In the last two million years more than 10,000 volcanoes have been formed on the earth and more than 500 have had eruptions which have been spoken about throughout history.
The following millennium of magic rituals, sacrifices, prayers and offerings testify to the terror and also the deep respect that man has always had for these forces of nature. The volcano, in fact, has not only been an instrument of death and destruction, but also a source of energy and life.
Until recently volcanic eruptions were therefore considered as an unlucky destiny or connected to the wrath of local divinities.
But man easily forgets, so only a few decades of inactivity are enough for a volcano to be considered extinct. In reality the average life of a volcano is thousands of years, even pauses of hundreds of years are really ephemeral. Research into the field of vulcanology has developed over the last 70-80 years, even if the first attempts at a scientific approach date back to the end of the last century.
The efforts of the scientific community are concentrated on the possibility of reducing the ‘risk’ deriving from eruption and working on the evaluation of a ‘probability’ parameter connected to the knowledge of volcanic activity from all possible points of view.
The island of Vulcano today represents the only example in the world of an active volcano under constant monitoring. The necessity for such control is clear if we recall some of the most violent eruptions of our time: Mt. Pinatubo (the Philippines), Paracutin (Colombia), Unzen (Japan) and Mt. St. Helens (USA). These volcanoes have shown an explosive activity which, as has been ascertained, has had serious consequences compared to the effusion of Hawaiian volcanoes or, for example, Etna.
Volcanoes in Italy have a pre-eminently explosive activity and are found mostly in proximity to inhabited centres, factors which heighten the risk.
Volcanic surveillance has been going on for no longer than 20 years but the commitment of researchers has allowed a great amount of information to be obtained, regarding not only surface volcanic activity, but also underwater activity. The archipelago of the Eolian islands represents a rich and surprising area for volcanic activity under the surface of the sea.
Investigations have developed mainly in the waters of those islands in which the emanation of different types of gas has been noticed.
Particularly intense fumaroles on Vulcano with a ground temperature of 500°C, weak gas emanations on Lipari and Panarea and no sign of gas emanation on the other islands. The Eolian islands emerge from the sea to varying heights of a few hundred metres (Panarea) to about one thousand metres (Stromboli and Salina).
Considering the fact that these islands reach depths of 1500/2000 metres, scientists have been obliged to look for signs of volcanic activity on the submerged slopes, also by using equipment installed on oceanographic vessels. The results have allowed the discovery of underwater gas emanation even on those islands like Filicudi, Alicudi and Salina, where signs of gas emanation do not exist on land.
Gas emissions in front of Panarea are both suggestive and impressive: some of them have a flow of more than 200,000 litres a day of gas, composed essentially of a mixture of carbon dioxide, sulphur, methane and hydrogen and they are surrounded by enormous deposits of white sulphur.
The information supplied by fluid samples from the islands allows a glimpse of the existence of a still active thermal supply and with rather high temperatures. On the islands of Salina, Filicudi and Alicudi the presence of cooling magma residues seems more probable.
The research surrounding these gas emanations is still underway and is leading us to the discovery of a hidden world, which still has many secrets to reveal.