摘要
利用华北地区2009—2014年GPS水平运动速度场数据,采用块体负位错模型反演了郯庐断裂带中南段断层深部滑动速率、断层闭锁程度分布、断层滑动亏损速率分布及地震矩积累率,结合地表应变率分布,对郯庐断裂带中南段深、浅部形变、应变特征以及华北地区的地壳形变模式进行了分析.结果表明:郯庐断裂中南段的北端主要为右旋走滑特性,南端则表现为右旋走滑兼拉张性运动,断层滑动速率在0.9mm·a^(-1)至1.2mm·a^(-1),且沿断层走向由北至南逐次增大.断层闭锁程度分布沿走向分布不均一,断层闭锁深度由最北端的27km增加到中段的32km,至最南端变为5km,断层闭锁最深处与1668年郯城MS8.5震中位置相对应.断层滑动亏损速率沿走向由0.9mm·a^(-1)增加到1.2mm·a^(-1),沿倾向由地表至深部逐渐减小为0mm·a^(-1).地震矩积累率在郯庐断裂带中南段郯城附近较大,而地表对应区域为第二应不变分量的低值区.华北地区地壳变形以块体运动为主,块体内部应变及断层闭锁产生的负位错效应次之;郯庐断裂带中南段断层形变沿走向呈条带状分布,形变宽度单侧小于50km,形变量不超过1mm·a^(-1),且上盘形变略大于下盘.
By using GPS-derived horizontal velocities of 2009—2014 and a dislocation model,we inverted the slip rate,fault coupling and slip rate deficit on the middle and southern segments of the Tanlu fault.We also calculated the moment accumulation rate based on the fault slip rate and the fault locking depth and analyzed crustal deformation in East China.Along the middle and southern segments of the Tanlu fault,the results predict 0.9mm·a-1 of right-lateral strike-slip at the northern end,gradually changing to 1.2dextrorotary extension at the southern end.The overall pattern of the interseismic locking depth is unevenly distributed along the middle and southern segments of the Tanlu fault.We estimated fault coupling down to 27 km depth or morefor the northern part,and 25~32km for the central part which is coincident with the epicenter of the 1668 Tancheng earthquake.The southern part,however,is only locked from 5km to 25 km depth.Similar to spatial distribution of the fault coupling,the slip rate deficit changes from a lower value in the northern part to a higher level in the southern part,ranging from 0.9mm·a-1to 1.2 mm·a-1 along the middle and southern segments of the Tanlu fault.And it gradually decreases to 0mm·a-1 along the dip.The seismic moment accumulation rate per unit length of the fault is high on the fault plane beneath Tancheng city;however,it is negatively correlated with the strain rate on the surface.Our results also show that tectonic deformation occurring in East China is dominated by block rotation.While most sites in East China are affected by elastic strain within blocks to some degree.However,only sites in a narrow strip（less than 50 km with velocities less than 1 mm·a-1）along the middle and southern segments of the Tanlu fault are affected by elastic strain loading due to fault coupling.Compared with sites on the footwall,sites on the hanging wall are affected more by strain loading due to fault coupling.
作者
李彦川
单新建
宋小刚
姜宇
甘卫军
屈春燕
王振杰
LI Yan-Chuan SHAN Xin-Jian SONG Xiao-Gang JIANG-Yu GAN Wei-Jun QU Chun-Yan WANG Zhen-Jie(State Key Laboratory of Earthquake Dynamics, Institute of Geology, CEA, Beijing 100029, China School of Geosciences, China University of Petroleum （East China）, Qingdao 266580, China)
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2016年第11期4022-4034,共13页
Chinese Journal of Geophysics
基金
国家自然科学基金(41461164002)
中央高校基本科研业务费专项资金(R1401038A)联合资助
作者简介
李彦川，男，1989年生，在读博士，主要从事GPS地球动力学研究．Email：yanliupc@163．com
通讯作者单新建，男，1966年生，研究员，主要从事地壳形变观测与动力学研究．E—mail：xjshan@163．com
