What, with a hurried view, seems to be a unique and majestic volcanic building, in reality represents a very complex volcanic area. Mount Etna Volcano is, in fact, made up of numerous more or less extensive volcanic edifices which have been superposed in the course of time over an area of about 1.250 km, and with its 3.345 m. height, it represents the highest active volcano in Europe.
The first eruptive manifestations, the base lavas, submarine-type, occurred about 500.000 years ago, within a wide gulf. The filling up of this gulf, due to the superposition of the products of the numerous eruptions which happened in the course of time, and the gradual rise of this area of Eastern Sicily, permitted to the formation of volcanic edifices no more of submarine-type.
THE ANCIENT ERUPTIVE CENTRES
(168.000 – 100.000 years ago) were the first modest sub aerial volcanic edifices (Calanna, Trifoglietto I, Monte Po) of an essential effusive type. Subsequently, due to a change of tectonic conditions in the area, two impressive and prevalently explosive strata volcanoes formed, the Trifoglietto and the Mongibello.
(80.000 – 64.000 years ago), in the frame of which it is possible to count at least five secondary eruptive centres (Serra Giannicola Piccola, Trifoglietto II, Zoccolaro Vavalaci and Belvedere), ceased to be active some time ago and is now almost totally demolished. In the area where it arose, the eastern sides of Mt. Etna, a vast depression can now be found, called the Bove Valley. This valley, originated in the course of time from the coalescence of various caldera collapses, caused by different secondary eruptive centres at the end of their activity, and widened, thus, by the erosion, represents a morphological structure of great scientific interest.From the studies of the volcanic products outcropping on its rocks and high (at times over 1.000 m.) walls, it is possible, in fact, to reconstruct the evolution of the ancient Trifoglietto volcano. These studies have evidenced that the Trifoglietto eruptive centres were all of explosive-type (and therefore more dangerous than the present active volcano), and that during their activity they erupted enormous amounts of scoriae, lapillus and ash, which now can be found in the form of tuffs, mainly on the eastern flank of Mt. Etna. These intense and violent explosive activities and/or the emptying of the tank and of the supply fissures, were the causes of the main and numerous collapses of the summit part of the various volcanic edifices which occurred over the time, with the formation of more or less extended calderas. The volcanic material derived from the dismantling of the various eruptive centres, gave way to a long and extended alluvial deposit, locally called “Chiancone”, which can be found in the short eastern side of Etna.
(34.000 – 0 years ago), the products of which have been superposed on the north-western flank of the ancient Trifoglietto, is the current active volcano. Secondary eruptive centres have also been found on Mongibello, and in the course of its evolution it has been possible to distinguish two eruptive periods. The period of ancient Mongibello (34.000 – 8.000 years ago) is characterized by explosive-type eruptive centres (Ellittico and Leone) similar to those of Trifoglietto, whereas the period of recent Mongibello (8.000 – 0 years ago), on the contrary, is characterized almost exclusively by effusive-type centres (Vulcano del Piano and the present volcano), from which vast amounts of lava have been emitted. At the moment, recent Mongibello, (3.345 m. height), is the highest and most extensive active volcano in Europe and, in the last twenty years, has been one of the most active in the world. Actually on Etna there are four active craters: the Central Crater that is divided in Voragine and Bocca Nuova, the North-East Crater and the South-East Crater.