A shear failure strength law of rock in the brittle‐plastic transition regime

As a first step to establish the law governing shear failure of typical crustal materials in the brittle‐plastic transition regime under lithospheric conditions, and thereby to properly estimate a depth profile of lithospheric strength in quantitative terms, the effects of the normal stress σ n across the fault surfaces and ambient temperature T on the shear failure strength of dry Westerly granite in the brittle to brittle‐plastic transition regimes are evaluated quantitatively, using experimental data published by earlier authors. The empirical law proposed can predict the shear failure strength at strain rates of 10 −4 ‐10 −5 /S under any (σ n , T ) conditions in the brittle to brittle‐plastic transition regimes.