Impact of massive deep-seated rock slope failures on mountain valley morphology in the northern Cottian Alps (NW Italy)

Abstract

Deep-seated rock slope failures represent effective mechanisms of natural rock mass-wasting, able to radically change mountain-valley morphology. In the northern Cottian Alps, an extraordinary concentration of instability phenomena occurs in extensive areas of the Susa and Chisone valleys. In the Main Map, at a scale of 1:30,000, a new representation of these deep-seated rock slope failures is proposed. Major effort has been invested in properly distinguishing between sackung-type deep-seated gravitational slope deformations and large landslides. Gravitational phenomena have affected the mountain landscape, with the development of impressive morphostructural features such as multiple-crested ridges and ridge top depressions. In the middle and distal portions of the slopes, sagging and toe bulging impose a marked change in the valley-slope profiles, in turn inducing secondary slope instabilities. Furthermore, mature deep-seated gravitational deformations and large landslides have, in some cases, made a significant impact on valley bottom morphology due to a partial or complete valley dam.

Geomorphology of the high-elevated flysch range – Mt. Babia Góra Massif (Western Carpathians)

“…In the British mountains the maximum area affected by RSF reach 10-20% in the selected massifs (Jarman, 2006;Jarman & Harrison, 2019). Conversely, in some valleys in the Italian Alps, extraordinary concentration rock mass-wasting could reach 38% of the area (Fioraso, 2017).…”

Structure from Motion Multisource Application for Landslide Characterization and Monitoring: The Champlas du Col Case Study, Sestriere, North-Western Italy

“…This huge phenomenon involves the metasedimentary successions of the Cerogne-Centiplagna unit, mainly constituted by heterogeneous calcschists. According to [52], the DsGSD movement corresponds to creep processes along discrete sliding surfaces, and along multiple listric surfaces. The movement rate, derived from high-resolution SAR images processing (i.e., COSMO-SkyMed (CSK) dataset from the WMS service of the GeoPortale Piemonte [53]) from 2011 to 2014, ranges from 20 to 35 mm/year along the LOS direction, for the area along the S.P.…”

“…Glacial deposits consist of Diamicton , poorly sorted unconsolidated sediment with clasts and blocky suspended in an abundant silty, silty-sandy matrix. Instead, the Cerogne-Ciantiplagna unit is part of a complex system of tectonostratigraphic units of different paleogeographic origin, forming the Pennidic system, bordered and/or crossed by important post-metamorphic fault systems that are variably oriented [52]. This unit consists primarily of monotonous sequences of calcschists with Epidote and micaceous marble including lenses of serpentinites and serpentionischists.…”

A mountain slope deformation in an alpine metaophiolitic massif (Ligurian Alps, Italy)

“…with slow movements) (i.e. Crosta, 1996;Crosta & Zanchi, 2000;Dikau et al, 1996;Dramis & Sorriso-Valvo, 1994;Fioraso, 2017).…”

“…Although mountain slope deformations are widespread and well-studied throughout the Italian western Alps (e.g. Fioraso, 2017;Mortara & Sorzana, 1987;Sanchez et al, 2010), scarce attention has been paid to its south-western segment facing the Ligurian sea (i.e. the Ligurian Alps; Figure 1).…”