Supershear Rupture Under Hydrostatic Pressure Condition

Abstract

The effects of friction coefficient, stress drop ratio, the ratio of residual strength to initial stress, and the dip angle of faults on the rupture velocity under hydrostatic pressure condition, as well as the stress distribution on the fault, are investigated using General Particle Dynamics code. The numerical results indicate three distinct regimes of rupture dynamics: (i) slow rupture, (ii) sub-Rayleigh rupture, and (iii) supershear rupture. This suggests that rupture-mode selection is coupled to friction coefficient, stress drop ratio, the ratio of residual strength to initial stress, and the dip angle of faults. Moreover, supershear rupture can occur under upper-crustal (< 250 MPa), lower-crustal (250 to 1000 MPa), and upper-mantle (1000 to 10000 MPa) conditions. Since rupture velocity is fastest under upper-crustal conditions, supershear rupture most easily occurs under these condition.