes.
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Fig 3: The Cat Fish
To determine seismic anomalous animal behavior prior to a major earthquake due
to seismic electric signals, an experiment on Albino rats, Mongolian gerbils (sand rats),
hair-footed Djungarian hamsters, guinea pigs, and red sparrows was organized. The
animals were kept in a cage with a wet conductive floor and electrodes. When Voltage
between 0.01 to 50 Volts was applied to the electrodes separated by 25 to 30 cm on the
floor of cages, between which wet tissue papers with resistivity of 20 KΩ were placed.
The film was recorded and it was noticed that initially these animals started grooming,
nervous looking and field avoidance behaviors. Finally as the ground electric field
increased from 1 to 1000 V/m they started running in panic, jumping, tumbling, crying,
standing up, biting wires, flying up and some time their behavior could not be judged.
By applying a pulsed electric field on silkworms, earthworms, lungworms, mollusc,
Japanese minnows, tropical fish, guppies and fresh water loachcs and observed as seismic
anomalous animal behavior (SAABs) as electrophysiological responses to the stimuli of
seismic electric signals (SES). It was observed that these animals became aligned
perpendicularly to the field direction since their skeletal muscle had a higher resistivity
perpendicular to the field direction than parallel to it. To correlate such type of voltages
an electromagnetic model of a fault based on piezoelectricity effect was proposed, in
which dipole charges, +q are generated due to the change of seismic stress, σ (t).
"When an earthquake is about to occur, snakes will move out of their nests, even
in the cold of winter," Jiang was quoted as saying. "If the earthquake is a big one, the
snakes will even smash into walls while trying to escape."
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Fig. 4: Frog came out their place before Sichuan Earthquake 2008.
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Animal
Behavior Reported Before
Earthquake*
Behavior Reported in Other Context
Cats
constant hiding, refuse to go outside
psychogenic shock
Chickens fly to high perches, mill and crowd together hysteria
Dogs
Fish
Mice
Mussels
Pigs
Rats
sudden darkness, loud explosion
Barking, follow owner constantly from room to territorial, stranger response, over
room
dependent pet
jump out of water change depth in water
quick turns, hunting
behave as if drunken, convulsions
audiogenic seizure with noise of 4-80
kHz, 90-130 dB
move to higher attachment sites
as water rose before hurricane
on seashore
biting each others' tails
overcrowded conditions
vigilance, jumpiness, vertical leaping, crouch like alarm response to ground predators,
gesture, muscle contractions
acoustic startle response
Table 2: Abnormal Animal Behavior Prior to Earthquakes and Other Contexts in Which
Similar Behavior Has Been Observed
ELECTRO TELLURIC CURRENTS
One of the most prominent methods is those based on electrical signals. Many
researchers world-wide have reported electrical signals preceding earthquakes and have
tried to correlate these with the pending earthquake. Reported variations of the electric
field occur over much different time scales with various signal characteristics, thus
special signal processing tools have to be used in each case. Particular signals have to
be detected, identified and linked to seismic activity. As it is often the case noise
presence obscures signal details and prevents accurate and robust estimation of signal
parameters that are useful in the prediction process.
SEISMIC ELECTRIC SIGNALS (SES)
SESs are weak, short time variations of the Geoelectrical field occurring prior to
an earthquake. SES signals are of relatively low voltage, in the milli volt range and
have usually a time duration from a few minutes to hours. These signals are often
embedded in noise. Local electrical industrial noise, electrical spikes and noise due to
variations of the earth's magnetic field, are among the most common causes. A
systematic observation of the Earth's electric field transients as earthquake precursors
has been conducted since 1981 by the VAN network of stations and a great amount
of data have been collected. Seismic electric signal generation is based on the theory
of piezo-stimulated current and originate from the earthquake’s epicentral region. The
earthquake is expected to occur within several weeks of the appearance of the SES.
The electric field at each station is usually monitored in two directions (N-S
and E-W) by an appropriate number of electrode pairs. Signal amplitude levels and
polarities in the two directions as well as the station's spatial location can be related
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to the magnitude and focal region of the pending earthquake. SES amplitude is among
others considered to be proportional to,
a. the earthquake magnitude M,
b. distance ‘r’ of the station from the epicentral region ,
c. obeying an analogous to l/r law ,
d. cite and signal propagation path characteristics,
e. Station sensitivity seems also to be a key issue.
RF DISTURBANCES
Many research workers have reported EM emissions prior to earthquakes and
volcanic eruptions. Among these, semidiurnal types (twice in a day) are
commonly seen. However diurnal type [appearing once in a day] of EM emissions were
also noticed in few cases. Both these types of EM emissions were observed during the
operation of an indigenously built radio tele-metered seismic network (RTSN) which
was commissioned at Bhatsa, Maharashtra state, India, to study the reservoirinduced seismicity (RIS) of the region and operated during 1989-1995. RF interference to
the radio links operated in UHF (Ultra High Frequency) band was witnessed prior to,
during and after the earthquake sequence from Valsad region. Semidiurnal type EM
emission related to earthquakes and volcanoes in different frequency band starting from
very low frequency (VLF) to microwave range. The diurnal signal intensity envelope
with frequency of 10 MHz was recorded along the Washington - Huankayo path prior to
the disastrous quake in Chile (22 May 1960). Anomalies in terms of sharp variations
were noticed between 08 - 12 hours and 19.00 hours almost all these days (17-23
May 1960), which had linearly modulated this intensity envelope. The onset timings of
the major foreshock, main shock and aftershocks also correspond to the timing of these
anomalies. A method of utilizing grid of RF network in the high seismicity area and
monitoring RF emission in HF-VHF-UHF band should provide good clues of any
impending event. Unlike other methods here one can monitor the emission on daily basis.
MAGNETIC MEASUREMENTS
It is evident that all wide amounts of types of magnetometers are restricted for this
application to only four ones:
a. flux-gate magnetometers (FGM),
b. Torsion magnetometers (TM),
c. search-coil magnetometers (SCM),
d. SQUID magnetometers.
For lower part of the frequency domain of interest FLUX GATE MAGNETOMETER
appear to be the best choice in order to get minimally possible noise value. But for
frequency starting from about 0.01 Hz and higher the SEARCH COIL AGNETOMETER
overcomes any other possible type of the magnetometers as to the noise level.
Triangular Network GPS Method
With the help of Geodesy and Geodetic Engineering, one can predict the
precursors 3 to 6 months before. The 3D positioning and Navigational Satellite System
can cover the entire earth’s surface. Simultaneous and continuous geodetic measurements
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and 3D analysis of large areas is possible. Earthquake prediction using GPS is a
significant contribution; the area change ratio is converted to annual change ratio [ppm].
If no crustal movements are involved then there could be an increase of 3 ppm. [In XY,
XZ or YZ plane].
An early warning could be given in three stages:
I stage: 4-9 ppm
II stage: 10 ppm
III stage: >10 ppm
Plus sign [tension] suddenly changes to zero or minus [compression] or vice
versa, indicating an EQ could take place in a few months.
IONOSPHERIC PRECURSORS OF EARTHQUAKES
Recent advances were made in scientific understanding of the problem of seismo ionospheric coupling. It is commonly accepted that the Good Friday Alaska earthquake
on March 27 of 1964 gave seismo-ionospheric coupling studies its initial impetus.
Fig. 5: Appearance of mysterious light before the occurrence of earthquakes
3-6 days
prior to the coming earthquake revealed tendency to increase of
maximum in electronic concentration. 1-3 days prior to the coming earthquake revealed
significant decrease of the maximum value in electronic concentration at F2 layer of the
ionosphere. The analysis of helio-geophysical situation, which carried out in the period
of study showed that it was quiet. That is why observed changes in electronic
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concentration can be provoked by the impact of seismic activities in seismic region. This
may be used as an earthquake precursor.
INTERFEROMETRIC SYNTHETIC APERTURE RADAR (InSAR)
The InSAR technique involves examining pairs of radar images of the same
landscape to determine changes in the land surface over very broad regions to within a
couple of inches (5 centimeters). The satellites can thus detect slight deformations in the
Earth's crust, which may indicate built up strain prior to an earthquake. Imaging radar is
an active illumination system, in contrast to passive optical imaging systems that require
the Sun's illumination. The illumination direction is side-looking with respect to the
vehicle's direction of travel.
The brightness (amplitude, A) of a reflected radar signal (echo) that has been
transmitted from an antenna mounted on an aircraft or spacecraft. The backscattered from
the surface of the Earth, and received a fraction of a second later at the same antenna, is
measured and recorded to construct the image. Consider an image to be a set of values
A(x, y). Where the “x” coordinates is in the direction of platform motion. The “y”
coordinate is in the direction of illumination. Then the value of y (related to the radar
range) and its resolution is based on the arrival time of the echo and the timing precision
of the radar. While the value of x (related to the radar azimuth) and its resolution depends
on the position of the platform and the beam width of the radar. Even though the typical
radar image displays only amplitude data, for this purposes the most important aspect of
SAR is that it is a coherent imaging system, retaining both amplitude and phase
information in the radar echo during data acquisition and subsequent processing. SAR
interferometry exploits this coherence, using the phase measurements to infer differential
range and range change in two or more SAR images of the same surface. We first
examine estimation of topographic height from the differential range measured by two
radar antennas looking at the same surface. Followed by a discussion of changes in
topography (displacement) based on range change in two or more successive SAR
images.
Consider two radar antennas, A1 and A2, simultaneously viewing the same
surface. They are separated by a baseline vector B with length B. The angle with respect
to horizontal “”.A1 is located at height “h” above some reference surface. The distance
between A1 and the point on the ground being imaged is the range “”. Where, “+” is
the distance between “A2” and the same point on the surface.
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Fig. 6: Basic imaging geometry for SAR interferometry. A1 and A2 represent two
antennas viewing the same surface simultaneously, or a single antenna viewing the same
surface on two separate passes.
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Fig. 7: InSAR image - 1999 Hector Mine earthquake.
SAR can provide high-resolution imagery of earthquake-prone areas, highresolution topographic data, and a high-resolution map of co-seismic deformation
generated by an earthquake. Other techniques are capable of generating images of the
Earth's surface and topographic data, but no other technique provides high-spatialresolution maps of earthquake deformation.
THERMAL INFRARED ANOMALY
Satellite thermal infrared (TIR) imaging data have recorded short-lived anomalies
prior to major earthquakes and associations with fault systems. Others have proposed
that these signals originate from electromagnetic phenomena associated with pre-seismic
processes, causing enhanced IR emissions, that we are calling TIR anomalies. These
short-lived anomalies:
a) Typically appear 4–14 days before an earthquake;
b) Affect regions of several to tens of thousands square km;
c) Display a positive deviation of 2 to 4 oC more; and
d) Die out a few days after the event.
Fig. 8 (a): January 06, 2001
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Fig. 8 (b): January 21, 2001
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Fig. 8 (c): January 28, 2001
OUTGOING LONG WAVES
Long wave radiation of the Earth is a major driver of the Earth system climate.
The reflection, absorption, and emission of the energy occur through a complex system of
clouds, aerosols, atmospheric constituents, oceans and land surfaces. OLR is the thermal
radiation flux emergent from the top of the atmosphere. It is connected with the earth–
atmosphere system in general, and it depends on cloud and surface temperature.
This energy has been measured at the top of the atmosphere by National Oceanic
and Atmospheric Administration (NOAA) 15, 16, and 17 satellites. It includes all of the
emission from the ground, atmosphere and clouds formation. The analysis of the
continuous outgoing long wave earth radiation (OLR) indicates anomalous variations
prior to a number of medium to large earthquakes.
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Fig. 9: Map of OLR bi-monthly variations for October-November 2004 (a) OLR monthly
December 2004 (b) forM9.0 Sumatra Andaman Island, Northern Sumatra of December
26, 2004. Epicenter (3.09N/94.26E) is marked with red star, tectonic plate boundaries
with red line, and major faults with brown color.
Fig. 10: Time-series of daily OLR anomaly for October 1, 2004–December 31, 2004 over
the epicenter (3.09N/94.26E) for M9.0 Sumatra Andaman Island, Northern Sumatra
earthquake occurred on December 26, 2004.
The most recent analysis of OLR is from the M9.0 Sumatra Andaman Islands
mega trust event. From the compared the reference fields for December 2001 to 2004, it
is found that OLR anomalous values, >80 W/m2, within the epicentral area on Dec 21,
2004, 5 days before the event.
Some of the recent findings give us, a clue that the celestial bodies are acting as a
triggering force for the occurrence of the devastated earthquakes. As the Earth spins
eastward beneath the moon and the moon's gravity slightly holds the Earth's surface layer
back. This "lunar drag" causes the crust to slip slowly backward (i.e.) in westward
direction (Scoppola, B. 2006). According to V. G. Kolvankar (2005), due to the steady
speed of rotation, it resulted in linear transformation from no stress to high stress at the
earthquake area. This was represented by the steady rise of the RF noise envelope. Again
when the planetary position is placed from that key position again due to earth rotation,
linear transformation takes place in the reverse order and RF noise level falls steadily. S.
R. N. Murthy (1990) states that though it is known that tectonic processes within the
earth cause earthquakes, the ultimate triggering could be due to fluctuations in the gravity
field which may have direct relation with extra terrestrial activities like solar flare.
Frequency occurrences of earthquakes are at maximum, at times of moderately high and
fluctuating solar activity (Simpson, 1968). G.P.Tamryzan (1967) formulated four general
regularities concerning the liberation of seismic energy from the interior part of the earth
in relation to tide formation effects. Kropotkin and Trapeznikov (1965) observed that
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during the first half of the 20th century show annual fluctuation in the earth’s gravitational
constant and they also state that there is a whole complex phenomena revealing an
association of seismicity with solar activity.
TIDAL GENERATION FORCE RESONANCE
Triggering of large earthquakes is due to Tidal Generation Force Resonance
[TGFR], which is due to the astronomical constellation of Moon and Celestial bodies
with Earth in a straight line. Movement of the moon’s relative motion to the earth, areas
of compression and decompression will be developed by TGFR. With TGFR technique
one can predict EQs from 15 days to two months and had a 40% success ratio.
SUN SPOT STUDY
The outermost layer of the sun is called corona. Activities in the corona lead to
the discharge of coronal particles from the sun spots called Coronal Mass Ejections.
Normally, these particles get lost in space or impact other planets. Sometimes, these
particles head towards the earth and collide with the magnetic field on the earth’s surface.
This collision leads to a disturbance in the earth’s equilibrium and earthquakes happen
because of this. Two well expressed maxima in the global yearly number of earthquakes
are seen in the 11- year sunspot cycle. One such increase in global earthquake activity is
coinciding with sunspot maximum and the other on the descending phase of solar
activity. A day to day study of the number of earthquakes worldwide reveals that the
arrival to the Earth of high speed solar streams is related to significantly greater
probability of earthquake occurrence.
Possible mechanism
The possible mechanism includes deposition of solar wind energy into the polar
ionosphere. Where, it drives ionospheric convection and auroral electro jets, generating in
turn atmospheric gravity waves that interact with neutral winds and deposit their
momentum in the neutral atmosphere. Increasing the transfer of air masses and disturbing
of the pressure balance on tectonic plates. The main source of high speed solar streams is
the solar coronal mass ejections which is maximum, when sunspot is maximum.
TIDAL COUPLING
Tidal forces are reciprocal. This reciprocal induction of tides in the bodies of the
Earth and the Moon leads to a complicated coupling of the rotational and orbital motions
of the two objects. The interiors of the Earth and Moon are heated by the tides in their
bodies, just as a paper clip is heated by constant bending. This effect is very small for the
Earth and Moon, but it can be dramatic for other objects that experience much larger
differential gravitational forces and, therefore, much larger tidal forces.
THE JUPITER EFFECT ON IO
Tidal forces exerted by Jupiter on its moon Io are so large that the solid surface of
Io is raised and lowered by hundreds of meters twice in each rotational period. This
motion heats the interior of Io so much that it is probably mostly molten; as a
consequence, Io is covered with active volcanoes and is the geologically most active
object in the Solar System.
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Fig. 11: The IO moon – Showing the active Volcanoes
GRAVITTIONAL STRESS ON EARTH BY CELESTIL BODIES
If two or more planets, Sun and Moon are aligned more or less in line (0o or 180o)
with the Earth, then the Earth would be caught in the middle of a huge gravity struggle
between the Sun and the planets. The gravitational stresses would change the speed of the
Earth in its orbit, and shift the centre of the solar system. When, the speed of rotation of
the earth changes, the tectonic plate motion is also affected, just as people collide with
each other when the bus driver applies the brake suddenly. Thus, the planetary forces act
as a triggering mechanism for the accumulated stress to be released abruptly.
Earth–Moon system and gravitational pull exerted by Moon over the Earth
In the Earth–Moon system, the moon exerts its gravitational force on Earth and it
pulls the Earth towards it. Of the three points on the earth’s surface, the point ‘A’,
farthest from the moon, experiences least gravitational force due to the gravitational pull
of the moon. On the other hand, it also experiences greatest centrifugal force in the
direction opposite to that of moon’s gravitational force. Therefore, the net force will be
solely due to the centrifugal force. The point ‘B’ on the Earth, which is at the centre of
the Earth experiences equal amount of gravitational force (due to the moon’s
gravitational pull) and centrifugal force, but as they are opposite to each other, they
nullify each other. So at point ‘B’ the net force is zero. The point ‘C’ on the Earth, which
is closest to the moon experiences greatest gravitational force due to the moon. At the
same time, it also experiences least centrifugal force but in the same direction of
gravitational force, which is due to the rotation of the Earth. Therefore, the net force will
be addition of these two forces at point ‘C’, acting away from the centre of the Earth. The
poles of the earth would be pulled towards the equator due to the inward pull by the force
of gravity, which would tend to squeeze the planet. This inward squeeze causes an
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outward squish at the "equator" of the earth. The aforesaid forces and the squeezing effect
produce two bulges along the circumference of the Earth.
Fig. 12: Diagram showing Earth –Moon system and gravitational pull exerted by moon
over the earth.
FORCE OF ATTRACTION BY PLANETS, SUN AND MOON
For the case of two planets alignment with the earth the planetary force can be
calculated by using Newton’s law of gravitation in the following way.
F1
= GMm1/r12;
F2
= GMm2/r22;
T. F = F1 + F2 N
Where,
F1 is force due to the first celestial body, which aligned with earth (N),
F2 is force due to the second celestial body, which aligned with earth (N),
G is Newton’s law of gravitation (6.673 x 10-11 Nm2kg-2),
M is mass of the earth (Kg),
m1 is mass of the first celestial body (kg),
m2 is mass of the second celestial body (kg),
r1 is the distance between the first celestial body and the Earth (m),
r2 is the distance between the second celestial body and the Earth (m),
T.F is the total force exerted by the celestial bodies on the Earth (N)
The total force acts at the epicenter in the opposite direction to the rotation of the
earth. This does not, however, mean that earthquakes will occur at all edges of the plate
boundaries. In order to trigger an earthquake in one particular place three conditions
should be satisfied. They are,
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Triggering distance (T.D.): Due to the alignment of celestial bodies with the earth, two
bulges are created along the circumference of the earth. If these bulges are considered as
crests of the sine wave and the total circumference of the earth ~ 40,072 km, the
wavelength λ = 20,036 km. = ½ circumference of the earth. Then from the maximum
peak of bulge the possible epicenter would be at distance of 0.125*λ/4 or at its multiples
called as “Triggering Distance” (T.D.), on the surface of the earth. Thus the external
force from the planetary alignment, would be acting on many points on the earth
simultaneously. If any of these triggering points fall in the seismic zone, which has
matured for earthquake and the force is acting in right direction, then this could directly
trigger earthquake or it can make this region vulnerable and earthquake can occur within
few days.
Effective Direction of Forces: As the water surface forms ripples in concentric circular
manner when it gets disturbed, the planetary forces are originating from the peak point
tidal bulge in concentric circles and acted in all possible direction. The angle between the
line of planetary force and the strike of the fault is important factor to give effective
triggering. For example for a normal fault, the line of force should act perpendicular to
the strike of the fault, so that can alter normal motion of the fault. The direction
corresponds the effective triggering is called as “Effective Direction”.
Effective Energy: Since the tidal bulges created by the celestial bodies on the surface of
the earth are part of the sine wave formation, each and every point of the tidal bulges can
be divided into two components, Potential energy (P.E.) component and Kinetic energy
(K.E.) component. The peak point of the tidal bulge has maximum P.E. component and
zero value in K.E. component. As the point moves from the peak and moving towards
equilibrium position (where the tidal bulge produce zero displacement to the earth crust)
P.E component value gets decreases and K.E. component value gets increased. Finally at
the equilibrium position the P.E. component will be zero and the K.E. component will be
the maximum. Triggering of earthquake depends on the ratio of the P.E. and K.E
component and Slip of the fault region. For example, thrust faults which are indicator of
the compressive forces for deformation of a region, hence the horizontal component of
the planetary force should be more than the vertical component. This change in
deformation force magnitude due to the addition of planetary forces with the stresses of
rocks will contribute to the sudden rupture in the fault, so that the earthquakes get
triggered.
PLANETARY CONFIGURATION AND PLANETARY FORCES: IMPLICATION
FOR AFTERSHOCKS
Between December 26, 2004 and January 01, 2005 the Andaman – Sumatra
region experienced as many as 250 aftershocks of magnitude 5.0 or above on the Richter
scale. During this one week period, the planetary alignment of Venus and Mercury with
the earth that triggered the great Sumatra earthquake on December 26, 2004 was
persistent. This resulted in a series of aftershocks that release the stress interminently.
Simultaneously, there was also a gradual decrease in the net planetary force as well as
number of aftershocks as is evident from Fig. 13.
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4.50E+16
160
4.45E+16
140
4.40E+16
4.35E+16
120
100
4.30E+16
80
4.25E+16
60
4.20E+16
4.15E+16
40
Planetary Force
1/
1/
20
05
31
/1
2/
20
04
30
/1
2/
20
04
29
/1
2/
20
04
28
/1
2/
20
04
0
27
/1
2/
20
04
20
4.05E+16
26
/1
2/
20
04
4.10E+16
Number of Events per day above 5.0
Fig. 13: Graph showing relation between planetary force and number of earthquakes in
Sumatra region 2004.
Fig. 14: Graph showing relation between planetary force and number of earthquakes in
Indo – Pak region 2005.
From the fig. 14, one can infer that the energy released from the aftershocks
increases with magnitude of planetary forces. As the day progress planetary forces
decreases and energy released from the aftershocks also get decreased. Again the energy
released from the aftershock increases with increase in planetary forces. This analysis
proves comprehensively the role of planetary configuration and its associated planetary
force in triggering not only the main event but also the ensuing aftershocks.
THE LARGEST EARTHQUAKES IN THE CONTIGUOUS UNITED STATES
The contiguous United States has been haunted over the past 25 years by nine big
earthquakes of magnitudes 5.5 to 7.8 killing hundreds of thousands of people (Freund,
1999). Analysis of largest earthquakes from the Cascadia Earthquake (26 January 1700)
to Landers, California Earthquake (26 August 1992) clearly indicates the importance of
direction of planetary forces acting at a particular point to trigger an earthquake. From
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EARTHQUAKE PREDICTION TECHNIQUES
Figure 5.5, it can be comprehended that out of 15 earthquakes, 9 occurred when planets
were positioned around 270o to 300o. Also, earthquakes with magnitude above 7.8 on the
Richter scale occurred when the planets were positioned between 270o and 290o. This
would imply that if the planets are in alignment with the Right Ascension range of 270o
to 300o, and the triggering distances coincide, the planets could exert the force on the
contiguous United States and trigger devastating earthquakes provided the accumulated
stress levels are sufficient enough in this region.
10
9
8
7
6
5
4
3
2
1
0
350
300
250
200
150
100
50
0
1
2
3
4
5
6
7
8
Magnitude
9
10 11 12 13 14 15
R.A.
Fig. 15: The relation between planetary positions and occurrence of earthquakes in
contiguous United States
SUCCESSES AND FAILURES IN THE HISTORY OF EARTHQUAKE
PREDICTION
One well-known successful prediction was for the Haicheng earthquake (China)
of 1975 (M 7.3). Evacuation warning was issued a day before the event occurred. In the
preceding months, changes in land elevation and ground water levels, widespread reports
of peculiar animal behaviour, and many foreshocks had led to a lower level warning. An
increase in foreshock activity triggered the evacuation warning.
In spite of innumerable warning signs at our disposal, most earthquakes
unfortunately do not have such obvious precursors. For example, there was no foreshocks
were observed before the 1976 Tang Shan earthquake (magnitude 7.6), which caused an
estimated 250,000 fatalities.
Sometimes these early warning signs before the major earthquakes may even be
misleading. For example, from August 12 – 19, 2003, in and around the Jamnagar taluk
in Gujarat some minor tremors of magnitude 3.0 were recorded. The Gujarat government
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EARTHQUAKE PREDICTION TECHNIQUES
geared itself to face another major disaster like Bhuj 2001 earthquake, but fortunately
nothing happened.
COMPARISON BETWEEN 1975 HAICHENG EARTHQUAKE AND 1976 TANG
SHAN EARTHQUAKE
Based on planetary configuration analysis, it is observed that for Haicheng
earthquake, Mars and Saturn, both of them outer orbit planets with respect to the Earth,
were more or less in a straight line (Table 3), while for the Tang Shan earthquake, Moon,
Mercury and Venus (inner orbit planets to nearer to the earth) were in alignment. The
inner orbit planets have relatively higher angular velocity in comparison with the outer
orbit planets. The alignment of Mercury, Venus and Moon in a more or less straight line
with the Earth was comparatively for a short duration thereby triggering the Tang Shan
earthquake without any foreshocks. In the case of Haicheng earthquake, however, Mars
and Saturn being outside of the earth’s orbit and farther from the Earth, they came in
alignment initially causing the foreshocks and finally the main event. Sufficient warning
signs were, therefore, noticed and the evacuation warning given. Moreover, the total
force that acted at the time of the Tangshan earthquake was 3.450884512 x 1028 N more
than the planetary force during the Haicheng earthquake. The total angular momentum of
planets that were in alignment was also greater by a value of 103 kgm2s-1. Both these
factors could be the reason for the higher magnitude of the Tangshan earthquake.
Parameters
Haicheng (M 7.0)
Tang Shan (M 7.5)
Planets aligned
Mars & Saturn
Mercury & Venus
Triggering Distance
1.25 /4
1.5 /4
Total Force
1.5488 x 1023 N
3.4509 x 1028 N
Total Angular Momentum
23.8 x 1036 kgm2s-1
2.7 x 1040 kgm2s-1
Table 3: A comparison between Haicheng, 1975 and Tang Shan, 1976 earthquakes
Another comparison between the Bhuj and Jamnagar quakes revealed some
interesting observations. Even though, the planetary configurations for both cases, was
favourable of triggering earthquakes, the magnitude of Bhuj earthquake was relatively
much higher (7.7). This is attributable to the action of planetary forces in north easterly
direction, perpendicular to the fault line. For the Jamnagar tremors, however, the action
of planetary forces was towards west, and not normal to the fault line at that place,
resulting in relatively less magnitude (~3).
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EARTHQUAKE PREDICTION TECHNIQUES
Planets Involved
Triggering Distance
Total Force
Direction of Force
Total Angular Momentum
Bhuj (M 7.7)
Jamnagar Mild Tremors
Mars & Saturn
Sun, Venus & Jupiter
1.125λ/4
No Coincidence with T.D.
1.5488 x 1023 N
3.4509 x 1028 N
NE direction
Western direction
23.8 x 1036 kgm2s-1
2.7 x 1040 kgm2s-1
Table 4: The comparison between the action of planetary forces for Bhuj 2001 Earthquake and
Jamnagar Mild tremors
If a fault segment is known to have broken in a past major earthquake, recurrence
time and probable magnitude can be estimated based on fault segment size, rupture
history, and strain accumulation. This forecasting technique can only be used for wellunderstood faults, such as the San Andreas. No such forecasts can be made for poorlyunderstood faults, such as those that caused the 1994 Northridge, California and 1995
Kobe, Japan quakes. Along the San Andreas Fault, the segment considered most likely to
rupture is near Parkfield, California.
Using a set of assumptions about fault mechanics and the rate of stress
accumulation, the United States Geological Survey (USGS) made a more precise
Parkfield prediction – of a M 6.0 earthquake between 1988 and 1992. Though that
prediction failed to materialize during the aforesaid period, an M6.0 earthquake did occur
on September 28, 2004, but its rupture was opposite to what had been predicted.
SCOPE AND SIGNIFICANCE OF THE WORK
Earthquakes are natural disasters killings human beings and damaging man-made
structures. Research efforts need to find methods by which people living in earthquake
prone areas can be warned a few days or a few hours, at least in advance, of an
impending disaster. This time frame is required for the evacuation of people to relatively
safe areas. By now, causes of earthquakes are well known and earthquake-prone areas are
also being indicated from time to time all over the world. However, earthquakes will
continue to occur with the same disastrous effect in the absence of accurate prediction.
The earthquake-related hazards are avoidable, if prediction can be made early and
accurately, which would enable mitigation of the natural hazard, reduce damage to life
and property drastically and facilitate precautionary measures by government and NGOs.
Dr. N.Venkatanathan
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