Earthquake Cycle Simulation in Poro-Viscoplastic Media: A Coupled Framework for Fault-Fluid-Inelasticity Interactions

Amr A. Ibrahim, & Ahmed E. Elbanna

Submitted September 7, 2025, SCEC Contribution #14907, 2025 SCEC Annual Meeting Poster #TBD

Earthquake cycles, in both natural and induced settings, are governed by complex interactions among fault slip, fluid pressure evolution, and inelastic deformation in surrounding rock. While previous research has advanced understanding of fault–fluid coupling through poroelastic theory, the influence of viscoplastic processes in fluid-saturated porous media on sequences of earthquakes and aseismic slip at geological scales remains largely unexplored. This gap is important because these processes involve a competition in which inelastic deformation dissipates energy and stabilizes the system, while poromechanical effects can either promote or suppress instability through fluid pressurization.

To address this, we develop a computational framework integrating rate-and-state friction, Biot’s poroelasticity, and Drucker–Prager viscoplasticity to characterize earthquake cycles in fluid-saturated, inelastic media. The framework is validated through benchmark tests, including a poro-elasto-plastic consolidation problem and cross-verification with an injection-induced slip case.

We apply this framework to an injection-induced slip problem with a rate-and-state fault embedded in poroviscoplastic fault zones, examining how variations in inelastic cohesion (with and without dilatancy), porosity–permeability enhancement, and fault leakage affect seismicity and deformation partitioning. Results show that inelastic deformation dissipates energy, delaying unstable slip; reduced cohesion further extends this delay. A semi-permeable fault can alter patterns of fluid migration and pressure evolution, thereby modify rupture onset and slip behavior. Porosity–permeability enhancement destabilizes the system, promoting earlier rupture, while dilatancy offers modest stabilization, slightly delaying rupture and altering slip evolution. The nature of far-field hydrological boundary conditions, whether promoting drainage or restricting fluid flow, can strongly influence the timing and characteristics of fault slip events.

Overall, inelastic deformation, dilatancy, porosity–permeability enhancement, fault permeability, and boundary conditions all affect rupture timing and recurrence. This framework supports future studies of heterogeneous, evolving damage zones in earthquake cycle modeling and hazard assessment.

Key Words
earthquake cycles, poroelasticity, viscoplasticity, rate-and-state friction, fluid-fault coupling, induced seismicity

Citation
Ibrahim, A. A., & Elbanna, A. E. (2025, 09). Earthquake Cycle Simulation in Poro-Viscoplastic Media: A Coupled Framework for Fault-Fluid-Inelasticity Interactions. Poster Presentation at 2025 SCEC Annual Meeting.

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