Dear Pat, i think that by applying the quiescence hypothesis as postulated by Prof.Ìax Wyss one can pinpoint areas that are prone to be struck by STRONG (M>6) main shocks. The duration of the anomaly in time is dependant on the magnitude of the impending shock but we never know exactly when the observed quiescence will end. So we have two parameters, place and magnitude. The time question in short term (days, months) can be solved buy use of accurate GPS, water level and radon level measurements that have shown promising results. In addition to that anomalous human and animal behaviour can further give us real short term (days) indications.
Best regards