Local redistribution of active zones as the precursor of large earthquakes in Lesser Antillean arc

P. N. Shebalin, I. M. Rotwain, and V. I. Keilis-Borok

N. Girardin, and J. Dubois

Abstract

We continue to study the phenomenon of short-term activation of locally less active seismic zones on the background of relative quiescence in locally more active zones. This phenomenon is observed in the epicentral area of a large earthquake for several months prior to its occurrence. A prediction algorithm based on this pattern was introduced previously and tested retrospectively using data from southern California and the Lesser Antilles. This algorithm identified areas of approximate size 100 km $\times$ 100 km in which the probability for occurrence of large earthquakes was increased for one-year periods. We propose a modification of this algorithm that offers a possibility to increase the number of large earthquakes through expanding the study territory. The retrospective prediction in the Lesser Antilles for the period between January 1984 and August 1995 indicates that eight out of nine large earthquakes were observed in time-space domains of increased probabilities (TSIPs) for the occurrence of large events. These TSIPs occupy 8% of the total study time-space volume.

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Computational Seismology, Vol. 4.