. A multi-fault model estimation from tsunami data: An application to the 2018 M7.9 Kodiak earthquake

Abstract
We developed a new search algorithm to find a multi-fault model of a complex earthquake, such as the January 23, 2018 Kodiak earthquake from the tsunami source model by utilizing a Green's function based time reverse imaging (GFTRI) with an adjoint sensitivity (AS) method. In this study, we applied the AS method with GFTRI to invert for the source of the M7.9 earthquake using tsunami waveform. From the reconstructed source we determined slip distribution on faults chosen based on the fault-parameters suggested by CMT solution but with different epicentral locations. We carried out a number of source inversions using different combinations of faults to find the best fault model that provides smallest residual error. Focal mechanism indicates that faulting occurred on a steeply dipping fault striking either N-S direction (right lateral) or E-W direction (left lateral) while subsequent work reveals a more complex pattern of strike-slip faulting. Our results suggest that the rupture occurred on four faults oriented in both approximately N-S and E-W directions.