July 2020 Simeonof Earthquake: Was slip in the earthquake contained within the interseismically locked region?

Abstract:

The July 22, 2020 Simeonof earthquake ruptured a portion of the Alaska megathrust at the edge of the Shumagin Islands. The epicenter was located east of the Shumagin islands, within a section of the megathrust that had been inferred to be partially locked, with a relatively high slip deficit rate. Geodetic models of the interseismic deformation suggest a series of sharp along-strike transitions, with slip deficit being very low in the segment corresponding to the Shumagin Islands, and most of the plate interface inferred to be creeping to the west of the islands. The larger aftershocks within the first few days after the mainshock fall primarily into clusters east and west of the Shumagin Islands, and the initial USGS finite fault model suggests that all slip in the earthquake occurred east of the islands or under the easternmost islands. However, such a slip distribution would leave the western aftershocks unexplained, unless they are occurring because of along-strike postseismic afterslip.

The occurrence of this earthquake allows us to ask a basic question: Was slip in the earthquake contained within the interseismically locked region? Or did the rupture extend along-strike into a part of the megathrust that was inferred to be creeping? To get the answer, you will have to see the presentation, which will show a slip model based on GPS static displacements and kinematic displacement records, InSAR, and teleseismic waveforms. The coseismic slip will be compared to the pattern of interseismic slip deficit.