SCEC Award Number 11154 View PDF
Proposal Category Collaborative Proposal (Integration and Theory)
Proposal Title The dependence of fault strength on rapid changes in normal stress and their implications for dynamic fault rupture
Investigator(s)
Name Organization
David D. Oglesby University of California, Riverside Nick Beeler United States Geological Survey Brian Kilgore United States Geological Survey
Other Participants Julian Lozos
SCEC Priorities A3, A8, A9 SCEC Groups FARM
Report Due Date 02/29/2012 Date Report Submitted N/A
Project Abstract
 Using the same laboratory apparatus as Linker and Dieterich’s classic normal stress experiments but with a more accurate recording system, we find that the response of fault friction to steps in normal stress does not appear to obey the Linker+Dieterich friction law or the alternative Prakash friction law. We are in the process of putting together a new frictional parameterization that matches these new and exciting results. The results may have important implications for rupture propagation and slip in regions of geometrical and material complexity, as well as for ground motion and seismic hazard.
Intellectual Merit The results of our high-resolution experiments are allowing us to construct laboratory-based frictional parameterizations that can be used in dynamic earthquake rupture models. The development of a better model for friction under the effects of time-variable normal stress will aid in modeling the dynamics of single earthquakes as well as long-term system-level behavior, with implications for rupture size, slip distribution, and ground motion. We anticipate that our results will have important implications for SCEC goals A3 (Develop a system-level deformation and stress-evolution model), A8 (Test hypotheses for dynamic fault weakening), A9 (Assess predictability of rupture extent and direction on major faults), and B1 (Develop kinematic and dynamic rupture representations consistent with seismic, geodetic, and geologic observations).
Broader Impacts The results may have important implications for rupture propagation and slip in regions of geometrical and material complexity, as well as for ground motion and seismic hazard.
Exemplary Figure Figure 2. Comparison of stress versus time data from new experimental results (top panel) with modeled experimental data from assuming the Prakash (bottom left) and Linker+Dieterich frictional parameterizations. Simulations include machine stiffness. Our new data appear to match Prakash’s model better, but the match is still not perfect.