Dynamics of slab detachment

We investigate the dynamics of slab detachment around the detachment zone and evaluate the amount of time necessary for slabs to detach. The study combines results of two‐dimensional (2D) state‐of‐the‐art thermomechanical numerical simulations and a 1D analytical solution for viscous necking under gravity. We show that the dominant deformation mechanism during slab detachment is viscous necking, independent of the depth of slab detachment. When the slab dip is moderate (35–70°), slab detachment is partly affected by localized simple shearing in the colder parts of the slab. Brittle fracturing (breaking) plays a minor role during slab detachment. Our 2D thermomechanical models indicate that the duration of slab detachment, quantified from the onset of slab thinning until the actual detachment (i.e. vanishing of slab‐pull force), is relatively short (250 km) can occur within a short time interval (