2025年1月7日西藏定日6.8级地震震源破裂机理及邻区应力变化  

SOURCE RUPTURE MECHANISM AND STRESS CHANGES TO THE ADJACENT AREA OF JANUARY 7,2025,M_(S)6.8 DINGRI EARTHQUAKE,XIZANG,CHINA

作　　者：杨建文[1,2] 金明培 叶泵[1] 黎朕灵 李庆[1,2] YANG Jian-wen;JIN Ming-pei;YE Beng;LI Zhen-ling;LI Qing(Yunnan Earthquake Agency,Kunming 650224,China;Field Scientific Observation and Research Station on Crustal Tectonic Activities in Northwest Yunnan,Dali 671000,China)

机构地区：[1]云南省地震局,昆明650224 [2]云南大理滇西北地壳构造活动野外科学观测研究站,大理671000

出　　处：《地震地质》2025年第1期36-48,共13页Seismology and Geology

基　　金：云南省地震科技创新团队(CXTD202411);中国地震局地震科技星火计划项目(XH23034YA)共同资助。

摘　　要：2025年1月7日西藏自治区定日县发生M_(S)6.8地震。文中基于升、降轨Sentinel-1A卫星影像数据,采用D-InSAR技术获取了此次地震的同震形变场。以升、降轨同震形变数据为约束,联合反演了该地震的震源滑动模型,并进一步计算了同震位错引起的周边地区的库仑应力变化,对定日地震的形变特征、震源破裂机理及其对邻区应力调整作用开展了研究。结果表明:1)InSAR升、降轨同震形变场长轴均呈近SN向展布,同震形变均表现为拥有东、西2个明显形变区域且呈现蝴蝶状的条纹样式,升、降轨LOS向形变量分别在-0.58~0.33m和-0.80~0.66m之间。2)联合升、降轨同震形变数据反演得到的定日地震的矩震级为MW7.06,地震破裂过程呈现出从初始破裂点开始沿断层面向N拓展的单侧破裂特征,断层错动为兼具少许走滑分量的正断机制。发震断层主要破裂区长约55km,滑动分布集中在地下0~15km深度范围内,最大滑动量为4.25m,出现在地下8.6km深度处。此次地震的主要破裂区已经到达地表,位于震中以北沿走向约35~53km处,潜在地表破裂长约18km。3)定日地震导致发震断层东、西两侧的同震库仑应力降低;断层破裂段南、北两端及其周围区域的库仑应力显著增加,加载量远大于地震触发阈值0.01MPa,这些区域未来有进一步发生有感余震的可能。According to the official determination of China Seismic Network,at 09:05 on January 7,2025,an M_(S)6.8 earthquake(hereinafter referred to as Dingri earthquake)occurred in Dingri County(28.50°-N,87.45°-E),Shigatse City,Xizang,with a focal depth of 10km.The earthquake occurred in the southern part of the Qinghai-Xizang Plateau,which is located in the intersection area of the Shenzha-Dingjie rift and the south of Xizang detachment system.The Dengmecuo fault(about 11km)is the closest to the earthquake,and the focal mechanism is tensile rupture.The earthquake had high magnitude,high intensity and shallow source,and the towns and villages in the epicenter area were relatively concentrated.In addition,the landform type of the epicenter and the surrounding area is a river alluvial plain,and the soil is soft,which amplifies the earthquake damage effect.Due to the comprehensive superposition of various factors,the earthquake caused severecasualties and building damage.The Dingri earthquake is a shallow-source normal-fault earthquake.The ground vibration and building(structure)damage caused by the release process of seismic radiation energy are higher than other earthquakes of the same magnitude,and the surface rupture characteristics are more significant.Therefore,the in-depth study of the Dingri earthquake,the acquisition of the co-seismic deformation field and the source sliding model,and the understanding of the earthquake's seismogenic mechanism and dynamic process can provide scientific and technological support for seismic damage assessment and secondary disaster analysis.In addition,based on the fault slip model,the Coulomb stress change in the surrounding area caused by co-seismic dislocation can be calculated,which is of great significance for the scientific evaluation of the future seismic risk and potential seismic disaster risk in the adjacent area.The Dingri earthquake occurred at a high altitude area,with an average elevation of about 4--471m within 10km near the epicenter.The harsh natural conditions and

关 键 词：定日M_(S)6.8地震 同震形变场 震源滑动模型 同震库仑应力 

分 类 号：P315.2[天文地球—地震学]