Study of regional seismicity and associated problems

This paper constitutes a compilation of seismicity data available in the literature plus regional and worldwide data obtained from the USCGS Preliminary Determination of Epicenter (PDE) lists. Data are presented in the form of the recurrence relationship of log N versus magnitude, where N is either cumulative or incremental number of earthquakes, and magnitude is either mb or MS. Relative shapes of these recurrence curves as regards mb versus MS, large magnitude versus small magnitude, shallow focus versus deep focus, etc. are discussed. Conclusions on variability of seismicity with time and on worldwide level of seismic activity are included.