Seismic Hazard Mapping for Italy in Terms of Broadband Displacement Response Spectra

A new representation of seismic hazard is proposed for Italy based on displacement elastic response spectra in a vibration period range that extends from 0 s to 20 s. This relies on an available seismotectonic zonation and earthquake catalogue, but makes use of a set of very recent, expressly developed attenuation relations. The long period picture of ground motion hazard is illustrated vis-agrave-vis the conventional one based on ground acceleration, and the feasibility of simple approximations of the displacement spectra, useful for design purposes, is shown. We give some foresight on the differences to be expected in hazard maps resulting from the use of a predominantly fault-based seismic source model, as opposed to the more conventional model that includes only spatially extended zones. Finally, we highlight the different hazard exposure of different regions depending on whether we represent hazard with a long or a short period parameter and we discuss the adequacy of recent code provisions regarding elastic displacement spectra.