[S-CG43] Environment formed and maintained by active faults

[SCG43-P03] Numerical simulation of rock rupture process in bending fault models

*Tada-nori Goto¹, Seiichiro Kawahara¹ (1.Graduate School of Science, University of Hyogo)

Keywords:DEM, Bending Fault, Seismic Activity

A number of model experiments using sandboxes and numerical simulations have been conducted to elucidate the formation process of active faults and the process of earthquake occurrences. These studies deal with a simple linear active fault; however, in actual earthquakes suggest the effects of the complexity of active fault shapes. For example, in the 1995 Hyogo-ken Nanbu Earthquake, the main shock occurred near a bend of the Rokko-Awajishima fault zone. The main shock of the 2016 Kumamoto earthquake is also caused near a bend of the Futagawa-Hinagu fault zone. The model studies including an active fault zone with bending has not been discussed. In this study, based on the numerical simulations, we investigated how the rock-mass model including the bending weak zones deforms and breaks. Although the laboratory experiment with a sandbox is useful for discussion of the fault shape on the surface, the numerical simulations give the stress, deformation, ruptures inside of the model. We used the three-dimensional distinct element method (DEM), suitable for reproducing large rupture. Adding the strike-slip fault motion to our rock-mass model, and we observed the three-dimensional distributions of shear deformation and ruptures. We compared our numerical results with the occurrence of actual large earthquake (1995 Hyogo-ken Nanbu Earthquake). It was found that the shear deformation and fracture indicate large differences between the deeper part and the near-surface of the model.