Theodore von Karman Lecture
The recent news of Italian scientists convicted in a criminal court of failing to provide adequate warning of an impending earthquake has starkly highlighted some of the limitations and misunderstandings of the science behind earthquake forecasts and predictions. Are predictions even possible? What difference is there between a prediction and a forecast? What scientific principles allow (or rule out) useful earthquake forecasts? This talk will review the past history and basic principles behind efforts to anticipate the location, size and timing of seismic events. New techniques in data collection and improved understanding of how the Earth works is leading to ever-improving forecast capability, but will the "holy grail" of routine specific earthquake predictions ever be a reality? These questions will be explored and some thoughts about impending southern California quakes will be discussed.