L. Cavarra and M.T. Pareschi (CSGSDA-CNR, v. S. Maria 53, I-56100 Pisa, Italy)

The Vesuvian area (near Naples, Italy) is potentially one of the most risky ones worldwide: some municipalities have a population density similar to that of Honk Kong, and the country is "dominated" by the Vesuvius volcano, quiescient today, but presenting, along its long history, ruinous explosive eruptions. In this context it is extremely useful to Civil Protection an "inventory" of the resources, that is a GIS of the area around Vesuvius. Here we present a GIS for the Vesuvian area containing digital information about elements having spatial connotations. The area concerns 18 municipalities, with a total extension of about 235 km2. The scale of the photo-restitution phase was 1:5,000. In the database each territorial datum (object) is defined by a set of georeferenced basic elements: points, lines, polylines, areal elements.
The territorial objects are organized according to different themes (layers), in turn enclosed in a smaller number of "families". For example the family "electricity" includes the layers electrical lines, pylons, stations, etc. The layers are more than a hundred and all the layers of a given family are displayed on the screen using the same colour. Each object of the data-base is described by alphanumeric information too (for example buildings are characterized by the seismic vulnerability and volcanic hazard, according to the place where it is located), which can be used to guide selective displays. The graphical representation of all the objects follows a dimensional criterion, according to which, only the parts of the object greater than a suitable dimension are represented. The hardware utilised is an IBM RISC6000 MODEL 540, 128 RAM Mb, internal HD 2Gb, 21" 24bit video, 1280x1024 resolution; the software is GEOMAX-XM.