ABSTRACT
Seismic vulnerability assessment on a territorial scale, implicitly related to the broader issue of seismic risk mitigation and reduction, is conditioned by factors of uncertainty related to the data process, that inevitably impact the analysis. The seismic vulnerability of historical centers at a territorial scale cannot be assessed performing detailed analysis which is usually adopted at the single building scale. The application of the theory of compositional data allows defining probabilistically floors heights starting from the knowledge of buildings height. The building total height and the size and position of walls openings can usually be measured with acceptable precision even from outside, by adopting traditional or remote sensing methods. "Provisions on the protection of architectural heritage and seismic risk mitigation" provides a new incremental approach that involves both the implementation of local interventions on buildings improving structural safety without involving sensitive additional costs and the improvement of reliability of seismic risk maps.
