2023年积石山Ms6.2地震发震断层倾向争议讨论与相邻断裂地震危险性评估  

Discussion on the controversies of seismogenic fault dipping direction for 2023 Jishishan Ms6.2 earthquake and seismic hazard assessment of its adjacent faults

作　　者：平孜菲 葛伟鹏[1,2] 张波 朱俊文[1] 曹曦予 PING Zifei;GE Weipeng;ZHANG Bo;ZHU Junwen;CAO Xiyu(Lanzhou Institute of Seismology,CEA,Lanzhou 730000,Gansu,China;Gansu Lanzhou Geophysics National Observation and Research Station,Lanzhou 730000,Gansu,China)

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

出　　处：《地震工程学报》2025年第2期480-491,共12页China Earthquake Engineering Journal

基　　金：国家自然科学基金(42372267);中国地震局科技星火计划项目(XH18048);甘肃省自然科学基金(17JR5RA340);中国地震局地震预测研究所基本科研业务专项(2014IESLZ05)。

摘　　要：2023年12月18日甘肃省积石山县发生Ms6.2地震。选取Sentine1-1A升、降轨SAR卫星影像,采用差分合成孔径雷达干涉测量(D-InSAR)技术获取此次地震的同震形变场。结果显示,升、降轨LOS向同震形变场长轴为NW—SE向,变形为正值,向卫星方向靠近,揭示出地表抬升,升、降轨LOS向最大形变量分别为12 cm和9 cm。以升、降轨形变数据为约束,采用梯度下降法(SDM)反演同震滑动分布。反演结果表明:发震断裂西南倾向和东北倾向断层模型均能较好地正拟合合成孔径雷达干涉测量(InSAR)同震形变场观测值,反映出积石山地震为逆冲兼走滑型。为解决此次地震发震断层及倾向争议,重点结合区域构造背景和余震分布,推测其发震断层为一条走向NW—SE且倾向SW的隐伏断层,走向~148.4°,倾角52°,滑动角~130°,可能为积石山东缘断裂分支断层。同震库仑应力模型显示,临潭—宕昌断裂东段、冷龙岭断裂东段、海原断裂西段、拉脊山南缘断裂西段、贵德断裂等断层段位于同震库仑应力变化(ΔCFS)正、负跨界转换处,应给予关注。On December 18,2023,an Ms6.2 earthquake occurred in Jishishan County,Gansu Province.The ascending and descending Sentinel-1A SAR satellite images were selected and the differential interferometric synthetic aperture radar(D-InSAR)technology was used to obtain the co-seismic deformation field of the earthquake.The results show that the long axis direction of co-seismic deformation field in the line of sight(LOS)direction is NW-SE,and the deformation is positive,indicating an approach towards the satellite and revealing surface uplift.The maximum deformation in the LOS direction of ascending and descending tracks is 12 and 9 cm,respectively.Subsequently,the co-seismic slip distribution was inverted using the steepest descent method with ascending and descending deformation data as constraints.The inversion results show that both the SW-dipping and NE-dipping fault models fit the observed values of InSAR co-seismic deformation field well,indicating that the Ms6.2 earthquake is a combined thrust/strike-slip faulting type.The tectonic background and aftershock distribution in the study area were discussed to solve the controversies on the seismogenic fault and its dipping direction of the event.It is inferred that the seismogenic fault of the Jishishan Ms6.2 earthquake is a hidden fault striking NW-SE and dipping SW,with a strike of approximately 148.4°,a dip angle of 52°,and a slip angle of approximately 130°,possibly a branch fault of the Jishishan east margin fault.Additionally,the co-seismic Coulomb stress model shows that the eastern section of Lintan-Tanchang fault,the eastern section of Lenglongling fault,the western section of Haiyuan fault,the western section of Lajishan southern margin fault,and the Guide fault are located at the positive-negative transition zone of co-seismic Coulomb failure stress change(ΔCFS),which should be given attention.

关 键 词：INSAR 积石山Ms6.2地震 同震形变场 SDM 断层滑动分布 

分 类 号：P315[天文地球—地震学]