An integrated approach to investigate slope instability affecting infrastructures

This article focuses on an area located at the northern border of the Monte Poro plateau along the Tyrrhenian coast of Calabria (southern Italy). The area is characterized by weathered gneissic rocks involved in widespread landslides. This research employed an integrated approach concerning the relationships between the geological and geomorphological setting and landslides triggered during the construction of a road. The data were obtained by geological, geomorphological, structural, and geomechanical field surveys, coupled with a geomorphological analysis carried out through a combination of aerial photographs, satellite images, and digital elevation models (DEMs). Rock mass classifications of the weathered gneissic materials were applied to evaluate the quality of the rock masses and to define the potential stability conditions of the slopes. Furthermore, a DEMs analysis of pre- and post-road construction was also performed to define a detailed evolution of the instability conditions affecting the studied escarpment. A total of 32 landslides were recognized before the road construction, while 27 landslides were collected after the road construction. Rotations are the most frequent type of mass movements and involved the more weathered rocks or eluvial/colluvial deposits. Complex landslides are less widespread than the previous ones involving different weathering grades. The results showed that the roadworks had a great impact on the geomorphological scenario in terms of landslide trigger in an area already characterized by a high landslide susceptibility. The approach used can provide a reliable tool to evaluate the hazard conditions in other regions with similar geological features.