Volcanism of Italy

Thevolcanism of Italyis due chiefly to the presence, a short distance to the south, of the boundary between theEurasian Plateand theAfrican Plate.Italyis avolcanicallyactive country, containing the only active volcanoes inmainland Europe(while volcanic islands are also present inGreece, in thevolcanic arc of the southern Aegean). Thelavaerupted by Italy's volcanoes is thought to result from thesubductionand melting of one plate below another.
Three main clusters of volcanism exist: a line of volcanic centres running northwest along the central part of the Italian mainland (see:Campanian volcanic arc); a cluster northeast ofSicilyin theAeolian Islands; and a cluster southwest of Sicily around the island ofPantelleria, in theMediterranean'sStrait of Sicily.Sardiniahas had a totally separategeologicalhistory from that of the rest of Italy, where several cycles of volcanic activity occurred, the last of which ended at the beginning of thePleistocene, but currently hosts only permanently extinct volcanoes.
Due to their position within densely populated areas,EtnaandVesuviushave been included in the list of "Volcanoes of the Decade", a global list of volcanoes to be kept under closer surveillance.In particular, the "Volcanoes of the Decade" is a list drawn up byInternational Association of Volcanology and Chemistry of the Earth's Interior, as part of aUnited Nationsproject, which includes, overall, 16 volcanoes distributed all over the world.
Italy was thefirst country to exploit geothermal energy to produce electricity.The high geothermal gradient that forms part of the peninsula makes it potentially exploitable also in other regions; research carried out in the 1960s and 1970s identified potential geothermal fields inLazioandTuscany, as well as in most volcanic islands.
Four of Italy's volcanoes have erupted in the last one-hundred and fifty years:
At least 10 other volcanic centres have seen eruptions in historic times. In order of the most recent eruptions, they are:
In addition to the volcanoes on land, there are threesubmarine volcanoesin the seas surrounding Italy, in particular in the south-eastern Tyrrhenian and in the Strait of Sicily:
In Italy there is also a large number of geological structures due to extinct volcanic centres. It is possible to group these volcanoes into various categories:
The volcanic system ofSomma-Vesuviusis generally characterized byexplosive eruptions. The most widely-known is the onethat destroyedtheRomancities ofPompeii,Herculaneum,StabiaeandOplontisin 79 AD, causing thousands of victims. It is estimated that this eruption had aVolcanic Explosivity Index(VEI) equal to 5, and is considered the archetype ofPlinian eruptions, which are named afterPliny the Younger, an eyewitness of the event.
Scholars have discovered that previously Vesuvius had given rise to even more violent Plinian eruptions,the last of which was that of thepumice of Avellinoabout 3,900 BP (estimated to have a VEI of 6). After 79 AD there were no more plinian eruptions, but at most sub-plinian. The most important were that of 472 AD(whose ash reachedConstantinople) andthat of 1631, which killed thousands of people (due to pyroclastic flows and lahars),) and which was taken as a reference byProtezione Civilefor the drafting of evacuation plans in the event of future eruptions.Due to this eruptive history, and the very high population density in theMetropolitan City of Naples, Vesuvius is considered one of the most dangerous volcanoes in the world.
Unlike Vesuvius, the nearbyPhlegraean Fieldsare not made up of a single large volcanic edifice, but are a vast volcanic field within which numerous eruptive vents have opened, often different from eruptions.The only eruption in historical times, which generatedMonte NuovoandLake Avernus, was of low intensity, and was preceded by a period of quiescence that lasted more than 3,000 years (before which there was a long sequence of close eruptions).However, the Phlegraean Fields are capable of producing violent eruptions, which earned them the title ofsupervolcano.
The most famous was that of theCampanian Ignimbrite eruption, which occurred about 40,000 BP, considered the most severe ever to occur in the Mediterranean area, having a VEI equal to 7, and which probably had effects on the climate worldwide.Only slightly less intense was that of the Neapolitan yellow tuff, which occurred about 15,000 BP.There are also indications of a third large-magnitude eruption, which probably occurred 29,000 BP.For this reason, the Phlegraean Fields are also closely monitored by theVesuvius Observatory.
They are also characterized by numerous secondary volcanic phenomena, of which the best known is the Phlegraeanbradyseism, which in the second half of the 1900s led to the evacuation of entire districts of the city ofPozzuoli.
Etna is characterized by an almost continuous eruptive activity, and, unlike Vesuvius, the eruptions of Etna tend to be effusive, with lava flows that can come from both the summit craters and side openings. These eruptions almost always do not cause high damage, but there are exceptions. The largesteffusive eruptionof Etna in historical timestook place in 1669, when thelavaburied numerous villages reaching the sea nearCatania, with a flow up to 17 km long. This eruption completely changed the landscape of the area, but due to its effusive nature there were no victims associated with the eruption.
Another eruption of similar magnitude occurred in 396 BC, when the lava flows, reaching the sea, hindered the advance of theCarthaginian armyofHimilcoduring theGreco-Punic wars(as described byDiodorus Siculus).A few dozen deaths were recorded inBrontein the eruption of 1843, due to a phreatic explosion due to contact between the lava and a source of water. The last highly destructive eruption occurred in 1928, when the lava buried the town ofMascali.In the 1979 eruption, a sudden explosion caused nine deaths and 23 injuries in a group of tourists on excursion, and in that same eruption the last official order to evacuate an inhabited centre was issued due to an eruption of Etna.
The great explosive eruption of 122 BC, a Plinian event, which caused serious damage to theRomancity of Catania, which for this reason was exempt from paying taxes toRomefor a decade, was completely different. A further explosive eruption, of a sub-Plinian type, occurred in 44 BC. This eruptive history, associated with the high population density of theMetropolitan City of Catania(but with a less problematic situation than that of Naples), therefore requires continuous surveillance of the volcano.
Stromboliis one of the most active volcanoes in the world, with almost persistent activity for at least 2,000 years, which is why it was nicknamed the "lighthouse of the Mediterranean". Usually this activity consists of a continuous degassing, interspersed with small bursts of low intensity, at temporal distances that can vary from a few minutes to a few hours, a type of eruption that is defined precisely asStrombolian.
About 1–2 times per decade, lava can overflow from the summit craters, forming flows that can also reach the sea. These flows usually go towards the north-western area of the island, in the so-calledSciara del Fuoco(a depression shaped like a horseshoe, formed about 6,000 BP,) away from the inhabited settlements. At irregular intervals, Stromboli can give rise to much more violent explosions than normal, called paroxysms,which can instead cause damage to the population.
On 11 September 1930, what is considered the most violent eruptive event of the volcano in the last 13 centuries,occurred with a massive fallout of volcanic material on the inhabited centre ofGinostraand the formation of apyroclastic flowoutside the Sciara del Fuoco. In total, there were four deaths and numerous buildings destroyed. The most recent paroxysmal events occurred on 3 July and 28 August 2019,with the former explosion causing the death of a hiker.In these eruptions, pyroclastic flows able to flow over the sea for a few hundred meters have also been observed.
A further source of danger about Stromboli is the risk oflandslides(often in correspondence with the paroxysms), both aerial and submarine, capable of causingtsunamiwaves. The last event of this type occurred on 30 December 2002, when the wave did damage to coastal buildings.An underwater landslide event of greater proportions could have caused thetsunami in the Gulf of Naples in 1343.