グリッド間隔と時間刻みを可変とする3次元差分法を用いた2000年鳥取県西部地震時の神戸地域における強震動評価

概要

論文の詳細を見る
This paper describes an analytical evaluation of strong ground motions in Kobe City during the 2000 Tottori-ken Seibu earthquake. A numerically efficient finite-difference technique combining nonuniform and discontinuous grid spacing is applied for the 3D wave propagation analysis. The entire soil region is divided at particular depth into two regions modeled by different nonuniform grids. Grids in the bottom region for bedrock are coarser than the top region including sediments, which largely cut down on the number of grids. The computational steps for calculation can be reduced to one-sixth by the coupling effects of the grid reduction and variable time steps. Three-dimensional analysis simulates well the velocity seismograms recorded in both mountain and sedimentary sites in the Kobe area. The PGVs in sediments gradually amplify from the basin edge to Osaka bay, which can be seen in both observed and synthetic motions. Site amplification near the basin edge is found to be different for the predominant period of the incident seismic wave.
2004-06-30