Applying geophysical techniques to investigate a segment of a creeping fault in the urban area of San Gregorio di Catania, southern flank of Mt. Etna (Sicily — Italy)

In an especially built-up area, such as the lower slopes of Etna volcano, the effects of surface faulting, caused bycoseismic ruptures and aseismic creep, contribute significantly to increase the risk to towns and villages and theirrelated infrastructure. This study aims to couple the geophysical and structural characteristics of an active faultzone, joining surficial and deep information, in the area of San Gregorio di Catania (Sicily—Italy). The occurrenceof this structure and its associated fracture field were related to variations in the physical and mechanical propertiesof the hosting rocks. Surface structural survey detected a fracture zone with maximumwidth of 40 m, characterizedwith fractures oriented consistently with the kinematics of the fault. The geophysical surveys (groundpenetrating radar, seismic tomography, and refraction microtremor), enabled to detect highly fractured rock volumesat variable depth whose occurrence has been linked to the presence of the fault at surface. The integrationof various techniques, with different spatial resolution and depth range, allowed to fully reconstruct the 3Dgeological structure of the site down to about 15 m.