Deep Seated Gravitational Slope Deformations geomorphometry. The case of Schlinig valley (Eastern Alps)

The Alpine regions are widely affected by slope instability, determined by various interactions between climate and local geological framework. Our research focuses on Deep Seated Gravitational Slope Deformations (DSGSDs), which are large mass movements with low rates of displacement (some mm/years) and involving wide portions of hillslopes with medium to high-relief slopes energy (> 500 m). They may occur on all rock types although are more common on highly foliated metamorphic lithologies. Although DSGSDs are characterized by specific landforms, the most distinctive ones being double ridges, scarps, counterscarps, trenches, these morphostructures can be classified in between landslides and tectonic landforms. In addition, depending on their stage of evolution and typology, DSGSDs can be masked by weathering and superficial erosion processes and the typical bulging at the hillslope foot of large mass movements can be not always present. For these reasons ready methodologies to unravel morphostructures related to DSGSDs are important and needed. Thus, we present procedures based on the calculation of morphometric indices from LiDAR-DEM, with the aim to improve the DSGSDs geomorphological identification and mapping. Our work has been focused on the Schlinig valley (Eastern Alps, South Tyrol) because it is affected by numerous DSGSDs types, evolving on various lithologies, which are in tectonic contact along a major alpine fault (Schlinig fault). In particular, the orthogneiss of the Scharl nappe crop out in the right side of the valley, whereas in the left-hand slope the Permo-Mesozoic cover of the same nappe are overlaid by the Ötztal paragneisses.