2015年西藏定日MW5.7地震震源参数估计和静态应力触发研究

采用InSAR形变监测资料计算2015年西藏定日M_W5.7地震同震形变场，反演发震断层几何参数和滑动分布。在此基础上，研究尼泊尔M_W7.8主震对定日地震的静态库仑应力触发影响。综合分析地震滑动机制和构造特征，认为定日断层为西倾隐伏断层。反演结果表明，地震破裂相对集中，主要深度在6~9 km，破裂以正断滑动为主。发震断层走向约178°，倾角约 48°，破裂区长约5 km，宽约5 km，最大滑动量约0.2 m，释放的地震矩约3.7×10¹⁷ N·m，对应矩震级M_W5.6。尼泊尔主震同震库仑应力在定日地震震源处约为0.2 bar，造成藏南申扎-定结拉张地堑应变加载。

Research on the Seismic Source Model and Static Stress Triggering of the 2015 Dingri MW5.7 Earthquake

Using the InSAR deformation monitoring data, we calculate the coseismic deformation field of the Dingri M_W5.7 earthquake in Tibet in 2015, and inverse the geometric parameters and slip distribution of seismogenic faults. Then, we analyze the static Coulomb stress triggering effect of the Nepal M_W7.8 main earthquake on Dingri earthquake. Based on the comprehensive analysis of seismic slip mechanism and structural characteristics, we consider that Dingri fault is a buried west-dipping fault. The inversion results show that the rupture is relatively concentrated and mainly distributed in the depth range of 6~9 km with a predominantly normal fault mechanism. The strike and dip of the seismogenic fault of Dingri earthquake are about 178° and 48°, respectively. The length and width of the rupture zones are approximately 5 km and 5 km, respectively, and the maximum slip is about 0.2 m. The released seismic moment is estimated to be about 3.7×10¹⁷ N·m, corresponding to a magnitude of M_W5.6. The coseismic Coulomb stress of Nepal earthquake is about 0.2 bar at the focal point of the Dingri earthquake; it caused the strain loading of the Xainza-Dinggye rift in southern Tibet.