关键词: 断层相互作用, 地震活动, 有限元模拟

Abstract: In this paper,seismicities along the main active faults in Sichuan-Yunnan region,including the Xianshuihe,Xiaojiang,Honghe,Longling-Lancang and Longmenshan-Ruili Faults,are analyzed.The results reveal four phenomena of fault interactions: 1)the active period of strong earthquake initiates at first on the Xianshuihe Fault,and then initiates in succession on the Xiaojiang,Honghe,Longling-Lancang and Long-menshan-Ruili Faults.The migration of the initiation time of active period of strong earthquake is consistent with the movement state of Sichuan-Yunnan continent characterized by southeastward horizontal slipping associated with clockwise rotation; 2)the b value and the activity of strong earthquakes on the Xianshuihe Fault bear a close relation to those on the Longling-Lancang Fault.The two faults are parallel to each other and have opposite sense of slip; 3)seismic activity on the NW-trending main faults in this region occurs alternately with that on the NE-trending Longmenshan-Ruili Fault; 4)seismicity on the Longmenshan-Ruili Fault is characterized by segmentation,which reflects the differential movement of the fault blocks bounded by various segments of the fault. In addition,finite element method is applied to simulate the variation process of stress field caused by fault interactions in Sichuan-Yunnan region.The results show that the fault interactions mentioned above are closely related to block movement and hence to the adjustment of stress fields.In this paper,three types of fault interactions are recognized through the analysis of seismicity along the main faults in Sichuan-Yunnan region.They include the migration of seismicity along block boundaries,the alternation of seismicity on parallel faults with opposite slip sense,and the alternation of seismicity on intersecting faults.

Key words: fault interactions, seismic correlation, finite element method