An Adjoint Sensitivity Method Applied to Time Reverse Imaging of Tsunami Source for the 2009 Samoa Earthquake
An Adjoint Sensitivity Method Applied to Time Reverse Imaging of Tsunami Source for the 2009 Samoa Earthquake
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DOI：
10.1002/2017gl076031
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发表时间：
2017-12
影响因子：
5.2
通讯作者：
M. Hossen;A. Gusman;K. Satake;P. Cummins
中科院分区：
文献类型：
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作者：
M. Hossen;A. Gusman;K. Satake;P. Cummins
我们之前开发了一种基于“时间逆成像”的海啸震源反演方法，并利用2011年东北地震海啸的海啸数据证明了该方法的计算效率很高，能够以较好的精度再现海啸震源模型。在本文中，我们将该方法应用于2009年萨摩亚地震海啸，该地震海啸是由正断层和逆冲断层组成的双重地震引发的。结果表明，该方法能够较好地恢复与正断层和逆冲断层相关的震源模型。我们发现，反演结果对某些必须从反演中去除的台站高度敏感。为了估计出一个真实的震源模型，我们采用伴随灵敏度法寻找最优台站集。我们发现，使用最优台站集后，反演结果有明显改善。此外，根据重建的震源模型估计了断层的滑动分布，并由此成功地确定了正断层地震的断裂面倾斜方向。结果表明，断平面向东北方向倾斜。
We have previously developed a tsunami source inversion method based on “Time Reverse Imaging” and demonstrated that it is computationally very efficient and has the ability to reproduce the tsunami source model with good accuracy using tsunami data of the 2011 Tohoku earthquake tsunami. In this paper, we implemented this approach in the 2009 Samoa earthquake tsunami triggered by a doublet earthquake consisting of both normal and thrust faulting. Our result showed that the method is quite capable of recovering the source model associated with normal and thrust faulting. We found that the inversion result is highly sensitive to some stations that must be removed from the inversion. We applied an adjoint sensitivity method to find the optimal set of stations in order to estimate a realistic source model. We found that the inversion result is improved significantly once the optimal set of stations is used. In addition, from the reconstructed source model we estimated the slip distribution of the fault from which we successfully determined the dipping orientation of the fault plane for the normal fault earthquake. Our result suggests that the fault plane dip toward the northeast.