SCEC Award Number 12070 View PDF
Proposal Category Collaborative Proposal (Data Gathering and Products)
Proposal Title Analysis of fault rupture processes by earthquake-like loading in the laboratory
Name Organization
Ze’ev Reches University of Oklahoma David Lockner United States Geological Survey
Other Participants Dr. Art Mcgarr, USGS
Jefferson Chang, PhD student, U of Oklahoma
Zonghu Liao, PhD student, U of Oklahoma
SCEC Priorities 3f, 3a, 2e SCEC Groups FARM, Simulators, Seismology
Report Due Date 03/15/2013 Date Report Submitted N/A
Project Abstract
The classical experimental approach to explore earthquake rupture is to conduct friction experiments under constant- or stepping- slip-velocity. The experimental results are used to derive a constitutive law, such as the well-known rate- and state- friction (RSF). We departed from the classical approach of constant/stepping velocity experiments, and conducted friction experiments at loading modes that are likely to operate during large earthquakes. In our recent experiments (Chang et al., 2012) we applied a finite amount of energy was supplied to the experimental fault by impacting it with a spinning flywheel. In this work, we experimentally simulate fault behavior when subjected to earthquake-like loading, and use the simulation results as input for numerical modeling of earthquake dynamic rupture. Based on these results, we think that such experimental procedure would link the dynamic weakening to specific mechanisms that operate at earthquake conditions.
Intellectual Merit The experimental investigation described here are expected to simulate the behavior of a fault patch during the rupture by the propagating earthquake front. By its intrinsic nature, the slip along a patch is a transient phenomenon with intense acceleration, deceleration, weakening and healing during a period up to a few seconds. We thus think that the fault constitutive relations described above provide good proxy for the transient nature of earthquake slip.
Broader Impacts Three PhD students were participated in the project: Mr. James Jeffers, who programed the unique power control option of the experimental systems, Mr. Liao Zong and Mr. Xiaofeng Chen who were involved in the experiments and analyses.
Exemplary Figure Fig. 6. Friction-velocity relations of granite. Left: the three modes of velocity histories. Right: the observed friction-velocity relations; large symbols with error bars on yellow background are mean friction coefficients during steady-state; corves marked by multiple small color dots are the temporal relations for the four variable velocity experiments, with black and red for the quake loading and the two green for the ramp loading.