Deep-seated gravitational slope deformations of Friuli Venezia Giulia Region (NE Italy)

Deep-seated Gravitational Slope Deformations (DGSDs) are common phenomena and are observed across various mountain belts worldwide. These phenomena are characterized by the presence of multiple landforms which are important for the recognition of the occurrence of DGSDs. The latter pose significant geological hazard due to their impact on society, economy and environment. They can affect vast areas, potentially endangering large sections of infrastructure, transportation routes, settlements and natural habitats. Furthermore, they cause collateral landslides that can evolve in catastrophic events.

In the past, a comprehensive inventory detailing DGSDs at the scale of the entire European Alps was compiled. This work shows a relatively limited DGSD population in Friuli Venezia Giulia, if compared to other mountain areas such as Central or Western Alps. The final objective of this study is to produce a detailed inventory of DGSDs that affect Alps of Friuli Venezia Giulia Region. Preliminary activities were aimed to desk activities such as analysis of historical documents, reports, aerial images and geomorphological interpretation of LiDAR-derived DTMs. We identified during preliminary activities several DGSDs and tens of possible gravity-induced landforms such as double ridges, ridge top depressions, uphill and downhill-facing scarps, trenches, toe bulges and persistent discontinuities. These gravity-induced features were validated by extensive field surveys carried out in 2023 and the beginning of 2024, also using HR images provided by low-altitude UAV surveys. DGSDs and their landforms were mapped and stored in a GIS.

DGSDs of Friuli Venezia Giulia Alps are favored by: (i) exceptionally high mean annual precipitation (ranging from 1400 to 3400 mm/y), (ii) the presence of several regional faults, (iii) the high-energy relief, (iv) the presence of different rock units (rigid materials and plastic terrains).