New 7 Natural Wonders of the World

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Vesuvius, Italy
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Vesuvius originated during the late Pleistocene Epoch, probably somewhat less than 200,000 years ago. Although a relatively young volcano, Vesuvius had been dormant for centuries before the great eruption of AD 79 that buried the cities of Pompeii and Stabiae under ashes and lapilli and the city of Herculaneum under a mud flow. [1]
Vesuvius slideshow	Mt Vesuvius, Italy across from Bay of Naples[2]

 

Mount Vesuvius (in Italian Monte Vesuvio and in Latin Mons Vesuvius) is a stratovolcano east of Naples, Italy. It is the only volcano on the European mainland to have erupted within the last hundred years, although it is not currently erupting. The two other volcanoes in Italy, (Etna and Stromboli) are located on islands.

Mount Vesuvius is on the coast of the Bay of Naples, about nine kilometres (six miles) east of Naples and a short distance from the shore. It is conspicuous in the beautiful landscape presented by that bay, when seen from the sea, with Naples in the foreground.

Mount Vesuvius is best known for its eruption in AD 79 that led to the destruction of the Roman cities of Pompeii and Herculaneum and the death of 10,000 to 25,000 people. It has erupted many times since and is today regarded as one of the most dangerous volcanoes in the world because of the population of 3,000,000 people living nearby and its tendency towards explosive (Plinian) eruptions. It is the most densely populated volcanic region in the world. Mount Vesuvius was regarded by the Greeks and Romans as being sacred to the hero and demigod Heracles/Hercules, and the town of Herculaneum, built at its base, was named after him.

Physical appearance

A view of the crater wall of Vesuvius, with Naples in the backgroundVesuvius is a distinctive "humpbacked" mountain, 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 Monte Somma. The Gran Cono was produced during the eruption of AD 79. For this reason, the volcano is also called Somma-Vesuvius or Somma-Vesuvio.

The caldera started forming during an eruption around 17,000 (or 18,300[2]) 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 height of the main cone has been constantly changed by eruptions but presently is 1,281 m (4,202 ft). Monte Somma is 1,149 m (3,770 ft) high, separated from the main cone by the valley of Atrio di Cavallo, which is some 3 miles (5 km) long. The slopes of the mountain are scarred by lava flows but are heavily vegetated, with scrub at higher altitudes and vineyards lower down. Vesuvius is still regarded as an active volcano, although its current activity produces little more than steam from vents at the bottom of the crater. Vesuvius is a stratovolcano at the convergent boundary where the African Plate is being subducted beneath the Eurasian Plate. Its lava is composed of viscous andesite. Layers of lava, scoria, volcanic ash, and pumice make up the mountain.

Formation

A view of Somma-Vesuvius, from a convent on the Sorrento PeninsulaVesuvius was formed as a result of the collision of two tectonic plates, the African and the Eurasian. The former was pushed beneath the latter, deeper into the earth. The crust material became heated until it melted, forming magma, a type of liquid rock. Because magma is less dense than the solid rock around it, it was pushed upward. Finding a weak place at the Earth's surface it broke through, producing the volcano.

The volcano is one of several which form the Campanian volcanic arc. Others include Campi Flegrei, a large caldera a few kilometres to the north west, Mount Epomeo, 20 kilometres (12 mi) to the west on the island of Ischia, 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 within 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.

Eruptions

An aerial photo of VesuviusMount Vesuvius has erupted many times. The famous eruption in 79 AD was preceded by numerous others in prehistory, including at least three significantly larger ones, the best known being the Avellino eruption around 1800 BC which engulfed several Bronze Age settlements. Since 79 AD, the volcano has also erupted repeatedly, in 172, 203, 222, possibly 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.[5] The volcano erupted again in 1631, six times in the 18th century, eight times in the 19th century (notably in 1872), and in 1906, 1929, and 1944. There has been no eruption since 1944, and none of the post-79 eruptions were as large or destructive.

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. [3]