The dynamics of the onset of frictional slip

Authors: Oded Ben-David, Gil Cohen and Jay Fineberg

The Racah Institute of Physics, The Hebrew University of Jerusalem, Givat Ram, Jerusalem Israel

The way in which a frictional interface fails is critical to our fundamental understanding failure processes in fields ranging from engineering to the study of earthquakes. Frictional motion is initiated by rupture fronts that propagate within the thin interface that separates two sheared bodies. By measuring the shear and normal stresses along the interface together with the subsequent rapid real contact area dynamics, we find that the ratio of shear stress to normal stress can locally far exceed the static friction coefficient without precipitating slip. Moreover, different modes of rupture selected by the system correspond to distinct regimes of the local stress ratio. These results indicate the key role of nonuniformity to frictional stability and dynamics with implications for the prediction, selection and arrest of different modes of earthquakes.