川滇地区主要断裂带上的库仑应力变化及其对地震危险性的指示  

COULOMB STRESS CHANGE ON ACTIVE FAULTS IN SICHUAN-YUNNAN REGION AND ITS IMPLICATIONS FOR SEISMIC HAZARD

作　　者：李玉江[1] 石富强[2] 张辉[3] 魏文薪[4] 徐晶[5] 邵志刚[4] LI Yu-jiang;SHI Fu-qiang;ZHANG Hui;WEI Wen-xin;XU Jing;SHAO Zhi-gang(Key Laboratory of Crustal Dynamics,Institute of Crustal Dynamics,China Earthquake Administration,Beijing 100085,China;Shaanxi Earthquake Agency,Xi′an 710068,China;Lanzhou Institute of Seismology,China Earthquake Administration,Lanzhou 730000,China;Institute of Earthquake Forecasting,China Earthquake Administration,Beijing 100036,China;The Second Crust Monitoring and Application Center,China Earthquake Administration,Xi′an 710054,China)

机构地区：[1]中国地震局地壳应力研究所,地壳动力学重点实验室,北京100085 [2]陕西省地震局,西安710068 [3]中国地震局兰州地震研究所,兰州730000 [4]中国地震局地震预测研究所,北京100036 [5]中国地震局第二监测中心,西安710054

出　　处：《地震地质》2020年第2期526-546,共21页Seismology and Geology

基　　金：国家重点研发计划项目(2017YFC1500500);国家自然科学基金(41874116);中国地震局地壳应力研究所基本科研业务专项(ZDJ2017-07);中国地震科学试验场专项(20150115);中国大陆地震重点监视防御区任务共同资助。

摘　　要：文中基于弹性位错理论与黏弹性分层介质模型,考虑川滇地区及邻区历史强震的同震位错与震后黏弹性松弛效应的影响,计算给出了1515年永胜M 7.8地震以来川滇地区主要块体边界断裂带与构造块体内部的库仑应力变化。计算结果显示,鲜水河断裂带南段、安宁河断裂带、小江断裂带北段、龙门山断裂带南段、楚雄-建水断裂带与小江断裂带的交会处、理塘断裂带沙湾段等断裂带上的库仑应力增加显著(≥0.1MPa)。同时,块体内部川滇藏交界区的库仑应力增加同样显著。综合地震空区、地震活动性参数及文中所给出的应力场变化结果分析认为,安宁河断裂带、小江断裂带北段、鲜水河断裂带南段、龙门山断裂带南段和川滇藏交界区未来的强震危险性值得密切关注。文中研究结果可为川滇地区未来的地震危险性分析提供力学参考。Coulomb stress change on active faults is critical for seismic hazard analysis and has been widely used at home and abroad.The Sichuan-Yunnan region is one of the most tectonically and seismically active regions in China's Mainland,considering some highly-populated cities and the historical earthquake records in this region,stress evolution and seismic hazard on these active faults capture much attention.From the physical principal,the occurrence of earthquakes will not only cause stress drop and strain energy release on the seismogenic faults,but also transfer stress to the surrounding faults,hence alter the shear and normal stress on the surrounding faults that may delay,hasten or even trigger subsequent earthquakes.Previously,most studies focus on the coseismic Coulomb stress change according to the elastic dislocation model.However,the gradually plentiful observation data attest to the importance of postseismic viscoelastic relaxation effect during the analysis of seismic interactions,stress evolution along faults and the cumulative effect on the longer time scale of the surrounding fault zone.In this paper,in order to assess the seismic hazard in Sichuan-Yunnan region,based on the elastic dislocation theory and the stratified viscoelastic model,we employ the PSGRN/PSCMP program to calculate the cumulative Coulomb stress change on the main boundary faults and in inner blocks in this region,by combining the influence of coseismic dislocations of the M≥7.0 historical strong earthquakes since the Yongsheng M 7.8 earthquake in 1515 in Sichuan-Yunnan region and M≥8.0 events in the neighboring area,and the postseismic viscoelastic relaxation effect of the lower crust and upper mantle.The results show that the Coulomb stress change increases significantly in the south section of the Xianshuihe Fault,the Anninghe Fault,the northern section of the Xiaojiang Fault,the southern section of the Longmen Shan Fault,the intersection of the Chuxiong-Jianshui Fault and the Xiaojiang Fault,and the Shawan section of the Lita

关 键 词：库仑应力变化 黏弹性分层模型 地震危险性 川滇地区 

分 类 号：P315.2[天文地球—地震学]