Anthropogenic tuff cavites in the southern metropolitan area of Caserta (southern Italy): hazard evaluation vs. Enhancement of the territory.

The Late Quaternary geological evolution of the northern Campania Plain (southern Italy) was affected by the volcanic activity of the Phlegrean Field. Among the volcanic events that have characterized this area, the ones that emplaced the Neapolitan Yellow Tuff (NYT) and the Campanian Grey Tuff (CGT) were the most important. Since the tuff has good mechanical properties, it was involved since historical times in an extensive mining activity, from which a very dense network of underground cavities was inherited, strongly related to the lithofacies distribution. The habit of man to excavate artificial cavities in the above area began long time ago and it is well known in Naples. In many urban centers north of Naples cavities have been reported as well in specific geological investigations, although their real extent is almost unknown. In these towns the underground mining activities were performed to extract tuffs for buildings. The urban development have sealed every signal of the presence of cavities, which thus represent a geological hazard and contribute to subsoil instability of many places. The present study is a first attempt in providing a geological underground database and a preliminary analysis of the hazard aspects related to the mining activities recognized in the metropolitan area of Caserta, north of Naples. First step of the investigation was the reconstrucion of the main geologic features of the study area based upon lithostratigraphic logs from boreholes, available from different sources. The marker key to correlate the different units was represented by the CGT deposits. A GIS project was then designed to manage a georeferenced cavity database and plot the cavity distribution on the numerical cartography. Where available, cavity plan views were collected and managed in GIS environment to outline the extent of hypogean distribution. The knowledge of such an hypogean system could be a useful contribution to the hazard evaluation in the considered densely urbanized area and will provide the local governments information for the civil protection and urban planning activities. All of these underground structures have the potential to be used in a manner that will contribute much more to the current culture of the towns (i.e. they could be used as concert halls, museums, galleries, exhibition areas, restaurants and touristic facilities). A further investigation concerning the physical status of the cavities is thus desirable in order to carry out monitoring on their conditions of stability and the state of deterioration, with the aim to combine and integrate preservation, management and protection of the underground cultural heritage.