Model of the 2011 Great East Japan earthquake (M = 9.0)

Abstract

Intraplate earthquakes are described by a model of a thrust fault in continuous or cracked media. Such a model can also be used to describe interplate earthquakes, in particular, strong earthquakes in subduction zones. However, new seismic, tectonic, and GPS data for this strong Japanese earthquake demand a more detailed model. One possible model can be a model of the elastic island plate coupled with a dipping oceanic plate with submarine mountings. These mountings, sitting on the dipping oceanic plate, hinder its motion due to coupling with asperities on the bottom of the island plate. When coupling ends, the bottom of the plate can be cut as if by a plough and an earthquake can take place. The decoupling of a mountain leads to a weaker interpolate earthquake, a forshock, and an aftershock. The main earthquake is a result of the effect of a basaltic plateau or a large mountain, which leads to the avalanching decoupling of all mountains on a large area of coupled plates. In the first approximation we can consider that, despite its deformation, an oceanic plate is constantly moving with a nearly constant velocity all times both during earthquakes and in between them. An island plate behaves similarly to an elastic plate, which permanently bends due to torque acting on its junction with a dipping oceanic plate. After the earthquake, the bending plate becomes straight. This leads to it thrusting on the oceanic plate with displacement toward the ocean, an uplift of its oceanic part, and the sinking of its island part by the following tsunami.