汶川地震同震形变场的GPS和InSAR邻轨平滑校正与断层滑移精化反演  

Correction of coseismic deformation field associated with Wenchuan earthquake with GPS observables and InSAR adjacent track smoothing and fault slip inversion

作　　者：杨莹辉[1] 陈强[1] 刘国祥[1] 程海琴[1,2] 刘丽瑶[1] 胡植庆[3] 

机构地区：[1]西南交通大学遥感信息工程系,成都610031 [2]华东交通大学土木建筑学院,南昌330013 [3]台湾大学地质科学系

出　　处：《地球物理学报》2014年第5期1462-1476,共15页Chinese Journal of Geophysics

基　　金：国家自然科学基金(41072220;51178404);国家973计划资助项目(2012CB719901);四川省应急测绘保障与地质灾害监测中心开放基金(K2014B006);2014年西南交通大学博士研究生创新基金;中央高校基本科研业务费专项资金资助

摘　　要：为克服InSAR观测汶川地震同震形变场的邻轨不连续问题，提出联合GPS观测值与邻轨平滑约束的同震位移校正方法，采用GPS观测形变去除PALSAR轨道误差引入的残留平地相位，基于形变平滑条件校正邻轨干涉相位的不连续性．ALOS／PALSAR干涉处理结果表明，校正后同震形变场的准确度与平滑性得以显著提高，InSAR高相干点残差达3．6cm，校正后精度提高约60％，低相干点精度提高约40％，校正后形变场的邻接平滑因子标准差减小约33％，验证了轨道误差校正与邻轨平滑约束方法的准确性与可靠性．进一步基于弹性半空间位错模型的断层滑移反演结果表明，断层滑移主要分布于映秀、北川和青川地区，集中于地壳深度0～16km范围，最大滑动量（位于北川县城）约为9．0m，GPS反演模型残差为5．5cm，InSAR反演模型残差达9．2cm，InSAR反演精度约有30％的显著提高，由模型反演计算得到的地震矩为8．0469×10^20N·m．In order to overcome the discontinuity of InSAR derived coseismic interferogram, a new method was proposed for the fringe correction with GPS observations and adjacent smoothening conditions. The GPS observations were employed to model the residual flat-earth phase and the interferometric fringes between adjacent orbits were smoothened with geometric constraints. The corrected coseismic deformation with ALOS/PALSAR images shows that the accuracy and smoothness were significantly improved. The RMSE of InSAR high coherent area reaches 3.6 cm with a 60% decrease, and that of low coherent area decreased by 40%. The smoothness factors are also improved by 33 %. The correction results validated the feasibility and reliability of proposed method. The fault slip model was derived from the Okada dislocation model with InSAR and GPS deformation field. The results show that the main fault slip happened in 0-16 km depth in the crust in Yingxiu, Beichuan and Qingchuan area. The maximum slip is about 9.0 m located in Beichuan area. The inversion residuals of GPS and InSAR observations reach 5.5 cm and 9.2 cm respectively. The inversion accuracy of InSAR corrected deformation field was improved by 30%. The derived seismic moment from the refined fault slip model reaches 8. 0469× 10^20 N · m.

关 键 词：同震形变 邻轨平滑 断层滑移模型 雷达干涉测量 GPS 

分 类 号：P228[天文地球—大地测量学与测量工程]