Intraslab Deformation in the 30 November 2018 Anchorage, Alaska, M W 7.1 Earthquake

Anchorage, Alaska, was strongly shaken on 30 November 2018 by an M W 7.1 earthquake that ruptured within the underthrust Pacific plate at depths of from 45 to 65 km. Ground failures occurred in saturated lowlands filled with sediments, producing notable road damage, but there was limited structural damage in Anchorage, only ~12 km south of the epicenter. The earthquake has a normal faulting geometry with a shallowly dipping east‐west tension axis indicating intraslab deformation, likely between the underthrust Yakutat terrane and adjacent Pacific seafloor. Separate and joint inversions of teleseismic P and SH waves, regional strong ground motions, and GPS static displacements provide a weak preference for a westward steeply dipping rupture plane with up to 2 m of slip distributed over a single slip patch with dimensions of 20 × 20 km. The ~12 s long rupture expanded northward. Aftershocks occur at shallower depths than the mainshock slip zone.