GPS测定的四川芦山Mw6.6地震同震形变  

COSEISMIC DEFORMATION OF LUSHAN MW6.6 EARTHQUAKE INFERRED FROM CONTINUOUS GPS

作　　者：赵斌[1,2,3] 谭凯[1,2] 黄勇[1,2] 王伟[1,2] 张锐[4] 廖华 乔学军[1,2] 杜瑞林[1,2] 

机构地区：[1]中国地震局地震研究所(地震大地测量重点实验室),武汉430071 [2]中国地震局地壳应力研究所武汉科技创新基地,武汉430071 [3]武汉大学卫星导航定位技术研究中心,武汉430079 [4]地壳运动监测工程研究中心,北京100036 [5]四川省地震局减灾救助研究所,成都610041

出　　处：《大地测量与地球动力学》2014年第4期21-26,共6页Journal of Geodesy and Geodynamics

基　　金：地震行业科研专项(201208006);科研院所基本科研业务费(所长基金)(IS201226042);国家自然科学基金青年科学基金项目(41304019)

摘　　要：对芦山地震震中周围的GPS连续站观测资料进行分析处理，获得静态同震水平位移和动态高频形变。震中50km范围内高频GPS同震形变波形清晰，最大震动幅度为70mm，震动持续时间约30S。同震水平位移分布符合逆冲断层破裂形变模式，同震位移矢量指向震中，大小随震中距离而衰减。距震中29km观测到最大水平位移为21mm，距震中150km同震位移约1～2mm。以GPS静态同震形变初步约束单断层的产状及滑移量，结果显示芦山地震主要破裂位于震中附近20km内，平均逆冲滑动量约0．6m。GPS测定的同震形变研究表明，芦山地震是发生在龙门山断裂带南段的一次逆冲型地震事件。Both static coseismic displacements and high rate GPS （Global Positioning System）time series are processed and analyzed for continuous GPS stations around the epicenter of the Lushan earthquake. GPS stations less than 50 km far away from the epicenter record high rate GPS time series clearly,with the largest horizontal kinematic variation of about 70 mm. The near-field surface deformation lasted for approximately 30 s. The static displacement pattern agrees well with the mechanism of thrust earthquake, such as 2008 Mw7.9 Wenchuan earthquake. Offsets are toward the epicenter,as amplitude decaying with distance. In our results ,the largest horizontal offset of 21 mm is ob- served at SCTQ station,29 km far away from the epicenter. About 1 -2 mm coseismic jumps could be detected up to about 150 km away from the epicenter. Observed surface displacements are modeled using Okada＇ s formulation of a single fault buried in infinite elastic half-space. Simulated annealing algorithm is used to inverse optimum resolutions for fault location,width,length,depth, dip angle and average fanlt slip. Strike angle of fault is constrained to the result from fault plane solution using seismic waves. Our fault slip result shows that Lushan earthquake is a purely thrust event ,which rupture only about 20 km around the epicenter in the fault plane ,with average inverse slip about 0.6 m.

关 键 词：芦山地震 同震静态位移 动态形变 破裂反演 逆冲型地震 

分 类 号：P315[天文地球—地震学]