A statistical study on seismicity patterns of intraplate earthquakes in the Japanese Islands.

Abstract

Since 1983, the Meteorological Research Institute has been conducting a research project on the prediction of intraplate earthquakes occurring in the Japanese islands. In connection with the project, a statistical study on the seismicity patterns has been carried out and is reported here. In the study are used 288 earthquake sequences whose main shock magnitude is 5 or larger. The identification of various seismic precursors in these events is executed as objectively as possible. The regional variations and the occurrence rates of various seismic precursors are studied by use of the identified precursors. Moreover, the selection of seismic precursors having stronger dependence on larger earthquakes and the relationship between the occurrence of the precursors and the main shock magnitude are statistically investigated. Based on the results obtained from the investigations, procedures of identifying significant precursors for long-term or medium-term earthquake prediction are proposed.