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汶川大地震震中位于震害活跃的龙门山断裂带上,其强度超过1976年唐山大地震.地震激发的地震波可以用来研究震源破裂过程及地球内部的层次结构.从弹性波理论基础出发,采用AK135理论地球模型,考虑地表地形、地球介质衰减及地球椭率等特性,利用谱元法结合高性能并行计算,分别对人工点源和复合源所激发的汶川大地震地震波的全球传播过程进行数值模拟重现.数值模拟结果显示了地震波在地球表面的传播形态.通过比较发现,复合源数值模拟结果较点源数值模拟结果更能体现汶川地震震源破裂过程的时空特性.另外,将两种震源的数值模拟结果分别与实际观测台站记录波形资料进行拟合对比,进一步定性地认识到多个点源组成的复合源的数值模拟结果较单个点源的数值模拟结果与实际观测资料的拟合程度更好,证明了汶川大地震破裂过程为多阶段破裂组成的一个复合破裂过程.
The epicenter of the Wenchuan earthquake was located on the Longmen Shan fault zone with strong earthquake damage and its intensity surpassed that of the Tangshan earthquake in 1976. The seismic waves stimulated by the earthquake can be used to study the source rupture process and the earth’s internal hierarchical structure.Based on the elastic wave theory, AK135 theoretical earth model, taking into account the characteristics of surface topography, attenuation of the Earth’s medium and the ellipticity of the Earth, using spectral element method combined with high-performance parallel computing, respectively, the value of the global transmission process of seismic waves triggered by artificial point source and compound source The simulation results show that the seismic waves propagate on the Earth’s surface.Comparison results show that the numerical simulation results of the composite source better reflect the spatial and temporal characteristics of the source rupture process than the point source simulation results.In addition, The results of numerical simulation are compared with those recorded by actual observational stations respectively. Furthermore, it is further qualitatively recognized that the numerical simulation results of the composite source composed of multiple point sources are more accurate than those of the single point source and the observed data The degree is better, which proves that the rupture process of Wenchuan earthquake is composed of multi-stage rupture A compound fracture process.