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84-512: Mount Natib is a stratovolcano type of volcano topped by a 6-by-7-kilometre (3.7 by 4.3 mi) acorn-shaped Natib Caldera that is open to the northwest. East of its caldera is the smaller 2-kilometre (1.2 mi) wide Pasukulan Caldera. The highest peak of Mount Natib has an elevation of 1,253 metres (4,111 ft) asl and is at the point of convergence of the two calderas. The caldera complex has an overall base diameter of 26 kilometres (16 mi). There are no historical eruptions within

168-458: A composite volcano , is a conical volcano built up by many alternating layers ( strata ) of hardened lava and tephra . Unlike shield volcanoes , stratovolcanoes are characterized by a steep profile with a summit crater and explosive eruptions. Some have collapsed summit craters called calderas . The lava flowing from stratovolcanoes typically cools and solidifies before spreading far, due to high viscosity . The magma forming this lava

252-473: A numismatic expert at the British Museum , Richard Abdy, concluded that the latest coin in the hoard was minted on or after June 24 (the first date of Titus' reign) and before September 1, 79 AD. Abdy states that it is "remarkable that both coins will have taken just two months after minting to enter circulation and reach Pompeii before the disaster." In October 2018, Italian archaeologists uncovered

336-560: A potentially active volcano. The rocks found on Natib are predominantly biotite , hornblende , andesite , trending to dacite flows and dacitic tuffs , which are similar to Mount Mariveles , the southern half of the Bataan Peninsula. Natib is part of the Western Bataan Lineament volcanic belt , which includes the active Mount Pinatubo . Stratovolcano A stratovolcano , also known as

420-562: A 2.8 m (9 ft) layer to the south, towards Pompeii. An earthquake caused buildings in Pompeii to collapse at this time. The following Pelean phase produced pyroclastic surges of molten rock and hot gases that reached as far as Misenum , to the west. Concentrated to the south and southeast, two pyroclastic surges engulfed Pompeii with a 1.8-metre-deep (6 ft) layer, burning and asphyxiating any living beings who had remained behind. Herculaneum , Pompeii , and Oplontis received

504-747: A 4-inch thick ash layer can weigh 120-200 pounds and can get twice as heavy when wet. Wet ash also poses a risk to electronics due to its conductive nature. Dense clouds of hot volcanic ash can be expelled due to the collapse of an eruptive column , or laterally due to the partial collapse of a volcanic edifice or lava dome during explosive eruptions . These clouds are known as pyroclastic surges and in addition to ash , they contain hot lava , pumice , rock , and volcanic gas . Pyroclastic surges flow at speeds over 50 mph and are at temperatures between 200 °C – 700 °C. These surges can cause major damage to property and people in their path. Lava flows from stratovolcanoes are generally not

588-411: A charcoal inscription reading "the 16th day before the calends (first) of November," or October 17, that was probably "made by a worker renovating a home", and which has subsequently been suggested as "the most likely date for the eruption". While the "graffito does not have a year listed [...] the nature of the writing suggests it was done just before the eruption of Vesuvius. It was found in an area of

672-440: A detailed stratigraphic study of ash layers based on excavations and surveys, published in 1982. They concluded that the eruption unfolded in two phases, Vesuvian and Pelean , which alternated six times. A first Plinian phase projected a column of volcanic debris and hot gases between 15 km (9 mi) and 30 km (19 mi) into the stratosphere . This phase lasted 18 to 20 hours and spread pumice and ashes, forming

756-479: A fast moving mudflow . Lahars are typically about 60% sediment and 40% water. Depending on the abundance of volcanic debris the lahar can be fluid or thick like concrete. Lahars have the strength and speed to flatten structures and cause great bodily harm, gaining speeds up to dozens of kilometers per hour. In the 1985 eruption of Nevado del Ruiz in Colombia , Pyroclastic surges melted snow and ice atop

840-515: A final intermediate composition . When the magma nears the top surface, it pools in a magma chamber within the crust below the stratovolcano. The processes that trigger the final eruption remain a question for further research. Possible mechanisms include: These internal triggers may be modified by external triggers such as sector collapse , earthquakes , or interactions with groundwater . Some of these triggers operate only under limited conditions. For example, sector collapse (where part of

924-481: A house that was in the process of being renovated, likely just before the volcano erupted", while the charcoal writing itself is "fragile and unlikely to have been preserved for years prior to the utter destruction of Pompeii." However, "it is not known whether the Oct[ober] 17 graffito referred to that day, or a day in the past or the future." A collaborative study in 2022 has determined a date of October 24–25 for

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1008-477: A major stratovolcano in Southern Italy , the best-known is its eruption in 79 AD, which was one of the deadliest in history . Mount Vesuvius violently spewed forth a cloud of super-heated tephra and gases to a height of 33 km (21 mi), ejecting molten rock , pulverized pumice and hot ash at 1.5 million tons per second, ultimately releasing 100,000 times the thermal energy of

1092-582: A prehistoric pyroclastic flow from the volcano that entered Subic Bay in Zambales province. Current activity on Natib is through five thermal areas. The hot springs in the Natib caldera are Asin, Mamot, Tigulangin, Uyong, and Paipit springs. The hot springs have temperatures ranging from 30-56 °C, with low flows, and a neutral to slightly alkaline water discharge. The Philippine Institute of Volcanology and Seismology (PHIVOLCS) lists Mount Natib as

1176-769: A result of intraplate volcanism on oceanic islands far from plate boundaries. Examples are Teide in the Canary Islands , and Pico do Fogo in Cape Verde . Stratovolcanoes in the East African Rift include Ol Doinyo Lengai in Tanzania, and Longonot in Kenya. Subduction zone volcanoes form when hydrous minerals are pulled down into the mantle on the slab. These hydrous minerals, such as chlorite and serpentine , release their water into

1260-455: A second letter, the younger Pliny details his own observations after the departure of his uncle. Pliny the Younger saw an extraordinarily dense cloud rising rapidly above the mountain: the appearance of which I cannot give you a more exact description of than by likening it to that of a pine-tree, for it shot up to a great height in the form of a very tall trunk, which spread itself out at

1344-462: A ship with possessions and was preparing to leave, but the same onshore wind that brought Pliny's ship to the location had prevented anyone from leaving. Pliny and his party saw flames coming from several parts of the mountain, which Pliny and his friends attributed to burning villages. After staying overnight, the party was driven from the building by its violent shaking. They woke Pliny, who had been napping and snoring loudly. They elected to take to

1428-461: A significant threat to humans or animals because the highly viscous lava moves slowly enough for everyone to evacuate. Most deaths attributed to lava are due to related causes such as explosions and asphyxiation from toxic gas . Lava flows can bury homes and farms in thick volcanic rock which greatly reduces property value. However, not all stratovolcanoes erupt viscous and sticky lava . Nyiragongo , near Lake Kivu in central Africa ,

1512-400: A slave to kill him to avoid the pain of incineration. How the slave would have escaped remains a mystery. There is no mention of such an event in his nephew's letters. In the first letter to Tacitus, his nephew suggested that his 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 (9.9 mi) from

1596-561: A study of prevailing winds in Campania showed that the southeasterly debris pattern of the first-century eruption is quite consistent with an autumn event and inconsistent with an August date. During June, July, and August, the prevailing winds flow to the west – an arc between the southwest and northwest – virtually all the time. As Emperor Titus of the Flavian dynasty (reigning June 24, 79 AD to September 13, 81 AD) garnered victories on

1680-533: A tremor woke him and his mother, prompting them to abandon the house for the courtyard. At another tremor at dawn, the population abandoned the village. After a third tremor, "the sea seemed to roll back upon itself, and to be driven from its banks", which is evidence of a tsunami . There is, however, no evidence of extensive damage from wave action. A black cloud obscured the early light through which shone flashes, which Pliny likens to sheet lightning, but more extensive. The cloud obscured Point Misenum near at hand and

1764-512: Is a mixture of minerals, each with its own Curie temperature; the authors, therefore, looked for a spectrum of temperatures rather than a single temperature. In the ideal sample, the PDC did not raise the temperature of the fragment beyond the highest blocking temperature. Some constituent materials retained the magnetism the Earth's field imposed when the item was formed. The temperature was raised above

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1848-531: Is a passive release of gas during periods of dormancy. As per the above examples, while eruptions like Mount Unzen have caused deaths and local damage, the impact of the June 1991 eruption of Mount Pinatubo was seen globally. The eruptive columns reached heights of 40 km and dumped 17 megatons of SO 2 into the lower stratosphere . The aerosols that formed from the sulfur dioxide (SO 2 ), carbon dioxide (CO 2 ), and other gases dispersed around

1932-459: Is never mentioned in Pliny the Younger's letter. Around 1:00 p.m., Mount Vesuvius erupted violently, spewing up a high-altitude column from which ash and pumice began to fall, blanketing the area. Over the next few hours, rescues and escapes occurred during this time. At some time in the night or early the next day, pyroclastic flows in the close vicinity of the volcano began; lights seen on

2016-476: Is often felsic , having high to intermediate levels of silica (as in rhyolite , dacite , or andesite ), with lesser amounts of less viscous mafic magma . Extensive felsic lava flows are uncommon, but can travel as far as 8 km (5 mi). The term composite volcano is used because the strata are usually mixed and uneven instead of neat layers. They are among the most common types of volcanoes; more than 700 stratovolcanoes have erupted lava during

2100-451: Is the most famous example of a hazardous stratovolcano eruption. It completely smothered the nearby ancient cities of Pompeii and Herculaneum with thick deposits of pyroclastic surges and pumice ranging from 6–7 meters deep. Pompeii had 10,000-20,000 inhabitants at the time of eruption. Mount Vesuvius is recognized as one of the most dangerous of the world's volcanoes, due to its capacity for powerful explosive eruptions coupled with

2184-450: Is typically between 700 and 1,200 °C (1,300-2,200 °F). Volcanic bombs are masses of unconsolidated rock and lava that are ejected during an eruption. Volcanic bombs are classified as larger than 64mm (2.5 inches). Anything below 64mm is classified as a volcanic block . When erupted Bombs are still molten and partially cool and solidify on their descent. They can form ribbon or oval shapes that can also flatten on impact with

2268-403: Is very dangerous because its magma has an unusually low silica content , making it much less viscous than other stratovolcanoes. Low viscosity lava can generate massive lava fountains , while lava of thicker viscosity can solidify within the vent, creating a volcanic plug . Volcanic plugs can trap gas and create pressure in the magma chamber, resulting in violent eruptions. Lava

2352-633: The Bay of Naples , particularly to Pompeii, on February 5, 62 AD. Some of the damage had still not been repaired when the volcano erupted in October 79 AD. Another smaller earthquake took place in 64 AD; it was recorded by Suetonius in his biography of Nero , and by Tacitus in Annales because it took place while Nero was in Naples performing for the first time in a public theater. Suetonius recorded that

2436-824: The Holocene Epoch (the last 11,700 years), and many older, now extinct, stratovolcanoes erupted lava as far back as Archean times. Stratovolcanoes are typically found in subduction zones but they also occur in other geological settings. Two examples of stratovolcanoes famous for catastrophic eruptions are Krakatoa in Indonesia (which erupted in 1883 claiming 36,000 lives) and Mount Vesuvius in Italy (which erupted in 79 A.D killing an estimated 2,000 people). In modern times, Mount St. Helens (1980) in Washington State , US, and Mount Pinatubo (1991) in

2520-579: The Philippines have erupted catastrophically, but with fewer deaths. Stratovolcanoes are common at subduction zones , forming chains and clusters along plate tectonic boundaries where an oceanic crust plate is drawn under a continental crust plate (continental arc volcanism, e.g. Cascade Range , Andes , Campania ) or another oceanic crust plate ( island arc volcanism, e.g. Japan , Philippines , Aleutian Islands ). Stratovolcanoes also occur in some other geological settings, for example as

2604-532: The atomic bombings of Hiroshima and Nagasaki . The event gives its name to the Vesuvian type of volcanic eruption, characterised by columns of hot gases and ash reaching the stratosphere , although the event also included pyroclastic flows associated with Pelean eruptions . The event destroyed several Roman towns and settlements in the area. Pompeii and Herculaneum , obliterated and buried underneath massive pyroclastic surges and ashfall deposits , are

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2688-891: The magma is too viscous to allow easy escape of volcanic gases . As a consequence, the tremendous internal pressures of the trapped volcanic gases remain and intermingle in the pasty magma . Following the breaching of the vent and the opening of the crater, the magma degasses explosively. The magma and gases blast out with high speed and full force. Since 1600 CE , nearly 300,000 people have been killed by volcanic eruptions . Most deaths were caused by pyroclastic flows and lahars , deadly hazards that often accompany explosive eruptions of subduction-zone stratovolcanoes. Pyroclastic flows are swift, avalanche-like, ground-sweeping, incandescent mixtures of hot volcanic debris, fine ash , fragmented lava , and superheated gases that can travel at speeds over 150 km/h (90 mph). Around 30,000 people were killed by pyroclastic flows during

2772-443: The mantle which decreases its melting point by 60 to 100 °C. The release of water from hydrated minerals is termed " dewatering ", and occurs at specific pressures and temperatures for each mineral, as the plate descends to greater depths. This allows the mantle to partially melt and generate magma . This is called flux melting . The magma then rises through the crust , incorporating silica-rich crustal rock, leading to

2856-616: The 1902 eruption of Mount Pelée on the island of Martinique in the Caribbean . During March and April 1982, El Chichón in the State of Chiapas in southeastern Mexico , erupted 3 times, causing the worst volcanic disaster in that country's history and killied more than 2,000 people in pyroclastic flows . Two Decade Volcanoes that erupted in 1991 provide examples of stratovolcano hazards. On 15 June, Mount Pinatubo erupted and caused an ash cloud to shoot 40 km (25 mi) into

2940-485: The 1982 eruption of Galunggung in Java , British Airways Flight 9 flew into the ash cloud, causing it to sustain temporary engine failure and structural damage. Although no crashes have happened due to ash, more than 60, mostly commercial aircraft , have been damaged. Some of these incidents resulted in emergency landings. Ashfalls are a threat to health when inhaled and are also a threat to property. A square yard of

3024-585: The 5,321 m (17,457 ft) high Andean volcano. The ensuing lahar killed 25,000 people and flooded the city of Armero and nearby settlements. As a volcano forms, several different gases mix with magma in the volcanic chamber. During an eruption the gases are then released into the atmosphere which can lead to toxic human exposure. The most abundant of these gases is H 2 O ( water ) followed by CO 2 ( carbon dioxide ), SO 2 ( sulfur dioxide ), H 2 S ( hydrogen sulfide ), and HF ( hydrogen fluoride ). If at concentrations of more than 3% in

3108-515: The Elder, the only casualties of the eruption to be known by name were the Herodian princess Drusilla and her son Agrippa, who was born in her marriage with the procurator Antonius Felix . It is also said that the poet Caesius Bassus died in the eruption. By 2003, approximately 1,044 casts made from impressions of bodies in the ash deposits had been recovered in and around Pompeii, with

3192-650: The Natib caldera complex. Studies in 1991 (Panum and Rayem) indicate that the last eruptive activity was probably Holocene to upper Pleistocene . An earlier study in 1971 (Ebasco Services) dated the eruptive products between 69,000 +/- 27,000 years old. A recent study by Dr. Kevin Rodolfo of the Department of Earth and Environmental Sciences at the University of Illinois at Chicago , had Mount Natib's latest eruption between 11,000 and 18,000 years ago after studying

3276-819: The air, when breathed in CO 2 can cause dizziness and difficulty breathing. At more than 15% concentration CO 2 causes death. CO 2 can settle into depressions in the land, leading to deadly, odorless pockets of gas. SO 2 classified as a respiratory, skin, and eye irritant if come into contact with. It is known for its pungent egg smell and role in ozone depletion and has the potential to cause acid rain downwind of an eruption. H 2 S has an even stronger odor than SO 2 as well as being even more toxic. Exposure for less than an hour at concentrations of over 500 ppm causes death. HF and similar species can coat ash particles and once deposited can poison soil and water. Gases are also emitted during volcanic degassing, which

3360-748: The air. It produced large pyroclastic surges and lahar floods that caused a lot of damage to the surrounding area. Pinatubo , located in Central Luzon just 90 km (56 mi) west-northwest of Manila , had been dormant for six centuries before the 1991 eruption. This eruption was one of the 2nd largest in the 20th century. It produced a large volcanic ash cloud that affected global temperatures, lowering them in areas as much as .5 °C. The volcanic ash cloud consisted of 22 million tons of SO 2 which combined with water droplets to create sulfuric acid . In 1991 Japan's Unzen Volcano also erupted, after 200 years of inactivity. It's located on

3444-491: The ash stopped falling, and the sun shone weakly through the cloud, encouraging Pliny and his mother to return home and wait for news of Pliny the Elder. The letter compares the ash to a blanket of snow. The earthquake and tsunami damage at that location were not severe enough to prevent continued use of the home. Pliny's uncle, Pliny the Elder , was in command of the Roman fleet at Misenum and had meanwhile decided to investigate

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3528-616: The battlefield (including his capture of the Temple of Jerusalem ) and other honors, his administration issued coins enumerating his ever-growing accolades. Given the limited space on each coin, his achievements were stamped on the coins using an arcane encoding. Two of these coins, from early in Titus' reign, were found in a hoard recovered at Pompeii's House of the Golden Bracelet. Although the coins' minting dates are somewhat in dispute,

3612-461: The brunt of the surges and were buried in fine pyroclastic deposits, pulverized pumice and lava fragments up to 20 m (70 ft) deep. Surges 4 and 5 are believed to have destroyed and buried Pompeii. Surges are identified in the deposits by dune and cross-bedding formations, which are not produced by fallout. The eruption is considered primarily phreatomagmatic , i.e. a blast driven by energy from escaping steam produced by seawater seeping into

3696-432: The current just before deposition. All crystal rock contains some iron or iron compounds, rendering it ferromagnetic , as do Roman roof tiles and plaster. These materials may acquire a residual field from several sources. When individual molecules, which are magnetic dipoles , are held in alignment by being bound in a crystalline structure, the small fields reinforce each other to form the rock's residual field. Heating

3780-410: The current long enough to acquire its temperature, which would have been much higher. Therefore, they distinguish between the depositional temperatures, which they estimated, and the emplacement temperatures, which in some cases, based on the cooling characteristics of some types and fragment sizes of rocks they believed they also could estimate. The final figures are considered to be those of the rocks in

3864-491: The date given in Pliny's original letter may have been corrupted. Manuscript experts believe that the date originally given by Pliny was one of August 24, October 30, November 1, or November 23. This odd scattered set of dates is due to the Romans' convention for describing calendar dates . The large majority of extant medieval manuscript copies (there are no surviving Roman copies) indicate a date corresponding to August 24. Since

3948-407: The deep-seated faults and interacting with hot magma. In an article published in 2002, Sigurðsson and Casey concluded that an early explosion produced a column of ash and pumice which rained on Pompeii to the southeast but not on Herculaneum, which was upwind. Subsequently, the cloud collapsed as the gases densified and lost their capability to support their solid contents. The authors suggest that

4032-408: The deposit. Considering the data for all the surge deposits arrived at a surge deposit estimate. The authors discovered that the city of Pompeii was a relatively cool spot within a much hotter field, which they attributed to the interaction of the surge with the "fabric" of the city. The investigators reconstruct the sequence of volcanic events as follows: The variable temperature of the first surge

4116-515: The discovery of the cities, this was accepted by most scholars and by nearly all books written about Pompeii and Herculaneum for the general public. Since at least the late 18th century, a minority among archaeologists and other scientists have suggested that the eruption began after August 24, during the autumn, perhaps in October or November. In 1797, the researcher Carlo Rosini reported that excavations at Pompeii and Herculaneum had uncovered traces of fruits and braziers indicative of autumn, not

4200-517: The emperor continued singing through the earthquake until he had finished his song, while Tacitus wrote that the theater collapsed shortly after being evacuated . Minor earthquakes were reported in the four days before the 79 AD eruption, but the warnings were not recognized. The inhabitants of the area surrounding Mount Vesuvius had been accustomed to minor tremors in the region; Pliny the Younger wrote that they "were not particularly alarming because they are frequent in Campania". Reconstructions of

4284-480: The eruption and its effects vary considerably in the details but have the same overall features. The eruption lasted for two days. Pliny the Younger , author of the only surviving written testimony, described the morning before the eruption as normal; however, he was staying at Misenum 29 kilometres (18 mi) from the volcano across the Bay of Naples. The first day of the eruption had little effect on Misenum. Pompeii

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4368-537: The eruption of Mount Vesuvius in Campania ." Writing well over a century after the actual event, Roman historian Cassius Dio (as translated in the Loeb Classical Library 1925 edition) wrote that, "In Campania remarkable and frightful occurrences took place; for a great fire suddenly flared up at the very end of the summer." For more than five centuries, until approximately 2018, articles about

4452-484: The eruption of Vesuvius typically stated that the eruption began on August 24, 79 AD. This date came from a 1508 printed copy of a letter addressed by Pliny the Younger to the Roman historian Tacitus , originally written some 25 years after the event. Pliny was a witness to the eruption and provided the only known eyewitness account. Over fourteen centuries of manuscript hand-copying up to the 1508 printing of his letters,

4536-423: The event. Observing the first volcanic activity from Misenum across the Bay of Naples from the volcano, approximately 29 kilometres (18 mi) away, Pliny the Elder (Pliny the Younger's uncle) 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

4620-411: The existence of carbonised wood in many of the buildings. These people were concentrated in the vaults at a density as high as three per square metre and were all caught by the first surge, dying of thermal shock and partly carbonised by later and hotter surges. The vaults were most likely boathouses, as the crossbeams overhead were probably for the suspension of boats used for the earlier escape of some of

4704-419: The experimenters raised the temperature of the sample in increments of 40 °C (70 °F) from 100 °C (210 °F) until it reached the low unblocking temperature. Deprived of one of its components, the overall field changed direction. A plot of direction at each increment identified the increment at which the sample's resultant magnetism had formed. That was considered the equilibrium temperature of

4788-443: The fields with pillows tied to their heads to protect them from rockfall. They approached the beach again, but the wind had not changed. Pliny sat down on a sail spread for him and could not rise, even with assistance. His friends then departed, escaping ultimately by land. Very likely, he had collapsed and died, the most popular explanation for why his friends abandoned him, although Suetonius offers an alternative story of his ordering

4872-439: The first ash falls are to be interpreted as early-morning, low-volume explosions not seen from Misenum, causing Rectina to send her messenger on a ride of several hours around the Bay of Naples, then passable, providing an answer to the paradox of how the messenger might miraculously appear at Pliny's villa so shortly after a distant eruption that would have prevented him. A 2006 study by Zanella, Gurioli, Pareschi, and Lanza used

4956-540: The flank of a volcano collapses in a massive landslide) can only trigger the eruption of a very shallow magma chamber . Magma differentiation and thermal expansion also are ineffective as triggers for eruptions from deep magma chambers . In recorded history , explosive eruptions at subduction zone ( convergent-boundary ) volcanoes have posed the greatest hazard to civilizations. Subduction-zone stratovolcanoes, such as Mount St. Helens , Mount Etna and Mount Pinatubo , typically erupt with explosive force because

5040-478: The ground. Volcanic Bombs are associated with Strombolian and Vulcanian eruptions and basaltic lava . Ejection velocities ranging from 200 to 400 m/s have been recorded causing volcanic bombs to be destructive. Lahars (from a Javanese term for volcanic mudflows) are a mixture of volcanic debris and water. Lahars can result from heavy rainfall during or before the eruption or interaction with ice and snow. Meltwater mixes with volcanic debris causing

5124-458: The high population density of the surrounding Metropolitan Naples area (totaling about 3.6 million inhabitants). In addition to potentially affecting the climate, volcanic ash clouds from explosive eruptions pose a serious hazard to aviation . Volcanic ash clouds consist of ash which is made of silt or sand sized pieces of rock, mineral, volcanic glass . Ash grains are jagged, abrasive, and don't dissolve in water. For example, during

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5208-504: The island of Kyushu about 40 km (25 mi) east of Nagasaki . Beginning in June, a newly formed lava dome repeatedly collapsed. This generated a pyroclastic flow that flowed down the mountain's slopes at speeds as high as 200 km/h (120 mph). The 1991 eruption of Mount Unzen was one of the worst volcanic disasters in Japan's history, once killing more than 15,000 people in 1792. The eruption of Mount Vesuvius in 79 AD

5292-439: The island of Capraia ( Capri ) across the bay. Fearing for their lives, the population began calling each other and moving back from the coast along the road. Pliny's mother requested him to abandon her and save his own life, as she was too fleshy and aged to go further, but seizing her hand, he led her away as best he could. A rain of ash fell. Pliny needed to shake off the ash periodically to avoid being buried. Later that same day,

5376-427: The lowest blocking temperature; therefore, some minerals on recooling acquired the magnetism of the Earth as it was in 79 AD. The broad field of the sample was the vector sum of the fields of the high-blocking material and the low-blocking material. This type of sample made it possible to estimate the low unblocking temperature. Using special equipment that measured field direction and strength at various temperatures,

5460-467: The magnetic characteristics of over 200 samples of lithic, roof-tile, and plaster fragments collected from pyroclastic deposits in and around Pompeii to estimate the equilibrium temperatures of the deposits. The deposits were placed by pyroclastic density currents (PDCs) resulting from the collapses of the Plinian column. The authors argue that fragments over 2–5 cm (0.8–2 in) were not in

5544-461: The material adds internal energy to it. At the Curie temperature , the vibration of the molecules is sufficient to disrupt the alignment; the material loses its residual magnetism and assumes whatever magnetic field might be applied to it only for the duration of the application. The authors term this phenomenon unblocking. Residual magnetism is considered to "block out" non-residual fields. A rock

5628-538: The most famous examples. Archaeological excavations have revealed much of the towns and the lives of the inhabitants leading to the area becoming the Vesuvius National Park and a UNESCO World Heritage Site . The total population of both cities was over 20,000. The remains of over 1,500 people have been found at Pompeii and Herculaneum. The total death toll from the eruption remains unknown. A major earthquake caused widespread destruction around

5712-466: The mountain were interpreted as fires, and people as far away as Misenum fled for their lives. The flows were rapid-moving, dense, and very hot, wholly or partly knocking down all structures in their path, incinerating or suffocating the remaining population. These were accompanied by additional tremors and a mild tsunami in the Bay of Naples. One or more earthquakes at this time were strong enough to cause buildings to collapse at least in Pompeii killing

5796-468: The occupants. By the evening of the second day, the eruption stopped affecting Misenum, with only haze in the atmosphere, screening sunlight. Pliny the Younger wrote: broad flames shone out in several places from Mount Vesuvius , which the darkness of the night contributed to render still brighter and clearer... It was now day everywhere else, but there a deeper darkness prevailed than in the thickest night. Sigurðsson , Cashdollar, and Sparks undertook

5880-403: 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 Bassus ) 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

5964-572: The population. As only 85 metres (279 ft) of the coast have been excavated, more casualties may be waiting to be unearthed. Vesuvius and its destructive eruption are mentioned in first-century Roman sources, but not the day of the eruption. For example, Josephus in his Antiquities of the Jews mentions that the eruption occurred "in the days of Titus Caesar ." Suetonius , a second-century historian, in his Life of Titus simply says that, "There were some dreadful disasters during his reign, such as

6048-400: The rescue of Rectina's party. He set off across the bay but encountered thick showers of hot cinders, lumps of pumice, and pieces of rock in the shallows on the other side. Advised by the helmsman to turn back, he stated " Fortune favors the brave " and ordered him to continue to Stabiae (about 4.5 km or 2.8 mi from Pompeii), where Pomponianus was. Pomponianus had already loaded

6132-449: The scattered bones of another 100. The remains of about 332 bodies have been found at Herculaneum (300 in arched vaults discovered in 1980). The total number of fatalities remains unknown. Thirty-eight percent of the 1,044 were found in the ash fall deposits, the majority inside buildings. This differs from modern experience over the last 400 years when ash falls have killed only around 4% of victims during explosive eruptions. This cohort

6216-419: The second surge, the irregularities were gone, and the city was as hot as the surrounding environment. During the last surge, which was very dilute, an additional 1 metre (3.3 ft) of deposits fell over the region. The only surviving eyewitness account of the event consists of two letters by Pliny the Younger , who was 17 at the time of the eruption, written to the historian Tacitus some 25 years after

6300-464: The size of Mount Pinatubo affected the weather for a few years; with warmer winters and cooler summers observed. A similar phenomenon occurred in the April 1815, the eruption of Mount Tambora on Sumbawa island in Indonesia . The Mount Tambora eruption is recognized as the most powerful eruption in recorded history. Its eruption cloud lowered global temperatures as much as 0.4 to 0.7 °C. In

6384-400: The summer. More recently, in 1990 and 2001, archaeologists discovered more remnants of autumnal fruits (such as the pomegranate ), the remains of victims of the eruption in heavy clothing, and large earthenware storage vessels laden with wine (at the time of their burial by Vesuvius). The wine-related discovery suggests that the eruption might have happened after the grape harvest. In 2007,

6468-435: The temperature reached 300 °C (572 °F), which was enough to kill people in a fraction of a second. The contorted postures of bodies as if frozen in suspended action were not the effects of long agony, but of the cadaveric spasm , a consequence of heat shock on corpses. The heat was so intense that organs and blood were vaporised, and at least one victim's brain was vitrified by the temperature. Herculaneum, which

6552-425: The top into a sort of branches. [...] it appeared sometimes bright and sometimes dark and spotted, according as it was either more or less impregnated with earth and cinders. These events and a request by 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, continuing to study and bathe, but that night

6636-418: The vent (roughly where the modern town of Castellammare di Stabia is situated), and his companions were apparently unaffected by the fumes, and so it is more likely that the corpulent Pliny died from some other cause, such as a stroke or heart attack. An asthmatic attack is also not out of the question. His body was found with no apparent injuries the next day once the plume had dispersed. Apart from Pliny

6720-412: The world. The SO 2 in this cloud combined with water (both of volcanic and atmospheric origin) and formed sulfuric acid , blocking a portion of the sunlight from reaching the troposphere . This caused the global temperature to decrease by about 0.4 °C (0.72 °F) from 1992 to 1993. These aerosols caused the ozone layer to reach the lowest concentrations recorded at that time. An eruption

6804-496: The year following the eruption, most of the Northern Hemisphere experienced cooler temperatures during the summer. In the northern hemisphere , 1816 was known as the " Year Without a Summer ". The eruption caused crop failures, food shortages, and floods that killed over 100,000 people across Europe , Asia , and North America . Eruption of Mount Vesuvius in 79 Of the many eruptions of Mount Vesuvius ,

6888-491: Was due to interaction with the buildings. 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. These were as low as 100 °C (212 °F), the boiling point of water. The authors suggest that elements of the bottom of the flow were decoupled from the main flow by topographic irregularities and made cooler by introducing turbulent ambient air. In

6972-399: Was much closer to the crater, was saved from tephra falls by the wind direction but was buried under 23 metres (75 ft) of material deposited by pyroclastic surges. It is likely that most, or all, of the known victims in this town, were killed by the surges, particularly given evidence of high temperatures found on the skeletons of the victims found in the arched vaults on the seashore and

7056-462: Was possibly sheltering in buildings when they were overcome. The remaining 62% of bodies found at Pompeii lay in the pyroclastic surge deposits, which probably killed them. It was initially believed that due to the state of the bodies found at Pompeii and the outline of clothes on the bodies, it was unlikely that high temperatures were a significant cause. Later studies indicated that during the fourth pyroclastic surge (the first surge to reach Pompeii),

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