Figure 6

Interpretation of supershear ruptures in poroelastic media through an effective seismic ratio. We simulate ruptures in a slip-weakening, strike-slip fault model (see Supplementary Material, Section 2, for the model setup). (a) We perform simulations with several dynamic friction coefficients, and verify that the transition for ruptures in elastic media occurs at the Andrews seismic ratio of 1.77 (red circles), while the transition for poroelastic media (\(\alpha _B\) \(=\) 0.95) occurs at a significantly larger value (blue squares). (b) By expressing the seismic ratio using effective, rather than total normal stresses (see Supplementary Material, Section 4, for the calculation of the effective residual strength), we recover the transition at an effective seismic ratio \(\text {S}'\) \(\approx\) 1.77.