Multiscale Dynamics of 3D Rupture Zones using a Continuum Damage Breakage Rheology

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

Published September 8, 2024, SCEC Contribution #13808, 2024 SCEC Annual Meeting Poster #134 (PDF)

The interplay of earthquakes and off-fault damage is crucial for understanding seismic hazards and risks. A three-dimensional setup offers a framework for studying fundamental topics in the mechanics of earthquakes and faults, including the organization of fracture networks, evolving seismicity, and stress/ strain leading to large failure events.
To this end, we extend our previous work on dynamic ruptures with an off-fault continuum damage-breakage model (CDBM) from 2D plane strain formulation using infinitesimal deformation (Zhao et al., 2024) to a fully 3D setting with finite strain kinematics. CDBM characterizes changes in elastic moduli during brittle deformation and phase transitions using damage (cracking) and breakage (granulation) variables, partitioning strain energy into damaged (visco-)elastic and granular phases. We focus on how depth-dependent variations in normal stress, temperature, and pore pressure influence damage evolution, energy dissipation, and ground motion, aiming to connect surface observations and seismicity to subsurface physics.
The 3D CDBM is implemented in our dynamic rupture simulator DynamicCDBM and DynamicCDBM_F. In DynamicCDBM, pre-existing fault zones are modeled as damaged tubular regions, and dynamic ruptures are nucleated by slightly increasing the damage in a localized region; slip and slip rates are computed from the strain across damage bands as solid-granular phase transitions occur. In DynamicCDBM_F, pre-existing faults are represented as discontinuous cohesive zone interfaces whose behavior is governed by friction laws. The off-fault simulation domains in both cases are governed by CDBM, allowing damage to heal or grow, in arbitrary directions, independent of the underlying mesh, with evolving deformation. While the damage zone thickness remains relatively narrow, it has a significant impact on rupture physics including enhancement of high-frequency waves, generation of isotropic source components, and manipulation of rupture speed and mode. The simulators developed in this study are available on the Quakeworx science gateway for democratizing access to earthquake simulations and data.

Citation
Zhao, C., Elbanna, A. E., & Ben-Zion, Y. (2024, 09). Multiscale Dynamics of 3D Rupture Zones using a Continuum Damage Breakage Rheology. Poster Presentation at 2024 SCEC Annual Meeting.

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