Balance of risks and benefits in preparation for earthquakes

Widespread proposals to benefit from lessons of the 17 October 1989 (Loma Prieta) earthquake dramatize the difficulties associated with reducing seismic risk. There are three main problems. First, the understanding of earthquake generation is far from complete. For example, the unanticipated source style of this earthquake raises vital questions; claims of predicting its occurrence are weak, and, for practical reasons, the detailed pattern of damaging strong ground shaking was not predicted. Second, although their interactions are not well understood, competing social forces continue to prevent the optimum growth and application of knowledge for earthquake hazard mitigation. Third, the recent use of the probabilities of seismic risk has had mixed results. Because of indecision between minimizing loss of life and maximizing broader benefits, general agreement on acceptable earthquake risk remains confused.