Amplification Characteristics of Long-period Ground Motions in Coastal Area of Osaka Bay and Effects of Seismic Wave Incident Direction and 3D Geological Condition of Uemachi Fault belts

Abstract

During the 2011 off the Pacific coast of Tohoku Earthquake, long-period ground motions were largely amplified in coastal area of the Osaka Bay, resulting in the large drift at the top of Osaka Prefectural Government Sakishima Building. Amplification characteristics of the long period ground motions are investigated for the 3-D geological model of the Osaka Plain subjected to the horizontally incident SH wave using the 3-D finite difference method. Synthetic waves in the Osaka Plain including the Bay area were in good agreement with the observed ground motions. The ground motions in the Osaka Bay area were amplified mainly by 3-D geological condition as the focusing effect of travelling waves.