Damage and rheology in a fibre-bundle model

In this paper, we consider the continuum deformation of the brittle upper continental lithosphere, utilizing the fibre-bundle model. Fibre failure is assumed to be a thermally activated process. We further assume that a failed fibre is replaced by a new unstressed fibre. This replacement is analogous to a migration of a dislocation, an earthquake rupture or a microcrack. We derive a non-Newtonian power-law viscous rheology. This is the rheology that has been used to explain the lithospheric deformation in Tibet. We also constrain the parameters in our model using aftershocks. A major advantage of our upper continental rheology is that it has a strong temperature dependence. We then use this model to define the strength envelope of the continental lithosphere. Our results suggest that a damage model is appropriate for the continuum rheology of the upper continental lithosphere.