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An earthquake prediction is a prediction that an earthquake of a specific magnitude will occur in a particular place at a particular time (or ranges thereof). Despite considerable research efforts by seismologists, scientifically reproducible predictions cannot yet be made to a specific hour, day, or month but for well-understood faults, seismic hazard assessment maps can estimate the probability that an earthquake of a given size will affect a given location over a certain number of years.

Once an earthquake has already begun, early warning devices can provide a few seconds' warning before major shaking arrives at a given location. This technology takes advantage of the different speeds of propagation of the various types of vibrations produced. Aftershocks are also likely after a major quake, and are commonly planned for in earthquake disaster response protocols.

Experts do advise general earthquake preparedness, especially in areas known to experience frequent or large quakes, to prevent injury, death, and property damage if a quake occurs with or without warning.

Prediction techniques

In the effort to predict earthquakes, people have tried to associate an impending earthquake with such varied phenomena as seismicity patterns, electromagnetic fields (Seismo-electromagnetics), ground movement, weather conditions and unusual clouds, radon or hydrogen gas content of soil or ground water, water level in wells, animal behavior, and the phases of the moon.

Many pseudoscientific theories and predictions are made, which scientific practitioners find problematic. The natural randomness of earthquakes and frequent activity in certain areas can be used to make "predictions" which may generate unwarranted credibility. These generally leave certain details unspecified, increasing the probability that the vague prediction criteria will be met, and ignore quakes that were not predicted. Rudolf Falb's "lunisolar flood theory" is a typical example from the late 19th century.

Evaluation of prediction theories

Official earthquake prediction evaluation councils have been established in California (the California Earthquake Prediction Evaluation Council) and the federal government in the United States (the National Earthquake Prediction Evaluation Council), but have yet to endorse any method of predicting quakes as reliable.

Scientific evaluations of prediction claims look for the following elements in a claim:

• A specific location or area
• A specific span of time
• A specific magnitude range
• A specific probability of occurrence

Attribution to a plausible physical mechanism lends credibility, and suggests a means for future improvement. Reproducibility and statistical analysis are used to distinguish predictions which come true due to random chance (of which a certain number are expected) versus those that have more useful predictive capability, and to validate models of long-term probability. Such models are difficult to test or validate because large earthquakes are so rare, and because earthquake activity is naturally clustered in space and time. "Predictions" which are made only after the fact are common but generally discounted.

Radon

Emission of radon as a quake precursor was studied in the 1970s and 1980s, with no reliable results. It is still under study at NASA as of 2009.

The VAN method

VAN is a method of earthquake prediction proposed by Professors Varotsos, Alexopoulos and Nomicos in the 1980s; it was named after the researchers' initials. The method is based on the detection of "seismic electric signals" (SES) via a telemetric network of conductive metal rods inserted in the ground. The method stems from theoretical predictions by P. Varotsos, a solid-state physicist at the National and Capodistrian University of Athens. It is continually refined as to the manner of identifying SES from within the abundant electric noise the VAN sensors are picking up. Researchers have claimed to be able to predict earthquakes of magnitude larger than 5, within 100 km of epicentral location, within 0.7 units of magnitude and in a 2-hour to 11-day time window.

Foreshock predictions

Foreshocks are medium-sized earthquakes that precede major quakes.

An increase in foreshock activity (combined with purported indications like ground water levels and strange animal behavior) enabled the successful evacuation a million people one day before the February 4, 1975 M7.3 Haicheng earthquake by the China State Seismological Bureau.

While 50% of major earthquakes are preceded by foreshocks, only about 5-10% of small earthquakes turn out to be foreshocks, leading to many false warnings.

Pattern theories

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 (November 11 issue) the journal Physical Review Letters, published by the American Physical Society, published an article by researchers from Israel and Germany that say that there is a way to predict when the next earthquake will hit.

Prof. Shlomo 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.

Fractoluminescence

One possible method for predicting earthquakes, although it has not yet been applied yet, is fractoluminescence. Studies at the Chugoku National Industrial Research Institute by Yoshizo Kawaguchi have shown that upon fracturing, silica releases red and blue light for a period of about 100 milliseconds. Kawaguchi attributed this to the relaxation of the free bonds and unstable oxygen atoms that are left when the silicon oxygen bonds have broken due to the stresses within the rock.

Satellite observations

Demeter microsatellite

The "Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions" satellite, constructed by CNES, has made observations which show strong correlations between certain types of low frequency electromagnetic activity and the seismically most active zones on the Earth, and have shown a sharp signal in the ionospheric electron density and temperature near southern Japan seven days before a 7.1 magnitude occurred there (on August 29 and September 5, 2004, respectively).

QuakeSat nanosatellite

Quakesat is an earth observation nanosatellite based on 3 CubeSats. It was designed to be a proof-of-concept for collecting Extremely low frequency earthquake precursor signals from space. The primary instrument is a magnetometer housed in a 2 foot (0.6 m) telescoping boom.

The ESPERIA Project

ESPERIA is an equatorial space mission mainly conceded with detecting any tectonic and preseismic related signals. More in general, it has been proposed for defining the near-Earth electromagnetic, plasma, and particle environment, and for studying perturbations and instabilities in the ionosphere-magnetosphere transition region. To study earthquake preparation processes and anthropogenic impacts in the Earth's surface, a phase A study has been realized for the Italian Space Agency.

Early warning

An earthquake warning system is a system of accelerometers, communication, computers, and alarms that is devised for regional notification of a substantial earthquake while it is in progress. Japan, Taiwan and Mexico all have earthquake early-warning systems.

Magnitude problem

In a paper in the journal Nature, 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) more powerful. Earthquake early warning provides an alarm that strong shaking is due soon to arrive, and the more quickly that the magnitude of an earthquake can be estimated, the more useful is the early warning. However, earthquake early warning can still be effective without the ability to infer the magnitude of an earthquake in its initial second or two.

Animal early warning

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.

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.

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.

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.

Earthquake-prone Japan has a long tradition associating catfish with earthquake prediction. From this idea emerged a long university research program 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.

Tidal forces

There are two flavors of tidal stressing that have been claimed to generate enhanced rates of earthquakes - diurnal and biweekly tides. The diurnal correlations would arise from more earthquakes only during the hours when the tidal stress is pushing in an encouraging direction, in contrast, biweekly effects would be based on earthquakes occurring during the days when the sinusoidal stressing oscillations are largest. The former, as most easily observed in the twice-daily rise and fall of the ocean tides, have occasionally been shown to influence tides (e.g.,, this paper shows there may be some weak tidal triggering of shallow, oceanic thrust-faulting earthquakes). The latter, which arises from the periodic alignment of the Sun and Moon, has often been claimed in the popular press to incubate earthquakes (sometimes termed the "syzygy" effect) and occasionally for small datasets in the scientific literature (e.g., ), but generally such effects do not appear in careful studies of large datasets.

Tidal forces are magnified during and after an eclipse. The solar tide is approximately a third of the lunar tide. When the sun and moon are in alignment these tidal forces are combined.

A paper published in Taiwan, by the Department of Astronomy, Beijing Normal University, found a significant relationship to tidal forces and earthquakes in China and Taiwan. The paper considers the relationship between 21 major earthquakes(Ms ≥ 7.0) in land and the offshore area of Taiwan island in the 20th century and the variance ratio of the lunar-solar tidal force. The result indicates that the time of these earthquakes is closely related to the variance ratio of the lunar-solar tidal force, and therefore that the tidal force possibly plays an important role in triggering earthquakes. The conclusion is this method may be used to help forecast earthquakes by studying the lunar perigee.

Syzygy, which is not given much credence in the scientific community, is motivated by the observation that, historically, there have been some great earthquakes whose timing coincides with tidal forces near their maximum. For maximum tidal force, three factors must coincide: First, when the moon (in its elliptical orbit) is closest to the earth; second, when it is within a day or two of a new moon (so that the tidal forces of the moon and sun are acting in concert); and third, when the earth (in its elliptical orbit) is at or near its closest distance to the sun.

Shallow earthquakes near mid-ocean ridges, volcanic earthquakes, and episodic tremor and slip have also been observed to sometimes correlate with the diurnal tides, with enhanced activity correlating with times that faults are unclamped.

History of prediction attempts

China

After a series of foreshocks, the Chinese government was a able to successfully evacuate much of the populace before the 1975 Haicheng earthquake. The Chinese government failed to predict the July 28, 1976 M7.8 Tangshan earthquake. This failure put Chinese earthquake prediction research in doubt for several years.

In the late 1990s, the Chinese government issued over thirty false alarms, but claimed successful prediction of the November 29, 1999, M5.4 Gushan-Pianling Earthquake in Haicheng city and Xiuyan city, Liaoning Province.

Japan

In the 1970s and 1980s, the Japanese government embarked on a major earthquake preparedness campaign, which some criticized as emphasizing prediction too much over mitigation. It failed to result in a prediction of the Great Hanshin earthquake which devastated the city of Kobe in 1995.

Failed Lima prediction

An earthquake predicted by a scientist at the U.S. Bureau of Mines to occur on June 28, 1981, in Lima, Peru, failed to materialize. Despite being dismissed by the U.S. National Earthquake Prediction Evaluation Council, the prediction caused popular fear and many left the city.

Failed Parkfield prediction

Based on a history of regularly spaced earthquakes, the USGS predicted a magnituge 6.0 quake in Parkfield, California between 1988 and 1992. This did not occur until after the end of the prediction window, in 2004.

Loma Prieta prediction

From 1968 to 1988 scientists in California mapped seismic activity on a cross section of the fault lines. They identified a "seismic gap" in the Loma Prieta area from various features of the regional seismicity. They therefore concluded that Loma Prieta was due for an earthquake. Smaller quakes several months beforehand were treated as possible foreshocks, but the warnings had expired by the date of the moment magnitude 6.9 quake, on 17 October 1989.

Jim Berkland

Jim Berkland claims to have predicted the Loma Prieta quake , but the mainstream scientific community does not endorse his techniques as repeatable, putting his success with this quake down partly to random chance.

A magnitude 4.5 earthquake in San Bernardino, California was also claimed to be predicted by Berkland and a meteorologist, reportedly using weather and tide patterns.

Failed SoCal prediction

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 of 2003 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 Prediction 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.

L'Aquila controversy

Giampaolo Giuliani claims to have predicted the 2009 L'Aquila earthquake, he was reported to Italian police for "causing fear" but he was acquitted . His prediction was dismissed by scientists and politicians as a fluke.

See also

• Forecasting
• Earthquake engineering
• Earthquake storm
• Earthquake weather

References

1. ^ Earthquake Prediction. Ruth Ludwin, U.S. Geological Survey.
2. ^ Expert: Earthquakes Hard To Predict. All Things Considered, 6 Apr 2009.
3. Scientist Says Aftershocks Impossible to Predict. All Things Considered, 21 May 2008.
4. Earthquake prediction: Gone and back again 7 Apr 2009, Earth magazine. (confirmation of partial list)
6. THE CHARLATAN GAME. Matthew A. Mabey, Assistant Professor of Geology, Brigham Young University.
7. Glenn Richard (2001). "Earthquake Prediction: Haicheng, China - 1975". Earth Science Educational Resource Center. Retrieved 2006-10-22. Course notes for a workshop held at the Mineral Physics Institute at the Stony Brook University.
8. Can Scientists Predict When Quakes Will Strike?
9. Yoshizo Kawaguchi (April 6, 1998). "Charged Particle Emission and Luminescence upon Bending Fracture of Granite". Jpn. J. Appl. Phys. 37: 3495–3499. doi:10.1143/JJAP.37.3495. Retrieved 2008-10-13.
10. "Satellite défilant du CNES (France)". Retrieved 2006-10-22. Template:Fr
11. http://www.springerlink.com/content/g2v4612216741003/
12. Rachel Abercrombie (November 9, 2005). "The start of something big?". Nature: 171. Retrieved 2006-10-22.
13. T. Bleier and F. Freund (2005). "Earthquake [earthquake warning systems]". Spectrum, IEEE. 42 (12): 22–27. doi:10.1109/MSPEC.2005.1549778. Retrieved 2006-10-22. {{cite journal}}: Unknown parameter |month= ignored (help)
14. E. S. Cochran and J. E. Vidale and S. Tanaka (2004). "Earth tides can trigger shallow thrust fault earthquakes". Science. 306. Science: 1164–1166. doi:10.1126/science.1103961. PMID 15498971.
15. John H. Glaser (2003). "Tidal correlations of seismicity". Geology: Online Forum - Breathing of the seafloor. 31. The Geological Society of America: e3. doi:10.1130/0091-7613(2003)031<0387:NGRAMT>2.0.CO;2. {{cite journal}}: Unknown parameter |month= ignored (help)
16. Juan Zhao, Yanben Han and Zhian Li (2000). "Variation of Lunar-Solar Tidal Force and Earthquakes in Taiwan Island of China". Earth, Moon, and Planets. 88 (3 / June, 2000). Springer Netherlands: 123–129. doi:10.1023/A:1016571114719. {{cite journal}}: Unknown parameter |month= ignored (help)
17. http://www.nature.com/nature/debates/earthquake/
18. "海城岫岩地震预测准确 (Roughly: Prediction of Youyan, Haicheng Earthquake was precise)". People's Daily. December 6, 1999. Retrieved 2006-10-22. Template:Zh icon
19. What Ever Happened to Earthquake Prediction? by Christopher Scholz. March 1997.
20. http://www.earthmagazine.org/earth/article/1fe-7d9-4-7
21. "Magnitude 4.5 - GREATER LOS ANGELES AREA, CALIFORNIA". United States Geological Survey. January 9, 2009. Retrieved 2009-01-09.
22. California Earthquake Prediction Evaluation Council (2002). "Report to the Director, Governor's Office of Emergency Services" (PDF). Retrieved 2006-10-22. {{cite web}}: Unknown parameter |month= ignored (help)
23. http://www.repubblica.it/ultimora/24ore/TERREMOTO-GIULIANI-PROSCIOLTO-DA-PROCURATO-ALLARME/news-dettaglio/3743013
24. http://news.bbc.co.uk/2/hi/europe/7986585.stm

External links

• Nature magazine - extensive debate on whether earthquake prediction is a realistic scientific goal
• Earthquake forecasting techniques and more research on the study of electromagnetic fields
• Studies on Tide-Forming Forces and Earthquakes were published in 1967 and 1968 by Elsevier, but the U.S. Geological Survey: Common Myths About Earthquakes contradicts this study.
• Plan for quake 'warning system' (BBC News)
• Shaky Forecasts (Science News)

• Earthquake and seismic risk mitigation
• Prediction
• Earthquakes