Mount Vesuvius

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Mount Vesuvius ( və-SOO-vee-əs) is a somma–stratovolcano located on the Gulf of Naples in Campania, Italy, about 9 km (5.6 mi) east of Naples and a short distance from the shore. It is one of several volcanoes forming the Campanian volcanic arc. Vesuvius consists of a large cone partially encircled by the steep rim of a summit caldera, resulting from the collapse of an earlier, much higher structure. The eruption of Mount Vesuvius in 79 AD destroyed the Roman cities of Pompeii, Herculaneum, Oplontis, Stabiae and other settlements. The eruption ejected a cloud of stones, ash and volcanic gases to a height of 33 km (21 mi), erupting molten rock and pulverized pumice at the rate of 6×105 cubic metres (7.8×105 yd3) per second. More than 1,000 people are thought to have died in the eruption, though the exact toll is unknown. The only surviving witness account consists of two letters by Pliny the Younger to the historian Tacitus. Vesuvius has erupted many times since. It is the only volcano on Europe's mainland to have erupted in the last hundred years. It is regarded as one of the most dangerous volcanoes in the world, marked as one of the Decade Volcanoes, because 3,000,000 people live...

Vesuvius was a name of the volcano in frequent use by the authors of the late Roman Republic and the early Roman Empire. Its collateral forms were Vesaevus, Vesevus, Vesbius and Vesvius. Writers in ancient Greek used Οὐεσούιον or Οὐεσούιος. Many scholars since then have offered an etymology. Given that peoples of varying ethnicity and language occupied Campania during the Roman Iron Age, the etymology depends to a large degree on the presumption of what language was spoken there at the time. Naples was settled by Greeks, as the name Nea-polis, "New City", testifies. The Oscans, an Italic people, lived in the countryside. The Latins also competed for the occupation of Campania. Etruscan settlements were in the vicinity. Other peoples of unknown provenance are said to have been there at some time by various ancient authors.

- From Greek οὔ 'not' prefixed to a root from or related to the Greek word σβέννυμι: 'I quench', in the sense of 'unquenchable'.

- From Greek ἕω = 'I hurl' and βίη 'violence' → 'hurling violence', * vesbia, taking advantage of the collateral form.

- From an Indo-European root, * eus- < * ewes- < h₁ews-, 'shine', 'burn', sense "the one who lightens', through Latin or Oscan.

- From an Indo-European root * wes = ' hearth ' (compare e.g. Vesta ) The Romans regarded Mount Vesuvius as being devoted to Hercules. The historian Diodorus Siculus relates a tradition that Hercules, in the performance of his labors, passed through the country of nearby Cumae on his way to Sicily and found there a place called "the Phlegraean Plain" ( Φλεγραῖον πεδίον, 'fiery'), "from the mountain which of old spouted forth a huge fire [...] the mountain is called Vesuvius." It was inhabited by giant bandits, "the sons of the Earth". With the gods' assistance, he pacified the region and continued. The facts behind the tradition, if any, remain unknown, as does whether Herculaneum was named after it. An epigram by the poet Martial in AD 88 suggests that both Venus, patroness of Pompeii, and Hercules were worshipped in the region devastated by the eruption of 79.

City of Naples with Mount Vesuvius viewed from the Castel Sant'Elmo

Vesuvius has a long historic and literary tradition. It was considered a divinity of the Genius type at the time of the eruption of AD 79: it appears under the inscribed name Vesuvius as a serpent in the decorative frescos of many lararia, or household shrines, surviving from Pompeii. An inscription from Capua to Iovi Vesuvio indicates that he was worshipped as a power of Jupiter ; that is, Jupiter Vesuvius.

Vesuvius is a "humpbacked" peak, consisting of a large cone ( Gran Cono ) partially encircled by the steep rim of a summit caldera caused by the collapse of an earlier (and originally much higher) structure called Mount Somma. The Gran Cono was produced during the A.D. 79 eruption. For this reason, the volcano is also called Somma-Vesuvius or Somma-Vesuvio.

The caldera started forming during an eruption around 17,000–18,000 years ago and was enlarged by later paroxysmal eruptions, ending in the one of AD 79. This structure has given its name to the term " somma volcano ", which describes any volcano with a summit caldera surrounding a newer cone.

The cliffs forming the northern ridge of Monte Somma's caldera rim reach a maximum height of 1,132 m (3,714 ft) at Punta Nasone. The summit of the main cone of Vesuvius is 1,281 m (4,203 ft) above sea level and more than 400 m (1,300 ft) above the 5 km (3.1 mi) long valley of Atrio di Cavallo (the northern floor of Monte Somma's caldera).

The volcano's slopes are scarred by lava flows, while the rest are heavily vegetated, with scrub and forests at higher altitudes and vineyards lower down.

Vesuvius is a stratovolcano and was formed as a result of the collision of two tectonic plates, the African and the Eurasian. The former was subducted at a convergent boundary beneath the latter, deeper into the Earth. As the water-saturated sediments of the African oceanic plate were pushed to hotter depths inside the planet, the water boiled off and lowered the melting point of the upper mantle enough to partially melt the rocks. Because magma is less dense than the solid rock around it, it was pushed upward. Finding a weak spot at the Earth's surface, it broke through, thus forming the volcano. [ citation needed ]

The volcano is one of several forming the Campanian volcanic arc. Others include Campi Flegrei, a large caldera a few kilometers to the north-west, and Ischia, a volcanic island 20 kilometres (12 mi) to the west, and several undersea volcanoes to the south. The arc forms the southern end of a larger chain of volcanoes produced by the subduction process described above, which extends northwest along the length of Italy as far as Monte Amiata in Southern Tuscany. Vesuvius is the only one to have erupted in recent history, although some of the others have erupted within the last few hundred years. Many are either extinct or have not erupted for tens of thousands of years.

Mount Vesuvius has erupted many times. Numerous others preceded the eruption in AD 79 in prehistory, including at least three significantly larger; an example is the Avellino eruption around 1800 BC, which engulfed several Bronze Age settlements. Since AD 79, the volcano has also erupted repeatedly, in 172, 203, 222, possibly in 303, 379, 472, 512, 536, 685, 787, around 860, around 900, 968, 991, 999, 1006, 1037, 1049, around 1073, 1139, 1150, and there may have been eruptions in 1270, 1347, and 1500. The volcano erupted again in 1631, six times in the 18th century (including 1779 and 1794), eight times in the 19th century (notably in 1872), and in 1906, 1929 and 1944. There have been no eruptions since 1944, and none of the eruptions after AD 79 were as large or destructive as the Pompeian one.

The eruptions vary greatly in severity but are characterized by explosive outbursts of the kind dubbed Plinian after Pliny the Younger, a Roman writer who published a detailed description of the AD 79 eruption, including his uncle's death. On occasion, eruptions from Vesuvius have been so large that the whole of southern Europe has been blanketed by ash; in 472 and 1631, Vesuvian ash fell on Constantinople ( Istanbul ), over 1,200 kilometres (750 mi) away. A few times since 1944, landslides in the crater have raised clouds of ash dust, raising false alarms of an eruption.

Since 1750, seven of the eruptions of Vesuvius have had durations of more than five years; only Mount Etna has had as many long-duration eruptions in the last 270 years. The two most recent eruptions of Vesuvius (1875–1906 and 1913–1944) each lasted more than 30 years.

Vesuvius is still regarded as an active volcano, although its current activity produces little more than sulfur-rich steam from vents at the bottom and walls of the crater.

Layers of lava, ash, scoria and pumice make up the volcanic peak. Their mineralogy is variable, but generally silica -undersaturated and rich in potassium, with phonolite produced in the more explosive eruptions (e.g. the eruption in 1631 displaying a complete stratigraphic and petrographic description: phonolite was firstly erupted, followed by a tephritic phonolite and finally a phonolitic tephrite ).

According to the Smithsonian Institution 's Global Volcanism Program, Vesuvius has had 54 confirmed eruptions during the Holocene Epoch (the last 11,700 years). A volcanic explosivity index (VEI) has been assigned to all but one of these eruptions.