川滇菱形块体东边界断裂带内库仑应力演化及危险性  

COULOMB STRESS EVOLUTION AND SEISMIC HAZARD ALONG THE EASTERN BOUNDARY OF THE SICHUAN-YUNNAN BLOCK

作　　者：徐晶[1] 季灵运[1] 姬存伟 孙赫[1] 赵强[1] XU Jing JI Ling-yunl JI Cun-wei SUN He ZHAO Qiang(Second Monitoring and Application Center, China Earthquake Administration, Xi＇an 710054, China Xi＇an Division of Surveying and Mapping, Xi＇an 710054, China)

机构地区：[1]中国地震局第二监测中心,西安710054 [2]西安测绘总站,西安710054

出　　处：《地震地质》2017年第3期451-470,共20页Seismology and Geology

基　　金：国家自然科学基金(41604015);中国地震局实验场项目(20150115)共同资助

摘　　要：采用分层黏弹模型,考虑了川滇菱形块体东边界1480年以来34个强震和大地震的同震位错和震后黏滞松弛效应,以及各断层段的震间长期构造加载作用,计算了川滇菱形块体东边界18个断层段的断层面上的库仑应力变化随时间的演化。系统地研究了川滇菱形块体东边界鲜水河、安宁河、则木河、小江断裂带间的相互作用,分析断裂带各断层段之间、各断裂带之间先发生的地震对后发生地震的促进或延迟作用,进一步基于断层面上的库仑应力变化计算结果分析各断层段的强震危险性。应力触发的计算结果显示,各断裂带各断层段上先发生的强震可能触发后发生的强震,相邻断裂带上发生的强震之间也可能存在触发作用。各断层段上累积库仑应力变化随时间演化的计算结果显示,鲜水河断裂带的中段及南部磨西段、安宁河断裂带冕宁—西昌段、小江断裂带北部巧家—东川段和南部建水段的库仑应力增加显著,强震危险性值得关注。Using a more realistic model of multi-layered the coseismic dislocation and the postseismic viscoelastic media, and considering the effects of viscoelastic relaxation caused by the 34 great earthquakes occurring along the eastern boundary of the Sichuan-Yunnan block since 1480 and the interseismic stress accumulation caused by the tectonic loading generated by plate motions which were modeled by introducing ＂virtual negative displacements＂ along the major fault segment in the region under study, we calculated the evolution of the Coulomb stress change in each fault plane of 18 major fault segments along the eastern boundary caused by the coseismic, postseismic and interseismic effects. We studied the interactions of the Xianshuihe, Anninghe, Zemuhe and Xiaojiang fault zones on the eastern boundary of the Sichuan-Yunnan block. By evaluating if the previous earthquake could bring another earthquake closer to or farther from failure, we analyzed the interactions of the earthquakes which occurred in the different segments in the same fault zone, or in the different fault zones respectively. And further based on the calculation results of the Coulomb stress change on the fault planes, we analyzed the seismic hazard of each fault segment. The results show that the previous earthquake may trigger another earthquake which can occur in the same fault zone or in the different fault zone. And the calculation results on the evolution of the cumulative Coulomb stress change in the each fault segment show that, the Coulomb stress increases significantly in the middle section and the Moxi segment of the Xianshuihe fault zone, the Mianning- Xichang segment of the Anninghe fault zone, the Qiaojia-dongchuan segment and the Jianshui segment of the Xiaojiang fault zone, and the seismic hazard in these fault segments is worthy paying attention to.

关 键 词：川滇菱形块体东边界 震后黏滞松弛 震间构造应力加载 库仑应力变化 强震危险性 

分 类 号：P315.72[天文地球—地震学]