Static stress changes and the triggering of earthquakes

Abstract

The tendency of rocks to fail in a brittle manner is thought to be a function of both shear and confining stresses, commonly formulated as the Coulomb failure criterion. This paper explores how changes in Coulomb conditions associated with one or more earthquakes may trigger subsequent events. It is found that the distribution of aftershocks for the Landers earthquake can be explained by the Coulomb criterion as follows: aftershocks are abundant where the Coulomb stress on optimally orientated faults rose by more than one-half bar, and aftershocks are sparse where the Coulomb stress dropped by a similar amount. Further, several moderate shocks raised the stress at the future Landers epicenter and along much of the Landers rupture zone by about a bar, advancing the Landers shock by 1 to 3 centuries. -from Authors