Modeling Dynamic Ruptures with High Resolution Fault Zone Physics

Xiao Ma, & Ahmed E. Elbanna

Published August 15, 2018, SCEC Contribution #8667, 2018 SCEC Annual Meeting Poster #200

Earthquakes are among the costliest natural hazards on earth. The dynamical instabilities responsible for the onset and propagation of these events are linked to fundamental physics- friction, fracture, heating, and compaction- of fluid filled granular materials and rocks in the subsurface subjected to extreme geophysical conditions.

Here, we present a new hybrid computational algorithm for modeling earthquake ruptures in complex fault zone structures. The hybrid method combines Finite element method (FEM) and Spectral boundary integral (SBI) equation through the consistent exchange of displacement and traction boundary conditions, thereby benefiting from the flexibility of FEM in handling problems with nonlinearities or small-scale heterogeneities and from the superior performance and accuracy of SBI. We validate the hybrid method using a benchmark problem from SCEC dynamic rupture simulation validation exercises. We further demonstrate the capability and computational efficiency of the hybrid scheme for resolving off-fault complexities using a first-of-its kind model of a fault zone with explicit representation of small scale secondary faults and branches enabling new insights into earthquake rupture dynamics that may not be realizable in homogenized isotropic plasticity or damage model. For example, we have observed that, for a range of parameters, when the secondary faults are activated they not only act as energy sinks but also as energy source by dynamically loading the main fault enhancing the rupture speed and slip rate of the main fault rupture. Furthermore, the interaction of the emitted waves with the explicitly represented secondary faults and branches lead to interference patterns that complexify the wave field and enhance high frequency generation. These observations enabled by our novel developments in computational dynamic fracture open new opportunities for multiscale modeling of earthquake physics for next generation seismic hazard models.

Key Words
Dynamic Rupture, Fault zone

Citation
Ma, X., & Elbanna, A. E. (2018, 08). Modeling Dynamic Ruptures with High Resolution Fault Zone Physics. Poster Presentation at 2018 SCEC Annual Meeting.

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