Intersonic Bilateral Slip

SUMMARY Symmetric "bilateral slip at constant intersonic velocity is investigated. Linear isotropic elasticity is assumed, and the idealization of a point-sized process region is adopted. The energy release rate is calculated for a slip propagation velocity equal to lh times the S-wave speed, which is the intersonic velocity for which stresses and strains are square-root singular in this idealization. The result shows a smaller energy release rate than at low subRayleigh velocities, but in general not much smaller: it equals approximately the energy release rate at about 95 per cent of the Rayleigh wave velocity for Poisson's ratio around 0.25. For other intersonic velocities the results were modified to include a finite process region, by using previously obtained results concerning steady-state propagation. In this way the energy flow to the process region can be obtained as a function of the slip propagation velocity in the whole intersonic region for each set of process region characteristics assumed. Numerical calculations, assuming a Barenblatt process region model, indicate little sensitivity to process region size and a somewhat flat maximum close to fi times the S-wave speed.