Temporal Clustering of Large Rare Earthquakes

This investigation focuses on: (1) large rare earthquakes from 1900 through 1995, and (2) the annual seismic energy release along ridge systems from 1964 through 1995. Clusters of large rare earthquakes appear to occur almost exclusively during episodes of heightened world-wide activity, 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-wide activity also seem to be somewhat contemporaneous with the highest levels of energy release along ridge systems, even though ridge system totals are generally less than 1 percent of the world totals. Although these suggested global episodes of seismic activity may provide an important perspective for earthquake prediction research, they may require further investigation using future decades of seismic data.