Figure 4

Impact of rock poromechanical properties on rupture speed. (a) The transition from sub-Rayleigh to supershear ruptures occurs at larger values of the Biot coefficient as the material becomes stiffer. The normalized rupture speed, \(\overline{V}_{R}\)/\(C_{S,0}\) indicates that ruptures tend to be sub-Rayleigh when poroelastic coupling is weak (smaller \(\alpha _B\)), while strong coupling (larger \(\alpha _B\)) favours supershear ones. For given confinement stresses, rock stiffness controls the transition from sub-Rayleigh, with \({\bar{V}}_R\) \(\approx\) \(0.8C_S\), to supershear beyond the Eshelby speed, \({\bar{V}}_R\) \(\ge\) \(\sqrt{2}C_{S,0}\). (b) Using the same results as in (a), we normalize rupture speeds using the Gasmann modification of the compressional wave speed, \(C_{P,G}\). Ruptures stabilize around a normalized speed of 0.8. The confinement conditions are \((\sigma _x,\sigma _y)\) \(=\) (130 MPa, 50 MPa).