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Þeistareykir Power Station
Theistareykjarbunga (Þeistareykjarbunga, ) is a shield volcano in north-eastern Iceland with two fissure vents called Þeistareykjahraun and Borgahraun , and two cones: the Stórahversmór and the , Stóravíti . They both are currently extinct, although there is evidence suggesting the potential for activity such as recent localised uplift and seismicity. The multiple vents make up the Theistareykir (Þeistareykir) volcanic system, with more recent evidence that the former classification as a shield volcano is better considered an embryonic central volcano with associated fissure swarm, as rhyolite has erupted in a limited area. The recent lava has picrite, olivine tholeiite basalt characteristics but before the ice age there were basaltic andesite and rhyolite eruptions. There is a central high temperature geothermal area with numerous steam vents and fumaroles. This has been utilised by a 90 MWe power station. Eruptions There have been three dated eruptions, all VEI-0 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Volcanoes In Iceland
There are too many presumed extinct or now inactive volcanic features to list all of these below, so most monogenetic volcanoes can not be mentioned individually. This list of volcanoes in Iceland only includes major active and dormant volcano, volcanic mountains, of which at least 18 vents have erupted since human settlement of Iceland began around 900 AD. Subsequent to the main list a list is presented that classifies the volcanoes into zones, systems and types. This is in the context that there are several classification systems and many of the volcanoes may have separate shallow magma chambers and a deeper common magma source. Where a major vent is part of a larger volcano this is indicated in the list comment. Since some of these vent eruptions have been very large, disruptive or been regarded in popular culture as a separate volcano they have been included in the list but where this is not the case it is not appropriate to duplicate or create entries. So for minor vent eru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Explosivity Index
The volcanic explosivity index (VEI) is a scale used to measure the size of explosive volcanic eruptions. It was devised by Christopher G. Newhall of the United States Geological Survey and Stephen Self in 1982. Volume of products, eruption cloud height, and qualitative observations (using terms ranging from "gentle" to "mega-colossal") are used to determine the explosivity value. The scale is open-ended with the largest eruptions in history given a magnitude of 8. A value of 0 is given for non-explosive eruptions, defined as less than of tephra ejected; and 8 representing a supervolcanic eruption that can eject (240 cubic miles) of tephra and have a cloud column height of over . The scale is logarithmic, with each interval on the scale representing a tenfold increase in observed ejecta criteria, with the exception of between VEI-0, VEI-1 and VEI-2. Classification With indices running from 0 to 8, the VEI associated with an eruption is dependent on how much volcanic materia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Systems Of Iceland
:''The volcano system in Iceland that started activity on August 17, 2014, and ended on February 27, 2015, is Bárðarbunga.'' :''The volcano in Iceland that erupted in May 2011 is Grímsvötn.'' Iceland experiences frequent volcanic activity, due to its location both on the Mid-Atlantic Ridge, a divergent tectonic plate boundary, and being over a hotspot. Nearly thirty volcanoes are known to have erupted in the Holocene epoch; these include Eldgjá, source of the largest lava eruption in human history. Some of the various eruptions of lava, gas and ash have been both destructive of property and deadly to life over the years, as well as disruptive to local and European air travel. Volcanic systems and volcanic zones of Iceland Holocene volcanism in Iceland is mostly to be found in the ''Neovolcanic Zone'', comprising the Reykjanes volcanic belt (RVB), the West volcanic zone (WVZ), the Mid-Iceland belt (MIB), the East volcanic zone (EVZ) and the North volcanic zone (NVZ) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polygenetic Shield Volcanoes
Polygenesis can refer to: * Polygenesis (linguistics), a theory of language origin * Polygenism, an obsolete theory of human origin * Gene duplication Gene duplication (or chromosomal duplication or gene amplification) is a major mechanism through which new genetic material is generated during molecular evolution. It can be defined as any duplication of a region of DNA that contains a gene ..., a form of genetic disorder resulting in the overexpression of a particular gene * Polygenetic landforms, landforms formed the accumulative action of various processes See also * Polygene, member of a group of interacting genes * Monogenism (other) {{disambig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North Volcanic Zone Of Iceland
North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating Direction (geometry), direction or geography. Etymology The word ''north'' is etymology, related to the Old High German ''nord'', both descending from the Proto-Indo-European language, Proto-Indo-European unit *''ner-'', meaning "left; below" as north is to left when facing the rising sun. Similarly, the other cardinal directions are also related to the sun's position. The Latin word ''borealis'' comes from the Ancient Greek, Greek ''boreas'' "north wind, north" which, according to Ovid, was personified as the wind-god Boreas (god), Boreas, the father of Calais and Zetes. ''Septentrionalis'' is from ''septentriones'', "the seven plow oxen", a name of ''Ursa Major''. The Greek ἀρκτικός (''arktikós'') is named for the same constellation, and is the source of the English word ''Arctic''. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shield Volcanoes Of Iceland
A shield is a piece of personal armour held in the hand, which may or may not be strapped to the wrist or forearm. Shields are used to intercept specific attacks, whether from close-ranged weaponry like spears or long ranged projectiles such as arrows. They function as means of active blocks, as well as to provide passive protection by closing one or more lines of engagement during combat. Shields vary greatly in size and shape, ranging from large panels that protect the user's whole body to small models (such as the buckler) that were intended for hand-to-hand-combat use. Shields also vary a great deal in thickness; whereas some shields were made of relatively deep, absorbent, wooden planking to protect soldiers from the impact of spears and crossbow bolts, others were thinner and lighter and designed mainly for deflecting blade strikes (like the roromaraugi or qauata). Finally, shields vary greatly in shape, ranging in roundness to angularity, proportional length and width, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Volcanic Eruptions In Iceland
This is an incomplete list of volcanic eruptions in Iceland. Please see External links below for databases of Icelandic eruptions which include over 530 events. ''For latest information about the current/ongoing series of eruptions near Grindavik on the Reykjanes peninsula - See 2023–2025 Sundhnúkur eruptions'' Index map of eruptions, fissures, glaciers and notable sites Alphabetic index of eruptions, fissures and notable sites Rome wasn't built in a day, (''Under construction.'') There are about 32 volcanic systems in Iceland. Volcanic system means a volcano-tectonic fissure system and – very often a bigger volcano, a so-called central volcano which in most cases is a stratovolcano and may contain a caldera. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanism Of Iceland
:''The volcano system in Iceland that started activity on August 17, 2014, and ended on February 27, 2015, is Bárðarbunga.'' :''The volcano in Iceland that erupted in May 2011 is Grímsvötn.'' Iceland experiences frequent volcanic activity, due to its location both on the Mid-Atlantic Ridge, a divergent tectonic plate boundary, and being over a hotspot. Nearly thirty volcanoes are known to have erupted in the Holocene epoch; these include Eldgjá, source of the largest lava eruption in human history. Some of the various eruptions of lava, gas and ash have been both destructive of property and deadly to life over the years, as well as disruptive to local and European air travel. Volcanic systems and volcanic zones of Iceland Holocene volcanism in Iceland is mostly to be found in the ''Neovolcanic Zone'', comprising the Reykjanes volcanic belt (RVB), the West volcanic zone (WVZ), the Mid-Iceland belt (MIB), the East volcanic zone (EVZ) and the North volcanic zone (NVZ). ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basaltic Andesite
Basaltic andesite is a volcanic rock that is intermediate in composition between basalt and andesite. It is composed predominantly of augite and plagioclase. Basaltic andesite can be found in volcanoes around the world, including in Central America and the Andes of South America. Description Basaltic andesite is a fine-grained (aphanitic) igneous rock that is moderately low in silica and low in alkali metal oxides. It is not separately defined in the QAPF classification, which is based on the relative percentages of quartz, alkali feldspar, plagioclase feldspar, and feldspathoids, but would fall in the basalt-andesite field. This corresponds to rock in which feldspathoid makes up less than 10% and quartz less than 20% of the total QAPF fraction, and in which at least 65% of the feldspar is plagioclase. Basaltic andesite would be further distinguished from basalt and andesite by a silica content between 52% and 57%. Although classification by mineral content is preferred by the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shield Volcano
A shield volcano is a type of volcano named for its low profile, resembling a shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more viscous lava erupted from a stratovolcano. Repeated eruptions result in the steady accumulation of broad sheets of lava, building up the shield volcano's distinctive form. Shield volcanoes are found wherever fluid, low-silica lava reaches the surface of a rocky planet. However, they are most characteristic of ocean Volcanic island, island volcanism associated with Hotspot (geology), hot spots or with Rift, continental rift volcanism. They include the largest active volcanoes on Earth, such as Mauna Loa. Giant shield volcanoes are found on other planets of the Solar System, including Olympus Mons on Mars and Sapas Mons on Venus. Etymology The term 'shield volcano' is taken from the German term ''Schildvulkan'', coined by the Austrian geologist Eduar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tholeiite Basalt
The tholeiitic magma series () is one of two main magma series in subalkaline igneous rocks, the other being the calc-alkaline series. A magma series is a chemically distinct range of magma compositions that describes the evolution of a mafic magma into a more evolved, silica rich end member. Rock types of the tholeiitic magma series include tholeiitic basalt, ferro-basalt, tholeiitic basaltic andesite, tholeiitic andesite, dacite and rhyolite. The variety of basalt in the series was originally called ''tholeiite'' but the International Union of Geological Sciences recommends that ''tholeiitic basalt'' be used in preference to that term.Le Maitre ''et al.'' 2002 Tholeiitic rock types tend to be more enriched in iron and less enriched in magnesium and aluminium than calc-alkaline rock types. They are thought to form in a less oxidized environment than calc-alkaline rocks. Tholeiitic basalt is formed at mid-ocean ridges and makes up much of the oceanic crust. Almost all the ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Olivine
The mineral olivine () is a magnesium iron Silicate minerals, silicate with the chemical formula . It is a type of Nesosilicates, nesosilicate or orthosilicate. The primary component of the Earth's upper mantle (Earth), upper mantle, it is a common mineral in Earth's subsurface, but weathers quickly on the surface. Olivine has many uses, such as the gemstone peridot (or chrysolite), as well as industrial applications like metalworking processes. The ratio of magnesium to iron varies between the two endmember (mineralogy), endmembers of the solid solution series: forsterite (Mg-endmember: ) and fayalite (Fe-endmember: ). Compositions of olivine are commonly expressed as Mole (unit), molar percentages of forsterite (Fo) and/or fayalite (Fa) (''e.g.'', Fo70Fa30, or just Fo70 with Fa30 implied). Forsterite's melting temperature is unusually high at atmospheric pressure, almost , while fayalite's is much lower – about . Melting temperature varies smoothly between the two end ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
