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Dynamic Rupture Modeling in a Complex Fault Zone with Discrete and Distributed Damage

Chunhui Zhao, Ahmed E. Elbanna, & Yehuda Ben-Zion

Submitted September 10, 2023, SCEC Contribution #13045, 2023 SCEC Annual Meeting Poster #101

Active fault zones have complex structural and geometric features that are expected to affect earthquake nucleation, rupture propagation with shear and volumetric deformation, and arrest. Earthquakes, in turn, dynamically activate co-seismic off-fault damage that may be both distributed and localized, affecting fault zone geometry and rheology, and further influencing post-seismic deformation and subsequent earthquake sequences. Understanding this co-evolution of fault zones and earthquakes is a fundamental challenge in computational rupture dynamics with consequential implications for earthquake physics, seismic hazard and risk.

Here, we implement a recently developed continuum damage breakage (CDB) rheology model (Lyakhovsky et al., 2016) in our MOOSE-FARMS simulator with slip weakening friction law and complex fault network geometries. The CDB rheology model combines aspects of a continuum viscoelastic damage framework for brittle solids with a continuum breakage mechanics for granular flow within dynamically generated slip zones. MOOSE-FARMS is inherited from MOOSE, an open source massively parallel finite element code from the Idaho National Lab (INL).

We demonstrate the effects of damage and breakage on rupture dynamics in the context of three prototype problems addressed currently in the 2D in-plane setting: (1) A single planar fault which serves as a reference case, (2) A major fault surrounded by a network of smaller fractures as a candidate for a mature fault zone, and (3) a fracture corridor as a candidate for an immature fault zone. We quantify the spatio-temporal reduction in the wave speeds associated with the dynamic rupture in each of these cases and track the evolution of the original fault zone geometry highlighting the growth and coalescence of localization bands as well the trade-offs between localized slip on the pre-existing faults vs. the inelastic deformation in the bulk. We quantify the source properties in the different scenarios showing evidence for non-couple double components, enhanced high-frequency generation associated with maneuvering the geometric complexity and damage accumulation, as well as localized volumetric deformations and fault openings. These results have important implications for long-standing problems in earthquake and fault physics as well as near-fault seismic hazard, and they motivate near-fault observations to uncover the processes occurring in earthquake rupture zones.

Zhao, C., Elbanna, A. E., & Ben-Zion, Y. (2023, 09). Dynamic Rupture Modeling in a Complex Fault Zone with Discrete and Distributed Damage. Poster Presentation at 2023 SCEC Annual Meeting.

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