Interseismic horizontal deformation in northern Honshu and its relationship with the subduction of the Pacific plate in the Japan trench

We investigate the origin of the geodetically observed interseismic horizontal deformation in northern Honshu by comparing shear strain rates, principal strain rates, and velocity fields determined from geodetic data with those calculated from the elastic dislocation models involving interplate motion at the Japan trench. The agreement between the observed and predicted directions of the principal strain axes indicates that the geodetic strain field in northern Honshu is primarily elastic strain transmitted from the Japan trench. In order to match the strain rate tensors and velocity magnitudes obtained from the geodetic data, the dislocation model requires that 35% to 60% of the NUVEL1-A Pacific-North American plate motion is locked at the plate interface along the Japan trench. The down-dip depth limit of the locked zone is inferred to be 55 km, which is consistent with the seismic data in the Japan trench.