Frictional melt and seismic slip

Abstract

[1] Frictional melt is implied in a variety of processes such as seismic slip, ice skating, and meteorite combustion. A steady state can be reached when melt is continuously produced and extruded from the sliding interface, as shown recently in a number of laboratory rock friction experiments. A thin, low-viscosity, high-temperature melt layer is formed resulting in low shear resistance. A theoretical solution describing the coupling of shear heating, thermal diffusion, and extrusion is obtained, without imposing a priori the melt thickness. The steady state shear traction can be approximated at high slip rates by the theoretical formunder a normal stress s n , slip rate V, radius of contact area R (A is a dimensional normalizing factor and W is a characteristic rate). Although the model offers a rather simplified view of a complex process, the predictions are compatible with experimental observations. In particular, we consider laboratory simulations of seismic slip on earthquake faults. A series of highvelocity rotary shear experiments on rocks, performed for s n in the range 1-20 MPa and slip rates in the range 0.5-2 m s À1 , is confronted to the theoretical model. The behavior is reasonably well reproduced, though the effect of radiation loss taking place in the experiment somewhat alters the data. The scaling of friction with s n , R, and V in the presence of melt suggests that extrapolation of laboratory measures to real Earth is a highly nonlinear, nontrivial exercise.

Thermo- and hydro-mechanical processes along faults during rapid slip

“…There are many studies of process (5), macroscopic melting in fault zones, of which the long-lived signature is noncrystalline pseudotachylyte veins along the fault surface and in side-wall injections. Recent contributions include Spray (1995), Tsutsumi and Shimamoto (1997), Fialko and Khazan (2004), Hirose and Shimamoto (2005), Sirono et al (2006), and Nielsen et al (2008). Noda et al (2006Noda et al ( , 2009 and Dunham et al (2008) have begun to integrate weakening by flash heating and thermal pressurization into elastodynamic numerical methodology for spontaneous rupture development.…”

Experimental investigation of frictional melting of argillite at high slip rates: Implications for seismic slip in subduction‐accretion complexes

“…These experimental data show a complex evolution of shear stresses prior to and after the onset of melting, and explained by coupled thermal-fluidmechanical models [Fialko and Khazan, 2005;Sirono et al, 2006;Nielsen et al, 2008]. Tsutsumi and Shimamoto [1997] and Hirose and Shimamoto [2005] reported a typical evolution of apparent friction of gabbro during HVRFE: the initial slip weakening followed by the slip strengthening up to a peak shear stress (related to the formation and coalescence of discontinuous melt patches) and finally by the secondary slip weakening toward the steady state shear stress (related to temperature-dependent melt rheology).…”

Frictional Instabilities and Carbonation of Basalts Triggered by Injection of Pressurized H2O‐ and CO2‐ Rich Fluids

“…This is in good agreement with the bulk temperature increase estimated along the slipping zone at the main frictional instability. If the heat production is (Beeler et al, 2008; Lachenbruch & Sass, 1980) $\mathrm{italicdQ}=\mathrm{normal\tau }V\mathrm{italicdt}$an estimate of the bulk temperature increase in the slipping zone during the experiments can be computed numerically using the approximation (Carslaw & Jaeger, 1959; Nielsen et al, 2008; Figure S6) $T\left(t\right)=\frac{1}{\rho ·C_p·\sqrt{\mathrm{\kappa \pi }}}·{\int }_0^t\frac{1}{2}·\frac{Q}{\sqrt{t-t^{\prime }}}\mathrm{italicdt}$(with, for basalts, thermal diffusivity κ = 0.012 cm 2 /s; Hanley et al, 1978), specific heat capacity Cp = 898 J · kg −1  · K −1 (Waples & Waples, 2004), and density ρ = 2,960 kg/m 3 ). The numerical solution revealed indeed the achievement of bulk temperatures of several hundred degrees Celsius once the main instability was triggered, as shown in Figure S6.…”