Probabilistic seismic hazard : a review of the seismological frame of reference with examples from Norway

A probabilistic seismic hazard analysis (PSHA) utilizes, in the conventional Cornell-McGuire approach, a quantitative model of the earthquake activity implying major simplifications which are important to assess in terms of their contributions to uncertainty. The goal is one of the basic principles in science, namely to establish a minimum parameter model that depicts nature with the optimum representativity (Occam's razor). All too often, underlying seismological issues remain obscure in PSHA analyses. On the basis of a specific analysis conducted in Norway we highlight how a combined seismicity analysis using both modern network data and historical data can be utilized in order to provide realistic insights into location precision and to establish magnitude homogeneity. All of this is aimed at improving the reliability of the seismic source models (i.e. the activity parameters), and to improve, without over-interpretation the earthquake catalog data, the spatial differentiation of the seismogenic zones.