地震波传播与地球内部结构

Seismic Wave Propagation and Structure of Earth’s Interior

研究内容：地震波在三维复杂介质中传播模拟的快速、准确方法，快速确定地震位置、机制解、破裂方向，为地震灾害快速评估提供基本参数，地球内部三维速度结构及地震波速度随时间变化检测。

研究方向1：地震参数快速确定。

利用地震波形快速确定地震位置、震级以及破裂方向。以汶川地震为例，用两个三分量地震台站就足够在10 s内对地震的震中位置给出误差范围在20 km的定位. 从P波初至的前4 s信号, 可以估计地震的震级为7级; 更准确的震级估计则可以利用耗时2 min的Pnl波形模拟来完成, 此时在500 km外的地震台站刚刚接收到S波. 利用震后2 h内发生的5级以上余震, 破裂区域能被很好的显示出来. 在几个小时内, 更详细的破裂过程和有限断层模型能通过分析远震体波记录来得到, 并可随时用来计算地面强震动, 从而在没有实时强震记录可用的情况下为救援工作提供重要资料.

研究方向2，地球内部结构

利用地震波形（多路径、转换震相等）、到时确定地球内部各个界面(Moho, 410km,660km, CMB,ICB)的尖锐程度及起伏形态和地壳、地幔和内核的三维速度分布。

Research Focus: Rapid or accurate simulation of seismic propagation in complex 3D media; Rapid determination of earthquake source parameters such as location, depth, focal mechanism and rupture directivity, which will be used in rapid seismic hazard assessment; Resolving 3D velocity structure of the Earth and monitoring temporal variation of seismic velocity.

Research Interest：1, Rapid Earthquake Source Parameters

Rapid determination of earthquake source parameters such as location, depth, focal mechanism and rupture directivity by modeling seismic waves. In the case of the great Wenchuan earthquake, it is demonstrated that the event can located with accuracy of 10km within 10 seconds using only two 3-component broadband seismic stations, and the magnitude can be estimated within accuracy of one magnitude unit with first 4 seconds of P waves. If 2 minutes of waveforms are used, the magnitude can be determined with much higher accuracy. Combining waveforms and aftershock pattern, rupture length can be well resolved.

Research Interest 2, Structure of Earth’s Interior

Determines topography and sharpness of various discontinuity inside the Earth with seismic waveforms (multipathing or converted phases), and 3D structure of the Earth with waveform and travel times.

组长：倪四道

成员：万柯松，曾祥方，吴文波

Program Principal Investigator: Dr. Sidao Ni

Member: Kesong Wan, Xiangfang Zeng, Wenbo Wu