中京地域で発生する長周期地震動に対する堆積盆地及び付加体の影響

Long-period seismic waves are affected by the propagation path, and have a different nature depending on the source location. In addition to the accretionary wedge and sedimentary basins could affect the long-period seismic waves. The characteristics of ground motions on the irregular sedimentary basin structure vary depending on the incident direction of the seismic wave and the type of incident seismic wave. Therefore it is important to focus on the source location, and to consider the path effect together with the effect of the sedimentary basin beneath the site.In this study, the 3D finite difference analysis based on the reciprocity theorem is employed to clarify the path effect and the effect of the sedimentary basin beneath the site. In regard to the path effect, the accretionary wedge could decrease the specific periodic band of seismic waves, in contrast to the Niigata sedimentary basin which could amplify the specific periodic band of seismic waves. In addition, the Kanto plain could so much not amplify the waves on the site in Chukyo area. In regard to the effect of the sedimentary basin beneath the site, the analysis confirm that the characteristic of ground motion fluctuates depending on the incident direction of seismic waves. Especially, the results of some observation points show that when the source located in a particular direction, the seismic wave is strongly amplified by the sedimentary basin.Specific amplification of seismic waves is examined by the numerical analysis of wave propagation using the simple soil structure models. As a result, it is revealed that the seismic waves are strongly amplified by the step of the layer near the site. Therefore, the ground motion at the site is amplified and the duration time is extended.At last, amplifications of seismic wave radiated from sources of various directions are compared at the site on Chukyo sedimentary basin using the seismic ground motion records. The study revealed that the amplification of the seismic wave radiated from eastern sources is larger than other direction at the specific periodic band. The behavior similar to the result of numerical analysis is shown by the study using the seismic ground motion records.According to the result that the effect of the wave propagation path and the sedimentary basin beneath the site varies with respect to the source location, the damage of specific long-period building could be large in specific cases of earthquakes. The examination of the