Fig. 4. Comparing theoretical predictions of supershear rupture velocities to numerical simulations for nonuniform prestress.

(A) Top: Spatially nonuniform τ₀ profiles with uniform τ_p profiles are considered. The imposed τ₀/τ_p profiles are shown. Bottom: Rupture velocities C_f(l) corresponding to the stress profiles in the top panel. Top and bottom: A high-stress nucleation patch (τ₀/τ_p = 0.8 region) facilitates a direct supershear transition. Black solid lines show theoretical predictions for the nonuniform loading described by Eq. 3. Note the difference of C_f(l) profiles with those in Fig. 2A for similar τ₀/τ_p profiles. Predicted locations for supershear–to–sub-Rayleigh transition are marked by gray triangles. (B) Comparison of supershear–to–sub-Rayleigh transition positions measured in 50 simulations, with the predicted transition position based on Eq. 3. In the considered τ₀(x) profiles, the size of the high-stress nucleation patch is modified [see yellow curve in (A)]. Dashed line with slope 1 and is given for reference. Colors indicate the minimal needed increase in τ₀ within the low-stress region that would negate the predicted supershear–to–sub-Rayleigh transitions. Gray triangles denote the simulations shown in (A).