Anomalously large complete stress drop during the 2016 Mw 5.2 Borrego Springs earthquake inferred by waveform modeling and near‐source aftershock deficit
Anomalously large complete stress drop during the 2016 Mw 5.2 Borrego Springs earthquake inferred by waveform modeling and near‐source aftershock deficit
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DOI：
10.1002/2017gl073338
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发表时间：
2017-06
影响因子：
5.2
通讯作者：
Z. Ross;H. Kanamori;E. Hauksson
中科院分区：
文献类型：
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作者：
Z. Ross;H. Kanamori;E. Hauksson
2016年的5.2级波雷戈斯普林斯地震发生在圣哈辛托断裂带的三岔区，产生了2.3万多次余震。我们分析了这次地震的震源特性以及12487个精确定位的余震震源，以获得这次中等地震的破裂过程和能量收支的异常详细的视图。源时间函数采用经验格林函数方法获得，并对断层面上的滑动分布进行了反演。断裂向西北方向单方面传播了1.8公里，产生了清晰的指向性信号。确定了2个凸点，最大滑移量为2.54 m，静应力降为78.2 MPa。超过97%的余震发生在距离滑动区超过1个断裂长度的地方。我们认为波雷戈泉地震具有完全的应力降，估计地震效率为15-26%。
The 2016 Mw 5.2 Borrego Springs earthquake occurred in the trifurcation area of the San Jacinto Fault Zone and generated more than 23,000 aftershocks. We analyze source properties of this earthquake along with 12,487 precisely located aftershock hypocenters to obtain an unusually detailed view of the rupture process and energy budget for this moderate earthquake. Source time functions are obtained using an empirical Green's function approach and are inverted for a slip distribution on the fault plane. The rupture propagated unilaterally to the northwest over a distance of 1.8 km, resulting in clear directivity signals. Two asperities are identified and the maximum slip is 2.54 m, resulting in a static stress drop of 78.2 MPa. Over 97% of the aftershocks occur more than 1 rupture length from the slip area. We conclude that the Borrego Springs earthquake had a complete stress drop and estimate the seismic efficiency to be 15–26%.