Geological evolution of Etna volcano

New stratigraphic and structural data obtained during recent geological surveys have allowed us to subdivide the almost continuous evolution of Etnean volcanism into four main phases. The oldest phase (Basal Tholeiitic) corresponds to a long period of dispersed fissure-type volcanism with tholeiitic affinity, from about 580 up to 260 ka. This phase represents the northward extension of the Plio-Pleistocene Hyblean volcanism to the Etnean region. The second phase (Timpe) started about 220 ka when eruptive activity was mainly concentrated on the Ionian coast along the NNW-SSE oriented Timpe fault system. In this area the occurrence of fissure-type eruptions formed a small shield volcano and the passage between tholeiitic to alkaline volcanics occurred. The third phase (Valle del Bove Centers) is marked by a main westward shift of the feeding system in the Valle del Bove (VdB) area forming some nested volcanic centers. The earliest volcanic edifices recognized are Tarderia and Rocche. Afterward the volcanism was mainly concentrated on the southwestern side of the VdB with the formation of Trifoglietto volcano. Local shifting of the feeder caused the formation of three different volcanic centers: Giannicola, Salifizio and Cuvigghiuni. Finally, in the fourth phase (Stratovolcano) the definitive stabilization of the plumbing system led to the construction of the main stratovolcano, Ellittico, which forms the bulk of the present edifice. Four caldera-forming Plinian eruptions, occurring at about 15 ka, marked the end of Ellittico activity. During the Holocene, persistent basaltic volcanic activity formed the Mongibello volcano, whose products cover at least 85% of the Mount Etna area.