岩盤上のアレイ観測によるsite特性の評価(1)

Abstract

We determine the time dependence of apparent velocities and arrival directions of S- andS coda waves obtained from the array observations on the rock site from local earthquakes. Thewaves at the direct S-wave part propagate from the epicenter directions to the site with higherapparent velocities than the medium S wave velocity. On the contrary, those at S coda partcome from various directions with equal or lower apparent velocity and variations of arrivaldirections depends on time. There is a possibility that the waves with lower apparent velocityare mainly constructed by surface waves generated by the scatterers in the crust.