THE SEISMIC ZONATION OF LATIUM REGION BASED ON NEW CRITERIA

In 2007 Latium Regional Administration and ENEA signed an Agreement of Research in order to define a new approach for the regional seismic zonation accordingly to the new criteria and laws recently approved in Italy for the building code in seismic areas. The resulting study was based on two methodologies: an historical and seismological analysis of the regional seismicity and a statistical and spatial analysis of uniform hazard response spectra related to sites included into the Latium boundary. The historical analysis produced an evaluation of the maximum historical intensity in every Municipality, together with the information on magnitude and epicentral distance of the related events: these data were used in querying international strong-motion databases in order to select a set of real ground-motion recordings. The statistical analysis outlined by a cluster technique six groups of spectra which characterise the regional seismic hazard and can be used to allocate each Municipality into the proper Seismic Zone. The selected time-histories, scaled to the spectral shape of each group, represent a useful tool for the structural design of buildings in seismic areas. The same clustering procedure was applied also to the site elastic spectra furnished by the new Italian legislation and the discrepancies between the resulting spectral shapes were discussed. Through this research, Regional Geological Survey produced two different scenarios of seismic zonation.