Misplaced Pages

#374625

46-401: The stratovolcano 's 1902 eruption destroyed the town of Saint-Pierre , killing 29,000 to 30,000 people in the space of a few minutes, in the worst volcanic disaster of the 20th century. The main eruption, on 8 May 1902, left only three known survivors. Ludger Sylbaris survived because he was in a poorly ventilated, dungeon -like jail cell . Léon Compère-Léandre , living on the edge of

92-747: 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

138-419: A clear change in the behavior of the volcanic system, the activity of which is increasing from the base level observed over several decades. The Martinique volcano frog, Allobates chalcopis , is endemic to Mount Pelée, and the only species among related frogs (family Aromobatidae ) endemic to an oceanic island. A 9,262 ha (22,890-acre) largely forested tract, encompassing the mountain and extending to

184-479: 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

230-515: 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

276-465: A long period of quiescence. This stage is grouped by the formation of the Morne Macouba lava dome, then later on, the Morne Macouba caldera . During the intermediate phase, there were several eruptions which produced pyroclastic flows like those that destroyed Saint-Pierre in the 1902 eruption. Around 25,000 years ago, a large southwest sector collapse occurred, forming a landslide . This event

322-769: 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

368-461: 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 ,

414-558: Is a geologist who focuses on understanding the formation and eruptive activity of volcanoes . Volcanologists frequently visit volcanoes, sometimes active ones, to observe and monitor volcanic eruptions , collect eruptive products including tephra (such as ash or pumice ), rock and lava samples. One major focus of inquiry in recent times is the prediction of eruptions to alleviate the impact on surrounding populations and monitor natural hazards associated with volcanic activity. Geologists who research volcanic materials that make up

460-531: 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

506-410: Is currently active. A few volcano tectonic earthquakes occur on Martinique every year, and Mount Pelée is under continuous watch by geophysicists and volcanologists ( IPGP ). Before the 1902 eruption—as early as the summer of 1900—signs of increased fumarole activity were present in the Étang Sec crater. Relatively minor phreatic (steam) eruptions that occurred in 1792 and 1851 were evidence that

SECTION 10

#1732787472375

552-505: Is of Etruscan origin, but unknown meaning. Volcanologists research many aspects of volcanic processes to better understand planetary formation or to monitor current and future volcanic eruptions in order to protect citizens living in volcanic hazard zones. Volcanologists work at universities, museums or other national research institutes (often including volcano observatories), or in industry. Volcanologists working in academia will be usually involved in teaching geology classes if based at

598-476: 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

644-555: Is required. Whether or not it is going to enter a new eruptive period is currently unknown. According to the MVO press release: The increase in seismicity of superficial volcanic origin (up to 4–5 km (2.5–3 mi) below the summit) observed since April 2019, is therefore clearly above the base level characteristic for Mount Pelée. In April 2019, volcanic seismicity appeared at depth around and under Mount Pelée (more than 10 km (6.2 mi) below sea level). It could correspond to

690-451: 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

736-450: 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

782-403: 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

828-537: The Caribbean Plate meets Atlantic oceanic crust belonging to the South American Plate . Other volcanoes in the island arc are also known for their volcanic activity, including Saint Vincent 's La Soufrière , Guadeloupe 's La Grande Soufriere volcano, Montserrat 's Soufrière Hills , and the submarine volcano Kick 'em Jenny . Volcanologists have identified three different phases in

874-824: 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

920-579: 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

966-891: 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

SECTION 20

#1732787472375

1012-443: 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

1058-616: 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

1104-485: 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

1150-585: 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

1196-623: The Martinique Nature Park. Stratovolcano A stratovolcano , also known as 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

1242-819: 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

1288-748: 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

1334-433: The arrival at depth of magmatic fluids. Finally, new recorded tremor-type signals were observed on November 8 and 9, 2020: they could correspond to a reactivation of the hydrothermal system. Even if, in the current state of measurements, there is no deformation of the volcano on the scale of the observation network, the appearance, in a few months, of these three different types of seismic signals of volcanic origin shows

1380-532: The city, escaped with severe burns. The third was a young girl named Havivra Da Ifrile, who fled to a nearby sea cave in a boat, enduring burns from falling ash. In 2023, it was listed as UNESCO World heritage site . Mount Pelée is the result of a typical subduction zone . The subduction formed the Lesser Antilles island arc , a curved chain of volcanoes approximately 850 kilometres (530 mi) in length, between Puerto Rico and Venezuela , where

1426-509: The evolution of Mount Pelée volcano: initial, intermediate, and modern. In an initial phase, called the "Paléo-Pelée" stage, Mount Pelee was a common stratovolcano. The cone of Paléo-Pelée was composed of many layers of lava flows and fragmented volcanic debris. Remains of the Paléo-Pelée cone are still visible at the northern view at the volcano today. A second stage, now called the intermediate phase, started around 100,000 years ago, after

Mount Pelée - Misplaced Pages Continue

1472-540: 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

1518-478: 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

1564-458: 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

1610-504: 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

1656-613: The sea on its north-western side, has been recognised as an Important Bird Area (IBA) by BirdLife International because it supports populations of bridled quail doves , Lesser Antillean swifts , green and purple-throated caribs , blue headed and Antillean crested hummingbirds , Caribbean elaenias , Lesser Antillean flycatchers , Lesser Antillean pewees , scaly-breasted and pearly-eyed thrashers , brown and grey tremblers , rufous-throated solitaires , Antillean euphonias , Martinique orioles , Lesser Antillean saltators and Lesser Antillean bullfinches . On September 16, 2023,

1702-464: 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

1748-641: The solid Earth are referred to as igneous petrologists. The word volcanologist (or vulcanologist ) is derived from the English volcanology ( volcano + -logy ), which was derived from the French volcanologie (or vulcanologie), which was further derived from the French word volcan (volcano), which was even further derived from Vulcanus , the Latin name of the Roman god of fire and metalworking . The Latin word

1794-467: The volcano was active. Signs of unrest are likely to precede any future eruptive activity from Mount Pelée, and its past activity (including the violent eruptions uncovered by carbon dating ) is an extremely important factor for hazard assessment. The city of Saint-Pierre was never fully rebuilt, though some villages grew up in its place. The estimated population of the Commune of Saint-Pierre in 2017

1840-471: The volcanoes and forests of Mount Pelée and the pitons of northern Martinique were listed as UNESCO World Heritage Site . The volcanic mountain range represents 12% of Martinique's territory. It is the 7th natural site in France to be listed as a UNESCO World Heritage site. World Heritage status could also have a positive impact on tourism and the economy, increasing visitor numbers by 30 to 40%, according to

1886-412: 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

Mount Pelée - Misplaced Pages Continue

1932-474: 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 . Volcanologist A volcanologist , or volcano scientist ,

1978-453: Was 4,123. On 6 December 2020, The Martinique Volcano Observatory (MVO) raised Mount Pelee's alert level to Yellow [Restless] from Green [Normal] due to an increase in seismicity under the volcano beginning in April 2019, and observations of tremors the previous month. As far as was known, this was the first sign of activity since the end of the 1929–1932 eruption. This volcano is, of course, highly dangerous, and great vigilance of its activity

2024-476: Was immediately evacuated. The 1929 eruption formed a second dome in the Étang Sec caldera and produced pyroclastic flows emptying into the Blanche River valley. Although there were pyroclastic flows, the activity was not as violent as the 1902 activity. It culminated in another "spine" or lava plug, albeit smaller than the 1902 plug, being emplaced at the summit. The activity ended in late 1932. The volcano

2070-424: Was similar to the eruption of Mount St. Helens in 1980 . The modern stage of the evolution of Mount Pelée has created most of the current cone, with deposits of pumice and the results of past pyroclastic flows. More than 30 eruptions have been identified during the last 5,000 years of the volcano's activity. Three thousand years ago, following a large pumice eruption, the Étang Sec (French for Dry Pond) caldera

2116-405: Was then formed. The 1902 eruption took place within the Étang Sec crater. This eruption formed many pyroclastic flows and produced a dome that filled the caldera. Mount Pelée continued to erupt until 4 July 1905. Thereafter, the volcano was dormant until 1929. On 16 September 1929, Mount Pelée began to erupt again. This time, there was no hesitation on the part of authorities and the danger area

#374625