SCEC Award Number 25313 View PDF
Proposal Category Collaborative Research Project (Multiple Investigators / Institutions)
Proposal Title Physics-based modeling of postseismic slip in the complex Ridgecrest fault system using tandem
Investigator(s)
Name Organization
Alice-Agnes Gabriel University of California, San Diego Yohai Magen University of California, San Diego Dave May University of California, San Diego Jeena Yun University of California, San Diego
SCEC Milestones C1,2,3-1, C1-1, C1-2 SCEC Groups FARM, Geodesy, RC
Report Due Date 03/15/2026 Date Report Submitted 05/08/2026
Project Abstract
 The July 6, 2019, Mw7.1 Ridgecrest earthquake ruptured a set of geometrically complex fault systems in the Eastern California Shear Zone, extending from the Garlock fault in the south to the Coso geothermal region in the north. Recent observations (Magen et al., 2024) of Ridgecrest’s post-seismic deformation, captured by Sentinel-1 Burst Overlap Interferometry (BOI) data, reveal a correlation between displacement rates and proximity to Coso’s geothermal field. This is also reflected in the spatial-temporal distribution of post-seismic seismicity. Such findings suggest that elevated heat flow plays a significant role in controlling fault frictional properties and accelerating aseismic slip. Capturing this phenomenon in a physics-based model will require accounting for both fault frictional properties and the complex fault geometry of the Ridgecrest earthquake fault system.
This proposal aims to create a physics-based 3D model of the post-seismic dynamics following the Mw7.1 Ridgecrest earthquake, leveraging BOI and GNSS datasets and focusing on the effects of complex multi-fault geometry. The model will analyze the influence of geothermal heat flow on fault frictional properties and post-seismic displacement rates. We will utilize Tandem, a high-performance computing (HPC) empowered discontinuous Galerkin method for Sequences of Earthquakes and Aseismic Slip (SEAS) simulations, to model aseismic slip across a multi-fault system. This approach will enable us to address the complex fault behavior and geometry, enhancing our understanding of California’s largest earthquake in the past 20 years.
Intellectual Merit This project advanced physics-based modeling of postseismic deformation by integrating high-resolution geodetic observations with 3D rate-and-state friction simulations of a complex multi-fault system. We demonstrate that along-strike variations in frictional properties, plausibly linked to elevated heat flow near the Coso geothermal region, can quantitatively reproduce BOI and GNSS observations of postseismic displacement following the 2019 Mw 7.1 Ridgecrest earthquake. Tandem passed the SCEC SEAS BP7 community benchmark, providing a verified, scalable, volumetric simulation tool for the SCEC community. We extended Tandem to support Maxwell viscoelastic rheology, validated against an analytical solution, enabling future investigations of coupled afterslip and viscoelastic relaxation.
Broader Impacts This award supported research training of an early-career postdoctoral scholar (Yohai Magen) and a graduate student (Jeena Yun) at SIO/UCSD. Piyush Karki, a Computer Science PhD student at LMU and TUM in Munich, Germany, led the viscoelasticity implementation. Tandem v1.2, with new viscoelastic capabilities, normal- and shear-stress perturbations, HDF5 I/O, scalable Green's function checkpointing, and an additional friction law, will be released open-source to the SCEC and broader earthquake-modeling community. The project's findings on the role of geothermal heat flow in modulating fault frictional behavior have implications for postseismic hazard assessment in California, expecially for complex geothermal-fault interactions.
Project Participants Alice-Agnes Gabriel, Yohai Magen, Dave A. May, Jeena Yun (all SIO / UCSD), Piyush Karki (LMU & TUM, Munich, Germany)
Exemplary Figure Figure 3. Postseismic slip distribution and first 150-day displacement data fit. (a) Cumulative postseismic slip during the first 150 days following the Ridgecrest earthquake, (b) fit to BOI data, and (c) fit to GNSS data.
Linked Publications

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