Ground motion models for the new seismic hazard model of Italy (MPS19): selection for active shallow crustal regions and subduction zones

The aim of this paper is to identify the ground motion models (GMMs), applicable in active shallow crustal regions (ASCRs) and subduction zones (SZs), to be used for the new release of the seismic hazard model of Italy (MPS19) for peak ground acceleration and 12 ordinates of the acceleration response spectra (5% damping) in the period range 0.05–4 s. The steps to achieve such goal are: (1) a pre-selection of the GMMs that takes into account the suitability for the application to the Italian territory and the fulfillment of the new hazard model requirements; (2) the assessment of a proper scoring of the pre-selected GMMs using strong-motion data recorded in Italy; (3) the selection of the GMMs to be used in the hazard calculation. The final set of GMMs describes satisfactorily the epistemic uncertainty of the ground shaking process, privileging the simplicity and flexibility of the functional form. Finally, the weights of the selected GMMs are assigned combining the results of the scoring and the weights obtained through an experts’ elicitation.