小江断裂带及邻区应力降特征分析  

Analysis on the Features of the Stress Drop in Xiaojiang Fault Zone and Its Adjacent Areas

作　　者：刘丽芳[1] 杨晶琼[1] 秦嘉政[1] 

机构地区：[1]云南省地震局,云南昆明650224

出　　处：《地震研究》2011年第4期498-503,共6页Journal of Seismological Research

基　　金：云南省应用基础研究重点项目(2010CC006);云南省重点项目(JCYB-20080601-4)联合资助

摘　　要：在对S波观测记录位移谱进行传播路径、场地响应和仪器响应等校正的基础上,根据Brune圆盘震源模型,利用遗传算法估算了小江断裂带及邻区335次ML2.0～5.3地震的应力降,分析了应力降的时空特征。结果表明:Δσ≥10.0MPa的高应力降地震主要分布在小江断裂带的东川、巧家及其以北地区和元谋、武定一带。小江断裂带北段、中段、南段Δσ≥10.0MPa的地震所占比例分别为10.2%、10.9%和1.6%,据此结合地震活动性分析了该断裂带不同段的强震危险性。结合震源位置和速度结构联合反演方法得到的震源位置精确定位结果,分析了应力降和震源深度变化情况及其所反映的断层深部延伸和分布情况。Doing the propagation path correction, site effect correction, and instrument response correction, etc. for the observational S-wave data, we obtained source spectra for the small - and moderate - earthquakes. Using Brune Source Model and by means of generalized inversion technique, we calculated the stress drop of 335 earthquakes （Ms2.0～5.3 ） in Xiaojiang Fault Zone and its adjacent areas. The temporal and spatial features of the stress drop showed that earthquakes with higher stress drop （Δα≥10. 0 MPa） mainly distribute in Dong- chuan, Qiaojia and the areas in the north of Qiaojia, Yuanmou, and Wuding region. The earthquakes with Atr Δα≥10.0 MPa account separately for 10. 2%, 10. 9% and 1.6% of the total in the northern, middle and southern segment of the Xiaojiang Fault Zone. According to the seismicity in the Zone, we analyzed the strong earth- quake risk in different segments of the Zone. On the basis of the precisely-relocated results from the simultaneous inversion of location and velocity structure, we also analyzed the variation of stress drop and focal depth, and the extension and distribution of the Zone in the deep Earth.

关 键 词：应力降 中小地震 小江断裂带 

分 类 号：P315.33[天文地球—地震学]