摘要
2023年10月24日甘肃酒泉市肃北县发生了M_(S)5.5地震,震中位于青藏高原前缘祁连山地震带上。为深入探究此次地震的发震机理及与构造应力场的关系,利用升、降轨Sentinel-1数据获取了此次肃北M_(S)5.5地震的InSAR同震形变场,并基于均匀位错模型确定了发震断层参数;在此基础上,采用分布式滑动反演方法获得了发震断层的精细滑动分布,并进一步分析了肃北M_(S)5.5地震引起的库仑应力荷载及区域震间应变率变化。研究结果表明:此次地震产生的地表形变场在InSAR升、降轨视线向分别达到12 cm、9 cm,形变主要表现为地表隆升;发震断层为位于疏勒南山断裂与中祁连北缘断裂之间的一条隐伏断层,走向角约为166.97°,倾角约为68.69°,滑动角约为110.39°;断层滑动主要集中在1.2~4.9 km深度范围内,最大滑动量为0.58 m,发生于地下约2.56 km深处;反演得到的矩震级为M_(W) 5.6,同震破裂以逆冲为主兼少许右旋走滑分量。此次地震事件导致了中祁连北缘断裂与疏勒南山断裂之间区域及疏勒河断裂带北侧地区出现一定程度的库仑应力加载特征。同时,区域面应变率在震间呈现明显挤压态势,在震区北侧面应变与最大剪应变率较高,历史地震多发生于应变高值向低值变化的梯度带上,结合区域的应力分布特征表明,该地区未来地震的危险性不容忽视。
[Objective]On October 24,2023,an M_(S)5.5 earthquake occurred in Subei County,Jiuquan City,Gansu Province.The epicenter was located in the Qilian mountain seismic belt at the northeastern margin of the Qinghai-Tibet Plateau.Understanding the seismogenic mechanism of this earthquake and its relationship with the tectonic stress field is crucial for analyzing the seismic hazard in the region.[Methods]The InSAR coseismic deformation field of the M_(S)5.5 earthquake in Subei was obtained using ascending and descending Sentinel-1 SAR data,and the parameters of the seismogenic fault were determined based on a uniform slip model.Subsequently,a distributed slip inversion method was applied to obtain a detailed slip distribution of the seismogenic fault.Furthermore,the earthquake-induced changes in the Coulomb stress and the regional interseismic strain rate were determined.[Results]The results indicate that the surface deformation values generated by this earthquake reached 12 cm and 9 cm in the ascending and descending InSAR line of sight,respectively.The deformation primarily manifests as surface uplift;the seismogenic fault is a concealed fault located between the Shule Nanshan Fault and the northern margin fault of the Central Qilian,the strike is approximately 166.97°,the dip angle is around 68.69°,and the slip angle is about 110.39°;the fault slip is primarily concentrated within the depth range of 1.2 km to 4.9 km,with a maximum slip of 0.58 m occurring at a depth of approximately 2.56 km;the moment magnitude obtained from the inversion is M_(W) 5.6,and the coseismic rupture is primarily characterized by thrust motion with a minor component of right-lateral strike-slip.This seismic event resulted in regional Coulomb stress changes between the northern margin fault of the Central Qilian and the Shule Nanshan Fault,as well as in the northern area of the Shule River Fault Zone.Additionally,the regional surface strain rate exhibited a distinct compressive trend before the earthquake,with higher surface strain and maximum shear strain rates observed on the northern side of the seismic zone.[Conclusion]The continuous accumulation of strain leads to an increased seismic hazard,with historical earthquakes often occurring in gradient zones where strain values transition from high to low.Considering the regional strain distribution characteristics and seismic activity,the seismic hazard in this area remains significant in the future and should not be overlooked.[Significance]The research findings have a certain guiding significance for understanding the tectonic background of the Qilian Block and its seismic hazard.
作者
熊国华
季灵运
陈玉鑫
朱良玉
刘传金
徐晶
蒋锋云
徐国彬
XIONG Guohua;JI Lingyun;CHEN Yuxin;ZHU Liangyu;LIU Chuanjin;XU Jing;JIANG Fengyun;XU Guobin(The Second Monitoring and Application Center,China Earthquake Administration,Xi'an 710054,Shaanxi,China;Gansu Earthquake Agency,Lanzhou 730000,Gansu,China;Heilongjiang Institute of Geological Sciences,Harbin 150036,Heilongjiang,China)
出处
《地质力学学报》
北大核心
2025年第2期287-300,共14页
Journal of Geomechanics
基金
国家自然科学基金项目(42474013,42104061)
中国地震局震情跟踪定向工作任务项目(2024010206)。
