TEMPORAL CLUSTERING OF LARGE RARE EARTHQUAKES

This investigation focuses on: (1) large rare earthquakes from 1900 th rough 1995, and (2) the annual seismic energy release along ridge syst ems from 1964 through 1995. Clusters of large rare earthquakes appear to occur almost exclusively during episodes of heightened world-wide a ctivity-the most recent episode being from about 1989 to the present, including unusual sequences of earthquakes in the Japan and California areas, as well as other regions. The most intense episodes of world-w ide activity also seem to be somewhat contemporaneous with the highest levels of energy release along ridge systems, even though ridge syste m totals are generally less than 1% of the world totals. Although thes e suggested global episodes of seismic activity may provide an importa nt perspective for earthquake prediction research. they may require fu rther investigation using future decades of seismic data.