3:00 PM - 3:15 PM
[SCG61-30] Revisiting the Coseismic Slip Distribution of the 2011 Tohoku-oki Earthquake Considering Early Postseismic Deformation, Non-linear Viscoelasticity, and Heterogeneous Structure
Keywords:The 2011 Tohoku-oki Earthquake, Postseismic deformation, Power-law rheology
Thus, we derived “pure” coseismic displacements based on 1-Hz site coordinate time series at GNSS sites of the Geospatial Information Authority of Japan estimated by utilizing kinematic PPP (precise point positioning) analysis and based on 1-min average seafloor level time series at OBP sites. The residual displacements were obtained by subtracting the pure coseismic displacement from that based on the daily site coordinate time series. The data showed subsidence and trenchward motions in the entire Tohoku district. These broad deformations could not be explained solely by aftershocks nor by afterslip on the plate interface. Viscoelastic deformation that occurs immediately after the main shock is required to explain the displacement field. We present the results of our investigations into coseismic slip distribution and early postseismic deformation by applying Green’s function, which is calculated by considering the shapes of surface terrain and subducting slabs as well as heterogeneous thermal structures and power-law rheology.
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