SCEC Award Number 11157 View PDF
Proposal Category Collaborative Proposal (Integration and Theory)
Proposal Title Laboratory Experiments on Fault Shear Resistance Relevant to Coseismic Earthquake Slip
Investigator(s)
Name Organization
David Goldsby Brown University Terry Tullis Brown University
Other Participants Giulio Di Toro, University of Padua, Italy (unfunded collaboratory)
SCEC Priorities A8, A11, B2 SCEC Groups FARM, Seismology, GMP
Report Due Date 02/29/2012 Date Report Submitted N/A
Project Abstract
 Within the past year, we have made significant progress in experimental studies of two dynamic fault-weakening mechanisms – flash heating and thermal pore fluid pressurization. Flash-heating experiments were focused on determining the influence of ambient fault-surface temperature on flash-heating behavior. Thermal pressurization tests were focused on providing the first conclusive evidence for this mechanism in the laboratory. The unexpected results of the flash heating experiments at elevated ambient temperatures, that the weakening velocity for flash heating INCREASES with temperature, were found to agree well with existing theory when the influence of temperature on heat capacity, density and other materials properties are accounted for in Rice's (2006) equation for the weakening velocity. Thermal pressurization experiments suggest that fluids become sufficiently highly pressurized in our experiments to breach the high pressure seals in our sample assembly. The experiments suggest that fluid pressurization is best studied at modest slip rates and large sliding displacements.
Intellectual Merit The research contributes to our understanding of the earthquake energy budget, strong ground motions, and accelerations associated with earthquake faulting, by providing fundamental knowledge of the coseismic shear resistance of faults.
Broader Impacts Results of our experiments are incorporated in coursework at Brown. The experiments have provided new sample fixtures and other enhancements to existing equipment that enhance the infrastructure for research and education. Society benefits from an acquisition of scientific knowledge and in improved understanding of earthquakes and how to mitigate their damage.
Exemplary Figure Figure 1.