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Sveifluháls
Sveifluháls () is a mafic hyaloclastite ridge of 397 m height in the southwest of Iceland in Gullbringusýsla (Reykjanes Peninsula). It is part of Krýsuvík volcanic system and of the protected area Reykjanes Fólkvangur. Geography The mountain is situated between lake Kleifarvatn and the valley ''Móhálsadalur'' . In some parts of the ridge, there are geothermal areas, esp. at Krýsuvík and Seltún.Lucía Magali Ramír ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Krýsuvík
''For the volcanic landforms around Krýsuvík, see also: Krýsuvík (volcanic system)'' Krýsuvík (also Krísuvík, both pronounced in Icelandic) is an area in Southwest Iceland at about 35 km from Reykjavík. Geography and access It is situated on the Reykjanes peninsula between Þorlákshöfn and Grindavík and accessed by Routes 42 and 427. Name The name Krýsuvík means "bay of Krýsa," a folk tale figure from the area. ''Krýsa'' was an old woman who, together with her cousin ''Herdís,'' could use witchcraft. They had a discussion about the borders of their respective lands; one wanted to cast a spell so that all the fish in a nearby lake would be hairy, the other intended to bring up a storm and let all fishermen die. The dispute ended with the death of both of them. The folk tale says that they were buried side by side, and the place of the graves is still known to locals. The ''Ögmundarhraun'' lava flows which were emitted by the nearby Krýsuvík volca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Krýsuvík (volcanic System)
The volcanic system of Krýsuvík (or Krísuvík, both pronounced in Icelandic), also Krýsuvík-Trölladyngja volcanic system, is situated in the southwest of Iceland on the Reykjanes peninsula. It is located in the middle of Reykjanes and on the divergent plate boundary of the Mid-Atlantic Ridge which traverses Iceland. It was named after the Krýsuvík area which is part of it and consists of a fissure system without a central volcano.Thorvaldur Thordarson, Ármann Höskuldsson: ''Postglacial volcanism in Iceland. Jökull No. 58'' (2008). Retrieved 20 August 2020. The volcanic system has a leng ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reykjanes Volcanic Belt
The Reykjanes Peninsula ( is, Reykjanesskagi ) in southwest Iceland is the continuation of the mostly submarine Reykjanes Ridge, a part of the Mid-Atlantic Ridge, on land and reaching from Esja in the north and Hengill in the east to Reykjanestá in the west.G.B.M. Pedersen, P. Grosse: ''Morphometry of subaerial shield volcanoes and glaciovolcanoes from Reykjanes Peninsula, Iceland: Effects of eruption environment. Journal of Volcanology and Geothermal Research 282'', (2014), 115-133. Retrieved 21 August 2020. Suðurnes (transl. |
Kleifarvatn
Kleifarvatn () is the largest lake on the Reykjanes Peninsula in Iceland, situated in the southern part of the peninsula. It is located on the fissure zone of the Mid-Atlantic Ridge. The lake has no visible water coming in or going out as most of its water comes and leaves underground. The lake can be reached via a track, and there are two areas with high temperature that can be found not far from it: Seltún/Krýsuvík and another to the east. The lake's greatest depth is 97 m. After the 2000 Iceland earthquakes, the lake began to diminish, and 20% of its surface has since disappeared. The novel ''Kleifarvatn'' by Icelandic writer Arnaldur Indriðason was named after the lake. See also *List of lakes of Iceland *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 ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Density Current
In fluid dynamics, a gravity current or density current is a primarily horizontal flow in a gravitational field that is driven by a density difference in a fluid or fluids and is constrained to flow horizontally by, for instance, a ceiling. Typically, the density difference is small enough for the Boussinesq approximation to be valid. Gravity currents can be thought of as either finite in volume, such as the pyroclastic flow from a volcano eruption, or continuously supplied from a source, such as warm air leaving the open doorway of a house in winter. Other examples include dust storms, turbidity currents, avalanches, discharge from wastewater or industrial processes into rivers, or river discharge into the ocean. Gravity currents are typically much longer than they are tall. Flows that are primarily vertical are known as plumes. As a result, it can be shown (using dimensional analysis) that vertical velocities are generally much smaller than horizontal velocities in the curren ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tuff
Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock containing 25% to 75% ash is described as tuffaceous (for example, ''tuffaceous sandstone''). Tuff composed of sandy volcanic material can be referred to as volcanic sandstone. Tuff is a relatively soft rock, so it has been used for construction since ancient times. Because it is common in Italy, the Romans used it often for construction. The Rapa Nui people used it to make most of the ''moai'' statues on Easter Island. Tuff can be classified as either igneous or sedimentary rock. It is usually studied in the context of igneous petrology, although it is sometimes described using sedimentological terms. Tuff is often erroneously called tufa in guidebooks and in television programmes. Volcanic ash The material that is expelled in a volcanic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tuff Cone
Volcanic cones are among the simplest volcanic landforms. They are built by ejecta from a volcanic vent, piling up around the vent in the shape of a cone with a central crater. Volcanic cones are of different types, depending upon the nature and size of the fragments ejected during the eruption. Types of volcanic cones include stratocones, spatter cones, tuff cones, and cinder cones. Stratocone Stratocones are large cone-shaped volcanoes made up of lava flows, explosively erupted pyroclastic rocks, and igneous intrusives that are typically centered around a cylindrical vent. Unlike shield volcanoes, they are characterized by a steep profile and periodic, often alternating, explosive eruptions and effusive eruptions. Some have collapsed craters called calderas. The central core of a stratocone is commonly dominated by a central core of intrusive rocks that range from around to over several kilometers in diameter. This central core is surrounded by multiple generations of lava f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fissure Vent
A fissure vent, also known as a volcanic fissure, eruption fissure or simply a fissure, is a linear volcanic vent through which lava erupts, usually without any explosive eruption, explosive activity. The vent is often a few metres wide and may be many kilometres long. Fissure vents can cause large flood basalts which run first in lava channels and later in lava tubes. After some time, the eruption tends to become focused at one or more spatter cones. Small fissure vents may not be easily discernible from the air, but the crater rows (see Laki) or the canyons (see Eldgjá) built up by some of them are. The Dike_(geology)#Magmatic_dikes, dikes that feed fissures reach the surface from depths of a few kilometers and connect them to deeper magma chamber, magma reservoirs, often under volcanic centers. Fissures are usually found in or along rifts and rift zones, such as Iceland and the East African Rift. Fissure vents are often part of the structure of shield volcanoes. Icelan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jökulhlaup
A jökulhlaup ( ) (literally "glacial run") is a type of glacial outburst flood. It is an Icelandic term that has been adopted in glaciological terminology in many languages. It originally referred to the well-known subglacial outburst floods from Vatnajökull, Iceland, which are triggered by geothermal heating and occasionally by a volcanic subglacial eruption, but it is now used to describe any large and abrupt release of water from a subglacial or proglacial lake/reservoir. Since jökulhlaups emerge from hydrostatically sealed lakes with floating levels far above the threshold, their peak discharge can be much larger than that of a marginal or extra-marginal lake burst. The hydrograph of a jökulhlaup from Vatnajökull typically either climbs over a period of weeks with the largest flow near the end, or it climbs much faster during the course of some hours. These patterns are suggested to reflect channel melting, and sheet flow under the front, respectively. Similar pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Igneous Intrusion
In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and compositions, illustrated by examples like the Palisades Sill of New York and New Jersey; the Henry Mountains of Utah; the Bushveld Igneous Complex of South Africa; Shiprock in New Mexico; the Ardnamurchan intrusion in Scotland; and the Sierra Nevada Batholith of California. Because the solid country rock into which magma intrudes is an excellent insulator, cooling of the magma is extremely slow, and intrusive igneous rock is coarse-grained (phaneritic). Intrusive igneous rocks are classified separately from extrusive igneous rocks, generally on the basis of their mineral content. The relative amounts of quartz, alkali feldspar, plagioclase, and feldspathoid is particularly important in classifying intrusive igneous rocks. Intrusions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tephra
Tephra is fragmental material produced by a volcanic eruption regardless of composition, fragment size, or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts. Once clasts have fallen to the ground, they remain as tephra unless hot enough to fuse into pyroclastic rock or tuff. Tephrochronology is a geochronological technique that uses discrete layers of tephra—volcanic ash from a single eruption—to create a chronological framework in which paleoenvironmental or archaeological records can be placed. When a volcano explodes, it releases a variety of tephra including ash, cinders, and blocks. These layers settle on the land and, over time, sedimentation occurs incorporating these tephra layers into the geologic record. Often, when a volcano explodes, biological organisms are killed and their remains are buried within the tephra layer. These fossils are later dated by scientists to determine the age of the fossil and its place within the geolo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dense-rock Equivalent
Dense-rock equivalent (DRE) is a volcanologic calculation used to estimate volcanic eruption volume. One of the widely accepted measures of the size of a historic or prehistoric eruption is the volume of magma ejected as pumice and volcanic ash, known as tephra during an explosive phase of the eruption, or the volume of lava extruded during an effusive phase of a volcanic eruption. Eruption volumes are commonly expressed in cubic kilometers (km3). Historical and geological estimates of tephra volumes are usually obtained by mapping the distribution and thickness of tephra deposits on the ground after the eruption is over. For historical volcanic explosions, further estimates must be made of tephra deposits that might have changed significantly over time by other geological processes including erosion. Tephra volumes measured in this way must then be corrected for void spaces ( vesicles – bubbles within the pumice, empty spaces between individual pieces of pumice or ash) to get ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
