On factors controlling precursor slip fronts in the laboratory and their relation to slow slip events in nature

Journal Article · 17 February 2017 · Geophysical Research Letters

DOI: https://doi.org/10.1002/2017GL072538 · OSTI ID:1479305

Selvadurai, Paul A.  ^[1]; Glaser, Steven D.  ^[1]; Parker, Jessica M. ^[1]

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1. Univ. of California, Berkeley, CA (United States). Civil and Environmental Engineering

Spatial variations in frictional properties on natural faults are believed to be a factor influencing the presence of slow slip events (SSEs). This effect was tested on a laboratory frictional interface between two polymethyl methacrylate (PMMA) bodies. We studied the evolution of slip and slip rates that varied systematically based on the application of both high and low normal stress (σ₀=0.8 or 0.4 MPa) and the far-field loading rate (V_LP). A spontaneous, frictional rupture expanded from the central, weaker, and more compliant section of the fault that had fewer asperities. Slow rupture propagated at speeds V_slow~0.8 to 26 mm s^-1 with slip rates from 0.01 to 0.2 μm s^-1, resulting in stress drops around 100 kPa. During certain nucleation sequences, the fault experienced a partial stress drop, referred to as precursor detachment fronts in tribology. Only at the higher level of normal stress did these fronts exist, and the slip and slip rates mimicked the moment and moment release rates during the 2013–2014 Boso SSE in Japan. The laboratory detachment fronts showed rupture propagation speeds V_slow/V_Rϵ (5 to 172) × 10^-7 and stress drops ~ 100 kPa, which both scaled to the aforementioned SSE. Distributions of asperities, measured using a pressure sensitive film, increased in complexity with additional normal stress—an increase in normal stress caused added complexity by increasing both the mean size and standard deviation of asperity distributions, and this appeared to control the presence of the detachment front.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 1479305
• Journal Information: Geophysical Research Letters, Journal Name: Geophysical Research Letters Journal Issue: 6 Vol. 44; ISSN 0094-8276
• Publisher: American Geophysical UnionCopyright Statement
• Country of Publication: United States
• Language: English