Selection and ranking of the ground motion prediction equations for the new Italian hazard map (MPS16)

The MPS16 project, started in 2015, aims at updating the existing reference seismic hazard model for Italy, released in 2004-2006 (Stucchi et al., 2011). As known, ground-motion prediction equations (GMPEs) play a basic role in probabilistic seismic hazard assessment and, thus, special care should be taken to select and rank them in a proper way. GMPEs predict an IM at a given location as a function of earthquake magnitude, style of faulting, distance from the earthquake source, site characteristics and other variables, depending on the complexity of the model. In PSHA calculations GMPEs are combined in a logic tree framework, in order to take into account epistemic uncertainties, therefore ranking/scoring procedures have become very popular, although the selection of branch models and weights is still treated rather informally. We briefly describe the preliminary selection and ranking of the ground motion models for the new Italian hazard map. We describe the procedure for the following IMs: PGA, PGV and acceleration spectral ordinates (SA).