Tectonic control on the morfology of the northeastern lower slope of Mount Etna Volcano (Sicily) Controllo tettonico sulla morfologia del basso versante nord-orientale dell'Etna (Sicilia)

Mount Etna lies in a structurally highly complex setting, close to the boundary between the Malta-Hyblean Platform and the Ionian Basin and at the intersection of the Malta Escarpment and the Messina-Giardini fault zone. Thus, volcanism and tectonics at Etna are clearly interacting and exerting a strong control on morphology. The studied area is located on the lower eastern slope of Mount Etna between Capo Schisò and Macchia Stream mouth. The study consisted of stereopairs and cartographic analyses supported by geological and geomorphological surveys. We recognize the System of Faults Giardini - Mascali (draws southern of the Messina - Fiumefreddo System), which intersects the low north-eastern slope of the volcanic building of Mount Etna. It is an active fault systems NE-SW and NNE-SSW trending, bounding horsts and grabens which influence river courses and submarine delta deposition. In particular, we analyse the course of Alcantara river, which is deviated from its original NW-SE trend to a NNE-SSW one along a graben. The graben is later filled with lava flow and subsequently the lava fill eroded for rejuvenation of the river due to the uplift of the area. Has been hypothesized a succession of tectonic events in the area of the mouths of the Alcantara River that has brought to the actual geomorfological framework. From the analysis of earthquakes catalogues, a complete lack of historical seismic events attributable to the activity of the System of Faults Giardini - Mascali is underlined; the attributable seismic events to this system are those related to the reactivation in 1795 December and in 1847 March of the mud volcano known with the name "Salsa di Fondachello" and to the sinking of the same one, happened in 1847 April. CH4 uprising gas activity is located along a fault with associated seismicity.