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
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In this research, we estimate the contribution of poroelastic rebound (PE) to the 2010 Mw8.8 Maule and 2014 Mw8.1 Iquique earthquakes. The thickness and Poisson ratio of the poroelastic layer in the crust and slab are explored. The poroelastic effect is investigated through improving the fit to the postseismic residuals (GPS observations minus predictions by viscoelastic relaxation model of the earthquake). We also try to evaluate the time duration of PE in both regions. This comparative analysis may give insight into the fluid flow processes in the upper crust in the Andes Subduction Margin. Research Members: Segun Steven Bodunde, Dr. Yan Hu, Yixing Zhang, Zhiping Hu
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Viscoelastic postseismic deformation after the 1964 Mw9.2 Alaska earthquake extends thousands of kilometers from the rupture region and lasts for decades, providing unique opportunities to better understand the three-dimensional rheological properties of the Alaska subduction zone. We have optimized a three-dimensional viscoelastic finite element model to study processes that control the postseismic deformation of the 1964 event. The model has determined the viscosities of the mantle wedge and shear zone to be 3 x 10^19 Pa s and 8 x 10^16 Pa s, respectively. The afterslip takes place mostly within the first 5 years after the earthquake and is up to 4 m, equivalent to a mo
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