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中强地震发震构造标志浅析——以2023年积石山Ms6.2地震为例

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地震地表破裂是地震发生的重要特征,是研究地震动力学、构造变形的重要手段.一般认为,M6%以上的地震才会形成地表破裂.但近年来,也有M6.0左右的地震发生了地表破裂.本文旨在探讨中强地震地表破裂的识别方法.中强地震发震构造的识别具有一定的挑战性,主要表现在以下几个方面:①中强地震地表破裂的规模(位错量、宽度、长度和深度)较小,容易被黄土层厚覆盖,掩盖地表破裂的痕迹,不易识别;②非构造成因裂缝干扰,使得难以区分构造成因地表破裂.本文以2023年积石山Ms6.2地震为例,对中强地震构造成因破裂的识别标志进行了初步分析,提出了以下识别标志:①地表破裂几何展布和剖面形态,地震伴生的次生灾害(滑坡、崩塌、砂土液化等)的线性分布为识别发震构造提供参考和线索;②地表破裂沿破裂走向呈现稳定地穿越不同地貌单元,至少穿越一条沟谷等低凹地貌;③地表破裂在地质剖面上表现出稳定的产状;④地表破裂伴生构造形态,地表沿破裂发育雁列式褶皱(挤压鼓包)与张裂缝交替出现的现象.本文提出的识别标志为中强地震发震构造的识别提供了新的思路.
Analysis of the Markers of Seismic Structures for Moderate Earthquakes:A Case Study of the 2023 Jishishan Ms6.2 Earthquake
Surface rupture is an important feature of earthquake occurrence,and a valuable tool for studying earthquake dynamics and tectonic deformation.It is generally believed that surface ruptures are only formed by earthquakes with magnitudes of M6%or greater.However,in recent years,surface ruptures have also been observed in earthquakes with magnitudes of M6.0 or less.This study aims to explore the methods for identifying sur-face ruptures in moderate earthquakes.The identification of the seismic structures of mod-erate earthquakes is challenging,mainly due to the following factors:① the relatively small scale of surface ruptures in moderate earthquakes(such as displacement,width,length,and depth),making them easily covered by thick loess and hidden;② non-tectonic fractures interfere with the identification of tectonic fractures.In this study,we conducted a preliminary analysis of the identification markers of the seismic structures of moderate earthquakes based on the Jishishan Ms6.2 earthquake.We proposed the following identifi-cation markers.① Geometric distribution and profile morphology of surface ruptures,lin-ear distribution of secondary disasters(landslides,collapses,sand liquefaction,etc.)as-sociated with earthquakes provides references and clues for identifying the seismic struc-ture;② the rupture runs stably across different geomorphic units along the rupture direc-tion and at least crosses one low terrain such as a gully;③ the rupture on the geological profile shows a stable dip;④ tectonic morphology associated with surface ruptures that develops alternating echelons folds(compressional mounds)and tension cracks along the rupture.The identification markers proposed in this study provide new ideas for the iden-tification of the seismic structures of moderate earthquakes.

Qinghai-Tibet PlateauLajishan fault zoneThe 2023 Jishishan Ms6.2 earth-quakeSeismic structureEarthquake surface rupture

张军龙、徐岳仁、李文巧、陈峰

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中国地震局地震预测研究所,北京 100036

青藏高原 拉脊山断裂带 2023年积石山Ms6.2地震 发震构造 地震地表破裂

国家重点研发计划国家重点研发计划地震动力学国家重点实验室开放基金国家自然科学基金中国地震局地震预测研究所基本科研业务费专项

2023YFC3012001-22023FY10150401LED2023B1041372215CEAIEF20230403

2024

地震
中国地震局地震预测研究所 中国地震学会地震预报专业委员会 中国地震学会地震流体专业委员会 中国地震学会地震电磁学专业委员会

地震

CSTPCD北大核心
影响因子:0.733
ISSN:1000-3274
年,卷(期):2024.44(1)