2023年12月18日甘肃省积石山6.2级地震的控震构造及特征  

Seismic structure characteristics of the 18 December 2023 M6.2 Jishishan earthquake, Gansu Province

作　　者：陆诗铭 吴中海[1,2] 李智超 Lu Shiming;Wu Zhonghai;Li Zhichao(Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China;Key Laboratory of Active Tectonics and Geological Safety,Ministry of Natural Resources,Beijing 100081,China;School of Earth and Space Sciences,Peking University,Beijing 100871,China)

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]自然资源部活动构造与地质安全重点实验室,北京100081 [3]北京大学地球与空间科学学院,北京100871

出　　处：《地震科学进展》2024年第1期86-93,共8页Progress in Earthquake Sciences

基　　金：中国地质调查项目(DD20221644);国家自然科学基金云南联合基金项目(U2002211);西藏自治区第1次全国自然灾害综合风险普查项目(2022年地震灾害部分)(XZLX-BMC-2022-053)共同资助。

摘　　要：2023年12月18日23时59分在甘肃省临夏州积石山县发生6.2级地震,造成了严重人员伤亡,及时了解此次地震的发震构造及其特征,对于分析区域未来强震危险性具有重要意义。综合区域地震构造、地质、震源机制、地震烈度和余震重定位等资料,对此次地震的控震构造及特征进行综合分析后认为,此次强震是发生在西宁—兰州断块内部的一次北北西向逆冲断层作用事件,距震中最近的拉脊山逆冲断裂带构成了此次地震的控震构造。该断裂带处于北西向日月山右旋走滑断层与北西西向西秦岭北缘左旋走滑断层交汇部位,整体呈北西至北北西向弧形展布,包含了南缘与北缘两条倾向相反的分支断裂带。震中位置、余震及烈度分布等数据指示此次地震的具体发震断层为拉脊山北缘逆冲断裂带南段的东支断层带,余震分布和极震区范围等符合逆断层型地震的上盘效应特征,但是否引起同震地表变形,还需进一步的现场调查确定。综合研究认为,此次积石山地震是在印度与欧亚板块持续陆陆碰撞作用下,青藏高原东北缘的西宁—兰州断块沿海原左旋走滑断裂向东侧向滑移过程中,在北东向挤压构造应力场下,引发日月山断层与西秦岭北缘断层构成的区域共扼走滑断裂系交汇挤压部位发生逆断层活动的结果。此次强震进一步指示青藏高原东缘的向东挤出构造体系仍是近年来我国陆内强震活动的主要控震构造,并警示应重视活断层相对发育的断块内部城镇密集区的强震灾害风险。On 18 December 2023,at Beijing time,a M6.2 earthquake struck Jishishan in Gansu Province.A thorough analysis of the earthquake structure and characteristics was conducted by combining information on regional seismic tectonics,geology,seismic source mechanism,seismic intensity,and aftershock relocation.The earthquake was a reverse fault event trending north-northwest within the Xining-Lanzhou fault block.The earthquake-controlling tectonics of the earthquake is the Lajishan reverse fault zone,which is closest to the epicentre of the earthquake.The fault zone is situated at the intersection of the northwest-trending Riyueshan dextral strike-slip fault and the east-west-trending Western Qinling North Rim left-trending strike-slip fault.It has an overall northwest-to-north-northwest striking angle and comprises two branch fault zones with opposite trends in the southern and northern rims.The earthquake’s epicentre location,aftershock distribution,and intensity distribution data suggest that the specific fault responsible for this earthquake is the east branch fault of the southern section of the reverse fault zone at the northern rim of Lajishan.This is consistent with the characteristics of the upward disc effect of reverse fault-type earthquakes.Further detailed field investigations are required to determine the deformation of the earth’s surface.The Jishishan earthquake is thought to have been caused by reverse fault activity at the intersection of the Riyueshan strike-slip fault and the northern edge of the Western Qinling fault.This was triggered by the eastward lateral slip along the original left-hand strike-slip fault along the Xining-Lanzhou fault block on the northeastern margin of the Tibetan Plateau.This occurred under the northeast-directed extrusion tectonic stress field resulting from the ongoing land-land collision between the Indian and Eurasian plates.This earthquake suggests that the extrusion tectonic system at the eastern margin of the Tibetan Plateau remains the primary structure controlling

关 键 词：甘肃积石山地震 发震构造 青藏高原东北缘 拉脊山北缘断裂带 西宁—兰州断块 

分 类 号：P315.2[天文地球—地震学]