Report on Early Warning Capabilities for
Geological Hazards (Oct. 1997)
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Short-Term Prediction

Short-term earthquake prediction depends on the existence, detection, and recognition of anomalous phenomena that are preparatory to the sudden onset of a hazardous event. There have been numerous reports of anomalies preceding strong shocks, but their significance with respect to a prediction capability has been hotly debated. See Sobolev (1993, 1995) for a review of the physical principles of earthquake prediction and Geller (1997) for a comprehensive bibliography on, and an evaluation of, short-term earthquake prediction.

The most comprehensive analysis of potential earthquake precursors has been carried out by the Sub-commission on Earthquake Prediction of the International Association for Seismology and Physics of the Earth’s Interior (IASPEI) (1991, 1997). The types of phenomena proposed as precursors to the Sub-commission include anomalies in crustal deformation, seismicity patterns, electromagnetic field, seismic-wave propagation, geochemistry, and climate. In the 1991 report of the Sub-commission, of 28 proposed precursors, only 3 were placed on the preliminary list as being causally related to a subsequent shock. Two more precursors were added in the 1997 report. The total of 5 precursors listed are:

i) Foreshocks (seismicity hours to month before an event) near Haicheng, China, in 1975.

ii) Pre-shocks (seismicity months to years before an event) near Tenant Creek, Australia, in 1988.

iii) Seismic quiescence before strong aftershock in several instances in Japan.

iv) Radon gas concentration and temperature decrease in ground water near Izu-Oshima-kinkai, Japan in 1978.

v) Ground water rise in the Kettleman Hills, California, in 1985.

Whether these and other reported anomalies are truly related to a subsequent earthquake is the critical question, and the literature includes numerous articles on this matter. A further question concerns the regularity or utility of such anomalies. In other words, if we accept that at least some of the reported anomalies are in fact genuine precursors, are they sufficiently regular or common to provide a basis for a useful short-term earthquake prediction capability?

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• Eq predicition (short-term)