Fully-dynamic Seismic Cycle Simulations in Co-evolving Fault Damage Zones Controlled by Damage Rheology
Description:
Both short-term coseismic off-fault damage and long-term fault growth during interseismic periods have been suggested to contribute to the formation and evolution of fault damage zones. Most previous numerical models focus on simulating either off-fault damage in a single earthquake or off-fault plasticity in seismic cycles ignoring changes of elastic moduli. Here we developed a new method to simulate the damage evolution of fault zones and dynamic earthquake cycles together in a 2D anti-plane model. We assume fault slip is governed by the laboratory-derived rate-and-state friction law while the constitutive response of adjacent off-fault material is controlled by a simplified version of the Lyakhovsky-Ben-Zion continuum brittle damage model. This newly developed framework opens a window to simulate the co-evolution of earthquakes and fault damage zones, shedding light on the physics of earthquakes on natural faults.
We find that the model can reproduce key features of fault damage zones including the spontaneous generation of flower structures, coseismic seismic velocity drop, interseismic healing, and long-term fault zone growth. Both the coseismic shallow slip deficit and long-term fault slip deficit accommodated by inelastic deformation are successfully captured. Moreover, we find that fault zone strength modulates seismicity through changing the spatial distribution of off-fault damage. A weak fault zone results in deep intense damage and cascading events including foreshocks and aftershocks with a migration speed of several kilometers per day. We also find an inherent difference between the energy budget of large and small earthquakes: a larger portion of strain energy is consumed by off-fault damage for smaller events. The fracture energy density of simulated earthquakes inherently scales with earthquake slip, which agrees with seismologically inferred values.
Session: Numerical Modeling in Seismology: Theory, Algorithms and Applications - II
Type: Oral
Date: 4/17/2025
Presentation Time: 11:00 AM (local time)
Presenting Author: Peng
Student Presenter: Yes
Invited Presentation:
Poster Number: 128
Authors
Peng Zhai Presenting Author Corresponding Author pengzhai@umich.edu University of Michigan |
Yihe Huang yiheh@umich.edu University of Michigan |
Chao Liang chao.liang@scu.edu.cn Sichuan University, Hong Kong Polytechnic University |
Jean-Paul Ampuero ampuero@geoazur.unice.fr Université Côte d’Azur, French National Research Institute for Sustainable Development, National Center for Scientific Research, Observatoire de la Côte d’Azur, Géoazur |
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Fully-dynamic Seismic Cycle Simulations in Co-evolving Fault Damage Zones Controlled by Damage Rheology
Category
Numerical Modeling in Seismology: Theory, Algorithms, and Applications