2022年青海门源Ms6.9地震地表破裂带及发震构造研究  

Coseismic surface rupture and seismogenic structure of the 2022 M;6.9 Menyuan earthquake,Qinghai Province,China

作　　者：潘家伟[1,2,3] 李海兵 Marie-Luce CHEVALIER[1,2,3] 刘栋梁 李超 刘富财[1] 吴琼 卢海建[1,2,3] 焦利青 PAN Jiawei;U Haibing;Marie-Luce CHEVALIER;LIU Dongliang;LI Chao;LIU Fucai u;WU Qiong;LU Haijian;JIAO Liqing(Key Laboratory of Deep-Earth 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,Jiangsu 222300,China;Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou),Guangzhou,Guangdcmg 511458,China)

机构地区：[1]中国地质科学院地质研究所,自然资源部深地动力学重点实验室,北京100037 [2]江苏东海大陆深孔地壳活动国家野外观测研究站,江苏东海222300 [3]南方海洋科学与工程广东省实验室(广州),广东广州511458

出　　处：《地质学报》2022年第1期215-231,共17页Acta Geologica Sinica

基　　金：第二次青藏高原综合科学考察研究项目(编号2019QZKK0901);国家自然科学基金项目(编号42020104007);南方海洋科学与工程广东省实验室(广州)人才团队引进重大专项(编号GML2019ZD0201);中国地质调查局项目(编号DD20221630);自然资源部深地动力学重点实验室项目(编号J1901)联合资助的成果。

摘　　要：2022年1月8日01时45分,青海省海北州门源县发生了M_(s)6.9级强烈地震,震中位于青藏高原东北缘海原断裂带中西段的冷龙岭断裂附近。震后的野外现场考察表明,这次地震在海拔3500~4100 m的高原北部祁连山区形成了一系列由张裂隙、张剪裂隙、剪切裂隙、挤压鼓包和裂陷等多类型破裂雁行状组合而成的同震地表变形带,表现为左旋走滑运动性质,总长约27 km。破裂带呈NWW—SEE走向,可分为南北两支,北支沿冷龙岭断裂西段分布,南支沿托莱山断裂东端分布,与北支间隔3 km呈左阶雁行排列。根据破裂带的走向变化和阶区特征,可将破裂带分为三段:西段、中段和东段,与地表同震位移分布特征较为吻合。西段为破裂带的南支,呈N93°E走向,长约4.5 km,最大左行水平位错约85 cm;中段为北支破裂带西侧部分,主要呈N102°E走向,长约7.5 km,最大左行水平位错约3.7 m;东段为北支破裂带东侧部分,走向呈N110~120°E走向,长约15 km,最大左行水平位错约3.0 m。门源地震震级与地表破裂带分布规模和变形强度的对比,表明本次地震的震源深度较浅,可能远小于10 km深。这次门源地震的发震断裂为海原断裂带呈挤压弯曲部分的冷龙岭断裂,具有花状构造特征。由于本次地震余震向SE方向扩展,表明具有应力向东迁移趋势,因此,冷龙岭断裂东侧处在海原断裂带上1920年海原大地震与2022年门源地震之间地震空区的金强河、毛毛山和老虎山断裂未来强震危险性升高,需要重点关注。At 01:45 Am on January 8, 2022, a relatively strong M;6.9 earthquake occurred in Menyuan County, Haibei Prefecture, Qinghai Province, China. The epicenter was located near the Lenglongling fault, which is the central western segment of the Haiyuan fault zone, northeastern Qinghai-Tibet Plateau. Field investigation from the day after the earthquake showed that it produced a series of co-seismic surface ruptures in the plateau’s mountainous area at an altitude of 3500~4100 m, with tension cracks, tensional-shear cracks, shear cracks, mole tracks and sags. The main rupture strikes NWW—SEE and is characterized by left-lateral strike-slip motion over a total length of ~27 km. The rupture zone is divided into two main branches: the northern and the southern branches. The northern branch follows the Lenglongling fault segment of the central and western Haiyuan fault, while the southern branch is located 3 km southwest of the northern branch’s western terminus, following the Tuolaishan fault, thus forming a left-step with the northern branch. Such trending variation and step characteristics suggest that the rupture zone can be divided into three segments: western, central, and eastern segments, consistent with the distribution of surface co-seismic displacements. The N93°E-striking, ~4.5 km-long western segment, i.e., the southern branch of the rupture zone, displays a maximum horizontal offset of ~85±10 cm. The N102°E-striking, ~7.5 km-long central segment, i.e., the western part of the northern branch, has a maximum horizontal offset of 3.7±0.1 m. The N110°~120° E-striking, ~15 km-long, eastern segment, i.e., the eastern part of the northern branch, exhibits a maximum horizontal offset of ~3.0±0.3 m. The fact that such rather small earthquake magnitude produced such long surface rupture and impressive surface deformation implies that the focal depth of 2022 Menyuan earthquake may be much shallower than 10 km. Seismogenic fault of the 2022 seismic event is the Lenglongling fault, forming a compression bend

关 键 词：门源M_(s)6.9地震 同震地表破裂 左旋走滑 海原断裂带 冷龙岭断裂 发震构造 青藏高原东北缘 

分 类 号：P315.2[天文地球—地震学]