海溝周辺に発生する地震の余震分布に関する一つの検討

Abstract

In this paper, we discuss the difference in distributions between larger and smaller after-shocks that followed some large earthquakes with magnitude larger than 7 at trenches of thePacific Ocean. By a method similar to the t-test, it seems probable that the epicenters ofthe smaller shocks are located slightly landward in comparison with those of the larger shocks, especially in South Kuril and Philippine.On the statistic basis mentioned above, epicenters of the main shocks are compared withthose of their aftershocks. It is ascertained that most of epicenters of the main shocks withreversal dip-slip fault are situated iandward, except the events in New Britain Trench andNew Hebrides.