RESEARCH

The postseismic deformation of the 2018 Mw 7.9 A

We have constructed a three-dimensional finite element model to investigate the viscoelastic postseismic deformation of the 2018 Mw7.9 Kodiak earthquake. We derived the first 2-year postseismic GPS observations to constrain the afterslip and upper mantle rheology in the south-central Alaska. The upper mantle is separated into the mantle wedge and oceanic upper mantle topped by an 80-km thick asthenosphere layer by the subducting slab. Results show that afterslip generally takes place in areas adjacent to the rupture zone and have a smaller magnitude of a few tens of millimeters. The steady-state viscosities of the asthenosphere and mantle wedge are determined to be in a ra