Abstract

The paper is based on the data of the largest earthquakes in the 68 years from 1897 to 1964, inclusive. The most complete list of pertinent earthquakes ever published was compiled and is attached as Appendix I. The circum-Pacific seismic belt is divided into eight regions showing different intensities of strain energy release and statistically different bcoefficients in the recurrence diagrams, which relate number of earthquakes to magnitude. The intensities and b-coefficients are correlated with each other, indicating that the b-coefficient depends on the stress pattern. Inferences are drawn as to the generation of aftershock sequences. The seismic energy release per year has decreased significantly in the time interval investigated in all depth ranges in the circum-Pacific belt and outside of it. However, any extrapolation beyond that time would be speculative.