Rock Fall Characterization in Climbing Spots: The Case Study of the “Napoleonica” Tourist Route (Trieste, NE Italy)

In NE Italy, fast-moving landslides represent a significant threat both to the population and the built environment. In the eastern portion of the Italian Alps, rock falls are common and are often responsible for casualties or severe damage to infrastructure. This type of landslide is characterized by strong relief energy and is triggered by earthquakes or copious rainfall, which often exceeds 2000 mm/yr. To assess rock fall hazard using software analysis, field surveys are crucial to accurately recognize the source areas of falling rock phenomena, to quantify the volumes of unstable blocks and identify the possible block trajectories. The current work takes in detailed geological and geomorphological mapping, through the identification of dislodged blocks, fractures and fallen blocks on a much-frequented limestone cliff in the Trieste Karst used as a climbing spot. Moreover, a popular tourist path (the Napoleonica) lies at the foot of the climbing cliffs. In-depth traditional activities, such as field surveys and aerial photo analysis were undertaken, including morphometric and geomechanical characterization of the whole rock mass, in order to perform a first identification of the more hazardous sections of the Napoleonica. The field data were collected using UAV (Unmanned Aircraft Vehicle) images and videos and this innovative technique allow the reaching and study of difficult sites with excellent resolution and precision. The final output is a GIS-developed map, that will be the starting point for future 2D and 3D simulations, that will lead to the creation of a rock fall susceptibility evaluation of the whole area.