西昌断陷盆地场地地震动差异分析

以汶川地震中的非发震断层安宁河断裂带周边西昌地区所获取的加速度记录为依据，研究了这些记录在峰值、频谱之间的差异，并通过这些地区的局部场地条件差异进行了初步解释。在此基础上通过数值模拟方法，利用基于显式有限元和局部透射人工边界的二维有限元模型对该地区的地面运动进行了模拟。数值试验结果表明：这些简单的理想化模型对这一地区地震动的本质特征进行重现，并对产生地面运动差异的机理进行合理解释。通过分析，初步揭示了由深部断层构造所控制的断陷盆地对地震动影响显著。

Study on Difference of Ground Motions in Faulted Basin of Xichang

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.