2023年积石山M_(S)6.2地震的地震裂缝及其成因机制  

Earthquake-induced fissures and their formation mechanisms in the 2023 M_(S)6.2 Jishishan Earthquake

作　　者：张波 王爱国[1,2] 姚赟胜 何小龙[1,2] 姚赛赛 朱俊文 蔡艺萌 ZHANG Bo;WANG Aiguo;YAO Yunsheng;HE Xiaolong;YAO Saisai;ZHU Junwen;CAI Yimeng(Gansu Lanzhou National Geophysical Observation and Research Station,Lanzhou 730000,Gansu,China;Lanzhou Institute of Seismology,China Earthquake Administration,Lanzhou 730000,Gansu,China)

机构地区：[1]甘肃兰州地球物理国家野外科学观测研究站,甘肃兰州730000 [2]中国地震局兰州地震研究所,甘肃兰州730000

出　　处：《地质力学学报》2025年第2期211-222,共12页Journal of Geomechanics

基　　金：中国地震局地震科技星火计划(XH23040A,XH19045Y);科技部第二次青藏高原综合科学考察研究专题(2019QZKK0901);国家自然科学基金项目(42372267,42072246,41602225);中国地震局地震预测研究所基本科研业务费专项(2021IESLZ06)。

摘　　要：2023年积石山M_(S)6.2地震在地表形成了大量的地震裂缝,但对地震裂缝的成因认识存在较多分歧。为了更好地认识中强地震中地震裂缝的发育特征及其成因机理,采用野外观测、统计分析、无人机摄影测量等方法,系统调查积石山地震形成的246条地震裂缝,总结其发育特征和成因机理。研究显示:2023年积石山M_(S)6.2地震在Ⅶ—Ⅷ度区内形成了大量的地震裂缝,总体可分为构造微裂缝和非构造裂缝两类,非构造裂缝又包括山脊重力裂缝、滑坡边缘裂缝和沟谷裂缝-沙土液化组合。构造微裂缝沿积石山东缘断裂发育,宽度为厘米~毫米(cm~mm)级,通过断层面、节理面等介质软弱部位,表现为构造对裂缝的控制作用,裂缝同时具有“趋弱”的特点,说明此类裂缝不是断层直接错动地表而形成。非构造裂缝主要发育在震中北侧的黄土丘陵和台塬-沟谷区,山脊(台塬)部位的裂缝规模大、延伸远,从山脊(台塬)向下经山坡至沟谷,裂缝宽度从分米(dm)级降低为毫米(mm)级。构造微裂缝经过约半年时间已基本自然愈合,非构造裂缝的愈合时间远长于构造微裂缝的愈合时间;一些滑坡边缘裂缝可能难以自然愈合而形成永久位移,而对人类造成严重威胁的裂缝,需要人为修复。对2023年积石山M_(S)6.2地震裂缝的分布、类型和成因机制的分析表明,2023年积石山M_(S)6.2地震没有形成地表破裂带。对积石山地震的地震裂缝的综合研究对于地震次生灾害的研究、灾害损失减轻和地震构造分析具有重要意义。[Objective]Seismic fissures,landslides and mudflows are common secondary hazards of earthquakes.Following the occurrence of moderately strong earthquakes,detailed investigations of landslides and mudflows are usually conducted,but earthquake-induced fissures often receive less attention,because the characteristics and causes of earthquake-induced fissures are controlled by a combination of factors.The 2023 M_(S)6.2 Jishishan Earthquake formed an extensive and dense earthquake-induced fissure zone in the Jishishan Mountain front and the interior of the Linxia Basin,but there are large differences in the understanding of the genetic mechanisms of earthquake-induced fissures.[Methods]In order to better understand the characteristics and genetic mechanisms of earthquake-induced fissures in the Jishishan Mountains,246 fissures were systematically investigated by field observation,statistical analysis,and drone photogrammetry;then,the distribution,characteristics and genetic mechanisms of the earthquake-induced fissures were analyzed.Combined with relevant published studies,the following new findings are made.[Results]First,the 2023 M_(S)6.2 Jishishan Earthquake formed a large number of fissures in the VII-VIII degree zone,which can be generally divided into two categories:tectonic-related fissures and non-tectonic fissures,and the non-tectonic fissures are further divided into ridge gravity fissures,landslide-related fissures,and valley fissure-sand liquefaction combinations on the basis of the topography associated with these fissures.Second,the tectonic-related fissures developed along the eastern margin fault of the Jishishan Mountains,with fissure widths at the cm-mm level.The tectonic-related fissures extend through fault planes,joints,and other weaknesses of the Jishishan fault zone,clearly showing that the more than 100 m wide fracture zone(i.e.,weak zone in the upper crust)of the eastern margin fault of the Jishishan Mountains dominates the distribution of the earthquake-induced fissures.Meanwhile,the tectonic

关 键 词：地震裂缝 积石山地震 积石山东缘断裂 地震地质灾害 地表破裂 

分 类 号：P694[天文地球—地质学]