Modeling Deformation and Stress States in the Island-arc Crust Considering Heterogeneous Rheological Structure

Modeling deformation and stress states in the island arc's crust and mantle is reviewed and discussed, and examples of numerical modeling for northeastern Japan are presented. When modeling deformation and stress states of an island arc, rheological properties of the island arc-friction and flow laws for brittle and ductile regions, respectively-need to be assumed. Consideration of gravity as a body force is important because friction and flow laws depend on absolute stress. The interactions between a subducting oceanic plate and an island arc lithosphere also need to be considered. Based on recent observations, a detailed rheological structure of the island-arc crust and mantle can be developed. Through 3D modeling of deformation, by considering geothermal structure and nonlinear viscoelasticity and plasticity, long-term mountain-building and stress state in northeastern Japan can be reproduced. The stress state in the region from the trench to the island arc in northeastern Japan is modelled considering the interaction between the subducting Pacific Plate and the island arc lithosphere. Although the frictional strength of the subducting plate interface is quite low, the region where friction acts is quite wide. Therefore, a large compressional force acts on the island arc crust. In future work, the interactions of plates with realistic 3D geometries of plate interfaces need to be considered, as well as the rheological structure of the island arc inferred from various observational information, such as seismic velocity and electrical resistivity structures.