Last 100 ka tephrostratigraphic record of Mount Etna

Abstract

The tephro- and chrono-stratigraphic synthesis of Etna pyroclastic deposits of the last 100 ka is presented here. Deposits correlation over the whole volcanic edifice allows the reconstruction of a continuous pyroclastic succession from about 100 ka to the Present. Tephra layers are composed of scoria or pumice lapilli and ash, representing pyroclastic fall or flow deposits interbedded with continental volcanogenic sedimentary deposits. They are grouped into five stratigraphic units corresponding to main periods of explosive activity. On the basis of the tephro- and chrono-stratigraphic data they are: (A) about 100 ka basaltic strombolian activity; (B) 80-100 ka benmoreitic plinian eruption that ends the activity of the Trifoglietto volcano; (C) 16-80 ka strombolian to subplinian eruptions, basaltic to mugearitic in composition, of the post-Trifoglietto (Giannicola, Salifizio and Cuvigghiuni and Ellittico) volcanoes; (D) 15-15.5 ka benmoreitic-trachitic caldera-forming plinian eruptions that end the activity of the Ellittico volcano; and (E) the last 12 ka basaltic subplinian eruptions and the 122 BC plinian eruption of the Mongibello volcano. The tephrostratigraphic reconstruction indicates that the explosive activity presented different features during the history of Etna. Eruptive styles cover a range from strombolian to plinian, producing some marker beds that have a great importance in the new geological reconstruction of Etna. High volatile content of Etna magmas seems to be the key factor for the origin of this strong explosive activity. The characterization of Etna explosive activity has given this kind of activity a new relevance and important implications for the volcanic hazard assessment at Etna, a volcano commonly considered, before these studies, just effusive.