Results and applications of two seismic risk assessment projects recently carried out in Italy are presented. One project addressed Catania city, in Sicily, and dealt with the problem of a densely urbanized area with high seismic hazard and high risk exposure. The second focused on the damage assessment of monuments and historical buildings in the small historical centers located in Western Liguria (NW Italy). Both projects made use of the same nation-wide source of data on residential buildings and population, and adopted the same recent methods for earthquake damage and loss assessment.

The seismic risk scenario studies on Catania initiated in 1996, with a 3-year national project funded by the Civil Protection Agency and the National Group for the Defence against Earthquakes (GNDT). Subsequently, from 2000 to 2004 the seismic risk of the city was further investigated in the framework of the EC project RISK-UE. In the latter, an improved and updated assessment approach was used that, owing to its modular features, could be applied to cities with widely different urban and seismic hazard contexts. Such variety was well represented by the other European cities participating in the project in addition to Catania, i.e. Barcelona, Bitola, Bucharest, Nice, Sofia and Thessaloniki.

Catania, with an overall urban area gathering some 500.000 inhabitants, is among the cities in Italy with the highest exposure to natural hazards (earthquakes and volcanic eruptions): its history tells that the city has been destroyed or very heavily damaged twice by large earthquakes in the last millennium. On the other hand, one should keep in mind that the city built environment is characterised by unrecorded post-earthquake repairs and modifications over some 200 years, unfavorable foundation conditions at some places (old debris and artificial fills), a peculiar historical centre and a large post-war expansion. The vulnerability of residential buildings was assessed using the data of the National Institute of Statistics (ISTAT,1999), greatly strengthened by additional data gathered in a more detailed city census (LSU survey). The ground shaking hazard has been estimated according to a deterministic scenario for a M7.2 earthquake occurring offshore, on the Malta Escarpment fault system, at 12 – 15 km from the city.

Results such as earthquake ground shaking levels, expected damage distribution for residential buildings, as well as distribution of the number of victims and shelters, have been disseminated in the form of GIS-generated digital maps.

Even though the interest and degree of involvement by local administrators in the project was increasing during the project, due to detailed level of the scenario analyses and the nature of the results, there were difficulties in transferring smoothly this kind of information into urban emergency plans. Efforts have been devoted to usefully re-focus some damage prediction studies onto objectives meeting more directly the practical needs of city officials, such as the evaluation of vulnerability for hospitals and schools, the assessment of probable road obstructions due to debris of collapsed buildings, the estimation of seismically hazardous gas pipeline systems, etc. A policy of close co-operation was steadily pursued, trying as much as possible to provide solutions meeting the city representatives’ requests. For instance, the latter indicated a densely inhabited central section of the city, with a critical ratio between buildings elevation and width of the roads, and asked to identify the streets likely to be obstructed by the debris of collapsed or damaged buildings in case of a strong earthquake. In this section, in addition to evaluating the damage scenario for residential buildings, also the strategic facilities such as schools, hospitals, and city offices were considered, together with the lifeline networks and the emergency shelter areas.

Moreover, since the health-care system represents a strategic element in the management of post-earthquake emergency, an analysis was carried out to identify potentially seismically hazardous hospital structures, using the RVS (Rapid Visual Screening) procedure developed by FEMA.

Because of the increasing awareness of the city high exposure to seismic risk, and thanks to the special powers (and funds) entrusted by the Italian Prime Minister Office to the Mayor of Catania to mitigate the impact of post-earthquake emergency, important actions have been undertaken by the local administration to decrease future seismic risk. Such actions included (i) improvement of the urban transportation system and of critical structures for civil defence and emergency management, (ii) the construction and relocation of hospitals and (iii) the retrofitting of existing public and private buildings (through the national legislative Act 433/91).

As regards the second project, conducted at a different scale within a seismic risk project on Western Liguria (GNDT, 2000-2002), studies were been carried out mainly on historical centers, characterized by moderate level of seismic hazard, but higher level of building vulnerability. Working in GIS environment, results have been obtained at detailed level, even at census tract resolution for all the considered municipalities. A Web-GIS instrument presenting and summarizing these results (http://adic.diseg.unige.it/gndt-liguria/), is mainly addressed to administrators and civil protection operators, as well as to generic public. Indeed, the Web-GIS structure is designed with an aim at supporting decisions of administrators (land planning, resources investments, etc.), facilitating mitigation actions (priority interventions, post-emergency measures, etc) and informing a more generic public. For these features, the Web-GIS is actually used in developing a tool for real-time scenario generation, of interest for the Civil Protection Agency of Liguria Region.