The underground cavity network of south-eastern Rome (Italy): an evolutionary geological model oriented to hazard assessment

There are many abandoned underground mines beneath the city of Rome, created in the Pleistocene pyroclastic deposits over thousands of years. These pose a serious public safety risk hence the study was undertaken to better assess the stability of the underground workings. The Villa de Sanctis public park was selected as a suitable test site, as in this area the cavity network can be inspected and the different steps of the progressive migration of voids toward the surface can be identified. In addition to an underground geological survey, geophysical investigations were undertaken to elucidate some key characteristics of the involved lithological units, including elastic stiffness and layer thickness. Recommendations are made for further studies of the accessible and inaccessible areas.