SCEC Award Number 08019
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Coupled Evolution of Earthquakes and Faults in a Regional Model with Damage Rheology
Name Organization
Yehuda Ben-Zion University of Southern California
Other Participants Wen-Zheng Wang
SCEC Priorities A7, A10, A3 SCEC Groups FARM, Seismology, Simulators
Report Due Date 02/28/2009 Date Report Submitted N/A
Project Abstract
Studies under this project continue our investigations on the coupled evolution of faults, earthquakes and related deformation fields in a rheologically layered model of the lithosphere. The basic questions we ask are how do localized and distributed zones of damaged rocks form and evolve in the brittle upper curst over many thousands of earthquake failure episodes, and how does the evolution of a regional network of fault zones changes in turn the properties of seismicity patterns and aseismic deformation fields? Our last year studies focused on the following three research directions: (1) Understanding the spatio-temporal evolution of damage zones associated with large strike-slip structures, including the depth distribution of on- and off-fault damage, evolving geometrical properties with cumulative slip, and coupling to the ductile substrate. (2) Inferring from observed ratios of aftershock productivities and theoretical damage rheology results the degree of seismic coupling in different regions of southern California. (3) Developing a model realization that can be used to study couple evolution of fault zone structures and deformation fields in the Mojave block of southern CA. The results from the first research direction led to 1 paper in press and another submitted papers, the results from the second direction led to 1 paper in press, and the studies on the third research direction are still in progress. Below we summarize the main results from the completed studies.
Intellectual Merit The studies contribute to the following long term goals of SCEC3: Earthquake Source Physics: “Develop full 3D model of fault-zone structure that includes the depth dependence of shear localization and damage zones … and geometric complexities at fault branches, step-overs, and other along-strike and down-dip variations.” Ground Motion Prediction: “… unsolved basic research problems … nonlinear wave effects, including nonlinear site response”. Fault System Dynamics: “Develop representations of postseismic and interseismic evolution of stress, strain, and rheology that can predict fault system behaviors within the Southern California Natural Laboratory”. EFP: “Understanding the physical basis for earthquake predictability”.
Broader Impacts The research supported 2 PhD students.
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