Regional inventory of DSGSDs in the Molise region (Central Apennines, Italy): influence of predisposing factors and river incision on the process onset

At the mountain scale, the onset and evolution of Deep-Seated Gravitational Slope Deformations (DSGSDs) are strictly related to different control factors, such as the geological-geomorphological setting of the slope and the relief dynamics. Furthermore, as time-dependent phenomena, DSGSDs are significantly related to the timing of landscape evolution and inherited tectonic deformation histories. In mountain areas that experienced glaciation-deglaciation cycles, during the glacial retreat, slope debuttressing, glacial rebound, stress redistribution, and changes in slope hydrology, as well as rock jointing favor the formations of DSGSDs and rock collapses. Within unglaciated mountain areas, the combined effects of tectonics, river incision, and hillslope processes are recognized to generate highrelief and deep-incised river valleys, such as narrow gorges and canyons, that allow the kinetic release for large portions of slopes. To deepen this topic, i.e., to better constrain the role of predisposing factors (inherited geological and morpho-structural settings) and preparatory conditions (long-term morphoevolutionary frame), in the frame of an hazard-oriented research project an original DSGSDs inventory was completed for the entire Molise region (Central Apennines, Italy), as it is highly representative of geological/structural conditions widespread in the whole central Apennines. DSGSD phenomena were mapped by means of a combination of aerial and satellite images interpretation, geomorphometric analyses, and field surveys. The study was integrated through InSAR analyses and allowed to determine the main characteristics of DSGSD phenomena. River longitudinal profile analysis, aimed at identifying the position and spatial distribution of the knickpoints, was also performed, integrated by the identification, through an automatic extraction from DEM, of the remnants of fluvial relict surfaces hanging at different heights above the valley bottoms. The latter can be considered as geomorphic markers of the river valley evolution, consequently, are useful to recognize the local and/or regional ancient base levels of erosion. Knickpoints and geomorphic markers were then compared with the DSGSDs elevations and spatial distribution to provide a relative chronology of the deformational process initiation. By means of these analyses it was possible to establish a general correlation between the analyzed deformations and some conditioning factors, such as geological, geomorphological, structural, and geodynamic setting of the region.