Microcrack interaction leading to shear fracture

In this paper we draw upon recent laboratory results concerning the nucleation and growth of shear fractures in brittle rock. In homogeneous, crystalline rock such as granite, fault nucleation occurs rapidly and with only subtle changes in precursory microcrack patterns. Once nucleated, the fault grows rapidly, restricting microcrack damage to a small region near the advancing fracture front. Observations of acoustic emission locations during fault nucleation and growth combined with determinations of microcrack densities in the fractured samples have led to a conceptual model in which brittle fracture is controlled by microcrack interactions.