A simplified methodology to assess seismic risk at district and building level

During the last fifty years, Italy has to face relevant damages to its architectural and artistic heritage caused by several seismic events. This has generated a strong debate about the need of preventing, where possible, the consequence of the seismic activity by evaluating exposure and vulnerability of urban contexts and raising public awareness about this issue. To this end, this paper present a method to evaluate the seismic risk and propose solutions to reduce it. The method is tested at two interrelated levels: building and district. The method is tested on a portion of the historical center of the city of Catania (Italy), an exemplar case study urban context characterized by an extreme high level of vulnerability and exposure. The seismic risk was studied starting by results obtained by previous international projects that were further locally refined to evaluate the parameters of hazard, vulnerability and exposure of risk. The hazard was estimated by modifying the microzonation studies already developed in the study area. The method of evaluation of vulnerability was based on an index related to the building’s characteristics and distinguished between masonry and r.c. buildings. The exposure was quantitatively evaluated by the number of people living or working in the study area and considering the uses, strategic functions and cultural value of the buildings. All the analysis were integrated in a GIS model, by using the single building of as the geographical unit for the evaluation of the three parameters. Results allowed to define different risk scenarios for the studied area, coherently with the high seismicity of the city. These scenarios were the starting points for the definition of projects for the reduction of the risk at district and building scale and long-term urban seismic regeneration