Sequential combination of multi-source satellite observations for separation of surface deformation associated with serial seismicevents
Sequential combination of multi-source satellite observations for separation of surface deformation associated with serial seismicevents
复制标题
多源卫星观测的顺序组合用于分离与连续地震事件相关的地表变形
DOI：
10.1016/j.jag.2017.10.005
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发表时间：
2017
影响因子：
7.5
通讯作者：
Xianwen Liu
中科院分区：
文献类型：
--
作者：
Qiang Chen;Qian Xu;Yijun Zhang;Qi Yong;Guoxiang Liu;Xianwen Liu
单星大地测量技术在绘制与系列地震事件相关的地表形变序列时存在弱点，如干涉合成孔径雷达重访周期长，容易导致多事件形变信号混杂。单星大地测量技术对单个地表形变和地震模式的准确识别能力提出了挑战。各种卫星观测数据的迅速增加为克服这一问题提供了很好的解决方案。在这项研究中，我们探索了ALOS/PALSAR，ENVISAT/ASAR和GPS观测的多个重叠数据集的顺序组合，以分离与2011年Mw9.0东北冲大地震和两个强余震，包括Mw6.6 Iwaki和Mw5.8茨木事件相关的地表变形。我们首先估计断层滑动模型的主震ASAR干涉和GPS位移作为约束。由于所使用的PALSAR干涉图跨越了所有地震的周期，因此我们通过正演预测去除主震的地表形变，从而得到与两次强余震相关的PALSAR干涉合成孔径雷达形变。考虑到与茨木地震相比，更高震级的磐城地震对地震的形变贡献占主导地位，利用精化的PALSAR形变反演了磐城余震的震源参数。在去除Iwaki地震的形变分量后，利用剩余的PALSAR干涉合成孔径雷达形变量，确定了茨木地震的断层滑动分布。最后，从多源卫星观测的序列组合中明确识别出了系列地震的完整震源模式，表明主震是一次以巨型逆冲断裂为主的地震，而两次余震则是正常的断层运动。东北冲、岩城和茨木事件的估计地震矩震级分别为Mw 9.0、Mw 6.85和Mw 6.11。
Single satellite geodetic technique has weakness for mapping sequence of ground deformation associated with serial seismic events, like InSAR with long revisiting period readily leading to mixed complex deformation signals from multiple events. It challenges the observation capability of single satellite geodetic technique for accurate recognition of individual surface deformation and earthquake model. The rapidly increasing availability of various satellite observations provides good solution for overcoming the issue. In this study, we explore a sequential combination of multiple overlapping datasets from ALOS/PALSAR, ENVISAT/ASAR and GPS observations to separate surface deformation associated with the 2011 Mw 9.0 Tohoku-Oki major quake and two strong aftershocks including the Mw 6.6 Iwaki and Mw 5.8 Ibaraki events. We first estimate the fault slip model of major shock with ASAR interferometry and GPS displacements as constraints. Due to the used PALSAR interferogram spanning the period of all the events, we then remove the surface deformation of major shock through forward calculated prediction thus obtaining PALSAR InSAR deformation associated with the two strong aftershocks. The inversion for source parameters of Iwaki aftershock is conducted using the refined PALSAR deformation considering that the higher magnitude Iwaki quake has dominant deformation contribution than the Ibaraki event. After removal of deformation component of Iwaki event, we determine the fault slip distribution of Ibaraki shock using the remained PALSAR InSAR deformation. Finally, the complete source models for the serial seismic events are clearly identified from the sequential combination of multi-source satellite observations, which suggest that the major quake is a predominant mega-thrust rupture, whereas the two aftershocks are normal faulting motion. The estimated seismic moment magnitude for the Tohoku-Oki, Iwaki and Ibaraki evens are Mw 9.0, Mw 6.85 and Mw 6.11, respectively.