SCEC Award Number 21150 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Including Diffusion Creep in the Community Rheology Model
Name Organization
Laurent Montesi University of Maryland
Other Participants Graduate Research Assistant (1 person)
SCEC Priorities 3b, 1c, 1b SCEC Groups CXM, SDOT, SAFS
Report Due Date 03/15/2022 Date Report Submitted 06/16/2022
Project Abstract
The Community Rheology Model (CRM) aims at providing agreed-upon formulations for these rheologies over the entirety of Southern California. The focus to date has been the ductile creep of rocks below the seismogenic zone. The current release of the CRM includes dislocation creep flow laws appropriate for relatively undeformed rocks. They were built based on mineral end-member flow laws developed in the laboratory. New efforts address the rheology of shear zones and take into consideration the fabric of highly deformed rocks. However, another characteristic of shear zones, reduced grain size, cannot be included at this point because it affects another deformation mechanism: diffusion creep. This project will address this limitation by 1) compiling diffusion creep flow laws for various minerals and using them as the foundation for grain-size-aware rock-level flow laws for inclusion in the CRM. 2) Add CRM-specific flow laws added to RHEOL-GUI, a graphical tool used to calculate strength profiles as part of a new release of the software that includes all CRM flow laws. 3) Discuss the effect of grain size on the rheology of CRM rocks.
Intellectual Merit This project advances understanding of lower crust rheology in shear zones such as may be present in the downward continuation of seismogenic faults. This will help improve estimates of the stress regime at the base of the seismogenic zone and its influence on earthquake nucleation.
Broader Impacts The results of this project will be sheared in an open-source code making it possible for the broader community to use the flow laws developed here.
Exemplary Figure None yet