GRANULAR FAILURE: THE ORIGIN OF EARTHQUAKES?

Via Molecular Dynamics simulations, we investigate the stick-slip motion in a model of fault, where two surfaces subject to a constant confining pressure P, and enclosing granular particles, are subject a shear stress ?. When the system sticks, the stress increases with a constant rate , while the stress decreases when the system flow. We dermine the system 'phase diagram' in the pressure P load velocity plane, locating the transition form the continuos flow regime to the stick-slip regimes, and show that the transition between these two regimes is characterized by the presence of large fluctuations. In the stick-slip regime, the system reproduces the behaviour of a segment of a fault of fixed lenght.