[S07-P] Poster

[S07-P-16] Broadband Ground Motion along the Joetsu Shinkansen during the 2004 Chuetsu Earthquake and Aftershock Sequence

^○Yifei Chen¹, Hiroe Miyake² (1.GSII, The University of Tokyo, Tokyo, Japan, 2.III, The University of Tokyo, Tokyo, Japan)

During the 2004 Mw 6.6 Chuetsu earthquake, many aftershocks occurred following the main shock. In the main shock, the seismic intensity meter of Kawaguchi-cho in Niigata prefecture recorded seismic intensity level 7, and equivalent seismic intensity level 7 was observed at K-NET Ojiya of NIED and Shinkawaguchi electrical substation of JR East (ARAIC, 2007). Large seismic intensity was observed in the watershed of the Shinano river where was near the epicenter and has a complex velocity structure with large site amplification factors. During the 2004 Chuetsu earthquake, the first derailment of Shinkansen under operation ever occurred in which was slight south of the Nagaoka station of the Joetsu Shinkansen. The strong motion along the Joetsu Shinkansen has been discussed by Mori and Kazuni (2005), Nakamura (2006), and ARAIC (2007). Mori and Kazuni (2005) pointed out the influence of strong motion whose period was less than 0.5 second. On the other hand, the predominant period of the observed strong motion ranged from Ojiya to Nagaoka during the 2004 Chuetsu earthquake was 1 second. The 2004 Chuetsu earthquake and its aftershocks occurred in conjugated fault plane systems, both the hypocenter and velocity structures of which were complex. We here focus on the arrival times of P-wave and S-wave for the 2004 Chuetsu earthquake and the distribution of strong ground motions. We also discuss the strong motion of the 2004 Chuetsu earthquake along the Joetsu Shinkansen by conducting ground motion simulation of aftershocks with point-source assumption. We deal with seismic intensity meters such as Niigata prefecture, JMA, K-NET, and KiK-net, using earthquake source models from F-net and Hikima and Koketsu (2005). We use J-SHIS as the initial velocity structure model. We also conduct broadband ground motion simulation by using 3-D finite difference method and the stochastic Green's function method. Calculation results are compared with the ground motion prediction equation.