Extended Data Fig. 3. Effect of slope angle on the propagation dynamics in standard Propagation Saw Tests (PSTs, top) and Centered Propagation Saw Tests (CPSTs, bottom).

a, Temporal evolution of the crack tip location. Blue squares and red circles correspond respectively to critical and super critical crack lengths. b, Normalized crack propagation speed as a function of slope angle. The transition to the supershear regime requires a smaller super critical crack length for larger slope angles. A steeper slope induces a shorter transient regime. c, Temporal evolution of the crack tip location. d, Normalized crack propagation speed as a function of the crack length for different values of slope angle. This CPST setup induces propagation in both upslope and downslope directions. While the complex interplay between slab bending induced by weak layer collapse and slab tension (upslope) or slab compression (downslope) breaks the propagation symmetry, the asymptotic speeds are essentially the same in both directions.