Fig. 2

Velocity dependence of steady-state friction (a − b) for anorthite, albite, and quartz, as determined by Eq. (2). a Dry conditions, P_c = 150 MPa (Ar gas); b wet conditions, P_c = 200 MPa (Ar gas), P_p (pore-water pressure) = 50 MPa (distilled water). The data for quartz and albite are from Masuda et al. (2019). The granite data for dry and wet conditions are from Lockner et al. (1986) and Blanpied et al. (1991), respectively. The velocity dependence of steady-state friction (a − b), as determined from Eq. (2), is represented by the difference between the parallel steady-state trend lines immediately before and after velocity step changes (inset diagram in a)