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

[SCG45-P11] A DEM-Based Analysis on Subduction Deformation Under Frictional and Structural Controls

*Jian Chen¹, Yanfang Qin¹, Yohei Hamada¹, Daisuke Nishiura¹, Mikito Furuichi¹ (1.Japan Agency for Marine-Earth Science and Technology)

Keywords:Subduction Deformation, Horst-graben structure, Discrete Element Method

Accretionary prisms are known to undergo complex and constant evolving deformation due to the influence of various boundary conditions and the properties of megathrust faults. The evolution of those deformations is of particular importance in the study of seismic hazards, as fault movement and deformation are closely tied to subduction processes and earthquake activity. In this study, we utilize the discrete element method (DEM) to investigate the impact of variations in basal friction and surface roughness, particularly Horst-graben structures, on the development of accretionary prisms. To this end, DEM-based numerical sandbox experiments are conducted to simulate the behavior of brittle rocks under tectonic forces. In the model, crust deformation is governed by the collective motion of interacting rigid grains, allowing faults to form naturally based on the evolution of surrounding stress and movement. The influence of basal friction and horst-graben geometry on thrust vergence and wedge deformation is investigated by varying these factors in the numerical sandbox experiments. Furthermore, by comparing geophysical data with the simulation results, we aim to deepen the understanding of how frictional properties and upper-plate structures shape seismic and aseismic activity in these tectonic environments.