SCEC Award Number 22135 View PDF
Proposal Category Collaborative Proposal (Integration and Theory)
Proposal Title Collaborative Proposal: Distinguishing the near- and the far-field signatures of earthquake sources in complex fault zones
Investigator(s)
Name Organization
Alice-Agnes Gabriel University of California, San Diego Ahmed Elbanna University of Illinois at Urbana-Champaign Yehuda Ben-Zion University of Southern California
Other Participants UCSD graduate student Jeena Yun; UIUC graduate student Mohamed Abdelmeguid
SCEC Priorities 2c, 2d, 3d SCEC Groups FARM, CS, GM
Report Due Date 03/15/2023 Date Report Submitted 11/12/2024
Project Abstract
 Earthquake fault zones are more complex, both geometrically and rheologically, than an idealized infinitely thin plane embedded in linear elastic material. The internal structure of fault zones in the upper continental crust exhibits considerable complexity. Mature faults consist of several basic structural elements including: (i) A zone of concentrated shear, the fault core, which is often defined by the presence of extremely comminuted gouge; (ii) A damage zone, with the primary fault core centralized in or bordering that damage zone, in addition to a segmented network of several secondary cores within the damage zone. Damage zones display a greater intensity of deformation relative to the surrounding host rock, and contain features such as secondary faults and fractures, microfractures, folded strata, and comminuted grains; and (iii) host country rock with little or no damage. In general, the intensity of damage increases towards the fault core and the transition from undeformed host rock to damage zone rock is often gradual. Overall, fault zones exhibit a combination of distributed damage as well as discrete anisotropic secondary fractures of different orientations and density leading to coupling of volumetric and deviatoric deformations with important implications for source physics and seismic hazard. Physics-based dynamic rupture modeling accounting for the volumetric character of fault zone shearing during earthquake rupture can analyze the spontaneous partition of fault slip into intensely localized shear deformation within weaker (possibly cohesionless/ultracataclastic) fault-core gouge and more distributed damage within fault rocks and foliated gouges.
Intellectual Merit This project advanced our understanding of complex fault zone mechanics by investigating the near- and far-field seismic signatures in multi-fault earthquake ruptures. Using physics-based dynamic rupture models, the study examines how distributed damage and concentrated shear in fault zones contribute to rupture dynamics and stress redistribution. Key findings include the role of scale-dependent fracture energy in facilitating multi-fault ruptures, insights into earthquake energy partitioning, and the identification of spectral fingerprints of earthquake physics. This contributes to a deeper understanding of the earthquake energy budget and how fault zone complexity may influence rupture mechanics.
Broader Impacts The project’s findings have implications for seismic hazard assessment, offering a framework to predict complex rupture behaviors in fault zones, which can inform preparedness strategies for large earthquakes. By analyzing ground motion variability and rupture dynamics, the research provides tools for interpreting near-field seismic data, potentially benefiting distributed acoustic sensing (DAS) and large array deployments. Additionally, the project has supported significant publications, trained researchers, and contributed models to community platforms, enhancing collaborative capabilities in earthquake research and computational geophysics.
Exemplary Figure Figure 1, top
Linked Publications

Add missing publication or edit citation shown. Enter the SCEC project ID to link publication.