Volcanism of Italy
Sardinia has had a totally separate geological history from that of the rest of Italy, where several cycles of volcanic activity occurred, the last of which ended at the beginning of the Pleistocene, but currently hosts only permanently extinct volcanoes.
The most important were that of 472 AD[33] (whose ash reached Constantinople) and that of 1631, which killed thousands of people (due to pyroclastic flows and lahars),[34]) and which was taken as a reference by Protezione Civile for the drafting of evacuation plans in the event of future eruptions.
They are also characterized by numerous secondary volcanic phenomena, of which the best known is the Phlegraean bradyseism, which in the second half of the 1900s led to the evacuation of entire districts of the city of Pozzuoli.
The largest effusive eruption of Etna in historical times took place in 1669, when the lava buried numerous villages reaching the sea near Catania, with a flow up to 17 km long.
[42] Another eruption of similar magnitude occurred in 396 BC, when the lava flows, reaching the sea, hindered the advance of the Carthaginian army of Himilco during the Greco-Punic wars (as described by Diodorus Siculus).
[45] The great explosive eruption of 122 BC, a Plinian event, which caused serious damage to the Roman city of Catania, which for this reason was exempt from paying taxes to Rome for a decade, was completely different.
This eruptive history, associated with the high population density of the Metropolitan City of Catania (but with a less problematic situation than that of Naples), therefore requires continuous surveillance of the volcano.
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 as Strombolian.
These flows usually go towards the north-western area of the island, in the so-called Sciara del Fuoco (a depression shaped like a horseshoe, formed about 6,000 BP,[46]) away from the inhabited settlements.
On 11 September 1930, what is considered the most violent eruptive event of the volcano in the last 13 centuries,[48] occurred with a massive fallout of volcanic material on the inhabited centre of Ginostra and the formation of a pyroclastic flow outside the Sciara del Fuoco.
