基于震源机制解分析山西长治地区应力场特征  

Analysis of Stress Field Characteristics in Changzhi Area ofShanxi Province Based on Focal Mechanism Solutions

作　　者：董春丽[1,2] 郭文峰 丁大业 丁学文[1,2] DONG Chunli;GUO Wenfeng;DING Daye;DING Xuewen(National Continental Rift Valley Dynamics Observatory of Taiyuan,Taiyuan 030025,China;Shanxi Earthquake Agency,Taiyuan 030021,China)

机构地区：[1]太原大陆裂谷动力学国家野外科学观测研究站,太原市030025 [2]山西省地震局,太原市030021

出　　处：《大地测量与地球动力学》2025年第5期456-463,共8页Journal of Geodesy and Geodynamics

基　　金：太原大陆裂谷动力学国家野外科学观测研究站项目(NORSTY2021-06);中国地震局震情跟踪定向工作任务(2024010115);山西省地震局项目(SBK-2220)。

摘　　要：收集山西长治及周边地区2009年以来M_L≥2.0地震事件的波形数据,利用Snoke初动符号加振幅比方法计算其震源机制解,最终获得其中M_L≥2.4且RMS≤0.45的42条天然地震和6条非天然地震的震源机制解。结果显示,研究区天然地震震源类型以走滑和正走滑型为主,主要受NEE-SWW向挤压和NNW-SSE向拉张作用;长治盆地区具有复杂而独特的小区域应力场特征,T轴近NS向,P轴沿文王山断裂为NEE-SWW向,其他区域以NE-SW为优势方向,并显示出震源节面具有较好的一致性和高倾角特征。探讨研究区内非天然地震的震源机制,发现矿山诱发地震多为正断型,塌陷为逆断型,其应力轴特征表现出P轴或T轴的大幅偏转,两轴夹角约180°,与天然地震的P轴和T轴接近垂直存在明显不同,这些特征可辅助判识地震类型。This article collected seismic waveform data for events of magnitude M L≥2.0 in Changzhi,Shanxi province,and its surrounding areas since 2009.The focal mechanisms of these events were determined using the Snoke first motion polarity and amplitude ratio method.Ultimately,42 focal mechanisms were obtained for natural earthquakes with M L≥2.4 and RMS≤0.45,alongside 6 for non-natural earthquakes.The results indicate that the focal mechanisms of natural earthquakes in the study area are predominantly strike-slip and normal strike-slip,primarily influenced by NEE-SWW compression and NNW-SSE extension.The Changzhi basin exhibits a complex and unique local stress field characterized by a nearly NS-oriented T-axes direction.The P-axes along the Wenwangshan fault follow an NEE-SWW orientation,while in other regions,NE-SW is the dominant direction,showing good consistency in fault plane solutions and high dip angles.The study also explores the focal mechanisms of non-natural earthquakes in the region.Mining-induced earthquakes are mostly normal faulting,while collapse events are reverse faulting.The stress axis characteristics of these non-natural events exhibit significant deviations,with the P-axes or T-axes showing large rotations and the angles between the two axes are about 180°,which is distinctly different from the natural earthquakes where the P-axis/T-axis are nearly perpendicular.These features can assist in distinguishing between different types of earthquakes.

关 键 词：震源机制解 长治盆地 构造应力场 

分 类 号：P315[天文地球—地震学]