Earthquake forecasting and earthquake prediction: different approaches for obtaining the best model

We consider the general problem of constructing or selecting the “best” earthquake forecast/prediction model. While many researchers have presented technical methods for solving this problem, the practical and philosophical dimensions are scarcely treated in the scientific literature, and we wish to emphasize these aspects here. Of particular interest are the marked differ- ences between approaches used to build long-term earthquake rupture forecasts and those used to conduct systematic earth- quake predictability experiments. Our aim is to clarify the dif- ferent approaches, and we suggest that these differences, while perhaps not intuitive, are understandable and appropriate for their specific goals. We note that what constitutes the “best” model is not uniquely defined, and the definition often depends on the needs and goals of the model’s consumer.