阿尔金断裂索尔库里段铜矿探槽长序列古地震记录  

Long records of paleoearthquakes along the Xorkoli section of the Altun Tagh fault

作　　者：袁兆德[1] 刘静 王伟[1] 邵延秀[3] 李占飞 李志刚 YUAN Zhaode;LIU Jing;WANG Wei;SHAO Yanxiu;LI Zhanfei;LI Zhigang(State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Beijing 100029,China;Institute of Surface-Earth System Science,Tianjin University,Tianjin 300072,China;Lanzhou Institute of Seismology,China Earthquake Administration,Lanz hou 730000,Gansu,China;Beijing Earthquake Agency,Beijing 100080,China;School of Earth Sciences and Engineering,SunYat-Sen University,Guangzhou 510275,Guangdong,China)

机构地区：[1]中国地震局地质研究所地震动力学国家重点实验室,北京100029 [2]天津大学表层地球系统科学研究院,天津300072 [3]中国地震局兰州地震研究所,甘肃兰州730000 [4]北京市地震局,北京100080 [5]中山大学地球科学与工程学院,广东广州510275

出　　处：《地质通报》2020年第2期147-163,共17页Geological Bulletin of China

基　　金：国家自然科学基金项目《以阿尔金断裂中段为例,走滑断裂的几何构造结对断裂活动习性的控制作用》(批准号:U1839203);国家自然科学基金青年基金项目《阿尔金断裂乌尊硝尔段古地震复发特征与级联破裂行为研究》(批准号:41902216);中央级公益性科研院所基本科研业务项目(编号:IGCEA1814)。

摘　　要：长序列古地震记录是理解断裂地震复发行为的关键,亦是区域地震危险性评价的重要基础。阿尔金断裂作为世界上最长的走滑断裂之一,其大地震复发行为一直是地震地质学家关注的重点。在该断裂中段索尔库里段开挖的探槽记录了8~9次古地震事件,发生时间分别为AD1598(1491~1740)、AD796(676~926)、668(732~590)BC、956(1206~716)BC、1301(1369~1235)BC、2105(2232~1987)BC、2664(2731~2601)BC、2818(2878~2742)BC和3411(3521~3205)BC。平均复发周期为620±410 a,变异系数为0.67,显示了弱准周期性。通过与其他研究点位的古地震数据对比,发现只有部分强震扩展至阿克塞弯曲内部。根据古地震复发周期和最新一次古地震的离逝时间,计算结果表明索尔库里段已经累积了3.3~4.6m的位移量,相当于Mw7.4~7.7地震,且未来30年发生强震的概率为0.07。Long records of paleoearthquakes are essential for understanding earthquake recurrence behavior of active faults and evaluating regional seismic hazard.The Altyn Tagh fault,one of the longest strike-slip faults in the world,is a research focus among seismic geologists.The authors documented a long paleoseismic record along the Xorkoli section of central Altyn Tagh fault.Eight or probably nine earthquakes were identified based on event evidence in the forms of open fissures,folds,unconformities,and upward fault terminations,with ages of AD1598(1491~1740),AD796(676~926),668(732~590)BC,956(1206~716)BC,1301(1369~1235)BC,2105(2232~1987)BC,2664(2731~2601)BC,2818(2878~2742)BC and 3411(3521~3205)BC respectively.The mean recurrence interval is 620±410 a with a coefficient of variation of 0.67,indicating that earthquake recurrence is weakly periodic.Synthesis of paleoseismic sites from the central Altyn Tagh fault indicates that not all earthquakes ruptured to the eastern end of the Xorkoli section,within the Aksay restraining bend.Given the 420 a elapsed time since the most recent event,a large surface-rupturing earthquake could occur at any time along the central section.

关 键 词：青藏高原 阿尔金断裂 活动构造 走滑断裂 古地震 

分 类 号：P618.41[天文地球—矿床学] P315.21[天文地球—地质学]