Spatial segmentation characteristic of focal mechanism of aftershock sequence of Wenchuan Earthquake
Spatial segmentation characteristic of focal mechanism of aftershock sequence of Wenchuan Earthquake
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DOI：
10.1007/s11434-009-0367-0
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发表时间：
2009-06
影响因子：
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通讯作者：
Qin-cai Wang;Zhang-li Chen;Si-hua Zheng
中科院分区：
文献类型：
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作者：
Qin-cai Wang;Zhang-li Chen;Si-hua Zheng
利用汶川地震序列周围450 km范围内6个台站的宽频带波形资料，采用时域矩张量反演方法，求出了88个地震的矩张量解。结果表明，震源机制解的类型具有明显的空间分段性。主破裂带由西南向北东沿着分为6段，其震源机制初为主逆冲型，终为主右行走滑型，在这两个区域之间存在一个过渡带，其特征是多种震源机制依次出现。小鱼洞镇附近发生了垂直于主破裂带的左旋走滑型地震。利用FMSI程序反演了各段的应力场，发现最大主应力方向沿主破裂带由西南向北东沿着由近EW向逐渐变为NW-SE向，最后又变回近EW向。
Moment tensor solutions of 88 earthquakes were determined by using the broadband waveform data recorded in six stations within 450 km around the Wenchuan Earthquake sequence by means of the time domain moment tensor inversion method. It was found that the type of the focal mechanism solution is characteristic of obvious spatial segmentation. There are six segments along the main rupture zone from southwest to northeast, where initially the focal mechanism is of main thrust type, finally of main right-lateral strike-slip type and between these two areas there is a transition zone characterized in multiple types of focal mechanisms appearing in turn. Earthquakes of left-lateral strike-slip type perpendicular to the main rupture zone occurred near Xiaoyudong Town. The stress field of each segment is inversed by means of the FMSI program, and it was found that, along the main rupture zone from southwest to northeast, the direction of the maximum principal stress is gradually changing from near EW to NW-SE, and finally changing back to near EW.