Optimizing a Model of Coseismic Rupture for the 22 July 2020 <i>M</i>_<i>W</i> 7.8 Simeonof Earthquake by Exploiting Acute Sensitivity of Tsunami Excitation Across the Shelf Break

Abstract The Shumagin seismic gap along the Alaska Peninsula experienced a major, M W 7.8, interplate thrust earthquake on 22 July 2020. Several available finite‐fault inversions indicate patchy slip of up to 4 m at 8–48 km depth. There are differences among models in peak and absolute placement plate boundary, resulting from data distributions, model parameterizations, inversion algorithms. Two representative obtained large geodetic sets produce very different tsunami predictions tide gauges deep‐water pressure sensors (DART stations), despite having only secondary distribution. This is found be result acute sensitivity excitation for rupture below continental shelf proximity an abrupt break. Iteratively perturbing by constraining fault extent dip strike, we obtain optimal compatible with teleseismic P SH waves, regional three‐component broadband strong‐motion recordings, hr‐GNSS time series static offsets, as well recordings DART stations remote gauges. Slip tightly bounded between 25 40 depth, up‐dip limit resolved well‐inland break, strike well‐constrained. coseismic increased Coulomb stress shallow boundary extending trench, but frictional behavior megathrust slope remains uncertain.