SOURCE MODELING AND STRONG GROUND MOTION SIMULATION OF THE 2007 NIIGATAKEN CHUETSU-OKI EARTHQUAKE (Mj=6.8) IN JAPAN

摘要

The Niigataken Chuetsu-oki earthquake (Mj=6.8) occurred on July 16, 2007, northwest-off Kashiwazaki in Niigata prefecture, Japan. In this earthquake, severe damages of fifteen people dead, about 1319 collapsed houses and so on around Kashiwazaki have been caused. In particular, strong ground motions struck the Kashiwazaki and Kariwa nuclear power plant (hereafter KK-site), and triggered a fire at an electric transformer and other troubles. although the all nuclear reactors in operation shut down safely and the damages fortunately appeared less than expected from the seismic design level by the design safety margin. The source mechanism of this earthquake is a reverse fault with the fault plane of SW-NE strike and SE dip. In this study, we tried to construct the source model by the forward modeling approach using the empirical Green's function method.Finally, we proposed the best model consisting of three asperities on the fault. In particular, we pointed out the significant pulse observed at KK-site was generated from the asperity located SW direction of the site and amplified by the folded underground structure between the asperity and the site region though the 3-D finite difference computation.