Val Venosta (Vinschgau) 2010

The landslide occurred in Val Venosta/Vinschgau Valley (Province of Bolzano, South Tyrol, Northern Italy) on the 12th of April 2010, aroun 9:03 in the morning. The event affected a natural slope that was formed as the result of the erosion produced by the flow of the Adige River on the cone of an alluvial deposit, an area of about 200 m2 in the central part of a hillside with average inclination of approximately 36° and length of 65 m. The slip surface (approximate length 20 m, width from 8 to 12 m) was located about 1.0 m below the slope profile, in the uppermost layers of a predominantly coarse, well-graded soil (see photo). The event was triggered by an accidental and extraordinary infiltration of water from a malfunctioning component of an irrigation system located on the uphill almost flat area (see plan). Although the slope appeared to be uniformly covered with vegetation, the landslide apparently occurred in an area where there were no trees. After the occurrence of the event, a number of activities were performed to characterize the area (before this report authors’ involvement). Samples collected from the slope near the slip surface show the different composition of the soil cover (30% silt, 35% sand, 30% gravel, Plasticity Index Ip = 2–6%) from the lower alluvial deposit (15% silt, 20% sand, 65% gravel and cobbles). Although the landslide dimensions were small, its consequences were catastrophic because it caused the loss of nine lives and the injury of 28 people, and it significantly damaged the local railway infrastructure.