Influence of heterogenous stress on rupture propagation along stepovers of strike-slip faults: Numerical results

Hui Wang, Mian Liu, Benchun Duan, & Jianling Cao

Submitted July 31, 2019, SCEC Contribution #9308, 2019 SCEC Annual Meeting Poster #147

Large earthquakes on intracontinental strike-slip faults usually rupture multiple fault segments by jumping over stepovers. Previous field observations and numerical modeling with a homogeneous stress field have suggested that stepovers more than ~ 5 km wide would stop the propagation of rupture, but many exceptions have been observed in recent years. Here we integrate a dynamic rupture model with a long-term tectonic model to explore effects of long-term stress perturbations at stepovers on dynamic rupture propagation along strike-slip faults. We also examine how frictional coefficients affect rupture propagation behaviors across stepovers.

Our models show significant effects of long-term stress perturbations at a stepover on the ability of a dynamic rupture to jump across the stepover. The addition of long-term stress perturbations to a homogeneous background stress field that was used in previous studies in producing a maximum jumping distance of about 5 km allows a dynamic rupture to jump across a 15-km wide overlapping releasing stepover or a 7-km wide overlapping restraining stepover. The effect of long-term stress perturbations on an underlapping stepover is weaker than that on an overlapping stepover, resulting in a smaller maximum jumping distance across an underlapping stepover. In addition, frictional coefficients also play a key role in rupture propagation across stepovers. The maximum jumping distance can reach 20 km in an overlapping releasing stepover with lower static frictional coefficients. Our results provide useful insights into estimating the maximum magnitude of potential earthquakes and assessing seismic hazard.

Citation
Wang, H., Liu, M., Duan, B., & Cao, J. (2019, 07). Influence of heterogenous stress on rupture propagation along stepovers of strike-slip faults: Numerical results. Poster Presentation at 2019 SCEC Annual Meeting.


Related Projects & Working Groups
Fault and Rupture Mechanics (FARM)