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Subaerial Eruption
In volcanology, a subaerial eruption is any sort of volcanic eruption that occurs on the land surface, or in the open air "under the air". They generally produce pyroclastic flows, lava fountains and lava flows, which are commonly classified in different subaerial eruption types, including Plinian, Peléan and Hawaiian eruptions. Subaerial eruptions contrast with subaqueous, submarine A submarine (often shortened to sub) is a watercraft capable of independent operation underwater. (It differs from a submersible, which has more limited underwater capability.) The term "submarine" is also sometimes used historically or infor ... and subglacial eruptions which all originate below forms of a water surface. References Volcanic eruption types {{volcano-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanology
Volcanology (also spelled vulcanology) is the study of volcanoes, lava, magma and related geology, geological, geophysical and geochemistry, geochemical phenomena (volcanism). The term ''volcanology'' is derived from the Latin language, Latin word ''Vulcan (mythology), vulcan''. Vulcan was the ancient Roman mythology, Roman god of fire. A volcanologist is a geologist who studies the eruptive activity and formation of volcanoes and their current and historic eruptions. Volcanologists frequently visit volcanoes, especially active ones, to observe volcanic eruptions, collect eruptive products including tephra (such as Volcanic ash, ash or pumice), Rock (geology), rock and lava samples. One major focus of enquiry is the prediction of eruptions; there is currently no accurate way to do this, but predicting or forecasting eruptions, like predicting earthquakes, could save many lives. Modern volcanology image:Icelandic tephra.JPG, Volcanologist examining tephra horizons in south- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Eruption
A volcanic eruption occurs when material is expelled from a volcanic vent or fissure. Several types of volcanic eruptions have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior has been observed. Some volcanoes may exhibit only one characteristic type of eruption during a period of activity, while others may display an entire sequence of types all in one eruptive series. There are three main types of volcanic eruptions. Magmatic eruptions involve the decompression of gas within magma that propels it forward. Phreatic eruptions are driven by the superheating of steam due to the close proximity of magma. This type exhibits no magmatic release, instead causing the granulation of existing rock. Phreatomagmatic eruptions are driven by the direct interaction of magma and water, as opposed to phreatic eruptions, where no fresh magma reaches the surface. Within these broad eruptive types are several subtypes. The we ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subaerial
In natural science, subaerial (literally "under the air") has been used since 1833,Subaerial in the Merriam-Webster dictionary. notably in and , to describe features and events occurring or formed on or near the 's land surface. They are thus exposed to Earth's atmosphere. This may be contrasted with '' subaqueous'' events or features located below a water surface, '' |
Pyroclastic Flow
A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at average speeds of but is capable of reaching speeds up to . The gases and tephra can reach temperatures of about . Pyroclastic flows are the deadliest of all volcanic hazards and are produced as a result of certain explosive eruptions; they normally touch the ground and hurtle downhill or spread laterally under gravity. Their speed depends upon the density of the current, the volcanic output rate, and the gradient of the slope. Origin of term The word ''pyroclast'' is derived from the Greek (''pýr''), meaning "fire", and (''klastós''), meaning "broken in pieces". A name for pyroclastic flows that glow red in the dark is (French, "burning cloud"); this was notably used to describe the disastrous 1902 eruption of Mount Pelée on Martinique, a Frenc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lava Fountain
Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or underwater, usually at temperatures from . The volcanic rock resulting from subsequent cooling is often also called ''lava''. A lava flow is an outpouring of lava during an effusive eruption. (An explosive eruption, by contrast, produces a mixture of volcanic ash and other fragments called tephra, not lava flows.) The viscosity of most lava is about that of ketchup, roughly 10,000 to 100,000 times that of water. Even so, lava can flow great distances before cooling causes it to solidify, because lava exposed to air quickly develops a solid crust that insulates the remaining liquid lava, helping to keep it hot and inviscid enough to continue flowing. Etymology The word ''lava'' comes from Italian and is probably derived from the Latin wor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plinian Eruption
Plinian eruptions or Vesuvian eruptions are volcanic eruptions characterized by their similarity to the eruption of Mount Vesuvius in 79 AD, which destroyed the ancient Roman cities of Herculaneum and Pompeii. The eruption was described in a letter written by Pliny the Younger, after the death of his uncle Pliny the Elder. Plinian eruptions eject columns of volcanic debris and hot gases high into the stratosphere, the second layer of Earth's atmosphere. They eject a large amount of pumice and have powerful, continuous gas-driven eruptions. Eruptions can end in less than a day, or continue for days or months. The longer eruptions begin with production of clouds of volcanic ash, sometimes with pyroclastic surges. The amount of magma ejected can be so large that it depletes the magma chamber below, causing the top of the volcano to collapse, resulting in a caldera. Fine ash and pulverized pumice can be deposited over large areas. Plinian eruptions are often accompanied by loud s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peléan Eruption
Peléan eruptions are a type of volcanic eruption. They can occur when viscous magma, typically of rhyolitic to andesitic type, is involved, and share some similarities with Vulcanian eruptions. The most important characteristic of a Peléan eruption is the presence of a glowing avalanche of hot volcanic ash, called a pyroclastic flow. Formation of lava domes is another characteristic. Short flows of ash or creation of pumice cones may be observed as well. The initial phases of eruption are characterized by pyroclastic flows. The tephra deposits have lower volume and range than the corresponding Plinian and Vulcanian eruptions. The viscous magma then forms a steep-sided dome or volcanic spine in the volcano's vent. The dome may later collapse, resulting in flows of ash and hot blocks. The eruption cycle is usually completed in a few years, but in some cases may continue for decades, like in the case of Santiaguito. The 1902 eruption of Mount Pelée ( VEI-4) is the first describ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hawaiian Eruption
A Hawaiian eruption is a type of volcanic eruption where lava flows from the vent in a relatively gentle, low level eruption; it is so named because it is characteristic of Hawaiian volcanoes. Typically they are effusive eruptions, with basaltic magmas of low viscosity, low content of gases, and high temperature at the vent. Very small amounts of volcanic ash are produced. This type of eruption occurs most often at hotspot volcanoes such as Kīlauea on Hawaii's big island and in Iceland, though it can occur near subduction zones (e.g. Medicine Lake Volcano in California) and rift zones. Hawaiian eruptions may occur along fissure vents, such as during the eruption of Mauna Loa in 1950, or at a central vent, such as during the 1959 eruption in Kīlauea Iki Crater, which created a lava fountain 580 meters (1,900 ft) high and formed a 38-meter cone named Puu Puai. In fissure-type eruptions, lava spurts from a fissure on the volcano's rift zone and feeds lava streams th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Submarine Eruption
Submarine eruptions are volcano eruptions which take place beneath the surface of water. These occur at constructive margins, subduction zones, and within tectonic plates due to hotspots. This eruption style is far more prevalent than subaerial activity. For example, it is believed that 70 to 80% of the Earth's magma output takes place at mid-ocean ridges.Parfitt, L. and Wilson, L. (2008) ''Fundamentals of Physical Volcanology'', Blackwell Publishing. Detection Submarine eruptions are less studied than subaerial volcanoes due to their inaccessibility. Developments in technology mean that submarine volcanoes can now be studied in greater detail. Despite this progress, understanding is still limited. Mid ocean ridges for example are the most active volcanic systems on Earth but roughly only 5% of their length has been studied in detail.Fagents, S.A., Gregg, T.K.P. and Lopes, R.M.C. (2013) ''Modelling Volcanic processes: the Physics and Mathematics of Volcanism'', Cambridge Univ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subglacial Eruption
Subglacial eruptions, those of ice-covered volcanoes, result in the interaction of magma with ice and snow, leading to meltwater formation, jökulhlaups, and lahars. Flooding associated with meltwater is a significant hazard in some volcanic areas, including Iceland, Alaska, and parts of the Andes. Jökulhlaups (glacial outburst floods) have been identified as the most frequently occurring volcanic hazard in Iceland, with major events where peak discharges of meltwater can reach 10,000 – 100,000 m3/s occurring when there are large eruptions beneath glaciers. It is important to explore volcano-ice interactions to improve the effectiveness of monitoring these events and to undertake hazard assessments. This is particularly relevant given that subglacial eruptions have demonstrated their ability to cause widespread impact, with the ash cloud associated with Iceland's Eyjafjallajökull eruption in 2010 resulting in significant impacts to aviation across Europe. Examples Dec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
