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 pre-seismic 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.

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.

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 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 earthquake-triggered 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 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 ( = 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 (), where, 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 = 20 and = 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 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)/j 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 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 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. 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 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 29 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 signicant 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.

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 pre-programmed 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 high-technological 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 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 earths surface, the displacement or relative movement of the earths gravitational center, a precursor in advance of an imminent EQ in 5 to 6 days. Given, at least 3 measuring points of earths 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]. EQs ISW frequency range is from 5 to 12 Hz, but whereas, EQs precursor frequency range is < 1 Hz. Wind pressure variations and ISW are separable, in later case signals are coherent over several kilometers. Atmospheric components are relatively dynamic than solid earths 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 EQs 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 long-term 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.

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 animals 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 animals 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.

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 K 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, (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."

Fig. 4: Frog came out their place before Sichuan Earthquake 2008.

EARTHQUAKE PREDICTION TECHNIQUES

Dr. N.VenkatanathanPage 6

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

sudden darkness, loud explosion

Dogs

Barking, follow owner constantly from room to room

territorial, stranger response, over dependent pet

Fish

jump out of water change depth in water

quick turns, hunting

Mice

behave as if drunken, convulsions

audiogenic seizure with noise of 4-80 kHz, 90-130 dB

Mussels

move to higher attachment sites

on seashore

as water rose before hurricane

Pigs

biting each others' tails

overcrowded conditions

Rats

vigilance, jumpiness, vertical leaping, crouch like gesture, muscle contractions

alarm response to ground predators, 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 earthquakes 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 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 reservoir- induced 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 earths surface. Simultaneous and continuous geodetic measurements 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 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.

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.

Fig. 7: InSAR image - 1999 Hector Mine earthquake.

SAR can provide high-resolution imagery of earthquake-prone areas, high-resolution 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-spatial-resolution 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 414 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, 2001Fig. 8 (b): January 21, 2001

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 earthatmosphere 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.

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, 2004December 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 during the first half of the 20th century show annual fluctuation in the earths 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 moons 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 earths surface.

This collision leads to a disturbance in the earths 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.

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.

EarthMoon system and gravitational pull exerted by Moon over the Earth

In the EarthMoon system, the moon exerts its gravitational force on Earth and it pulls the Earth towards it. Of the three points on the earths 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 moons 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 moons 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 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 Newtons 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 Newtons 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,

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 = 20,036 km. = circumference of the earth. Then from the maximum peak of bulge the possible epicenter would be at distance of 0.125*/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.

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 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.

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 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 earths 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).

Bhuj (M 7.7)

Jamnagar Mild Tremors

Planets Involved

Mars & Saturn

Sun, Venus & Jupiter

Triggering Distance

1.125/4

No Coincidence with T.D.

Total Force

1.5488 x 1023 N

3.4509 x 1028 N

Direction of Force

NE direction

Western direction

Total Angular Momentum

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 well-understood faults, such as the San Andreas. No such forecasts can be made for poorly-understood 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.

STATISTICAL METHODS

Recurrence Frequency

Seismic Gap Theory

Slip Rates

Using Trees to Date Earthquakes And Crustal Movements

CN AND M8 ALGORITHMS

4.05E+16

4.10E+16

4.15E+16

4.20E+16

4.25E+16

4.30E+16

4.35E+16

4.40E+16

4.45E+16

4.50E+16

26/12/200427/12/200428/12/200429/12/200430/12/200431/12/2004

1/1/2005

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Planetary ForceNumber of Events per day above 5.0

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