Toward a Ground-Motion Logic Tree for Probabilistic Seismic Hazard Assessment in Europe
Résumé
The Seismic HAzard haRmonization in Europe (SHARE) project, which began in June 2009, aims at establishing new standards for probabilistic seismic hazard assessment (PSHA) in the Euro-Mediterranean region. In this context, a logic tree for ground-motion prediction in Europe has been constructed. Groundmotion prediction equations (GMPEs) and weights have been determined so that the logic tree captures epistemic uncertainty in ground-motion prediction for six di erent tectonic regimes in Europe. Here we present the strategy that we adopted to build such a logic tree. This strategy has the particularity of combining two complementary and independent approaches: expert judgment and data testing. A set of six experts was asked to weight pre-selected GMPEs while the ability of these GMPEs to predict available data was evaluated with the method of Scherbaum et al. (2009). Results of both approaches were taken into account to commonly select the smallest set of GMPEs to capture the uncertainty in ground-motion prediction in Europe. For stable continental regions, two models, both from Eastern North America, have been selected for shields and three GMPEs from active shallow crustal regions have been added for continental crust. For subduction zones, four models, all non-European have been chosen. Finally, for active shallow crustal regions, we selected four models, each of them from a di erent host region but only two of them were kept for long periods. In most cases, a common agreement has been also reached for the weights. In case of divergence, a sensitivity analysis of the weights on the seismic hazard has been conducted, showing that once the GMPEs have been selected, the associated set of weights has a smaller in uence on the hazard.
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