抄録
A new concept “seismic diversity” (SD) is proposed as a new measure of magnitude-frequency distribution. SD is defined as
H=1/nlog(n!/n1!n2!…ns!)
where n is the total number of earthquakes in a given set of observations, and ni′s (i=1, 2, …, s) are the number of events in evenly devided magnitude ranges. This formulation assumes neither specific form of distribution for the population nor random samplings from a population for the data set. Thus it is more appropriate for treating actual seismic data than the conventional constant b value formulation. The concept of SD is extended as a practical measure to represent the spacial distribution of earthquakes. It is shown that variations of both magnitude and spacial distributions of earthquakes are adequately represented by using this new measure.
