逆断層の震源近傍における強震動の上盤効果と距離指標

－最大加速度を対象とした等価震源距離と断層最短距離の適用性について－

抄録

We investigated distance measuring indices to express peek ground accelerations in the near source region of reverse faults. Two indices, the equivalent hypocentral distance, Xeq, and the shortest distance to the fault, Xsh, are often applied to ground motion prediction equations (GMPE). Strong motions in the near fault region are calculated based on the Stochastic Green's function method for the hypothetical fault model. Advantage of Xeq in comparison with Xsh is shown to explain the distribution of peak ground accelerations in the near source region, including the hanging wall effect. Near source strong motion records from two events, the 2004 Mid Niigata prefecture earthquake and the 1999 Chi-Chi earthquake in Taiwan, are also investigated. We confirmed that the strong motion generation areas play an important role when we apply the Xeq to GMPE as distance measuring indices.