Heterogeneous Earth structure controls on surface deformation caused by the 2011 Tohoku earthquake

The M9.1 2011 Tohoku earthquake occurred in a region with complex heterogeneous Earth structure, including non-uniform slab geometry and strong velocity contrasts. Prior studies of the deformation caused by this earthquake have generally utilized simplified Earth structures based on homogeneous or layered models. Here, we present an analysis of the Tohoku earthquake deformation field based on a model that incorporates realistic Earth structure, including three-dimensional (3D) velocity structure, slab geometry, and topography and bathymetry. We find that the presence of 3D material structure significantly alters predicted surface displacement by producing greater uplift far from the trench and smaller near-trench uplift, and by reducing near-trench horizontal displacement. These findings demonstrate the potential for 3D structural variations in the Tohoku region to bias slip estimates for the 2011 Tohoku earthquake. Our results suggest that it may be appropriate to re-visit conclusions drawn from prior analysis of geodetic data for the Tohoku earthquake.