There are some methods for medium and short range earthquake forecasting.

These methods are concerned with forecasting earthquake of a particular intensity over a specified locality within a specified time limit.

by

Dr. Nitish Priyadarshi

Tectonic earthquakes are attributed to rupture in the rock masses which occur following accumulation of strain. Earthquakes present a frightening experience in the lives of men. The disaster strikes suddenly, similar to that of lightning, tornadoes or nuclear explosions. It is estimated that an average, about 15,000 human lives are lost every year, while in a singe year of 1976 about 200, 000 were killed by earthquakes in china, Guatemala, Philippines and in other parts of the world. The damage to property runs into billions of dollars.

Earthquakes generate a variety of effects. Some are temporary, such as the shaking ground, swinging objects, rattling windows and oscillating trees. Permanent effects include damage to buildings, transportation, water supply systems and the landslides.

Till today there is no perfect method to forecast earthquakes. There are some methods for long, medium and short range earthquake forecasting. My article is more concentrated on medium and short range earthquake forecasting.

Medium term prediction means forecast of an earthquake a few months to a year or more ahead, while short term prediction implies forecast ranging from a few hours to some day in advance. The medium and short range stages in earthquake prediction are concerned with forecasting the occurrence of an earthquake of a particular intensity over a specified locality within a specified time limit. Satisfying this criterion, a few earthquakes have been successfully predicted in Japan, USA former USSR, India and China. It is actually these two stages of earthquake prediction which save the largest population from disaster in terms of life or property, and is more often demanded by public as well as Government. Even though the medium and short range prediction techniques are broadly similar using several disciplines of geophysics, some simple observations like earthquakes lights or sounds, unusual behaviour of animals, changes in the level and colours of well water, hydrochemical changes and foreshocks can be of great assistance from the point of view of short range prediction of large earthquakes.

Unusual animal behaviour: Unusual behaviour of animals prior to earthquakes received wide publicity after the Haichang earthquake of February 4, 1975 was successfully predicted in China. The official report was presented by the Chinese delegation at the Inter-governmental meeting convened at UNESCO, Paris in February 1976 which stimulated considerable scientific interest. Prior to this, however, several instances of abnormal animal behaviour were noticed before occurrence of some of the damaging earthquakes in different parts of the world, but they were considered more as historical legend. In Japan, innumerable rats were seen every day in a restaurant in Nagoya city, which suddenly disappeared on the evening prior to the Nobi earthquake of 1891.
Hyodrochemical precursors: Regular observations of the chemical composition of underground water were taken during 1997 in seismically active regions of Tadzhik, and Uzbekistan. The water samples were analyzed in the following two ways:
· The concentration levels of dissolved mineral components like sodium and calcium ions, bicarbonate and chloride ions were measured before, during and after the earthquakes.
· The gaseous components of water like helium and hydrogen sulfide were analyzed at various intervals of time.
The following results were obtained:
· During seismically inactive period, the concentration levels of dissolved minerals and gaseous components remained almost constant.
· About 2 to 8 days before an earthquake, appreciable increase in the concentration for dissolved minerals was noticed. Also, the maximum volume of helium gas in thermal water occurred 3 to 5 days before the increase in seismic activity.

Significant pre-disaster and post disaster hydro geo-logical changes rendering the groundwater turbid were observed during Jabalpur earthquake, 1997 (I.M.D. Report 1998).

The mechanism of the behaviour of these hydro geochemical precursors is attributed to the upsetting of balance in the rock/interstatial solution/ underground water system prior to earthquake. This is due to increase of stress and the consequent appearance of permeable fissures through which an increased inflow underground fluid from the subsurface zones of the earth’s crust takes place.
Temperature changes: A rise of temperature by 10 degree c. and 15 degree c. was reported before earthquakes in Lunglin, China (1976) and Przhevalsk, Russia (1970). Same relationship between magnitude and geothermal anomaly has been found for earthquakes in China.
Water level: Unusually muddy and fall in the level of water was reported in several wells a few days before the great Nankai earthquake (1946) in Japan. However, rise of water level by 3 and 15 cm was also reported before the Lunglin (China) and Przhevalsk (Russia) earthquakes. Similarly, water level rose by 3 cm a few hours before the earthquakes in Meckering, Australia (1968). In general a pre-seismic variations at observation wells follows this sequence:1) A gradual lowering of water levels of a period of months or years2) An accelerated lowering of water levels (rate often exponential) in the final few months or weeks preceding the earthquake. 3) A “rebound” where water levels begin to increase rapidly in the last few days or hours before the main shock.In the monitoring of water levels in deep wells, care must be taken to correct the data for “earth tides”. This is due either to volume changes caused in fractured aquifers by tidal strain, or perhaps by changes in gravitational acceleration alone. In either case, it is important that data is corrected for this phenomenon. In addition water extraction from the aquifer must also be considered. In many part’s of the planet the water table is falling due to water abstraction for drinking and irrigation. It is quite possible that such drops could be mistaken for a long-term seismic precursor.


Radon gas: The first evidence of a correlation between radon and earthquake came from Tashkent Basin prior to destructive earthquake in 1966. Radon observations revealed many precursory changes in its concentration as far as 1800 km from their respective epicenters. The measured radon in soils could be strongly disturbed by meteorological parameters, seasonal factors as well as a deeper phenomenon of seismic activity. Variety of studies which use complex mathematical methods have been done in order to distinguish between the variations of radon caused by environmental factors.

Work carried out in this direction was based upon the assumption that significant changes take place in the emission of gases such as radon and trapped in the earth crust before the arrival of a 'physical jolt' of an earthquake. This change takes place because of the physical stresses which are built up within the earth crust to trigger an earthquake. Work so far done has indicated the existence of a relationship between earthquake producing processes and radon movement. It has been noted that variation in radon levels is related to the intensity of an approaching earthquake.

Radon is a radioactive gas with a half-life of about 2.5 days. It is discharged from rock masses prior to an earthquake and dissolves in the well water which shows increase in its concentration.
Oil wells: some cases of sharp fluctuations in the oil flow prior to earthquakes were reported for wells in Israel, northern Caucasus and China. It is argued that when the tectonic stress accumulates to certain level, the pore pressure within a deep oil bearing strata may reach its breaking strength causing oil to spout along the oil wells.
Changes in the Electrical Resistivity of Rocks - Electrical resistivity is the resistance to the flow of electric current . In general rocks are poor conductors of electricity, but water is more efficient a conducting electricity. If microcracks develop and groundwater is forced into the cracks, this may cause the electrical resistivity to decrease (causing the electrical conductivity to increase). In some cases a 5-10% drop in electrical resistivity has been observed prior to an earthquake.
Ground Uplift and Tilting of the ground - Measurements taken in the vicinity of active faults sometimes show that prior to an earthquake the ground is uplifted or tilts due to the swelling of rocks caused by strain building on the fault. This may lead to the formation of numerous small cracks (called microcracks). This cracking in the rocks may lead to small earthquakes called foreshocks.


Reference:

Srivastava, H.N. 1983. Earthquakes, Forecasting and Mitigation. National Book Trust, India, New Delhi.

Gupta, D. and Shahani, D.T. 2011. Estimation of Radon as an Earthquake Precursor: A neural network approach. Jr. of Geol. Soc. Of India, Vol.78, pp. 243-248.

http://www.fujitaresearch.com/reports/earthquakes.html
http://earthsci.org/processes/struct/equake3/EQPredictionControl.html http://www.medicaljournal-ias.org/Belgelerim/Belge/KhanFXTDIRNGCH45570.pdf

Can animals predict earthquakes?

Most animals show increased restlessness before an earthquake.

Govindpur in Jharkhand animals were nervous before earthquake.

by

Dr. Nitish Priyadarshi

Picture credit: animalsandearthquakes.com/etho-g5.gif
In order to reduce the risk of an earthquake and reduce and mitigate its effects, it is necessary to predict where and when a future, large earthquake may occur. For example, it would be important to know when such an earthquake will hit, where it will strike, and what the level of its destructiveness may be. Earthquake prediction at the present time is not an exact science, and forecasts of earthquake occurrences have not been very accurate. Presently predictions are given in statistical terms. For example, when a prediction is made that :here is a 90% chance that an earthquake will occur in the next 50 years", it does not mean that this earthquake cannot happen tomorrow or it may not be delayed by 50 years. Thus, present predictions are not within a reasonable time frame that can be of usefulness to planners, policy makers, and those in government that deal with public safety.

Unusual behaviour of animals prior to earthquakes received wide publicity after the Haichang earthquake of February 4, 1975 was successfully predicted in China. The official report was presented by the Chinese delegation at the Inter-governmental meeting convened at UNESCO, Paris in February 1976 which stimulated considerable scientific interest. Prior to this, however, several instances of abnormal animal behaviour were noticed before occurrence of some of the damaging earthquakes in different parts of the world, but they were considered more as historical legend. In Japan, innumerable rats were seen every day in a restaurant in Nagoya city, which suddenly disappeared on the evening prior to the Nobi earthquake of 1891.
Since the beginning of recorded history, observations of unusual animal behavior before earthquakes have been recorded by people from almost all civilizations. The animal behavior reports are often ambiguous and not consistently observed. In folklore, some animals have had more reports of being able to predict earthquakes than others, especially dogs, cats, chickens, horses, and other smaller animals. There have been reports with elephants, as well. Goats, cows, and most larger animals are generally reported as being less able to predict earthquakes.

In 1920, the largest earthquake to hit China with a magnitude of 8.5 occurred in Haiyuan County, Ninghxia Province. According to reports of eyewitnesses, prior to this earthquake, wolves were seen running around in packs, dogs were barking unusually, and sparrows were flying around wildly. It is reported that prior to the 6.8 magnitude earthquake in 1966 in Hsingtai County, Hopei Province, in Northern China, all the dogs at a village near the epicenter had deserted their kennels and thus survived the disaster.

The earliest reference we have to unusual animal behavior prior to a significant earthquake is from Greece in 373 BC.

As early as 1886, a seismologist named Milne had mentioned that dogs escaped from the city of Talcahuano in Chile before an earthquake (1835). Flocks of birds flew inland before the Chilean earthquakes of 1822 and 1835. Monkeys were reported to have become restless a few hours before the Managua earthquake (1972) in Nicaragua. In the Tientsin region of China, chickens refused to enter their dens, tigers became restless, yaks declined to eat and horses and sheep started running restlessly a few hours before the earthquakes of July 18, 1969. Hens and cocks were reported restless about an hour prior to the 1896 Ryukyu earthquake in Japan. In Yugoslavia, birds in zoo started crying before the 1963 earthquake. Deer gathered and cats disappeared from villages in northern Italy two or three hours before a damaging earthquake occurred in 1976. Such observations have also been noticed among animals who live underground, like snakes, insects and worms, and those living in water (fishes).

In Japan, fishes were reported to have disappeared before the Kanto earthquakes of 1923. Just before the 1855 Edo earthquake on November 11, many grass snakes were reported to have come out of the ground near the epicentral area, despite severe cold. Other instances involving fishes have been reported in Japan near north-western coast before the 1896 earthquake and the Tango earthquake of 1927 when abundant fishes were caught near the coast.

An interesting instance of unusual behaviour of dogs (but not of other animals) was reported before the destructive earthquake on November 24, 1976 in Turkey (Toksoz,1979).

Although several destructive earthquakes have occurred in the Himalayan region and elsewhere only one authentic observation of unusual animal behaviour was reported in India. In Govindpur in Jharkhand state of India, on February 19, 1892, animals were noticed to sniff the ground and exhibit nervousness such as dog shows in the presence of an unaccustomed object, while the air had distinctly sulphurous smell an hour before the shock.

During the recent damaging earthquakes in India of Uttarkashi (1991), Latur (1993), Jabalpur (1997), Chamoli (1999) and Bhuj (2001), there were reports of isolated cases of unusual behaviour of pet dogs, but the phenomenon was not observed on a large scale. According to the Chief conservator of forests for the Indian state of Tamil Nadu, a few minutes before the killer tsunami waves generated by an underwater earthquake hit the Indian coastline in December 2004, a herd of 500 blackbucks rushed away from the coastal areas to the safety of a nearby hilltop.

The Group of Earthquakes Research of the Institute of Biophysics, China (1979) carried extensive survey of the animal behaviour before damaging earthquakes occur. Its results are summarized below.
1. Most animals show increased restlessness before an earthquake.
2. The precursor time varies from a few minutes to several days, with increased restlessness at 11 hours which becomes still more marked about 2 to 3 hours before the earthquake. In general, the precursor times of various animals are mostly within 24 hours before the earthquake.
3. These observations have been noticed predominantly in the high intensity or epicentral regions close to active faults.
4. Changes in animal behaviour are observed during earth- quakes of magnitude 5 or more.
5. More intense responses can be noticed with the increase of intensity of earthquakes.

We can easily explain the cause of unusual animal behavior seconds before humans feel an earthquake. Very few humans notice the smaller P wave that travels the fastest from the earthquake source and arrives before the larger S wave. But many animals with more keen senses are able to feel the P wave seconds before the S wave arrives. As for sensing an impending earthquake days or weeks before it occurs, that's a different story.
There is little evidence for animals being able to sense earthquakes before they happen, although it is likely they can sense the initial, weaker P-wave or ultrasonic wave generated by a big underground explosion or the rupture of an earthquake, even if the waves are too small for humans' senses. These waves travel faster than the S-wave and Rayleigh earthquake waves that most strongly shake the ground and causes the most damage. It is speculated that when this happens, animals can detect the incoming earthquake wave, and start behaving agitatedly or nervously.

Others postulate that the animal behavior is simply their response to an increase in low-frequency electromagnetic signals. The University of Colorado has demonstrated that electromagnetic activity can be generated by the fracturing of crystalline rock. Such activity occurs in fault lines before earthquakes. According to one study, electromagnetic sensors yield statistically valid results in predicting earthquakes.

Accounts of similar animal anticipation of earthquakes have surfaced across the centuries since. Catfish moving violently, chickens that stop laying eggs and bees leaving their hive in a panic have been reported. Countless pet owners claimed to have witnessed their cats and dogs acting strangely before the ground shook—barking or whining for no apparent reason, or showing signs of nervousness and restlessness.

But precisely what animals sense, if they feel anything at all, is a mystery. One theory is that wild and domestic creatures feel the Earth vibrate before humans. Other ideas suggest they detect electrical changes in the air or gas released from the Earth.

Geologists, however, dismiss these kinds of reports, saying it's "the psychological focusing effect," where people remember strange behaviors only after an earthquake or other catastrophe has taken place. If nothing had happened, they contend, people would not have remembered the strange behavior.

Reference:

Srivastava, H.N., 1983.Earthquakes. National Book Trust, India.

Toksoz, M.N. 1979. Field investigations of the 24 November 1976 earthquakes in Turkey and its precursors. Int. Symp. Eathq. Pred. (UNESCO, Paris), Abstracts.

http://www.drgeorgepc.com/EarthquakePredictionChina.html
http://earthquake.usgs.gov/learn/topics/animal_eqs.php
http://news.nationalgeographic.com/news/2003/11/1111_031111_earthquakeanimals.html

Khejri Tree can predict earthquakes- says a report.

Khejri plants are available in plenty in desert areas of India.

by

Dr. Nitish Priyadarshi.

Earthquakes present a frightening experience in the lives of the men. The disaster strikes suddenly, similar to that of lightning, tornadoes or nuclear explosions. It is estimated that, on an average, about 15,000 human lives are lost every year, while in a single year of 1976 about 2,00,000 were killed by earthquakes in China, Guatemala, Philippines and in other parts of the world. The damage to property runs into billions of dollars. The growing demand on seismologists to predict earthquakes is therefore, not unjustified.

It is easy to achieve better success in forecasting those disciplines of science which are directly accessible to observations, such as atmosphere. In the case of solid earth, however, difficulties of digging even a few kilometers to reach the focal zone of earthquakes for in situ observations are well known. Nevertheless, a beginning has been made to evolve methods of forecasting earthquakes and limited success has been achieved.

Of the other forecasting methods, plants like Khejri (Prosopis cineraria ) is now catching the eyes of geoscientists. According to a research report in Rajasthan State of India, we can gauge the geological tremors through the leaves of Khejri. In case, the activities under the earth decrease, then the leaves of Khejri trees faint. The geologists say that the loss of life and property can be prevented through the pre-indication of Khejri leaves planted in the earthquake –prone areas. The specialists advise to plant and protect the Khejri tree.

Prosopis cineraria tree grows in dry and arid regions of Arabia and in regions of India mainly Rajasthan, Haryana, Punjab, Gujarat, Western Uttar Pradesh and drier parts of Deccan and extends as far as South in Tuticorin. In this region also it is confined only to comparatively drier areas where the normal annual rainfall is less than 500 mm. In the most important areas of Prosopis cineraria distribution, the climate is dry to arid and rainfall shows considerable variation 100 to 600 mm annually with a long dry season.

But before coming to any conclusion more research is needed on this plant.

Earlier unusual behaviour of the animals prior to earthquake received wide publicity after the Haichang earthquake of February 4, 1975 was successfully predicted in China. In Japan, innumerable rats were seen every day in a restaurant in Nagoya city, which suddenly disappeared on the evening prior to the Nobi earthquake of 1891. As early as 1886, a seismologist named Miline had mentioned that dogs escaped from the city of Talcahuano in Chile before an earthquake of 1835. Flocks of birds flew inland before the Chilean earthquakes of 1822 and 1835.

However, any scientific explanation at present does not appear to be acceptable unless the phenomenon is observed almost universally. Charles Richter once said, “Only fools, charlatans, and liars predict earthquakes.”