Seismic hazard mapping for adminsitrative purposes

Local soil conditions, roughly summarised by considering a reference soil for each mu- nicipality of the Friuli – Venezia Giulia region in NE Italy, are introduced into probabilistic seismic hazard estimates: the subsequent improvement is checked by comparing these new results and the maximum observed intensities in each municipality to investigate if the major differences between probabilistic estimates and actually observed data can be explained by local site effects and/or by the geometry of the seismogenic zones used in the computation. In addition, a comparison between the new probabilistic hazard results, and the standard ones referred to rock is made for the present and the proposed Italian seismic zonation. The results underline the influence of the seismogenic model used, but are not determinant on the role of site effects.