Statistical Characteristics of Inland Seismicity in Japan

Alternation of Active and Quiet Periods and Successiveness of Large Earthquakes

Abstract

We investigated statistical characteristics in a space-time distribution of large shallow inland earthquakes in Japan during the period from 1600 through 2000 using data from the following three catalogues : Chronological Scientific Tables (National Astronomical Observatory, 2001) for 1600-1884, Utsu (1979, 1982, 1985) for 1885-1925 and the catalogue of the Japan Meteorological Agency for 1926-2000. It is shown that an alternation of active and quiet periods is commonly observed for each district : inland seismicity tends to be active in the periods before and after great interplate earthquakes. Further, we show that another large earthquake is likely to occur after one during the period of 10-20 years within a distance of several tens of kilometers. We think this feature of the successiveness of large earthquakes is significant and we can utilize it for assessing seismic hazards.