Litho-structural control, morphotectonics, and deep-seated gravitational deformations in the evolution of Alpine relief: A case study in the lower Susa Valley (Italian Western Alps)

An integrated study of Quaternary geology and geomorphology, structural geology, and morphotectonic lineament analysis has been performed for the Lower Susa Valley in order to evaluate the relationships between neotectonics of the central-internal side of the Italian Western Alps and the morphodynamics of the mountain relief. A regional NNE–SSW fault system, the Colle delle Finestre Fault Zone (CFFZ), separates two sectors, the Middle and the Lower Susa Valleys, characterized by different fault patterns. ENE–WSW regional faults represent the main brittle structures in the Middle Susa Valley, while E–W faults prevail in the Lower Susa Valley. Geomorphic anomalies, Plio-Quaternary deformed deposits and distribution of glacial deposits suggest differential uplift of fault-bounded sectors. Distribution of deep-seated gravitational-slope deformations and landslides depends on lithological and structural controls, suggesting a close relationship between post-glacial morphodynamic evolution and Quaternary fault activity. This activity is also indicated by instrumental data and historical earthquakes (Ms ranging from 4 to 5) that struck the Lower Susa Valley.