2008年于田M_W7.2地震滑动分布反演及三维同震形变场解算  

Slip Distribution Inversion and 3D Co-seismic Deformation Field Calculation of the 2008 Yutian M_W7.2 Earthquake

作　　者：余晨晖 申旭辉[2] 张景发[2] 李永生[2] YU Chen hui;SHEN Xu hui;ZHANG Jing- fa;LI Yong sheng(Institute of Earthquake Forecasting, CEA Beijing 100036, China;Institute of Crustal Dynamics, CEA. Beijing 100085, China)

机构地区：[1]中国地震局地震预测研究所,北京100036 [2]中国地震局地壳应力研究所,北京100085

出　　处：《地震》2018年第3期24-34,共11页Earthquake

基　　金：国家自然科学基金项目(41602223)资助

摘　　要：基于ENVISAT ASAR升降轨数据,利用InSAR获取2008年于田MW7.2地震同震形变场;采用SDM反演本次地震断层滑动分布;使用PSCMP正演获取于田MW7.2地震南北向模拟形变量,并结合升降轨同震形变场,解算三维同震形变场。同震形变场分析表明,2008年于田MW7.2地震以正断为主,且带有走滑运动特征,破裂带走向为NNE向。同震滑动分布反演结果显示,断层沿走向被分为4段F1、F2、F3、F4,其滑动分布集中在0~14km区间,以F2、F3段为主,最大滑动量约5.31m,位于F2段深部2.76km处;沿破裂带走向,左旋走滑位移与垂直位移比值有增大的趋势;反演获得的地震矩M0=5.58×1019 N·m,相当于矩震级MW7.1。三维同震形变场解算结果显示,断层上盘整体表现为沉降,断层下盘整体表现为隆升,且沉降量明显大于隆升量,表明地震以正断破裂为主;除靠近断裂带中上部表现为向东南运动外,上盘整体上表现为向西南运动;断层下盘则整体表现为向东北运动,证明破裂兼有左旋走滑运动。滑动分布反演、正演与三维同震形变场解算结果皆表明,于田MW7.2地震破裂以正断为主,且带有一定的左旋走滑。We obtained the co-seismic deformation fields of the 2008 Yutian MW7.2 earthquake using InSAR based on ascending and descending orbits of ENVISAT ASAR data.SDM is used to invert the fault slip distribution.Using PSCMP to forward and obtain the simulated NS direction deformation,then combining with the co-seismic deformation fields of ascending and descending orbits to calculate the 3 Dco-seismic deformation field.The analysis of the co-seismic deformation fields shows that the 2008 Yutian MW7.2 earthquake is mainly rupturing along the NNE-trending normal fault with a slight strike-slip component.The inversion of the co-seismic slip distribution shows that the fault is divided into four segments along strike,and slip distribution mainly concentrates in 0 to 14 km depth and fault plane of F2 and F3,the largest slip is about 5.31 mlocated in depth of 2.76 km along the fault plane of F2,the ratio of left-lateral strike-slip deformation to vertical deformation along the rapture tends to increase,the inverted seismic moment is about M0=5.58×1019 N·m,which is equal to a moment magnitude of MW7.10.The result of threedimensional co-seismic deformation field calculation shows that the hanging wall of fault is subsidence deformation,the footwall of fault is uplift deformation,and the subsidence is obviously larger than the uplift,which proves that the earthquake is mainly normal fault.Except that the mid-upper part of the hanging wall near the fault zone moved to ES direction,the hanging wall moved to WS direction,however,the footwall moved EN direction on the whole,which demonstrates that the rupture has left-lateral strike-slip.Forward and inversion of the slip distribution and calculation of three-dimensional deformation field show that the 2008 Yutian MW7.2 earthquake is mainly normal fault with a significant leftlateral strike-slip.

关 键 词：于田MW7.2地震 INSAR 滑动反演 三维形变场 

分 类 号：P315.7[天文地球—地震学]