The history of Etna
The first activities of Mount Etna started around 600.000 years ago in the inferior Pleistocene.
The theories that confirm that the Etna was born as a result of the first stretching activity of the Mediterranean seabed, and is precisely the heightening of the Mount Etna the most impressive one.
The first phases of the volcanic activity did not occur on the earth’s atmosphere but beneath the sea giving place to different levels of tholeiitic basalt in the area between Adrano and Acitrezza.
Initially the magma came out from more than one place because the central crater did not exist yet. When, thanks to the different levels of lava emerges the outline of a structure that exceeds the sea level, the magma begins to form a conduct and changes the type of products due to the differentiation, for which the rocks that mark this transformation are richer in alkalis.
The volcanic activity is characterised by lava of low viscosity and therefore quite fluid and viscose lave, testify an explosive activity; today we are in a position to affirm that, thanks to the alternation of lava with tuffs.
Thanks to Gemellaro (illustrious volcanologist Catanese of 1800 by many considered the father of volcanology), Lyeel, Sartorius (by which name the craters have been named, as also for A. Rittman), and then subsequently von Waltershowsen and A. Rittman, were recognised two major eruptive centres: current edifice Mongibello (mountain par excellence), Trifoglietto current Valle del Bove were they were recognised within it other minor centres.
Let’s try to understand the most important phases that represent the evolution of the volcano.
After the first activities taking place beneath the sea off the coast line of Sicily and today testified by Acicastello, Lachea Island and Acitrezza, started the eruptive activity in continental atmosphere.
A classic example is “The Timpa of Acireale” that is a steep scarp (caused by a fault) formed by overlapping lava dating back to 200.000 years.
It represents the progressive evolution towards the current volcanic edifice of Monte Calanna towards North-West direction formed 120.000 years ago.
In the same period from other spots would flow a considerable quantity of lava, an example it is the Neck of Motta Sant’Anastasia (200.000 years ago). Still following the North direction, we find the centres of Rocca Capra dating back to 100.000 years ago, also one of the wrecks of the eruptions of the Valle del Bove.
Here 60.000 years ago started the formation of the Trifoglietto a major eruptive centre of which today we find the remains along the south wall of the Valle del Bove, it touched 2.500 metres above the sea level, after a period of stagnation the erosion began to dismantle the Trifoglietto, but two other volcanic structures succeeded Salifizio (South) and Serra Grande Giannicola (North), but these will be followed by a third volcanic structure the Cuvigghiuni whose craters were placed at 2.700 metres above the sea level.
As we can see reviewing any paper or map the eruptive axe moves towards the direction North-West.
34.000 years ago some lave flows from the last eruptive centres a dominant edifice starts building up with a height above 3.700 metres above the sea level, but due to a catastrophic eruptive event dated 15.000 years ago the new edifice collapsed and its height was reduced of around 800 metres.
So where before there was the majestic cone now there is a caldera formed by the collapse of the volcanic edifice and the rapid emptying of the magma chamber.
Today you can admire on the side placed most West (Pizzi Deneri, where currently there is the volcanological observatory CNR) the elliptical shape that he had taken before the collapse.
Inside the latter continued the volcanic activity giving rise to overlapping of volcanic material that formed the Mongibello.
Today, Mount Etna could be considered a “good” volcano characterised by an explosive activity in continuous evolution in the summit area, where we currently recognised four craters, Central, Bocca Nuova, Crater North-East and South-East that have lately needed our major attention; and other effusive activities at a lower heights with the opening of new craters. Central crater and South-East crater.