SCEC Award Number 11092 View PDF
Proposal Category Collaborative Proposal (Data Gathering and Products)
Proposal Title Collaborative Proposal: Frictional Behavior of Disaggregated Punchbowl Ultracataclasite at Intermediate to High Slip Rates
Name Organization
Hiroko Kitajima Pennsylvania State University Judith Chester Texas A&M University
Other Participants Shimamoto, Toshihiko
Chester, Frederick
1 Ph.D student from Texas A&M University
SCEC Priorities A8, A7, A9 SCEC Groups FARM, Geology
Report Due Date 02/29/2012 Date Report Submitted N/A
Project Abstract
Eight rotary friction tests were conducted on the Punchbowl fault ultracataclasite at slip-rates of 10-6 to 1 m/s to understand the evolution of frictional behavior over a wide range of slip rates. The tests include three kinds of tests, (1) constant velocity experiments, (2) velocity stepping experiments, and (3) changing velocity experiments. The evolution of frictional behavior is different for dry and wet samples. Dry samples indicate increase in friction coefficient at the slip rates of less than 0.1 m/s, and decrease in friction at slip rates of larger than 0.1 m/s. On the other hand, friction coefficient of wet samples only decreases as velocity increases. The evolution of in-situ friction coefficient during the changing velocity experiments is different from the steady-state friction coefficient from both constant velocity experiments and velocity stepping experiments at slip velocity ranging from 10-3 to 0.1 m/s, suggesting that the friction coefficient during the changing velocity experiments is not steady state probably associated with transient increase in pore pressure caused by frictional heating.
Intellectual Merit Friction experiments on gouge materials over a wide range of slip rates contribute better understanding of the evolution of friction strength of faults in the seismic cycle and constructing friction constitutive relation for low-speed friction to high-speed friction.
Broader Impacts This is a collaborative research between researchers from US and China. Kitajima visited China Earthquake Administration to conduct experiments. We believe more international collaboration will be promoted in the SCEC community.
Exemplary Figure Figure 1. Friction coefficient of all experiments as a function of slip velocity. Steady-state friction coefficient was presented for both constant velocity experiments and velocity stepping experiments, while in-situ friction coefficient was shown for changing velocity experiments.