西南天山迈丹断裂周缘地壳应力演化及地震危险性分析  

The stress evolution surrounding the Maidan fault in Southwest Tianshan and implications for the future seismic hazard

作　　者：庞亚瑾 武艳强[1] 苏广利[1] 陈长云[1] 杨少华[2,3] 李海兵 PANG YaJin;WU YanQiang;SU GuangLi;CHEN ChangYun;YANG ShaoHua;LI HaiBing(The First Monitoring and Application Center,China Earthquake Administration,Tianjin 300180,China;Key Laboratory of Continental Dynamics of Ministry of Natural Resources,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;Jiangsu Donghai Continental Deep Hole Crustal Activity National Observation and Research Station,Donghai 222300,China)

机构地区：[1]中国地震局第一监测中心,天津300180 [2]中国地质科学院地质研究所,自然资源部大陆动力学重点实验室,北京100037 [3]江苏东海大陆深孔地壳活动国家野外科学观测研究站,东海222300

出　　处：《岩石学报》2024年第12期4020-4029,共10页Acta Petrologica Sinica

基　　金：国家重点研发计划(2022YFC3003703-06);中国地质调查局地质调查项目(DD20221630);第二次青藏高原综合科学考察研究项目(2019QZKK0901);地震科技星火项目(XH23056YA);国家自然科学基金项目(42174125)联合资助。

摘　　要：迈丹断裂是一条位于西南天山南缘的相对高角度断裂,历史记录到的强震活动较少。2024年1月迈丹断裂东段发生了乌什7.1级地震,引发了对迈丹断裂孕震环境和未来地震危险性的关注。除持续的构造加载外,迈丹断裂周围的地壳应力还可能受一系列强震和冰川融化的影响。本文通过计算震间构造加载、历史强震和地表水文质量损失引起的地壳应力变化,定量分析迈丹断裂周缘的地壳应力积累特征。数值模拟结果表明,震间构造加载驱动迈丹断裂库仑应力增加,速率约为1.1~1.4kPa/yr。历史强震导致迈丹断裂主要断层段库仑应力降低,其中,在2024年乌什7.1级地震震中位置处,库仑应力下降约37kPa,因此历史强震可能推迟了这次地震事件的发生。尽管地表水文质量卸载造成天山山脉明显的垂直形变,但与长期构造加载相比,其引起的地壳应力变化量很小,可以忽略不计。综合区域地壳应力演化、地震活动和构造变形特征,本文认为迈丹断裂东段具有较高的应力积累,未来地震危险性更高。The Maidan fault is a high-angle fault located on the south edge of Southwest Tianshan,with fewer large earthquakes.A M7.1 earthquake occurred in January 2024 on the eastern segment of the Maidan fault,which provokes attention to its seismogenic settings and the future seismic risk nearby.In addition to the sustaining tectonic loading,the crustal stress surrounding the Maidan fault is possibly affected by a series of strong earthquakes and glacier melting.Here,we quantitatively analyzed the stress evolution surrounding the Maidan fault,by calculating crustal stress changes caused by the interseismic tectonic loading,historical strong earthquakes nearby and surface hydrological mass loss.The numerical results show that the interseismic tectonic loading leads to regional Coulomb stress increases,with the rate of approximately 1.1~1.4kPa/yr along the Maidan fault.The historical strong earthquakes led to Coulomb stress decreases on most part of the Maidan fault.In particular,the Coulomb stress decreased by approximately 37kPa in the epicenter of 2024 M7.1 Wushi earthquake,indicating that historical strong earthquakes nearby may have delayed the occurrence of the latest earthquake event.Though the surface hydrological mass unloading has caused observable vertical deformation in the Tianshan mountain range,the crustal stress changes are minor and negligible compared with the long-term tectonic loading.Combining the Coulomb stress evolutions,the present-day seismicity,and tectonic deformation,the east segment of the Maidan fault is experiencing higher stress changes denoting more seismic hazards in the future.

关 键 词：迈丹断裂 震间构造加载 历史强震 地表水文质量变化 地壳应力演化 

分 类 号：P65[天文地球—地质学]