‘Mungibeddu’ (‘the mountain’ in the Sicilian dialect) has impressive credentials. It is a candidate to join UNESCO‘s World Heritage list, and was designated as a ‘Decade Volcano’ by the International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI) – one of 16 volcanoes deemed worthy of particular study in light of their history of large, destructive eruptions and proximity to populated areas. It is the biggest and tallest active volcano in Europe, measuring more than 3,300m in height – and it is one of the most active volcanoes in the world, with almost continuous eruptions from its summit craters and frequent lava flows from fissures which open on its flanks. In addition, Parco dell’Etna was the first nature park to be instituted in Sicily, back in March 1987.
Etna, like Vesuvius and Krakatoa, is a stratovolcano, characterised by a conical shape with steep sides, created by several layers of solidified lava, ash and pumice. The magma in a stratovolcano has a medium to high content of silica which makes it more viscous than an iron-rich magma. As a consequence, the lava covers a shorter distance before solidifying, hence the steep conical shape. The exact height of Etna changes following each eruption.
Harbouring silica-rich magma in your magma chamber can be catastrophic. Stratovolcanoes periodically experience explosive eruptions: trapped gases, unable to escape to the surface, build up inside the thick magma. If the blockage or some other part of the volcanic mountain suddenly gives way, the pressure is released quickly with an explosion of searing gas and a rain of extremely hot large boulders or volcanic bombs and finer ash in the form of pyroclastic flow. A tell-tale sign of such occurrences in the rock record is the presence of graded bedding, with larger rocks at the bottom and smaller rocks, ash and dust towards the top, as well as pumice stones.
A Brief History of Etna
Etna started its life as an underwater volcano during the Quaternary era, about 600,000 years ago. The area lies above the convergent margin between the African and the Eurasian plates which causes the presence of other volcanoes – nearby in the volcanic Aeolian Islands, for example – as well as devastating earthquakes. The earthquake of the nearby towns of Messina and Reggio on 28 December 1908 is considered one of the worst natural disasters of the twentieth century and the biggest ever recorded in Europe, based on number of victims. But eruptions have been recorded throughout human history, with the Roman poet Virgil writing what was probably a first-hand description of an eruption of Etna in The Aeneid about 20 BC.
Etna has experienced a variety of eruption styles and for some time has extruded basaltic (iron-rich) as well as silica-rich lava. Since the 1970s more explosive eruptions have been observed, especially from the four craters at the summit: ‘paroxysms’ which included lava fountains and gas and ash columns. Eruptions can also occur from the craters along the side of the volcano, all the way down to a few hundred metres above sea level. The summit craters have been generally active continuously for many years, while the side craters have periodic interruptions in activity, although in the last forty years these have only lasted two years on average.
The longest eruption of the twentieth century, lasting 473 days, started in December 1991 and spurred the inhabitants into quick action, with diggers working round the clock to create an earth barrier 20m high to protect the town of Zafferana Etnea. It worked, but in 2001 this technique was not sufficient to keep the lava flow away from inhabited areas. On that occasion the Italian navy had to use 7 tonnes of plastic explosive (C4) inside the main canal.
Agriculture on Etna
So, who on earth would want to live near such a dangerous ‘beast’, above such an unstable spot on our planet? As a matter of fact 25% of the total population of the island of Sicily does! Catania, the 10th biggest town in Italy, is situated just a (pumice) stone’s throw from Etna’s craters and it has been periodically destroyed by it. You might think that the fatalistic attitude of Sicilians has made them particularly resigned to live under the shadow of an active volcano. But in fact it was the fertile soil that attracted their ancestors to live there.
When volcanic rock breaks down and releases its precious minerals, a rich volcanic soil is created. Vineyards, olive, pistachio and hazelnut tree groves and orchards of local varieties of apples are still being lovingly tended along the slopes of Etna. Particular attention is devoted to organic agriculture and the conservation of rare varieties of apples, to preserve biodiversity.
The importance of agriculture and the human influence on the landscape of the volcano, with all the richness of tradition and culture, has been acknowledged by the Ente Parco dell’ Etna, which manages the nature park. While in the area designated as Zone A no human settlements are allowed, Zone B is made of smallholdings, with beautiful old farm houses, terraces storehouses, millstones, and wine-processing structures, as well as the old landlords’ villas. Zone C and D are different still, mostly devoted to tourist facilities
Special Flora and Fauna
As you can imagine, living on a volcano can be an unsettling experience for a plant: as well as the harshness of the weather and the lack of water, at higher altitudes at least you also have to factor in periodic lava flows which could burn down entire forests. At lower altitudes we can find oak forests as well as the orchards of hazelnuts, apples and sweet chestnuts. From over 2,000m above sea level we find beeches, reaching here their southernmost distribution limit, and a very special tree – the Betula aetnensis (Rafin.). This is a rare relict species, endemic to Etna. This species of Betula has had to adapt its vascular system in order to survive extreme heat and cold, and it is only found on the east and west slopes of Mount Etna, between 1,300 and 2,100m, where other trees cannot survive. Higher still we will find astragalus, senecio, violets and cerastium and pioneer plants. Beyond the limit of the astragalus, between 2,450 and 3,000m, the conditions are so harsh and the rock so new that no vascular plants are to be found.
Although wolves, wild boars and deer have long disappeared from Etna, we can still find porcupines, foxes, wild cats, martens, rabbits and hares, together with weasels, hedgehogs, dormice and several species of mice and bats. As well as many insects, snakes and birds of prey are common: the poisonous viper has increased in numbers in recent years due to the fall in the numbers of its predators. Among the diurnal birds of prey we can count sparrow-hawks, buzzards, kestrels, peregrines, and the golden eagle. Nocturnal birds of prey include the Barn Owl, the Scops Owl, the Tawny Owl, and the Long-eared Owl. Jays, rock pigeons, and the rock partridge have also been sighted, as well as many song birds – warblers, tits, cuckoo, and many others. A special mention goes to the wheatear, which can be seen flying its irregular flying style around the lava fields.
Waking the Volcano!
Etna is one of the most accessible active volcanoes in the world, so much so that even a young family can visit it. During our trip to Mount Etna in spring 2010, our youngest daughter, then aged five, asked us with a certain amount of apprehension if the volcano could erupt. We told her that the volcano was ‘asleep’ (in Italian, ‘dorme’, meaning sleeps, sounds very much like the English ‘dormant’) although strictly speaking that was not true. All through the trip she whispered and told us off if we raised our voice – in case we woke up the sleeping volcano!
A few days later our trip came to an end, but we found we could not fly back home: nothing less than an enormous cloud of volcanic ash had enveloped Europe and paralysed air traffic. It was no use trying to explain to our youngest daughter that the volcano which had caused the airport chaos was not Etna but the unpronounceable Eyjafjallajökull, many miles further north, in Iceland. All she knew was that she had told us to be quiet, we had ignored her advice and we had woken up the volcano!