A brief outline of Geography, Geology and Tectonics
Mount Etna is a majestic volcano located on the eastern side of the island of Sicily (37°44′00″ N 15°00′00″E) . Its height, over 3300 meters above the sea level, makes it the highest and widest subaerial volcano in continental Europe, the highest mountain of the mediterranean basin and also the most elevated italian peak south of the mountain range of the Alps.
It overlooks the Jonian sea on its eastern side, it is surrounded by the Simeto river to the western and the southern side and to the North by the Alcantara river.
This volcano covers an area of approximately 1600 km2 , it has a North-South diameter of about 35 km, a perimeter of about 200 km , a volume of about 500 km3 and is bordered to the North by the Nebrodi and Peloritani mountains and to the South by the highland of Iblei mountain.
Starting from the sea level all the way to the summit, the changes in terms of landscape and habitats are astonishing that together with the richness of its naturalistic peculiarities, make this place an unique geo-site and a paradise for hikers, photographers, naturalists, volcanologists and nature lovers. Eastern Sicily shows a great diversity of landscapes, but it also offers an incredible variety on the geological point of view.
Within a distance of only about 200 km , going through the provinces of Messina, Catania and Syracuse, there are two different tectonic plates, rocks of very different types from metamorphic to igneous and sedimentary ones, a subduction zone, many regional fault lines, Mt.Etna, the active volcanoes of the Eolian islands and the outcrops of an ancient volcanism in highland of the Iblei mountains.
Beneath Etna there is a thick and sedimentary substratum that reach the altitude of 1000 mt. above the sea level and therefore the thickness of the volcanic rocks accumulated in half million year is about 2000 mt.
The sedimentary rocks at the base of this volcano are argillaceous turbidite sequences from Miocene in the northern and western sides, whereas in the southern and eastern side there are Pleistocene clay-rich marine sediments.
This area, on the contrary that in the rest of Sicily, is rich of water because of the hydrogeology of this volcano. In fact the lava rocks are highly permeable and act as aquifers and they lay on the impermeable and non-porous sedimentary basement. We can visualize Etna like a huge spounge that absorbes the winter rains and the spring snow-melt. All this water travels through the body of the volcano and eventually comes out in springs, expecially close to the contact between the impermeable and permeable rocks.
Etna lies at the crossroad of major faults lines and within a complex geodynamic framework characterized by the presence of two converging tectonic plates. To the North there is the european plate, represented by the Nebrodi and Peloritani mountains, and to the South there is the african plate represented by the Hyblean plateau. Starting from about 50 million years ago, the two plates have converged, then they have collided and eventually the african one was subducted under the european one.
This movement, that keeps on happening at a rate of only few cm a year, in geological time has progressively reduced the size of the mediterranean from an open ocean to a closed sea, it has formed the mountain range of the Alps and the Appennini and it is also the engine of the volcanism and of the seismicity of the mediterranean basin.
Etna danger and charm
The area around mount Etna is therefore a dangerous part of the world with a high potentiality to have events such as lava flows, explosions, major earthquakes and even tsunamis. Despite all this dangers this land has been inhabited since many thousand of years and presently there is about a million people living around this volcano. Mt. Etna is a place where we can see nature working in a powerful, fast, irresistible and charming way.