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Comparison of earthquake prediction approaches in the Tokai area of Japan and in California

CALIFORNIA DEPARTMENT OF CONSERVATION DIVISION OF MINES AND GEOLOGY, 1416 NINTH STREET, SACRAMENTO, CALIFORNIA 95814
WOODWARD-CLYDE CONSULTANTS ONE WALNUT CREEK CENTER, 100 PRINGLE AVENUE, WALNUT CREEK, CALIFORNIA 94596

Abstract

The Japan Meteorological Agency (JMA) has lead responsibility to predict the anticipated M 8+ Tokai earthquake which can seriously affect Shizuoka prefecture and environs. The Japan Meteorological Agency maintains a continuous staff observation of records from onshore and offshore seismic stations (events to M 1), strainmeters, tiltmeters, tide gauges, and ground water conditions. The Earthquake Assessment Committee, composed of six seismologists, has the responsibility to predict the Tokai event based upon this Japan Meteorological Agency data. They expect to provide a short-term prediction with a lead time of hours to several days. Criteria for convening the Earthquake Assessment Committee in emergency session with a significant likelihood of issuing the prediction include: strain unit change in excess of 0.5 x 10^–6 within a 3-hr period at one station accompanied by notable changes at three other monitored locations; or 10 earthquakes with at least three in excess of M 4 in a swarm-like pattern during a period of at least 2 hr and accompanied by observable changes at a minimum of two strain-monitoring stations.

California relies upon the California Earthquake Prediction Evaluation Council and the National Earthquake Prediction Evaluation Council to appraise predictions coming from either government laboratories or university sources. The size and imminence of a repeat of the 1857 Fort Tejon earthquake on the southcentral San Andreas fault segment is comparable to the pending Tokai earthquake. Review of observational data and procedures for making prediction conclusions are more decentralized and informal in California. Attention should be given to the elements of the Japanese approach to earthquake predication that would be applicable and transferable for use in California.