Poster #144, Fault and Rupture Mechanics (FARM)

Laboratory investigation of multiple controls on fault stability and rupture dynamics

Cheng Mei, Sylvain D. Barbot, & Wei Wu
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Poster Presentation

2021 SCEC Annual Meeting, Poster #144, SCEC Contribution #11395 VIEW PDF
The stability of frictional sliding affects the spectrum of fault slip, from slow-slip events to earthquakes. In laboratory experiments, the transition from stable sliding to stick-slip is often explained by the ratio of the stiffness of the loading system to a critical value that depends on the effective normal stress and other physical properties. However, recent theoretical considerations indicate other controls on fault stability that have not been validated experimentally. Here, a series of direct-shear experiments are performed on the polycarbonate fault under varying stress conditions at a wide range of load-point velocities to investigate the recurrence pattern of ruptures. We exploi...t the dependence of frictional properties on load-point velocity to explore the dynamics of frictional sliding with gradual variations of frictional properties. We use the period-multiplying and chaotic cycles that appear at the transition between stick-slip and stable sliding as a sensitive indicator of fault stability. In addition to the stiffness ratio, we find that the ratio of the parameters that describe the dependence on velocity and state constitutes another control on the stability of faulting and rupture dynamics. In nature, phenomena that occur near the parametric stability transition — creep waves, slow-slip events, slow earthquakes, period-doubling tremors — may be greatly affected by varying loading rates during the seismic cycle, which may affect the dominant healing mechanism and the resulting fault dynamics.