Abstract:In this study, by analyzing the peak ground acceleration (PGA) and spectral characteristics of the earthquake acceleration records from the main shock of the Wenchuan earthquake, the difference of the ground motion at both sides of the Anninghe fault zone is discussed. By analyzing the local site conditions at the observation stations, such as local site soil, topography, and tectonics, a preliminary explanation of the discrepancy is obtained, and the numerical solution of 2D model of this site derived by the explicit finite element combined with the local multi transmitting artificial boundary method is used to interpret the mechanism causing the difference in the ground motion. The results of numerical calculations indicate that in spite of its simplicity, such an idealized model is also successful in reproducing many of the essential characteristics of ground motion and the mechanism causing the difference in ground motion within the fault zones of Anninghe. The characteristics of the faulted basin under control of the Anninghe fault zone may be used to interpret observed seismic data obtained during the Wenchuan main shock and theoretical calculations of nearby fault responses in Xichang.
