2次元盆地端部構造の地震動増幅と表面波の干渉

概要

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This study investigates the amplification of ground motions in 2D basin edge structure with a vertical bedrock-sediment discontinuity using a simple and realistic subsurface structure for the vertical SV wave incidence. In the case of simple basin edge structure used here, the ground motion amplification near the basin edge can be recognized when the Ricker wavelets with higher normalized characteristic periods than 0.8 act as a vertically incident S-wave. The wave induced at the bedrock-sediment discontinuity is decomposed into surface waves to make clear mechanism of the constructive interference of the ground motion adjacent to the basin edge. The higher modes of Rayleigh waves make great contribution to the constructive interference with the direct S-wave, propagating vertically upwards. In the case of the 1995 Kobe earthquake, the second higher mode is largely induced at the bedrock-sediment discontinuity and contributes to the constructive interference, which caused "heavily damaged belt zone".
2002-02-28