Influence of Coseismic and Postseismic Stress Induced by the 2011 M9.0 Tohoku-Oki Earthquake on Regional Medium Properties and Seismicity

Date: 4/26/2019

Time: 01:45 PM

Room: Vashon

Megathrust earthquakes produce large coseismic and postseismic lithospheric displacements that induce changes in static stress and medium properties in regional distances. The 2011 M9.0 Tohoku-Oki megathrust earthquakes produced large displacements up to regional distances. The lithospheric displacements directing to the epicenter on the convergent plate boundary developed transient uniaxial tension field over the backarc lithospheres. We observed Vp/Vs changes between -0.0458 and 0.0422 in the upper crust of Japanese islands. The medium-property changes appeared to recover to the original state in a couple of years to a decade. The upper crust presents complicated deformation in short distances from the epicenter. The Vp/Vs changes display a 2 theta azimuthal variation, suggesting azimuthal-anisotropic deformation. The lower crust of the Korean Peninsula in distances of ~1300 km displayed coseismic velocity changes of 3 % after the megathrust earthquake, which recovered gradually with time for several years. A series of moderate-sized earthquakes occurred as a consequence of medium response to the temporal evolution of stress field.

Presenting Author: Tae-Kyung Hong

Authors