Joint analysis of the 2014 Kangding, southwest China, earthquake sequence with seismicity relocation and InSAR inversion
Joint analysis of the 2014 Kangding, southwest China, earthquake sequence with seismicity relocation and InSAR inversion
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2014年西南康定地震序列地震活动重定位与InSAR反演联合分析
DOI：
10.1002/2015gl063750
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发表时间：
2015-05-16
影响因子：
5.2
通讯作者：
Xu, Caijun
中科院分区：
文献类型：
--
作者：
Jiang, Guoyan;Wen, Yangmao;Xu, Caijun
2014年11月22日至29日，中国西南鲜水河断裂康定西北部发生1000多次地震，其中最大的两次地震为5.9兆瓦和5.6兆瓦。799次重定位地震的震源特征表明，鲜水河断裂的色拉哈支支和哲多塘支支分别存在两个独立的主震-余震子序列。一张干涉合成孔径雷达干涉图(2014年9月26日至12月5日)的断层滑动反演结果表明，MW5.9级主震在~9 km深度处产生了~0.47 m的最大滑动。然而，没有明显的滑动与MW5.6主震有关。干涉合成孔径雷达测得的力矩为2.36 × 1018 Nm，刚度为30 Gpa，相当于MW6.2，约为InSAR时间跨度内所有记录地震的总地震力矩的两倍。大地测量矩和地震矩估计之间的这种巨大差异表明，在5.9级主震后的两周内，可能发生了快速的无地震余滑。该地震序列释放的地震能量远小于1955年712级地震以来在同一断裂支上累积的应变能，表明鲜水河断裂色拉哈-康定段地震危险性较高。
Over 1000 earthquakes struck the northwest of Kangding on the Xianshuihe fault in southwest China between 22 and 29 November 2014, including two largest events of Mw 5.9 and Mw 5.6. The hypocenters of 799 relocated earthquakes suggest that two independent main shock‐aftershock subsequences occurred on the Selaha and Zheduotang branches of the Xianshuihe fault, respectively. Fault slip inversion results from one interferometric synthetic aperture radar (InSAR) interferogram (26 September 2014 to 5 December 2014) show that the Mw 5.9 main shock produced a maximum slip of ~0.47 m at the depth of ~9 km. However, there is no distinct slip associated with the Mw 5.6 main shock. The InSAR determined moment is 2.36 × 1018 Nm with a rigidity of 30 GPa, equivalent to Mw 6.2, which is about twofold the total seismic moment of all the recorded earthquakes during the InSAR time span. This large discrepancy between geodetic and seismic moment estimates indicates that there was probably rapid aseismic afterslip in the 2 weeks following the Mw 5.9 main shock. The released seismic energy of this earthquake sequence is far less than the accumulated strain energy since the 1955 M 712 earthquake on the same fault branch, which implies that the seismic risk on the Selaha‐Kangding segment of the Xianshuihe fault remains high.