Abstract
Basing on the Bayesian statistics, a new method to quantify seismicity is proposed. Earthquake occurrences are assumed to follow a non-stationary Poisson process of which the parameter (Poisson rate) changes both in time and in space Time-space for study is divided into hundreds of segments, and earthquakes are sorted into these segments. The Poisson rate is assumed to be constant in each segment, and the time-space variation of the rate is estimated by using Akaike's Bayesian Information Criterion (ABIC). To demonstrate the effectiveness of this method, the time-space variation in seismicity was studied for the area of the Nemuro-oki earthquake of June 17, 1973(MJMA=7.4). As a result of the analysis, seismicity in the source area is found to be rather constant for the period of 1927-1972. The precursory seismic quiescence pointed out in earlier works should be attributed to the high seismic activities in the surrounding areas due to aftershocks of the 1952, 1968, and 1969 earthquakes.
