Compressional branching during the 2012 Mw 8.6 Off-Sumatra Earthquake: Implications from Earthquake Cycle Simulations

Yuqing Xie, & Lingsen Meng

Published August 14, 2018, SCEC Contribution #8516, 2018 SCEC Annual Meeting Poster #215

The 2012 Mw 8.6 Off-Sumatra earthquake is the largest strike-slip intraplate earthquake ever recorded by modern seismology. Previous Back-projection studies of this earthquake suggests two episodes of rupture branching into compressional fault segments with elevated dynamic normal stress, leaving the dilatational segments unbroken or broken with a delay. Understanding the mechanism of such counter-intuitive rupture scenario could provide a physical basis to assess the maximum earthquake size in complex fault system. The compressive branching may involve many factors, among which the stress state is considered an essential one and has large uncertainties. The variation of stress state caused by previous earthquakes may create favorable condition of rupture propagation on the compressional branch. One possible scenario is that the stress is low on the dilatational branch due to a recent event and high on the compressional branch due to seismic quiescence. To investigate the details about the development of stress state on such a complicated fault system, we conduct the quasi-dynamic simulations of earthquake cycles on a T-shaped fault system using a rate- and state-dependent friction law. The preliminary results show that irregular earthquake sequences including compressional branching can be generated in such fault systems. We plan to use more realistic geometry and parameters in our subsequent research work. Particularly, we will explore how the normal stress σ, the steady slip rate Vslip in deep region of the faults and the characteristic slip distance Dc, affect the interactions between fault segments.

Key Words
2012 Off-Sumatra Earthquake compressional branching, simulation

Citation
Xie, Y., & Meng, L. (2018, 08). Compressional branching during the 2012 Mw 8.6 Off-Sumatra Earthquake: Implications from Earthquake Cycle Simulations . Poster Presentation at 2018 SCEC Annual Meeting.

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