2014年鲁甸6.5级地震GPS同震位移及反演分析

本文综合GPS流动和连续观测结果，并利用最速下降法（SDM）反演方法，给出并分析了2014年鲁甸6.5级地震同震位移、断层面滑动位移分布特征.GPS同震位移结果表明：此次地震沿北西方向表现出左旋应变释放特征、沿北东向表现出拉张应变释放的同震特征，并且随着离开断裂带距离的增加，拉张变形衰减；受包谷垴—小河断裂控制的左旋剪切应变释放的位移在莲峰、昭通—鲁甸断裂附近较弱，说明该断裂可能没有完全切割昭通—鲁甸断裂，不属于该区域主干断裂；昭通—鲁甸断裂带有一定的右旋应变释放，而逆冲应变释放不明显，表明该断裂带处于受南东向挤压的强闭锁状态.SDM反演结果表明，鲁甸地震以左旋走滑为主并兼有拉张性质，地震矩震级为M_W6.3左右.综上所述，并结合其他研究成果，我们认为莲峰、昭通—鲁甸断裂带仍存在强震危险性.

Coseismic displacements from GPS and inversion analysis for the 2014 Ludian 6.5 earthquake

Based on campaign and continuous GPS observations, this work analyzes the coseismic displacement and the slip distribution on the rupture of the 2014 Ludian 6.5 earthquake using the Steepest Decent Method (SDM) inversion method. The results show the left-lateral strain releases in the north-west direction, and the tensile strain releases in the north-east direction which is attenuated with the distance away from the fault. The displacement of the left-lateral shear strain controlled by the Baogunao-Xiaohe fault is weak in the vicinity of the Lianfeng and Zhaotong-Ludian faults, which indicates that the ruptured fault may not completely cut throuh the Zhaotong-Ludian fault and the ruptured fault is not a major feature in this area. The Zhaotong-Ludian fault has a certain right-lateral strain release, on which thrust strain release is not obvious, implying that the Zhaotong-Ludian fault is highly locked due to the south-east compression. The results of SDM inversion show that the Ludian earthquake is dominated by left-lateral and tensile motion, and the magnitude of the earthquake is around M_W6.3. Combined with other research results, we suggest that the Lianfeng and Zhaotong-Ludian fault zones still have high seismic risk.