Везувий: Активный вулкан в Неаполитанском заливе

Active stratovolcano in the Gulf of Naples, Italy

Mount Vesuvius (/v//ᵻ/'/s//uː//v//i//ə//s/ vissOOveeəs) is a somma stratovolcano located on the Gulf of Naples in Campania, Italy, about 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 several other settlements. The eruption ejected a cloud of stones, ashes and volcanic gases to a height of , erupting molten rock and pulverized pumice at the rate of per second. More than 1,000 people are thought to have died in the eruption, though the exact toll is unknown. The only surviving eyewitness account of the event consists of two letters by Pliny the Younger to the historian Tacitus.

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 VESVVIO indicates that he was worshipped as a power of Jupiter; that is, Jupiter Vesuvius. 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 88 AD suggests that both Venus, patroness of Pompeii, and Hercules were worshipped in the region devastated by the eruption of 79.

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 at Punta Nasone. The summit of the main cone of Vesuvius is above sea level and more than above the 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. 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, Ischia, a volcanic island 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. 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 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. (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.

In AD 79, Vesuvius erupted in one of the most catastrophic eruptions of all time. Historians have learned about the eruption from the eyewitness account of Pliny the Younger, a Roman administrator and poet. The latest evidence supports earlier findings and indicates that the eruption occurred after 17 October. The volcano ejected a cloud of stones, ashes and volcanic gases to a height of , spewing molten rock and pulverized pumice at the rate of per second, ultimately releasing 100,000 times the thermal energy released by the Hiroshima Nagasaki bombings. The cities of Pompeii and Herculaneum were destroyed by pyroclastic surges and the ruins buried under tens of metres of tephra.

The AD 79 eruption was preceded by a powerful earthquake in 62, which caused widespread destruction around the Bay of Naples, and particularly to Pompeii. Some of the damage had still not been repaired when the volcano erupted. becoming more frequent over the next four days, but the warnings were not recognized.

Reconstructions of the eruption and its effects vary considerably in the details but have the same overall features. The eruption lasted two days. The morning of the first day was perceived as normal by the only eyewitness to leave a surviving document, Pliny the Younger. In the middle of the day, an explosion threw up a high altitude column from which ash and pumice began to fall, blanketing the area. Rescues and escapes occurred during this time. At some time in the night or early the next day, pyroclastic surges in the close vicinity of the volcano began. Lights were seen on the peak, interpreted as fires. People as far away as Misenum fled for their lives. The flows were rapid moving, dense and very hot, knocking down, wholly or partly, all structures in their path, incinerating or suffocating all population remaining there and altering the landscape, including the coastline. Additional light tremors accompanied these and a mild tsunami in the Bay of Naples. By late afternoon of the second day, the eruption was over, leaving only haze in the atmosphere through which the sun shone weakly. The latest scientific studies of the ash produced by Vesuvius reveal a multi phase eruption. The initial major explosion produced a column of ash and pumice ranging between high, which rained on Pompeii to the southeast but not on Herculaneum upwind. The chief energy supporting the column came from the escape of steam superheated by the magma, created from seawater seeping over time into the deep faults of the region, which interacted with magma. Subsequently, the cloud collapsed as the gases expanded and lost their capability to support their solid contents, releasing it as a pyroclastic surge, which first reached Herculaneum but not Pompeii. Additional blasts reinstituted the column. The eruption alternated between Plinian and Peléan six times. Surges 3 and 4 are believed by the authors to have buried Pompeii. Surges are identified in the deposits by dune and cross bedding formations, which are not produced by fallout. Another study used the magnetic characteristics of over 200 samples of roof tile and plaster fragments collected around Pompeii to estimate the equilibrium temperature of the pyroclastic flow. The magnetic study revealed that on the first day of the eruption a fall of white pumice containing clastic fragments of up to fell for several hours. It heated the roof tiles up to This period would have been the last opportunity to escape. The collapse of the Plinian columns on the second day caused pyroclastic density currents (PDCs) that devastated Herculaneum and Pompeii. The depositional temperature of these pyroclastic surges reached up to Any population remaining in structural refuges could not have escaped, as gases of incinerating temperatures surrounded the city. The lowest temperatures were in rooms under collapsed roofs, at approximately .

The only surviving eyewitness account of the event consists of two letters by Pliny the Younger to the historian Tacitus. Pliny the Younger describes, amongst other things, the last days in the life of his uncle, Pliny the Elder. Observing the first volcanic activity from Misenum across the Bay of Naples from the volcano, approximately , the elder Pliny launched a rescue fleet and went himself to the rescue of a personal friend. His nephew declined to join the party. One of the nephew's letters relates what he could discover from witnesses of his uncle's experiences. In a second letter, the younger Pliny details his own observations after the departure of his uncle. The two men saw an extraordinarily dense cloud rising rapidly above the peak. This cloud and a request by a messenger for an evacuation by sea prompted the elder Pliny to order rescue operations in which he sailed away to participate. His nephew attempted to resume a normal life, but that night a tremor awoke him and his mother, prompting them to abandon the house for the courtyard. Further tremors near dawn caused the population to abandon the village and caused disastrous wave action in the Bay of Naples. A massive black cloud glistering with lighting obscured the early morning light, a scene Pliny describes as sheet lightning. The cloud obscured Point Misenum near at hand and the island of Capraia (Capri) across the bay. Fearing for their lives, the population began to flee the shore along the road. An ash rain fell, causing Pliny to shake it off periodically to avoid being buried. Later that same day, the pumice and ash stopped falling, and the sun shone weakly through the cloud, encouraging Pliny and his mother to return to their home and wait for news of Pliny the Elder. Pliny's uncle, Pliny the Elder, was in command of the Roman fleet at Misenum and had meanwhile decided to investigate the phenomenon at close hand in a light vessel. As the ship was preparing to leave the area, a messenger came from his friend Rectina (wife of Tascius) living on the coast near the foot of the volcano, explaining that her party could only get away by sea and asking for rescue. Pliny ordered the immediate launching of the fleet galleys to the evacuation of the coast. He continued in his light ship to the rescue of Rectina's party. He set off across the bay but, in the shallows on the other side, encountered thick showers of hot cinders, lumps of pumice and pieces of rock. Advised by the helmsman to turn back, he stated, "Fortune favors the brave" and ordered him to continue to Stabiae (about 4.5 km from Pompeii). Pliny the Elder and his party saw what they believed to be flames coming from several parts of the crater. After staying overnight, the party was driven from the building by an accumulation of material, presumably tephra, which threatened to block all egress. They woke Pliny, who had been napping and emitting loud snoring. They elected to take to the fields with pillows tied to their heads to protect them from the raining debris. They approached the beach again, but the wind prevented the ships from leaving. Pliny sat down on a sail that had been spread for him and could not rise even with assistance when his friends departed. Though Pliny the Elder died, his friends ultimately escaped by land. In the first letter to Tacitus, Pliny the Younger suggested that his uncle's death was due to the reaction of his weak lungs to a cloud of poisonous, sulphurous gas that wafted over the group. However, Stabiae was 16 km from the vent (roughly where the modern town of Castellammare di Stabia is situated), and his companions were unaffected by the volcanic gases. It is more likely that the corpulent Pliny died from another cause, such as a stroke or heart attack. His body was found with no apparent injuries the next day, after dispersal of the plume.

Along with Pliny the Elder, the only other noble casualties of the eruption to be known by name were Agrippa (a son of the Herodian Jewish princess Drusilla and the procurator Antonius Felix) and his wife. By 2003, around 1,044 casts made from impressions of bodies in the ash deposits had been recovered in and around Pompeii, with the scattered bones of another 100. The remains of about 332 bodies have been found at Herculaneum (300 in arched vaults discovered in 1980). What percentage these numbers are of the total dead or the percentage of the dead to the total number at risk remain unknown. Thirty eight percent of the 1,044 were found in the ash fall deposits, the majority inside buildings. These are thought to have been killed mainly by roof collapses, with the smaller number of victims found outside of buildings probably being killed by falling roof slates or by larger rocks thrown out by the volcano. The remaining 62% of remains found at Pompeii were in the pyroclastic surge deposits, killed more than 100 people and ejected the most lava ever recorded from a Vesuvian eruption. Italian authorities were preparing to hold the 1908 Summer Olympics when Mount Vesuvius violently erupted, devastating the city of Naples and surrounding comunes. Funds were diverted to reconstructing Naples, and a new site for the Olympics had to be found. Vesuvius was active from 1913 through 1944, with lava filling the crater and occasional outflows of small amounts of lava. That eruptive period ended in the major eruption of March 1944, which destroyed the villages of San Sebastiano al Vesuvio, Massa di Somma, and Ottaviano, and part of San Giorgio a Cremano. From 13 to 18 March 1944, activity was confined within the rim. Finally, on 18 March 1944, lava overflowed the rim. Lava flows destroyed nearby villages from 19 March through 22 March. On 24 March, an explosive eruption created an ash plume and a small pyroclastic flow. In March 1944, the United States Army Air Forces (USAAF) 340th Bombardment Group was based at Pompeii Airfield near Terzigno, Italy, just a few kilometres from the eastern base of the volcano. The tephra and hot ash from multiple days of the eruption damaged the fabric control surfaces, the engines, the Plexiglas windscreens and the gun turrets of the 340th's B 25 Mitchell medium bombers. Estimates ranged from 78 to 88 aircraft destroyed. The eruption could be seen from Naples. Different perspectives and the damage caused to the local villages were recorded by USAAF photographers and other personnel based nearer to the volcano.

Large Vesuvian eruptions which emit volcanic material in quantities of about , the most recent of which overwhelmed Pompeii and Herculaneum, have happened after periods of inactivity of a few thousand years. Sub Plinian eruptions producing about , such as those of 472 and 1631, have been more frequent with a few hundred years between them. From the 1631 eruption until 1944, there was a comparatively small eruption every few years, emitting 0.001–0.01 km3 of magma. For Vesuvius, the amount of magma expelled in an eruption increases roughly linearly with the interval since the previous one, and at a rate of around for each year. This gives an approximate figure of for an eruption after 75 years of inactivity. Magma sitting in an underground chamber for many years will start to see higher melting point constituents such as olivine crystallizing out. The effect is to increase the concentration of dissolved gases (mostly sulfur dioxide and carbon dioxide) in the remaining liquid magma, making the subsequent eruption more violent. As gas rich magma approaches the surface during an eruption, the huge drop in internal pressure caused by the reduction in weight of the overlying rock (which drops to zero at the surface) causes the gases to come out of solution, the volume of gas increasing explosively from nothing to perhaps many times that of the accompanying magma. Additionally, the removal of the higher melting point material will raise the concentration of felsic components such as silicates, potentially making the magma more viscous, adding to the explosive nature of the eruption. The government emergency plan for an eruption therefore assumes that the worst case will be an eruption of similar size and type to the 1631 VEI 4 eruption. In this scenario, the volcano's slopes, extending out to about from the vent, may be exposed to pyroclastic surges sweeping down them, whilst much of the surrounding area could suffer from tephra falls. Because of prevailing winds, towns and cities south and east of the volcano are most at risk from this. It is assumed that tephra accumulation exceeding —at which point people are at risk from collapsing roofs—may extend out as far as Avellino to the east or Salerno to the south east. Near Naples, this tephra fall hazard is assumed to extend barely past the volcano's slopes to the northwest. and by offering sufficient financial incentives to people for moving away. One of the underlying goals is to reduce the time needed to evacuate the area, over the next twenty to thirty years, to two or three days. The volcano is closely monitored by the Osservatorio Vesuvio in Naples with extensive networks of seismic and gravimetric stations, a combination of a GPS based geodetic array and satellite based synthetic aperture radar to measure ground movement and by local surveys and chemical analyses of gases emitted from fumaroles. All of this is intended to track magma rising underneath the volcano. as of 2010, no magma has been detected within 10 km of the surface, so the volcano is classified by the Observatory as at a Basic or Green Level of hazard.

The area around Vesuvius was officially declared a national park on 5 June 1995. The summit of Vesuvius is open to visitors, and there is a small network of paths around the volcano that are maintained by the park authorities on weekends. There is access by road to within of the summit (measured vertically), but after that, access is on foot only. There is a spiral walkway around the volcano from the road to the crater.

Mount Vesuvius' first funicular — a type of vertical transport that uses two opposing, interconnected, rail guided passenger cars always moving in concert — opened in 1880, subsequently destroyed by the March 1944 eruption. "Funiculì, Funiculà", a Neapolitan language song, was written to commemorate the opening of the first funicular on Mount Vesuvius.