Link between Seismic Velocity Structure and the 2010 Ms 7.1 Yushu Earthquake, Qinghai, China: Evidence from Aftershock Tomography
Link between Seismic Velocity Structure and the 2010 Ms 7.1 Yushu Earthquake, Qinghai, China: Evidence from Aftershock Tomography
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DOI：
10.1785/0120110138
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发表时间：
2012-02-01
影响因子：
3
通讯作者：
Chen, Yongshun John
中科院分区：
文献类型：
--
作者：
Pei, Shunping;Chen, Yongshun John
通过余震层析成像，给出了2010年4月14日玉树7.1级地震震中周围上地壳的高分辨率二维（水平）地震波速模型。该波速模型是采用一种类似Pn波的简单层析成像方法获得的，其中包括台站和事件深度校正。最显著的结果是玉树 - 甘孜断裂（YGF）震中处存在一个高速异常体。主破裂起源于这个高速异常体内，并向东南方向传播到玉树的一个低速异常体中。2010年5月29日在附近一条断层上发生的第二大余震也位于这个高速异常体内。这些结果清楚地表明，上地壳地震波速结构的横向变化控制了2010年玉树地震的发震（应力积累）、破裂传播以及余震分布。这里介绍的简单二维Pg波走时层析成像方法引入了一种利用丰富余震数据研究大地震破裂过程的新方法。
A high-resolution 2D (horizontal) seismic velocity model is presented for the upper crust around the epicenter of the 14 April 2010 M-s 7.1 Yushu earthquake from aftershock tomography. The velocity model is obtained using a simple Pn-like tomography method including both station and event depth corrections. The most striking result is a fast-velocity anomaly at the epicenter on the Yushu-Garze fault (YGF). The main rupture originated within this fast-velocity anomaly and propagated southeastward into a slow-velocity anomaly at Yushu. The second largest aftershock on 29 May 2010 on a nearby fault also occurred within this fast-velocity anomaly. These results demonstrate a clear example that lateral variation in seismic velocity structures of the upper crust controlled the origination (stress accumulation) and rupture propagation of the 2010 Yushu earthquake and distribution of aftershocks as well. The simple 2D Pg wave travel-time tomography method presented here introduces a new approach utilizing abundant aftershocks data for investigating the rupturing process of a major earthquake.