The influence of inelastic yielding on dynamic rupture termination and ground deformation at fault bends

Evan O. Marschall, & Roby Douilly

Submitted September 7, 2025, SCEC Contribution #14347, 2025 SCEC Annual Meeting Poster #TBD

Natural fault zones are complex structures that normally do not conform to the framework of a single plane embedded in a homogeneous elastic medium. Faults can often have geometric complexities, such as fault bends, which can act as barriers to rupture. Geologic studies have highlighted numerous earthquakes which have terminated at fault bends, making them an interesting and pertinent area of focus for rupture modelling. Previous dynamic rupture models of fault bends in an elastic medium have highlighted several factors that influence rupture behavior around a fault bend; these factors include the initial resolved stress, the angle of the fault bend and whether the bend is releasing or restraining. While a common assumption of these studies is that the surrounding material is purely elastic, geometric complexities likely cause non-elastic deformation occurring co-seismically within the fault zone.

Through dynamic rupture simulations, inelastic off-fault yielding has been shown to reduce slip rates, lower the slip magnitude in the shallow portion of the fault, damp high frequency radiation, affect multi-fault rupture and cause localized uplift. However, the interplay between inelastic yielding and geometric complexities is still not fully understood, and off-fault rheologies are difficult to constrain. In this study we conduct systematic 3D dynamic rupture simulations on strike-strike slip faults using a linear slip weakening friction law to investigate the effects of inelastic yielding on rupture propagation and ground deformation around fault bends. We independently vary the bend angle from -30° to 30° and the material response to parse and highlight the contributions from inelastic yielding. Preliminary results show that the incorporation of off-fault yielding has significant impacts on rupture termination and the associated ground deformation at fault bends, with important implications for better understanding the hazard of geometrically complex fault systems.

Key Words
Dynamic Rupture, Fault Bends, Inelastic Deformation

Citation
Marschall, E. O., & Douilly, R. (2025, 09). The influence of inelastic yielding on dynamic rupture termination and ground deformation at fault bends. Poster Presentation at 2025 SCEC Annual Meeting.

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