Artificial cavities under worship places: case studies from the province of Caserta (Italy).

In northern Campania (Southern Italy), the historic center of many towns is characterized by the widespread presence of cavities in the subsoil, excavated over the centuries for quarrying tuff blocks for buildings, along with cathedrals, churches and chapels. A singular feature of these places of worship is, in fact, the presence of a wide and frequently connected network of underground cavities and tunnels, which were used for hydraulic, religious or connecting purposes. Very often the above cavity network is unknown, abandoned or even buried, thus representing a risk for their susceptibility to sinkholes. Such elements are important as cultural heritage of inestimable value and, then, as attractors for tourism; for this reason the multidisciplinary study conducted on two places of worship in the Caserta area is illustrated herein: the Cloister of Sant’Agostino, in Caserta (XVI century CE), and the Monumental Complex of San Francesco delle Monache, in Aversa (XIII century CE). A geological characterization of the subsoil was performed at first. A laser scanner survey of the accessible cavities and the external churchyard was carried out. The resulting 3D model of the underground sector allowed a clear understanding of the room size, their location, the levels and the path of the corridors. In order to understand the extension and layout of the crypts, Electrical Resistivity Tomography (ERT) surveys were undertaken in the surrounding areas. The analysis of the ERT measurements revealed some anomalies that could be ascribed to unknown structures (crypts). The results allowed us to improve the knowledge of the study sites and provide useful tools for the planning of future targeted investigations, providing indispensable support both in the management and mitigation of geological risks in urban areas and in the sustainable reuse of hypogea.