PhD Final Defense – Amr Ibrahim
- Event Type
- Seminar/Symposium
- Sponsor
- Department of Civil and Environmental Engineering
- Location
- Newmark 2218
- Date
- Jan 9, 2026 9:00 am
- Originating Calendar
- CEE Seminars and Conferences
Multiphysics Modeling of Earthquake Cycles and Dynamic Rupture Processes in Complex Fault Zones
Advisor: Professor Ahmed Elbanna
Abstract
Earthquakes rank among the most devastating natural hazards, causing widespread humanitarian and economic losses worldwide. Understanding the physical mechanisms governing earthquake cycles remains a fundamental challenge. A major obstacle stems from data scarcity—large earthquakes are infrequent, and instrumental records span only decades while fault systems evolve over centuries. This gap necessitates physics-based models capable of capturing the full spectrum of fault slip behaviors across multiple spatial and temporal scales. This dissertation develops advanced computational frameworks integrating inelastic deformation, material heterogeneity, fluid–solid coupling, and damage evolution to investigate how these mechanisms govern earthquake cycles and rupture dynamics.
We first show that heterogeneous viscoplastic rheology exerts first-order control on earthquake cycle behavior. Heterogeneous plastic deformation governs rupture characteristics and partitions tectonic loading between inelastic strains and localized fault slip, together providing new physical explanations for fault segmentation, fault maturation, and seismicity shutdown. Extending this framework establishes a new paradigm for small repeating earthquakes where spontaneous segmentation reproduces observed moment-recurrence scaling and stress drops. For the first time, we capture temporal shutdown of active segments as documented in the 2004 Parkfield sequence. Notably, plastic deformation accommodates a substantial fraction of the slip budget, offering a physical resolution to the long-standing slip-deficit paradox.
We then investigate fluid–fault interactions through fully coupled poro-visco-elasto-plastic simulations. Results reveal competing mechanisms where fault destabilization governed by poroelasticity competes with energy dissipation through viscoplastic deformation. Lower yield strength zones counter-intuitively require higher critical pore pressures for rupture. Permeability evolution accelerates nucleation by creating more efficient fluid pathways, while shear-zone hydraulic properties fundamentally control induced seismicity timing and magnitude.
Finally, we develop and validate a thermodynamically consistent hydro-mechanical continuum damage-breakage formulation. We also show through fully dynamic rupture simulations that fluid inertial effects are negligible for impermeable faults. Building on this framework, 3D dynamic rupture simulations show that two-way hydro-mechanical coupling fundamentally alters rupture dynamics through pore-pressure variations, while damage evolution generates complex off-fault fracturing and modulates rupture behavior.
These advances enable more realistic seismic hazard assessment for both natural and induced seismicity.