## 2 The Valle d'Aosta Region, Northern Italy
### Mass Movement in the Valle d'Aosta Region  
The slopes of VDA are characterized by high density of mass movements, which can be synthetically grouped in glaciers, rock glaciers, and landslides. These phenomena are mainly related to the long- and short-term evolution of glacial, periglacial, and paraglacial processes [63; 64]. Glaciers nowadays occupy as much as 5% of the regional territory, which represent one-third of the Italian glaciers [65]. The rate of ground deformation vary significantly passing from glacier flows, which is characterized by rates of tens to hundreds of meters per year, to permafrost creep, in order of cm to m per year [63; 66; 67]. The alpine permafrost has a very variable and fragmented distribution, showing creep deformation depending on permafrost temperature [68]. Rock glaciers (RGs), i.e., periglacial landforms common in high alpine environments, occupy about 2% of the VDA territory [69; 70]. RGs are defined as lobate to tongue-shaped structure of frozen rock debris, with steep front and side slopes, interstitial ice cement, ice lenses, a core of massive ice, or a combination thereof. These ice-rocky structures may creep depending on the mountain permafrost condition. Due to the ice content, the RGs are classified as active, inactive, or relict [70; 71; 72]. Active RGs have higher ice content and move downslope with velocities ranging from several cm/year to several m/year [73]. Inactive RGs contain some ice, but do not move. Finally, relict RGs present a front slope less steep gradient and are frequently covered by vegetation, do not contain ice, and do not move. In VDA, 937 rock glaciers were identified, and most of them (56%) were classified as relict [74; 75; 76]. The intact RGs are located at a higher altitude, presenting a lower limit variable from 2126 m and 3150 m a.s.l., and a prevalently northeast-to-northwest exposure. The relict RGs are located not below 1600 m a.s.l. altitude, and reach on average at the upper limit of 2700 m a.s.l., presenting variable exposure.  
Another important gravitational process that affects 18% of the VDA territory [77; 78] are landslides. These phenomena vary in size and typology, from shallow landslides (soil slips, planar, and rotational sliding) to large slope instabilities. In the VDA region, deep-seated gravitational slope deformations (DsGSDs) affect at least 13.5% of the regional territory [77], for a total of 280 phenomena inventoried. These large slope instabilities are widespread phenomena in mountain areas of the entire European Alps [11; 79] and represent a large mass movement of an entire high-relief flank valley [80]. Their evolution is controlled by the interaction of different factors: lithology, geology, climate weathering, seismicity, and deglaciation [11]. In most cases, DsGSDs are located in initially glacial valleys and related to Lateglacial trigger [80]; for these phenomena, the major cause of instability is ascribed to glacial debuttressing. These phenomena generally present very slow-slow deformation rates, variable from a few millimeters per year to a maximum of a few centimeters per year in uncommon cases [81].