A computer prototype has been developed that implements a methodology for seismic risk assessment. Standard procedural codes, geographic information systems (GIS) and artificial intelligence techniques compose the prototype. Permits 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 case of 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 serve better 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. Identifying various geographical levels of analysis is not a mere question of dimension; on the contrary entities to be studied correspond to areas defined by administrative and geographical borders. The prototype was applied in the following areas: Toscana in Italy, for the regional level, the Garfagnana area in Toscana, for the sub-regional level, and some areas in Barcelona, Spain, for the local level.
Elements and procedures to carry out a proper seismic risk assessment have been implemented in a computer architecture made of two main cores, a GIS (Arc/Info) and an expert system shell (Nexpert), connected by a bridge. A specific interface WESRE (Work Environment Seismic Risk Evaluation) has been designed for the prototype, to help end-users navigate among all the programs, codes and maps without having necessarily to know each one of them in detail. The whole system has been developed by the Neuron Data Inc Case, Elements Environment 2.0, using in particular the Open Interface module. All WESRE main code is in C language with the extensions supplied by the Neuron Data tool. The SERGISAI prototype is a new attempt, in the seismic domain field, to integrate tools, codes and methods for assessing the expected damage which have been originally developed separately one from the other.
