SCEC Award Number 21179 View PDF
Proposal Category Individual Proposal (Data Gathering and Products)
Proposal Title Refinements to the Community Rheology Model and Stress Estimates for the Community Stress Model
Investigator(s)
Name Organization
Elizabeth Hearn Capstone Geophysics
Other Participants
SCEC Priorities 1c, 1e, 3b SCEC Groups CXM, SDOT, Geodesy
Report Due Date 03/15/2022 Date Report Submitted 06/07/2024
Project Abstract
 During the award period, I pursued three activities related to the CRM. I worked with the CRM TAG on how to implement shear zones in the next CRM product; developed and refined codes for generating effective viscosities from CRM lithologies and flow laws and CTM temperatures; and I substantially revised and nearly completed a manuscript on the CRM, for the open-source journal Earth and Space Sciences (ESS). The initial version of the CRM (v. 20.9) provides ductile rheologies for low-strain rocks. It is available for download from the CRM webpage, and its DOI is https://doi.org/10.5281/zenodo.4579627.
Intellectual Merit The CRM is poised to contribute to SCEC research endeavors relating to static deformation, fault mechanics, and interseismic stress transfer between fault systems in the lithosphere. The CRM could also provide a foundation for SEAS-type models that take ductile rheology of the lower lithosphere into account. Comparing CRM effective viscosities to independent estimates and evaluating their sensitivity to temperature, stress rate, and lithology variations makes the CRM a more useful product and highlights important knowledge gaps.
Broader Impacts SCEC community models provide freely-accessible knowledge infrastructure that enables cutting-edge representation of Earth properties in models of static and dynamic deformation. By leveraging these community-created products and tools, researchers can improve the current understanding of fault slip rates, rupture propagation, off-fault deformation, and other factors governing seismic hazard in southern California. The CRM is already publicly accessible via Zenodo, but publishing the CRM manuscript and sharing codes and viscosity tables via another public repository should encourage its use.
Exemplary Figure Figure 1. CRM effective viscosities versus values inferred from postseismic deformation stud- ies. In all four panels, viscosity profiles for the indicated CRM provinces assuming strain rates ranging from 10−15 to 10−14/s are shown as shaded regions, and colored boxes indicate Maxwell element (steady-state) effective viscosity estimates from postseismic deformation models. Panels (a) and (b) show CRM viscosities and viscosity estimates from El Mayor Cucapah earthquake postseismic deformation models, for the Salton region and the Peninsular Ranges. Panel (c) shows Mojave region viscosity estimates from models of the 1999 Hector Mine earthquake super- imposed on the Mojave GF province CRM viscosity profile. Panel (d) shows effective viscosities estimated from postseismic models of the 2019 Ridgecrest earthquake with CRM viscosity profiles for the indicated GF provinces. References to these models are given in Hearn et al. (2024).