SCEC Award Number 24113 View PDF
Proposal Category Collaborative Research Project (Multiple Investigators / Institutions)
Proposal Title Transitional fault friction behavior from dynamic rupture to frictional sliding
Investigator(s)
Name Organization
Xiaofeng Chen Texas A&M University Frederick Chester Texas A&M University
SCEC Milestones B1-1 SCEC Groups FARM
Report Due Date 03/15/2025 Date Report Submitted 03/14/2025
Project Abstract
 Earthquakes begin with dynamic rupture propagation from the nucleation site, followed by frictional sliding along the fault. However, experimental simulations often treat rupture and friction separately, neglecting how dynamic faulting evolves into prolonged frictional sliding, and the interaction between fracturing and friction during earthquakes remains unclear. In this work, we performed high-speed sliding and spontaneous stick-slip tests on Westerly Granite, a quartzite, and Carrara Marble using a unique pneumatically powered high-speed double direct shear apparatus with high acceleration up to 500 m/s2. We analyzed experimental friction data, focusing on the characteristics of the transient friction behavior during fault acceleration and deceleration. Our data demonstrates the dominating velocity-weakening behavior at transient stages of fault acceleration and deceleration, with a 1/V dependence for peak friction and deceleration lobe consistent with the flash-heating model but with the acceleration lobe consistently deviating from the 1/V dependence. Our analysis of velocity-dependent friction between dynamic rupture events, stick-slips, and high-speed friction tests reveals the significance of high acceleration in influencing transient fault weakening during dynamic weakening. In-situ fault surface temperature monitoring and post-mortem microstructural analysis showed a predominantly frictional dissipation process for high-speed sliding runs, whereas stick-slip events have limited frictional process involved due to negligible temperature rise of a few °C. We further demonstrate that the deviation of the friction-velocity curve from the 1/V trend during fault acceleration is associated with the contribution of the dynamic rupturing process during the initiation of fault slip.
Intellectual Merit This study offers new insights into earthquake mechanics, confirming the broad applicability of the flash heating mechanism in rock friction. The consistent coseismic re-strengthening during fault deceleration implies overestimated stress drops in laboratory tests. The agreement of breakdown work scaling between laboratory tests and natural earthquakes suggests that natural earthquakes exhibit both small-slip and large-slip characteristics. Higher stress drops and fracture energy in triaxial stick-slips highlight the difference between direct measurements and seismological estimations. In contrast, frictional processes in the tail zone play a significant role in large earthquakes.
Broader Impacts Key project activities will broaden the significance of our research and provide educational training opportunities to the students. The interdisciplinary nature of this research provides new quantitative insights into understanding faulting and earthquake mechanics. It also provides opportunities for future collaboration with other research teams with diverse skill sets besides experimental work. Our findings can be used as inputs for computational earthquake modeling and seismological data interpretation approaches.
Project Participants Xiaofeng Chen, Boone Pickens School of Geology, Oklahoma State University
Frederick M Chester, Department of Geology and Geophysics, Texas A&M University
Exemplary Figure Figure 1. Compilation of breakdown work versus seismic slip for laboratory experiments (circles and squares) and natural earthquakes (triangles and diamonds), with a fitted power-law relation (dashed line). More datasets are compiled and available in Cocco et al. (2023).
Linked Publications

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