Seismic microzonation of the central archaeological area of Rome: results and uncertainties

The paper summarizes the results of a multidisciplinary study aimed at seismic microzonation of the Central Archeological Area of Rome including the Palatine hill, Roman Forum and Coliseum. A large amount of subsoil data, available mainly from adjacent subway lines and from the archaeological superintendence, were collected and used to plan new multidisciplinary investigations, carried out in 2010-2011. First, the paper describes the integrated subsoil model aimed at numerical modeling of site effects. The results of equivalent linear 2D site response analyses carried out on seven representative cross-sections of the area are then presented and discussed. Ground motion amplification factors defined in terms of Housner Intensity were computed in different ranges of period, covering the different fundamental vibration periods pertaining to the monuments and structures. The contouring of amplification factor values from all the numerical simulations, based on morphological and geological constrains, eventually allowed to create microzonation maps. Finally, a sensitivity study was carried out to investigate the effects of uncertainties of input parameters and soil heterogeneity on microzonation.