In this study, we developed a new search algorithm to find a multi-fault model of a complex earthquake using tsunami data, and applied it to the January 23, 2018 M7.9 Kodiak earthquake. Our method includes a Green’s function based time reverse imaging (GFTRI) approach to invert for sea surface displacement using tsunami waveforms, followed by inversion of the sea surface displacement for the earthquake slip distribution. The global CMT focal mechanism for this event indicates that faulting occurred on a steeply dipping fault striking either N–S (right lateral) or E–W (left lateral), while subsequent work reveals a more complex pattern of strike-slip faulting. We carried out a number of source inversions using different combinations of faults to find the model based on an extremum for residual errors. Our results suggest that the rupture occurred on at least three faults oriented in approximately N–S and E–W directions. We further explored the fault-geometry parameters by perturbing them within a range suggested by previous work. We found that the sea surface displacement model is best fit by our preferred three fault-model with the set of parameters (strike, dip, rake): ( $$165^{\circ }$$ 165 ∘ , $$60^{\circ }$$ 60 ∘ , $$154^{\circ }$$ 154 ∘ ) and ( $$265^{\circ }$$ 265 ∘ , $$60^{\circ }$$ 60 ∘ , $$10^{\circ }$$ 10 ∘ ) for N–S and E–W directions, respectively.

中文翻译：

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基于海啸数据的多断层模型估计：在 2018 年 M7.9 科迪亚克地震中的应用

在这项研究中，我们开发了一种新的搜索算法，使用海啸数据寻找复杂地震的多断层模型，并将其应用于 2018 年 1 月 23 日的 M7.9 科迪亚克地震。我们的方法包括基于格林函数的时间逆向成像 (GFTRI) 方法，使用海啸波形反演海面位移，然后反演地震滑动分布的海面位移。该事件的全球 CMT 震源机制表明，断层发生在一条陡峭的断层上，撞击 N-S（右侧）或 E-W（左侧），而随后的工作揭示了更复杂的走滑断层模式。我们使用不同的故障组合进行了许多源反演，以找到基于残差极值的模型。我们的研究结果表明，破裂发生在至少三个断层上，这些断层大致分布在 N-S 和 E-W 方向。我们通过在先前工作建议的范围内扰动它们来进一步探索断层几何参数。我们发现海面位移模型最适合我们首选的三个断层模型，其中包含一组参数（冲击、倾角、倾斜度）：( $$165^{\circ }$$ 165 ∘ , $$60^{\circ }$$ 60 ∘ , $$154^{\circ }$$ 154 ∘ ) 和 ( $$265^{\circ }$$ 265 ∘ , $$60^{\circ }$$ 60 ∘ , $10^{\circ }$$ 10 ∘ ) 分别用于 N–S 和 E–W 方向。