An integrated analysis of data coming from completely different scientific sectors and concerning the area of Palermo's historic centre is introduced, implemented by using a GIS application developed on a data_model oriented to issues of urban geology. GIS technology has been an effective tool in daborating a reliable litostratigraphic database, the starting line for any valuation of the local seismic response. Palermo's historic centre has been divided using an applied grid characterized by square module geometry, each of which has a spread of 100m per side. The analysis of the litostratigraphic data, facilitated by the GIS, has allowed us to establish the trend of the most important factors controlling the seismic hazard in the area. For many grid elements we have defined the characterising lithoteenical succession model, the average thickness of soils characterized by poor geomechanical characteristics and the average well depth. The seismic response map constructed by Guidoboni and Mariotti on the grounds of the cumulative effects caused of the three most damaging earthquakes felt in the Palermo area over the last three centuries has been compared with the map reporting the trend of the evaluated hazard factors. The agreement has been quite remarkable. The grid elements exhibiting higher level damages are characterized by the worst conditions of the seismic hazard factors examined. Only a very small number of grid elements is characterized by damage that appears to be anomalous on the grounds of local geology. This anomalous damage may be result of many other factors, first and foremost an higher vulnerability of the buildings. The presented case_study shows that research and applications based on data crossing can be simplified and thus enhanced using GIS technology.
