Two‐dimensional viscosity structure of the northeastern Japan islands arc‐trench system

Abstract

Two‐dimensional viscosity profiles were constructed for the northeastern Japan islands arc‐trench system covering the source area of the 2011 Tohoku‐Oki earthquake. From seismologically determined models of lithospheric structure, experimentally derived constitutive laws of various rocks, and densely measured geothermal gradient data, we have predicted the steady state effective viscosity across the subduction zone. The profile reveals strong lateral viscosity gradients both parallel and normal to the trench axis. The detailed viscosity structures presented here contribute to accurate evaluation of viscoelastic relaxation components when modeling geodetically measured postseismic deformation at high spatial and temporal resolution.