We developed a flexible finite-fault inversion method for teleseismic P
waveforms to obtain a detailed rupture process of a complex
multiple-fault earthquake. We estimate the distribution of potency-rate
density tensors on an assumed model plane to clarify rupture evolution
processes, including variations of fault geometry. We applied our method
to the 23 January 2018 Gulf of Alaska earthquake by representing slip on
a projected horizontal model plane at a depth of 33.6 km to fit the
distribution of aftershocks occurring within one week of the mainshock.
The obtained source model, which successfully explained the complex
teleseismic P waveforms, shows that the 2018 earthquake ruptured a
conjugate system of N-S and E-W faults. The spatiotemporal rupture
evolution indicates irregular rupture behavior involving a
multiple-shock sequence, which is likely associated with discontinuities
in the fault geometry that originated from E-W sea-floor fracture zones
and N-S plate-bending faults.