Mass movements related to tectonics in the Aspromonte massif (southern Italy)

Geomorphic and structural studies have been carried out on the headwaters of Vallone Colella Torrent, in an area intensely affected by mass-movement phenomena on the Aspromonte massif of southern Italy. Rock types outcropping in the area are mostly gneiss and granitoids, with subordinate presence of metarenites, phyllites, and biotite schists; all lithologies experienced low-grade metamorphism, as indicated by petrographic analysis. Structural surveys, performed at macroscopic and mesoscopic scale, allowed recognition of several sets of discontinuities related to different deformation events. The upper reaches of Vallone Colella Torrent present a large, active landslide zone, the debris materials of which feed the debris flows along the drainage system towards the main valley. Mass-movement phenomena are both shallow and deep-seated; the latter are limited to a sector of the study area, while shallow processes are present throughout the landslide zone. Some considerations of the relationship between tectonics and mass movement are presented, with particular reference to the presence of a large-scale downthrown wedge (bounded by structural surfaces on both sides of the valley), located in the same area affected by deep-seated phenomena.