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From micro-crack to crustal fault
Major fault systems dissect the Earth’s crust at the boundaries of tectonic plates. On human time scales, faults may slip catastrophically during earthquakes, but fault lines remain steady features of tectonic landscapes. On geological time scales, new fault lines can form, shape mountains and basins as they accumulate offset, while others can heal and disappear. I will present a simple mechanical framework describing the initiation, growth and termination of major fault systems in terms of the visco-elastic-brittle rheology of the crust. I will then challenge key aspects of this framework, and discuss brittle faulting as a mechanism that spans multiple spatial scales, from mineral (10^-3 m) to crust (10^4 m), and should be described as such in continuum models of tectonic deformation.