Earthquake prediction

Animal behavior

Animals can detect the 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 earthquake wave that most strongly shakes the ground and causes the most damage. When this happens, animals can detect the incoming earthquake wave, and start behaving agitatedly or nervously, the same way a human would behave if they heard a loud explosion right outside their house.

Some people believe that in this way animals sense the immediate onset of earthquakes. In support of this claim, instances are cited when people have witnessed flight of animals just before an earthquake disaster. In fact, according to the Chief conservator of forests for Tamilnadu, a few minutes before the killer tsunami waves generated by an underwater earthquake hit the Indian coastline in December 2004, a 500-strong herd of blackbucks rushed away from the coastal areas to the safety of a nearby hilltop. Since the beginning of recorded history, observations of unusual animal behavior before earthquakes have been recorded by people from almost all civilizations. The Chinese began a systematic study of this unusual animal behavior and in December 1974 predicted a major earthquake that did, in fact, occur in February 1975. But skeptics claim to debunk nearly all such observations. In fact, the 1975 prediction relied most heavily on a series of strong foreshocks. The animal behavior reports are often ambiguous and not consistently observed. There is little evidence for animals being able to sense impending earthquakes, although it is likely they can sense the initial, weaker P-waves before people. Seismometers remain much more sensitive than even the animals, however.

In folklore, some animals have had more reports of being able to predict quakes than others. Likely: Dogs, cats, chickens and other smaller animals. There have been reports with elephants, too. Unlikely: Goats, horses, cows, and larger animals.

Japan has a long tradition associating catfish with earthquake prediction. From this idea emerged a long university research programme concluding in 2004 in which it was proposed that the (established) high sensitivity of catfish to electric fields was involved in detecting fields of a few hertz because of piezoelectric effects on deeply buried quartz crystals. Actual monitoring of catfish and correlation with earthquakes gave results that are not promising.

Other predictions

In early 2004, a group of scientists at the University of California, Los Angeles, lead by Dr. Vladimir Keilis-Borok, predicted that a quake similar in strength to the San Simeon earthquake would occur in a 12,000 square mile (31,100 km) area of Southern California by September of that year. The odds were given as 50/50.

In April 2004, the California Earthquake Predicition Evaluation Council (CEPEC) evaluated Keilis-Borok's prediction and reported to the California State Office of Emergency Services. CEPEC concluded that the "uncertainty along with the large geographic area included in the prediction (about 12,400 square miles) leads (us) to conclude that the results do not at this time warrant any special policy actions in California.” The predicted time window came and went with no significant earthquake.

Based on the historic record of the various published efforts to predict a quake, one might conclude that earthquake prediction is usually imprecise, but remains an art that is scientifically and socially useful.

According to new research to be published by Prof. Shlomo Havlin, of Bar-Ilan University's Department of Physics, earthquakes form patterns which can improve the ability to predict the timing of their recurrence. In November 2005 (Nov 11 issue) the journal Physical Review Letters, published by the American Physical Society, published an article by researches from Israel and Germany that say that there is a way to predict when the next earthquake will hit.

Prof. Shlomi Havlin's from Bar-Ilan University in Israel, in collaboration with Prof. Armin Bunde, of the Justus-Liebig University in Giessen, Germany, and Bar-Ilan University graduate student Valerie Livina used the "scaling" approach from physics to develop a mathematical function to characterize earthquakes of a wide range of magnitudes in order to learn from smaller magnitude earthquakes about larger magnitude earthquakes. The team's findings reveal that the recurrence of earthquakes is strongly dependent on the recurrence times of previous earthquakes.

This memory effect not only provides a clue to understanding the observed clustering of earthquakes, but also suggests that delays in earthquake occurrences, as seen today in Tokyo and in San Francisco, are a natural phenomenon.

In another paper in the journal Nature (November 9 issue, [link]), Richard Allen of the University of California claims that the distinction between small and large earthquakes can be made from the very first seconds of seismic energy recorded by seismometers, though other scientists are not convinced. If correct this may make earthquake early warning (as distinct from prediction) possible.

Loma Prieta, California

From 1968 to 1988 scientists in California mapped seismic activity on a cross section of the fault lines. They identified a big "seismic gap" in the Loma Prieta area where no earth shaking had occurred during the study. They therefore concluded that Loma Prieta was due an earthquake. In 1989 a quake measuring 7.1 hit the area causing 63 deaths. This prediction, however was not very useful as it couldn't predict the exact date.

See also

• Earthquake storm
• Earthquake weather
• Jim Berkland (and the role of the moon)

References