The frictional behavior of serpentinite: Implications for aseismic creep on shallow crustal faults

Abstract

Serpentine is common in many active faults and may be responsible for aseismic creep along segments of these faults. To test this, we have conducted a series of velocity stepping experiments to determine the frictional velocity dependence of serpentinite. We slid initially bare, rough surfaces of antigorite serpentinite at room temperature, with velocities from 0.0032 to 10.0 μm/s (1.0×102 to 3.2×105 mm/yr) and normal stresses from 25 to 125 MPa. We find that the velocity dependence of serpentinite undergoes a transition from velocity weakening at fast loading velocities to velocity strengthening at slow velocities and that this change is accompanied by other changes in the constitutive behavior. These results suggest that serpentinite should not be the site of instability initiation during sliding at plate velocities, but may permit propagation of unstable slip initiated elsewhere.

Frictional properties of the shallow Nankai Trough accretionary sediments dependent on the content of clay minerals

“…As already described in Takahashi et al (2013), claystone sample C2516 exhibited an asymptotic change in μ following instantaneous and decayed responses after a stepwise change in V axial (Figure 4). Such frictional behavior had also been observed during friction experiments on serpentinite (Reinen et al 1991;Takahashi et al 2011) and has been ascribed to a flow component during frictional sliding (Takahashi et al 2011(Takahashi et al , 2013. We fit the observed friction data with the mixed friction-flow law proposed by Takahashi et al (2011Takahashi et al ( , 2013.…”

The geological record of oceanic crustal accretion and tectonism at slow-spreading ridges

“…The lack of teleseismic activity beneath the rift mountains suggests that outward-facing faults there do not generate large-moment events, although microearthquakes have been recorded up to -15 km off axis at 29°N (Wolfe eta !., 1995). The presence of serpentine on a fault may result in aseismic creep (Reinen, et al, 1991); if outward-facing faults sole in serpentinites at depth, or even incorporate mobile (e.g., diapiric) serpentinites along the fault plane in deeper parts of the crust, they may be relatively aseismic or have greatly reduced seismic moments.…”

“…Serpentinite is weak, and its presence favors the localization of strain and the formation of weak faults (Reinen, 1991;Escartfn et al, 1996).…”

Frictional properties of the active San Andreas Fault at SAFOD: Implications for fault strength and slip behavior

“…In order to reduce this error, in our inversions we begin with the measured stiffness of the apparatus based on the applied vertical load (that is, accounting for nonlinearity in stiffness at low loads) and then measure the stiffness for each velocity step and allow for minor changes that may arise from thinning of the layer and changes in porosity. Furthermore, while not the goal of this study, we note that there is a variety of "designer" friction laws that have been invoked to describe possible physical mechanisms underlying complex responses to velocity perturbations [e.g., Reinen et al, 1991;Kato and Tullis, 2001;Niemeijer and Spiers, 2007]. …”