The role of historical-archaeological sources integrated into the GIS environment with geological and geophysical data in the mitigation of geological risks in some urban areas

Numerous geological risks characterise urban areas, one of the most undervalued of which is the sinkhole risk connected to underground cavities. In the Lazio Region, the subsoil of many beautiful art cities like Rieti and Viterbo is rich in underground cavities, mainly anthropogenic because of their thousand-year history and the geological substrate’s peculiar characteristics. These cavities have very different ages and types, the oldest dates back to the Etruscan and Archaic times. However, their excavation continued uninterrupted during the Roman and Medieval times until the Second World War, when many were readapted as bomb shelters. An interdisciplinary approach that combines geological and geotechnical aspects integrated by geophysics with historical and archaeological data in a GIS project can allow an efficient census of these cavities, defining not only their morphology and their functions but also hypothesising their continuation in unexplored or collapsed traits. Such a census is indispensable to estimate and, therefore, mitigate the sinkhole’s risk and better define risk, including the seismic response of a subsoil articulated and altered by many levels of underground cavities.