[S-CG40] Science of slow-to-fast earthquakes

[SCG40-P43] Laboratory-scale numerical simulation of the earthquake cycle on the bending fault

*Ran Xu^1,2, So Ozawa³, Ryoya Matsushima¹, Kazunori Muramatsu¹, Ryosuke Ando¹, Kaiwen Xia² (1.Graduate School of Science, University of Tokyo, 2.School of Civil Engineering, Tianjin University, 3.Department of Geophysics, Stanford University)

Keywords:Earthquake cycle, Bending fault, Numerical modeling, Laboratory earthquake

Natural faults are typically not flat faults in shape, and the fault structure tends to show more complex shapes, such as bending faults. The bending points on these faults can affect earthquake nucleation, propagation, and termination. In addition, due to the presence of bends, the stress state on the faults can shift under the effect of earthquake cycles, which will have an impact on the rupture mode of the faults. In laboratory earthquakes, where we use a biaxial loading method and full-field optical and localized stress measurements to capture the interactions between faults (PMMA sample), we find increasing stresses on the compressive side and decreasing stresses on the tensile side near the bending point. Therefore, based on the investigations of multi-cycle laboratory earthquakes on bending faults, we use rate and state friction law and material properties similar to laboratory earthquakes to conduct a 2D quasi-dynamic boundary element method that models fault interactions in experiments. In addition, we simulated more complex laboratory conditions to investigate the control mechanisms of bend faults, such as nonuniform stress states, bending angles, and nonuniform friction parameters, on the interactions between bend faults. These investigations not only broaden the investigation of inflected faults in laboratory earthquakes but also provide evidence for field observation and earthquake retrospectives.