Seismic Risk Evaluation

This paper reports the main results of the EC-Project SERGISAI. The project developed a computer prototype where a methodology for seismic risk assessment has been implemented. Standard procedural codes, Geographic Information Systems and Artificial Intelligence Techniques compose the prototype, which permits a seismic risk assessment to be carried out through the necessary steps. Risk is expressed in terms of expected damage, given by the combination of hazard and vulnerability. Two parallel paths have been followed with respect to the hazard factor: the probabilistic and the deterministic approach. The first provides the hazard analysis based on historical data, propagation models, and known seismic sources. The deterministic approach provides the input for scenarios, by selecting a specific ground motion. With respect to the vulnerability factor, several systems have been taken into account apart from buildings, which are usually considered in this type of analysis. Defining vulnerability as a measure of how prone a system is to be damaged in the event of an earthquake, an attempt has been made to move from the assessment of individual objects to the evaluation of the performance of urban and regional areas. Another step towards an approach which can better serve civil protection and land use planning agencies has been made by adapting the analysis to the following geographical levels: local, sub-regional and regional. Both the hazard and the vulnerability factors have been treated in the most suitable way for each one, in terms of level of detail, kind of parameters and units of measure. In this paper are shown some results obtained in two test areas: Toscana in Italy, for the regional level, the Garfagnana sub-area in Toscana, for the sub-regional level, and a part of the city of Barcelona, Spain, for the local level.