SCEC Award Number 13051 View PDF
Proposal Category Workshop Proposal
Proposal Title Ductile Rheology of the Southern California Lithosphere: Constraints from Deformation Modeling, Rock Mechanics and Field Observations
Investigator(s)
Name Organization
Wayne Thatcher United States Geological Survey Elizabeth Hearn United States Geological Survey Greg Hirth Brown University Yuri Fialko University of California, San Diego
Other Participants 20-25 Workshop participants
SCEC Priorities 1, 2, 5 SCEC Groups Geodesy, SDOT, WGCEP
Report Due Date 05/31/2013 Date Report Submitted N/A
Project Abstract
 A workshop was held May 1-2, 2013 in Menlo Park, California to investigate properties and processes of ductile lithosphere deformation. This workshop provided overviews of the newest results from lab, field and geodetic modeling disciplines relevant to better understanding earthquake processes in southern California. A principal goal of the workshop was to bring together niche experts in tectonic geodesy, laboratory rock mechanics, and field observations of ductile rocks to gain better interdisciplinary understanding of the stress transfer process between brittle-elastic upper crust and ductile lithosphere in southern California. Principal outcomes of the meeting were (1) a greatly improved understanding of the relation between the lab- derived transient and steady state flow laws, their relation to field examples of crustal flow, and their application to modeling surface crustal deformation; (2) near unanimous agreement that relatively narrow ductile shear zones exist beneath active faults in the seismogenic crust; and (3) a goal of mapping of the southern California ductile lithosphere using results of seismic imaging and anisotropy to constrain rock type and flow, combined with laboratory inferences of appropriate ductile flow laws at relevant pressure, temperature and state conditions
Intellectual Merit The rheology of the ductile lithosphere and its coupling to the seismogenic upper crust strongly influences the state of stress in the lithosphere, determines the geodetically-measured surface deformation throughout the earthquake cycle and affects geodetically estimated fault slip rates.
Broader Impacts The rheology workshop provided a fundamental basis for making progress on the Community Geodetic Model (CGM) and Community Stress Model (CSM) during the lifetime of SCEC4. It promoted interdisciplinary collaboration among tectonic geodesists, laboratory rock mechanicians and field geologists.
Exemplary Figure Figure 1