Fracture process in rocks and earthquakes

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Due to its brittle nature, rock breaks at all length scales: from micro-cracks in grains (or along grain boundaries) with sizes smaller than a millimeter to huge earthquake ruptures along faults that define tectonic boundaries with lengths of hundreds of kilometers. Fractures and fracture processes play an important role in the determination of the constitutive response of rocks and the characteristics of geological hazards that are associated with catastrophic rock faults. Thus, the investigation of fractures in rocks will help us understand and mitigate geological hazards (seismic, landslide, etc.), address safety issues in mines (e.g., slope instability, rockbursts), and improve the management of groundwater and radioactive waste. Historically, research efforts to understand rock fractures have been focused mainly on laboratory static fractures and on the seismic observations and numerical simulations of earthquakes. In order to understand the dynamic properties of rocks involved in catastrophic failures, specially designed experiments are necessary. Following the applicant's earlier work in the laboratory earthquake experiments and spontaneous fracture experiments, he will study the characteristics of earthquake faulting in both two- and three-dimensions. The applicant will also systematically measure the dynamic fracture toughness of rocks and the dynamic tensile strength of rocks, two important parameters in the quantification of dynamic rock failure. The research will be carried out using the Rock Dynamic Fracture Facility (CFI-Young lead PI) at the University of Toronto, the high speed camera, and the gas gun through collaboration. In addition, the applicant is building a gas gun using the start-up award from the University of Toronto and is preparing a CFI/LOF proposal to request an ultra high speed camera.