Prediction of failure times in the Earth for a time-varying stress.

A theory is presented which describes the acceleration of a crack tip from initially slow (sub-critical) rates due to stress corrosion to rapid catastrophic rupture under conditions of gradually increasing stress. Failure times depend on initial conditions such as crack length, crack-tip velocity, residual frictional stress following a previous earthquake, stress-corrosion index and the rate of stress input. The regularity of earthquake recurrence intervals observed on some faults is seen as a consequence of the persistence of these initial conditions, perhaps as a result of the persistence of asperity characteristics over a few cycles. However, this regularity does not necessarily imply a constant repetition of characteristic fault lengths demanded by simple time- or slip-predictable models.-from Author