2022年门源M_(W)6.7地震的同震破裂模型及应力研究  

THE COSEISMIC RUPTURE MODEL AND STRESS CHANGE OF THE 2022 MENYUAN M_(W)6.7 EARTHQUAKE

作　　者：于书媛[1,2] 黄显良[1,2] 郑海刚[1,2] 李玲利[1,2] 骆佳骥[1,2] 丁娟[1,2] 范晓冉 YU Shu-yuan;HUANG Xian-liang;ZHENG Hai-gang;LI Ling-li;LUO Jia-ji;DING Juan;FAN Xiao-ran(Anhui Earthquake Agency,Hefei 230031,China;Anhui Mengcheng National Geophysical Observatory,Anhui Earthquake Agency,Mengcheng 233527,China;State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Beijing 100029,China)

机构地区：[1]安徽省地震局,合肥230031 [2]安徽省地震局,安徽蒙城地球物理国家野外科学观测研究站,蒙城233527 [3]中国地震局地质研究所,地震动力学国家重点实验室,北京100029

出　　处：《地震地质》2023年第1期286-303,共18页Seismology and Geology

基　　金：国家自然科学基金(41802224);安徽蒙城地球物理国家野外科学观测研究站联合开放基金(MENGO-202114);安徽省青年基金(20220206)共同资助。

摘　　要：2022年1月8日,青海省门源县发生M_(W)6.7地震。文中运用Sentinel-1A数据,采用InSAR技术获取震区的LOS向形变场,其中最大形变量分别为7.0cm和7.2cm,结合升、降轨卫星的飞行方向,判定发震断层的运动性质以左旋走滑为主,其中最大形变量位于冷龙岭破裂段。此外,以InSAR形变场数据为约束,基于Okada弹性位错模型,厘定了发震断层的几何结构及破裂面的精细滑动分布特征,反演结果揭示出2个断层破裂面。冷龙岭破裂段是滑动主要集中的区域,最大左旋滑动量为3.66m,最大滑动深度为5km;而托莱山断裂处存在1.95m的左旋滑动量,位于5km深度处。判定发震断层为冷龙岭断裂西段,地震同时使托莱山断裂发生破裂。在此基础上,计算了库仑应力变化,结果显示震中300km区域内的库仑应力变化图像呈现走滑型地震特有的四象限分布特征。同时,震中破裂的NW-SE区域和NE-SW端的ΔCFS≥0.01MPa,这些区域后续的地震危险性值得关注。最后,相对于鄂尔多斯块体的GPS速度场显示冷龙岭地区存在一个显著的面应变高值区,未来该区的地震活动性可能持续较强。此外,文中还讨论了2016年和2022年2次门源地震的发震构造特征及发震关系,2次地震整体都是该地区应力积累的一次局部调整,它们都是青藏高原向NE推挤运动的表现。On January 8,2022,an earthquake of M_(W)6.7 occurred in Menyuan County,Qinghai Province.The epicenter of the earthquake is located in the middle eastern section of the Qilian Mountains seismic belt on the northeast edge of the Qinghai-Tibet Plateau.Under the northward push by the Qinghai-Tibet Plateau plate,and the push and subduction in the northeast direction of the Qilian Mountains,and also blocked by the Alxa block and affected by the push in the southwest direction of the Longshou Mountains uplift area at its front edge,a ramp structural pattern of compressive depressions was formed in the Hexi Corridor basins area.As a result,most of the active faults in this area are mainly NW-trending,and the active features are mostly characterized by compressional thrusting and strike slip.This paper reconstructs the coseismic deformation field of Menyuan earthquake through the European Space Agency Sentinel-1A C-band radar satellite data and D-In SAR technology,determines the geometric characteristics of the seismogenic fault through the inversion method of optimum fault slip distribution,and determines the seismogenic fault of this earthquake.The results show that the deformation range of the radar line of sight is-0.42~0.7m for the ascending track deformation field and-0.63~0.72m for the descending track deformation field,and the maximum deformation locates in the Lenglongling section.The data of ascending and descending tracks show that there are two obvious deformation regions with a butterfly-like stripe pattern.The sign of LOS deformation variable observed in InSAR deformation field of ascending and descending orbits in the same area is opposite.Combined with the flight direction of ascending and descending satellites,it is determined that the motion of seismogenic fault is mainly left-lateral strike slip.Among them,the Lenglongling Fault and Tolaishan Fault pass through the fracture surface revealed by InSAR deformation field,which means that the above fault is highly likely to be the seismogenic fault of the Me

关 键 词：2022年门源地震 哨兵InSAR 同震反演 发震断层 青藏高原 静态库仑应力变化 

分 类 号：P315.725[天文地球—地震学]