[S-CG45] Science of slow-to-fast earthquakes

[SCG45-P07] Brittle deformation to ductile deformation in subduction zone: numerical simulation for deformation on sediments and oceanic basalts

*Ayumu Miyakawa¹, Hanaya Okuda² (1.Geological Survey of Japan, AIST, 2.Atmosphere and Ocean Research Institute, The University of Tokyo)

Keywords:Brittle-ductile transition, Subduction zone, Numerical simulation

It is known that rocks constituting the earth's crust undergo brittle deformation in shallow, low-temperature, low-pressure environments, whereas they undergo ductile deformation in deep, high-temperature, high-pressure environments. In particular, in subduction zones, the environment changes from one in which brittle deformation is dominant in the shallow part to one in which ductile deformation is dominant in the deep part as the oceanic plate is subducted. In addition, slow seismic events are known to occur in the subduction zone at depths deeper than those at which large earthquakes occur. This transition from the shallow seismozenic zone to the deep slow earthquake zone is likely to correspond to the transition from a brittle deformation-dominated environment to a ductile deformation-dominated environment. The effect of this change from brittle to ductile deformation on the geological structure in the subduction zone will be investigated using geodynamic modeling.