小江断裂带近场活动特征分析

Evaluation of Near Field Activity in Xiaojiang Fault Zone

采用2009—2018年小江断裂带跨断层近场形变观测资料,通过应变参数最小二乘法求解该时间段内小江断裂带上不同区段最大剪应变率和面应变率近场结果并进行对比分析。结果显示小江断裂带上的最大剪应变率和面应变率在各区段存在较大差异性,最大剪应变速率变化范围为(1.03～4.10)×10^(-6)/a,面应变率变化范围为(-1.18～0.33)×10^(-6)/a。该断裂呈现出北段强剪切张性、中段弱剪切强挤压、南段强剪切兼挤压活动的分段活动特征,进一步分析得到该断裂中南段为应变积累区段,地震危险性高于其他区段。

The near-field deformation data of the faults from 2009 to 2018 were used to solve the results of maximum shear strain rate and surface strain rate of near-field in different sections in Xiaojiang fault zone by the least squares method of strain parameters.The results show that the maximum shear strain rate and surface strain rate on the belt in Xiaojiang fault are different from each segment.In a whole,the maximum shear strain rate ranges from 1.03×10-6/a to 4.10×10-6/a as well as the surface strain rate are(-1.18~0.33)×10-6/a.The fault exhibits the segmental activity characteristics of the strong shearing ductility in the northern section,weak shearing in the middle section,strong shearing and squeezing activities in the southern section.Further analysis shows that the mid-south section of the fault is a strain accumulation section.The seismic hazard of the segment is higher than that of the other segments.