基于重力场与InSAR的2021年青海玛多M_(S)7.4地震形变特征研究  

Research on the Deformation features of the 2021 Maduo M S7.4 Earthquake Based on the Gravity Field and InSAR

作　　者：于博 张庆云 李勇江[1] 徐顺强[1] 杨利普[1] YU Bo;ZHANG Qingyun;LI Yongjiang;XU Shunqiang;YANG Lipu(Geophysical Exploration Center,China Earthquake Administration,Zhengzhou 450002,Henan,China;The First Monitoring Center of China Earthquake Administration,Tianjin 300180,China)

机构地区：[1]中国地震局地球物理勘探中心,河南郑州450002 [2]中国地震局第一监测中心,天津300180

出　　处：《地震研究》2025年第4期641-649,共9页Journal of Seismological Research

基　　金：中国地震局地球物理勘探中心青年基金资助项目(YFGEC2023007);中国地震局地震科技星火计划项目(XH24055YA).

摘　　要：基于2019—2023年的流动重力观测资料,使用经典平差获得各测期测点重力值,得到研究区不同时间尺度的重力场变化结果;使用GAMMA软件对InSAR同震观测数据进行干涉处理,获取2021年青海玛多M S7.4地震的同震形变场。结果显示:玛多M S7.4地震震前研究区异常变化主要集中在震中附近,以负变化为主;地震前后1年期的重力场变化形成了“四象限”的分布特征;震后研究区重力场发生大范围的反向变化,但随着震后调整,震中区域东部的重力场变化量较西部更大,与双断层滑动模型给出的滑动量分布结果一致。玛多地震在LOS向最大位移约为1.29 m,发震断层为走滑型;通过断层滑动分布反演得到双断层模型的滑动主要集中在20 km深度内,发震主断层最大滑移量约为4.8 m,分支断层最大滑移量约为2 m。联合InSAR形变场与2020—2021期重力场变化开展分析后发现,玛多M S7.4地震的发震构造与重力场变化一致性较好,表明重力资料与InSAR资料的联合应用有助于更好地分析大震发震构造及机制。This paper analyzes the 2021 Maduo M S7.4 earthquake by using the measured mobile gravity data from 2019 to 2023 and the co-seismic InSAR observation data.The gravity values at the measuring points of the mobile gravimetric network in 5 measuring periods were obtained through classical adjustment method,which in turn provided the gravity field changes on different time scales in the study area.The Sentinel-1 data was interferometrically processed with GAMMA software to obtain the co-seismic deformation field of the Maduo M S7.4 earthquake.The results indicate that the changes in the regional gravity field before and after the Maduo M S7.4 earthquake exhibited a distribution pattern similar to“four quadrants”in the epicentral area.Observations of the post-earthquake gravity field adjustments,particularly in the cumulative variation over a two-year scale,proved that the gravity field variations in the eastern part of the epicenter were more significant than those in the western part;this feature was consistent with the slip distribution derived with the double-fault slip model.The InSAR co-seismic deformation showed a maximum displacement of 1.29 m or so in the Line of Sight(LOS)direction.The Maduo earthquake was caused by double seismogenic faults,with a maximum slip of about 4.8 m on the main fault and 2 m on the branch fault.The InSAR deformation field and the gravity field changes from 2020 to 2021 revealed good consistency between the seismogenic structure and the gravity field changes,suggesting that the joint application of gravity data and InSAR data can help better analyze the seismogenic structure and the seismogenic mechanism of major earthquakes.

关 键 词：时变重力 INSAR 玛多M S7.4地震 同震形变 断层滑动模型 

分 类 号：P315.727[天文地球—地震学]