利用 GPS 和 InSAR 数据反演2011年日本东北 MW9.0地震断层的同震滑动分布

摘要

To determine the causative fault slip distribution of the Tohoku MW 9.0 earthquake in Japan,the coseismic deformation field of this earthquake was obtained with synthetic aperture radar interferometry (InSAR)technique based on Envisat/ASAR data.With detailed analysis and comparison of differ-ent methods used to resample InSAR deformation data,the fringe rate method taking into account spatial coherence of the interferogram was chosen for data resampling.Based on the elastic half-space dislocation model,the slip distribu-tion of causative fault was inverted from InSAR and GPS data using the least squares method.The research results show that the fringe rate with coherence method is more suitable for data resampling of wider range InSAR deformation field,within which there are finite boundaries except fault.The majority of the fault slips occurred mainly in the range of 50 km below the surface,and the maximal slip on the fault is 49.9 m,meanwhile,the moment tensor is 4.89 × 1022 N·m,the corresponding moment magnitude is MW 9.1.All these are con-sistent well with the results from seismological inversion, suggesting this inversion result in this study is reliable.%本文首先对 Envisat／ASAR 数据进行干涉处理，获取2011年日本东北 MW 9．0地震的地表 InSAR 同震形变场；然后通过对 InSAR 同震形变数据重采样方法的深入分析，选择条纹率法结合干涉图的空间相干性对 InSAR 同震形变数据进行重采样；最后基于弹性半空间位错模型，联合 InSAR 与 GPS 形变数据，采用最小二乘法反演发震断层的滑动分布．研究结果表明：考虑相干性的条纹率重采样方法，更适用于形变场中存在除断层外的有限边界、且形变场范围较大的 InSAR 数据重采样处理；断层滑动主要发生在地表以下50 km 范围内，最大滑动量为49．9 m，矩张量为4．89×1022 N·m，所对应的矩震级为 MW 9．1，与地震学反演的结果比较吻合．