Lateral spreading phenomena and weathering processes from the Tropea area (Calabria, southern Italy)

This paper describes the lateral spreadinglandslides, the weathering processes and the hydrogeologicalrisk patterns of the NW sector of Monte Poro (Calabria,southern Italy), based on the development of amultidisciplinary research. The tectonic uplift of the areacombined with the litho-structural features of the sedimentarydeposits overlying the intensely weathered granitoidcomplex produces important gravitational phenomenacharacterized by lateral spreading kinematics. The contactbetween deposits with a different behaviour, together withthe high slope energy related to the tectonic uplift processes,is the main cause of widespread fracturing anddisjoint of the lithologies associated with lateral spreadingphenomena. These phenomena are also testified by thevarious trenches and cracks characterized by a parallelorientation relatively to the main fluvial incisions. Measuresof these deformations were obtained with a quantitativeresult by the use of ‘‘Interferometric Stacking’’methods. The experimental results confirm this morphologicalscenario characterized by strain values rangingbetween 20 and 25 mm/year relatively to the landslidesdetected. Geomorphological analysis of the drainage basinsin the study area indicates a juvenile stage of the streamnetworks. This pattern is consistent with the high rate oftectonic uplift of the area, hence the continuous rejuvenationof the stream networks and their low level of hierarchy.These conditions of geomorphic equilibrium of thestream networks, the widespread occurrence of geologicalinstability in continuous evolution, are the main causes ofhigh hydrogeological risk conditions for this coastal area.