Lava is molten rock expelled by a volcano during an eruption. In Geology, rock is a naturally occurring aggregate of Minerals and/or Mineraloids The Earth's outer solid layer the ‘ Lithosphere Plate tectonics and hotspots Divergent plate boundaries At the When first expelled from a volcanic vent, it is a liquid at temperatures from 700 °C to 1,200 °C (1,300 °F to 2,200 °F). Liquid is one of the principal States of matter. A liquid is a Fluid that has the particles loose and can freely form a distinct surface at the boundaries of Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature Although lava is quite viscous, with about 100,000 times the viscosity of water, it can flow great distances before cooling and solidifying, because of its thixotropic and shear thinning properties [1], [2]. Viscosity is a measure of the resistance of a Fluid which is being deformed by either Shear stress or Extensional stress. Viscosity is a measure of the resistance of a Fluid which is being deformed by either Shear stress or Extensional stress. Thixotropy is the property of some non-Newtonian pseudoplastic fluids to show a time-dependent change in Viscosity; the longer the fluid undergoes A pseudoplastic material is one in which Viscosity decreases with increasing rate of shear (also termed shear thinning)
A lava flow is a (moving) outpouring of lava, which is created during a non-explosive effusive eruption. Effusive eruptions are a Volcanic phenomenon in some ways the opposite of Explosive eruptions An effusive eruption is characterized by an outpouring of low Viscosity When it has stopped moving, lava solidifies to form igneous rock. Igneous rocks (etymology from Latin ignis, fire are rocks formed by solidification of cooled Magma (molten rock The term lava flow is commonly shortened to lava. Explosive eruptions produce a mixture of volcanic ash and other fragments called tephra, rather than lava flows. An explosive eruption is a Volcanic term to describe a violent explosive type of Eruption. Volcanic ash consists of small Tephra, which are bits of pulverized rock and glass created by volcanic eruptions less than in diameter Tephra is air-fall material produced by a volcanic eruption regardless of composition or fragment size The word 'lava' comes from Italian, and is probably derived from the Latin word labes which means a fall or slide. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. [1][2] The first use in connection with extruded magma (molten rock below the earth's surface) was apparently in a short account written by Francesco Serao on the eruption of Vesuvius between May 14 and June 4, 1737. Magma (Plurals magmas and magmata) is molten rock that sometimes forms beneath the surface of the Earth (or any other Terrestrial planet Mount Vesuvius (in Italian Monte Vesuvio and in Latin Mons Vesuvius) is an active Stratovolcano east of Naples Events 1264 - Battle of Lewes: Henry III of England is captured in France making Simon de Montfort the Events 781 BC - The first historic Solar eclipse is recorded in China. Year 1737 ( MDCCXXXVII) was a Common year starting on Tuesday (link will display the full calendar of the Gregorian calendar (or a [3] Serao described "a flow of fiery lava" as an analogy to the flow of water and mud down the flanks of the volcano following heavy rain. Rain is Liquid precipitation. On Earth it is the condensation of atmospheric Water vapor into drops heavy enough to fall often making it to
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Lava composition
In general, the composition of a lava determines its behavior more than the temperature of its eruption. Igneous rocks, which form lava flows when erupted, can be classified into three chemical types; felsic, intermediate, and mafic. Felsic is a term used in Geology to refer to Silicate minerals, Magma, and rocks which are enriched in the lighter elements such as Silicon Mafic is an adjective describing a Silicate mineral or rock that is rich in magnesium and iron the term was derived by contracting "magnesium" and "ferric" These classes are primarily chemical; however, the chemistry of lava also tends to correlate with the magma temperature, its viscosity and its mode of eruption.
Felsic lavas such as rhyolite and dacite typically form lava spines, lava domes or 'coulees' (which are thick, short lavas) and are associated with pyroclastic (fragmental) deposits. Felsic is a term used in Geology to refer to Silicate minerals, Magma, and rocks which are enriched in the lighter elements such as Silicon This page is about a volcanic rock For the ghost town see Rhyolite Nevada, and for the satellite system see Rhyolite/Aquacade. Dacite ( deɪsaɪt) is an igneous, volcanic rock with a high iron content A lava spine is an upright cylindrical mass of Lava caused by the upward squeezing of pasty lava inside a Volcanic vent. In Volcanology, a lava dome or plug dome is a roughly circular Mound -shaped protrusion resulting from the slow eruption of Felsic Lava Pyroclastic rocks or pyroclastics (derived from the Greek πῦρ, meaning fire and κλαστός, meaning broken are Clastic rocks Most felsic lava flows are extremely viscous, and typically fragment as they extrude, producing blocky autobreccias. The high viscosity and strength are the result of their chemistry, which is high in silica, aluminium, potassium, sodium, and calcium, forming a polymerized liquid rich in feldspar and quartz, which thus has a higher viscosity than other magma types. The Chemical compound silicon dioxide, also known as silica or silox (from the Latin " Silex " is an Oxide WikipediaNaming Potassium (pəˈtæsiəm is a Chemical element. It has the symbol K (kalium from qalīy Atomic number 19 and Atomic mass 39 Sodium (ˈsoʊdiəm is an element which has the symbol Na( Latin natrium, from Arabic natrun) atomic number 11 atomic mass 22 Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 A polymer is a large Molecule ( Macromolecule) composed of repeating Structural units typically connected by Covalent Chemical bonds Feldspar is the name of a group of rock-forming Minerals which make up as much as 60% of the Earth 's crust. Quartz (from German) is the most abundant Mineral in the Earth 's Continental crust (although Feldspar is more common in Felsic magmas can erupt at temperatures as low as 650 to 750 °C. Unusually hot (>950 °C) rhyolite lavas, however, may flow for distances of many tens of kilometres, such as in the Snake River Plain of the northwestern United States. The Snake River Plain is a geologic feature located primarily in the American state of Idaho.
Intermediate or andesitic lavas are lower in aluminium and silica, and usually somewhat richer in magnesium and iron. For the extinct cephalopod genus see Andesites. Andesite (ˈændəsaɪt is an igneous, Volcanic rock, of intermediate Magnesium (mægˈniːziəm is a Chemical element with the symbol Mg, Atomic number 12 Atomic weight 24 Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Intermediate lavas form andesite domes and block lavas, and may occur on steep composite volcanoes, such as in the Andes. For the extinct cephalopod genus see Andesites. Andesite (ˈændəsaɪt is an igneous, Volcanic rock, of intermediate The Andes form the world's longest exposed Mountain range. They lie as a continuous chain of highland along the western coast of South America. Poorer in aluminium and silica than felsic lavas, and also commonly hotter (in the range of 750 to 950 °C), they tend to be less viscous. Greater temperatures tend to destroy polymerized bonds within the magma, promoting more fluid behaviour and also a greater tendency to form phenocrysts. A phenocryst is a relatively large and usually conspicuous Crystal distinctly larger than the grains of the rock groundmass of a Porphyritic Igneous Higher iron and magnesium tends to manifest as a darker groundmass, and also occasionally amphibole or pyroxene phenocrysts. The matrix or groundmass of rock is the fine-grained mass of material in which larger grains or Crystals are embedded Amphibole (pronounced amfi-bowl defines an important group of generally dark-colored rock-forming inosilicate Minerals composed of double chain SiO4 The pyroxenes are a group of important rock-forming Silicate minerals found in many Igneous and metamorphic rocks. A phenocryst is a relatively large and usually conspicuous Crystal distinctly larger than the grains of the rock groundmass of a Porphyritic Igneous
Mafic or basaltic lavas are typified by their high ferromagnesian content, and generally erupt at temperatures in excess of 950 °C. Mafic is an adjective describing a Silicate mineral or rock that is rich in magnesium and iron the term was derived by contracting "magnesium" and "ferric" Basalt (bəˈsɔːlt ˈbeisɔːlt ˈbæsɔːlt is a common Extrusive Volcanic rock. Basaltic magma is high in iron and magnesium, and has relatively lower aluminium and silica, which taken together reduces the degree of polymerization within the melt. Owing to the higher temperatures, viscosities can be relatively low, although still thousands of times more viscous than water. The low degree of polymerization and high temperature favors chemical diffusion, so it is common to see large, well-formed phenocrysts within mafic lavas. Basalt lavas tend can produce low-profile shield volcanoes or 'flood basalt fields', because the fluidal lava flows for long distances from the vent. A shield volcano is a large Volcano with shallow-sloping sides A flood basalt or trap basalt is the result of a giant Volcanic eruption or series of Eruptions that coats large stretches of land or the Ocean floor The thickness of a basalt lava, particularly on a low slope, may be much greater than the thickness of the moving lava flow at any one time, because basalt lavas may 'inflate' by supply of lava beneath a solidified crust. Most basalt lavas are of a'a or 'pahoehoe' types, rather than block lavas. Underwater they can form 'pillow lavas', which are rather similar to entrail-type pahoehoe lavas on land. Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures
Ultramafic lavas such as komatiite and highly magnesian magmas which form boninite take the composition and temperatures of eruptions to the extreme. Ultramafic (also referred to as ultrabasic) rocks are igneous and meta -igneous rocks with very low Silica content (less than 45% generally Komatiites are Ultramafic mantle-derived Volcanic rocks They have low SiO2 low K2O low Al2O3 and high to extremely high Boninite is a Mafic Extrusive rock high in both Magnesium and silica formed in fore-arc environments typically during the early stages Komatiites contain over 18% magnesium oxide, and are thought to have erupted at temperatures of 1600 °C. At this temperature there is no polymerization of the mineral compounds, creating a highly mobile liquid with viscosity as low as that of water. Most if not all ultramafic lavas are no younger than the Proterozoic, with a few ultramafic magmas known from the Phanerozoic. The Proterozoic (ˌproʊtərəˈzoʊɪk is a geological eon representing a period before the first abundant complex life on Earth. The Phanerozoic (occasionally Phanaerozoic) Eon is the current eon in the Geologic timescale, and the one during which abundant animal life has existed No modern komatiite lavas are known, as the Earth's mantle has cooled too much to produce highly magnesian magmas.
Lava behavior
The viscosity of lava is important because it determines how the lava will behave. Lavas with high viscosity are rhyolite, dacite, andesite and trachyte, with cooled basaltic lava also quite viscous; those with low viscosities are freshly erupted basalt, carbonatite and occasionally andesite. This page is about a volcanic rock For the ghost town see Rhyolite Nevada, and for the satellite system see Rhyolite/Aquacade. Dacite ( deɪsaɪt) is an igneous, volcanic rock with a high iron content For the extinct cephalopod genus see Andesites. Andesite (ˈændəsaɪt is an igneous, Volcanic rock, of intermediate Trachyte is an Igneous, Volcanic rock with an Aphanitic to Porphyritic texture Basalt (bəˈsɔːlt ˈbeisɔːlt ˈbæsɔːlt is a common Extrusive Volcanic rock. Carbonatites (kɑrˈbɒnətaɪt are Intrusive or extrusive Igneous rocks defined by mineralogy that comprises more than 50 volume-% Carbonate For the extinct cephalopod genus see Andesites. Andesite (ˈændəsaɪt is an igneous, Volcanic rock, of intermediate
Highly viscous lava shows the following behaviors:
- tends to flow slowly, clog, and form semi-solid blocks which resist flow
- tends to entrap gas, which form vesicles (bubbles) within the rock as they rise to the surface
- correlates with explosive or phreatic eruptions and is associated with tuff and pyroclastic flows
Highly viscous lavas do not usually flow as liquid, and usually form explosive fragmental ash or tephra deposits. Volcanic gases include a variety of substances given off by active (or at times by dormant Volcanoes These include gases trapped in cavities ( Vesicles) in The term phreatic is used in Earth sciences to refer to matters relating to ground water below the static Water table (the word originates from the Greek Tuff (from the Italian "tufo" is a type of rock consisting of consolidated volcanic ash ejected from vents during a volcanic eruption Pyroclastic rocks or pyroclastics (derived from the Greek πῦρ, meaning fire and κλαστός, meaning broken are Clastic rocks Tephra is air-fall material produced by a volcanic eruption regardless of composition or fragment size However, a degassed viscous lava or one which erupts somewhat hotter than usual may form a lava flow.
Lava with low viscosity shows the following behaviors:
- tends to flow easily, forming puddles, channels, and rivers of molten rock
- tends to easily release bubbling gases as they are formed
- eruptions are rarely pyroclastic and are usually quiescent
- volcanoes tend to form broad shields rather than steep cones
There are three forms of low-viscosity lava flows: ʻaʻā, pāhoehoe, and pillow lava. They are described in relation to basaltic flows from Hawaii, shown in the following sections.
Lavas also may contain many other components, sometimes including solid crystals of various minerals, fragments of exotic rocks known as xenoliths and fragments of previously solidified lava. This article concerns the geologic term for other uses see Xenolith (disambiguation A xenolith ( Greek: 'foreign rock' is a rock
Volcanic morphologies
The physical behaviour of lava creates the physical forms of a lava flow or volcano. More fluid basaltic lava flows tend to form flat sheet-like bodies, whereas viscous rhyolite lava flows forms knobbly, blocky masses of rock.
General features of volcanology can be used to classify volcanic edifices and provide information on the eruptions which formed the lava flow, even if the sequence of lavas have been buried or metamorphosed. Volcanology (also spelled vulcanology) is the study of Volcanoes, Lava, Magma, and related geological and Geophysical phenomena
The ideal lava flow will have a brecciated top, either as pillow lava development, autobreccia and rubble typical of ʻaʻā and viscous flows, or a vesicular or frothy carapace such as scoria or pumice. The Pacific Ocean is the largest of the Earth 's Oceanic divisions The Island of Hawaii, also called the Big Island or Hawaii Island, is a volcanic Island in the U Breccia (ˈbrɛtʃiə ˈbrɛʃiə breach is a rock composed of angular fragments of several Minerals or rocks in a matrix, that is a cementing material Scoria is a textural term for macrovesicular Volcanic rock. It is commonly but not exclusively Basaltic or andesitic in composition Pumice is a textural term for a volcanic rock that is a solidified frothy lava composed of highly microvesicular glass Pyroclastic with very thin translucent The top of the lava will tend to be glassy, having been flash frozen in contact with the air or water.
The centre of a lava is commony massive and crystalline, flow banded or layered, with microscopic groundmass crystals. The more viscous lava forms tend to show sheeted flow features, and blocks or breccia entrained within the sticky lava. The crystal size at the centre of a lava will in general be greater than at the margins, as the crystals have more time to grow.
The base of a lava may show evidence of hydrothermal activity if the lava flowed across moist or wet substrates. The lower part of the lava may have vesicles, perhaps filled with minerals (amygdules). Amygdules form when the vesicular cavities (created by expanding gas bubbles in Volcanic Lava) are filled with a secondary Mineral such as The substrate upon which the lava has flowed may show signs of scouring, it may be broken or disturbed by the boiling of trapped water, and in the case of soil profiles, may be baked into a brick-red terracotta. Terra cotta ( Italian: "baked earth" is a Ceramic. Its uses include vessels water & waste water pipes and surface embellishment in Building construction
Discriminating between an intrusive sill and a lava flow in ancient rock sequences can be difficult. In Geology, a sill is a tabular Pluton that has intruded between older layers of Sedimentary rock, beds of Volcanic However, some sills do not usually have brecciated margins, and may show a weak metamorphic aureole on both the upper and lower surface, whereas a lava will only bake the substrate beneath it. However, it is often difficult in practise to identify these metamorphic phenomenon because they are usually weak and restricted in size. Peperitic sills intruded into wet sedimentary rocks, commonly do not bake upper margins and have upper and lower autobreccias, closely similar to lavas.
ʻAʻā
ʻAʻā (also spelled aa, aʻa, ʻaʻa and a-aa, pronounced [ˈʔɑʔɑː] in Hawaiian English, from Hawaiian meaning "stony with rough lava", but also to "burn" or "blaze") is one of three basic types of flow lava. Hawaii Pidgin English, Hawaii Creole English, HCE, or simply Pidgin, is a Creole language based in part on English The Hawaiian language (Hawaiian ‘Ōlelo Hawai‘i) is an Austronesian language that takes its name from Hawai'i, the largest island in the tropical ʻAʻā is basaltic lava characterized by a rough or rubbly surface composed of broken lava blocks called clinker. Basalt (bəˈsɔːlt ˈbeisɔːlt ˈbæsɔːlt is a common Extrusive Volcanic rock.
The loose, broken, and sharp, spiny surface of an ʻaʻā flow makes hiking difficult and slow. The word 'hiking' is understood in all English-speaking countries but there are differences in usage The clinkery surface actually covers a massive dense core, which is the most active part of the flow. As pasty lava in the core travels downslope, the clinkers are carried along at the surface. At the leading edge of an ʻaʻā flow, however, these cooled fragments tumble down the steep front and are buried by the advancing flow. This produces a layer of lava fragments both at the bottom and top of an ʻaʻā flow.
Accretionary lava balls as large as 3 m (10 ft) are common on ʻaʻā flows. ʻAʻā is usually of higher viscosity than pāhoehoe. Pāhoehoe can turn into ʻaʻā if it becomes turbulent from meeting impediments or steep slopes.
The sharp, angled texture makes ʻaʻā a strong radar reflector, and can easily be seen from an orbiting satellite (bright on Magellan pictures). The Magellan spacecraft was a space probe sent to the planet Venus, the first post- Voyager unmanned spacecraft to be launched by NASA
ʻAʻā lavas typically erupt at temperatures of 1000 C to 1100 °C
Pāhoehoe
Pāhoehoe (also spelled pahoehoe, pronounced /pəˌhoʊeˈhoʊe/, Hawaiian English, from Hawaiian, meaning "smooth, unbroken lava") is basaltic lava that has a smooth, billowy, undulating, or ropy surface. Basalt (bəˈsɔːlt ˈbeisɔːlt ˈbæsɔːlt is a common Extrusive Volcanic rock. These surface features are due to the movement of very fluid lava under a congealing surface crust.
A pāhoehoe flow typically advances as a series of small lobes and toes that continually break out from a cooled crust. It also forms lava tubes where the minimal heat loss maintains low viscosity. Lava tubes are natural conduits through which Lava travels beneath the surface of a lava flow expelled by a Volcano during an eruption The surface texture of pāhoehoe flows varies widely, displaying all kinds of bizarre shapes often referred to as lava sculpture. With increasing distance from the source, pāhoehoe flows may change into ʻaʻā flows in response to heat loss and consequent increase in viscosity. Pahoehoe lavas typically have a temperature of 1100 to 1200 °C.
The rounded texture makes pāhoehoe a poor radar reflector, and is difficult to see from an orbiting satellite (dark on Magellan pictures).
Pillow lava
Pillow lava is the rock type typically formed when lava emerges from an underwater volcanic vent or a lava flow enters the ocean. The National Oceanic and Atmospheric Administration ( NOAA) is a scientific agency within the United States Department of Commerce focused on the conditions of the Submarine volcanoes are underwater fissures in the earth's surface from which magma can erupt However, pillow lava can also form when lava is erupted beaneath thick glacial ice. The viscous lava gains a solid crust on contact with the water, and this crust cracks and oozes additional large blobs or "pillows" as more lava emerges from the advancing flow. Since the majority of Earth's surface is covered by water, and most volcanoes are situated near or under it, pillow lava is very common. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001
Lava landforms
Because it is formed from viscous molten rock, lava flows and eruptions create distinctive formations, landforms and topographical features from the macroscopic to the microscopic.
Volcanoes
Volcanoes are the primary landforms built by repeated eruptions of lava and ash over time. Plate tectonics and hotspots Divergent plate boundaries At the They range in shape from shield volcanoes with broad, shallow slopes formed from predominantly effusive eruptions of relatively fluid basaltic lava flows, to steeply-sided stratovolcanoes (also known as composite volcanoes) made of alternating layers of ash and more viscous lava flows typical of intermediate and felsic lavas. A shield volcano is a large Volcano with shallow-sloping sides A stratovolcano, also called a composite volcano is a tall conical Volcano composed of many layers of hardened Lava, Tephra, and Volcanic
A caldera, which is a large subsidence crater, can form in a stratovolcano, if the magma chamber is partially or wholly emptied by large explosive eruptions; the summit cone no longer supports itself and thus collapses in on itelf afterwards. A caldera is a cauldron-like volcanic feature formed by the collapse of land following a volcanic eruption Such features may include volcanic crater lakes and lava domes after the event. However, calderas can also form by non-explosive means such as gradual magma subsidence. This is typical of many shield volcanoes.
Cinder and spatter cones
Cinder cones and spatter cones are small-scale features formed by lava accumulation around a small vent on a volcanic edifice. Volcanic cones are among the simplest Volcano formations in the world A cinder cone or scoria cone is a steep conical Hill of volcanic fragments that accumulate around and downwind from a Volcanic vent. Cinder cones are formed from tephra or ash and tuff which is thrown from an explosive vent. Tephra is air-fall material produced by a volcanic eruption regardless of composition or fragment size Volcanic ash consists of small Tephra, which are bits of pulverized rock and glass created by volcanic eruptions less than in diameter Tuff (from the Italian "tufo" is a type of rock consisting of consolidated volcanic ash ejected from vents during a volcanic eruption Spatter cones are formed by accumulation of molten volcanic slag and cinders ejected in a more liquid form.
Kīpukas
Another Hawaiian English term derived from the Hawaiian language, a kīpuka denotes an elevated area such as a hill, ridge or old lava dome inside or downslope from an area of active volcanism. A kīpuka is an area of land completely surrounded by one or more younger Lava flows Hawaii Pidgin English, Hawaii Creole English, HCE, or simply Pidgin, is a Creole language based in part on English The Hawaiian language (Hawaiian ‘Ōlelo Hawai‘i) is an Austronesian language that takes its name from Hawai'i, the largest island in the tropical New lava flows will cover the surrounding land, isolating the kīpuka so that it appears as a (usually) forested island in a barren lava flow.
Lava domes
Lava domes are formed by the extrusion of viscous felsic magma. They can form prominent rounded protuberances, such as at Valles Caldera. Valles Caldera (or Jemez Caldera) is a very large Volcano (a Supervolcano) at the heart of the Jemez Mountains of northern New Mexico As a volcano extrudes silicic lava, it can form an inflation dome, gradually building up a large, pillow-like structure which cracks, fissures, and may release cooled chunks of rock and rubble. The top and side margins of an inflating lava dome tend to be covered in fragments of rock, breccia and ash. Breccia (ˈbrɛtʃiə ˈbrɛʃiə breach is a rock composed of angular fragments of several Minerals or rocks in a matrix, that is a cementing material
Examples of lava dome eruptions include the Novarupta dome, and successive lava domes of Mount St Helens. Novarupta, meaning "new eruption" is a Volcano located on the Alaska Peninsula in the Katmai, about southwest of Anchorage. Mount St Helens is an active Stratovolcano located in Skamania County, Washington, in the Pacific Northwest region of the United States
Lava tubes
Lava tubes are formed when a flow of relatively fluid lava cools on the upper surface sufficiently to form a crust. Lava tubes are natural conduits through which Lava travels beneath the surface of a lava flow expelled by a Volcano during an eruption Beneath this crust, which by dint of being made of rock is an excellent insulator, the lava can continue to flow as a liquid. When this flow occurs over a prolonged period of time the lava conduit can form a tunnel-like aperture or lava tube, which can conduct molten rock many kilometres from the vent without cooling appreciably. Often these lava tubes drain out once the supply of fresh lava has stopped, leaving a considerable length of open tunnel within the lava flow.
Lava tubes are known from the modern day eruptions of Kīlauea, and significant, extensive and open lava tubes of Tertiary age are known from North Queensland, Australia, some extending for 15 kilometres. Queensland is a state of Australia, occupying the north-eastern corner of the mainland continent For a topic outline on this subject see List of basic Australia topics.
Lava cascades and fountains
The eruptions of lava are sometimes attended by peculiarities which impart to them much additional grandeur. Snow-covered Villarrica, one of Chile 's most active Volcanoes rises above the lake and town of the same name Instances have occurred in which the fiery stream has plunged over a sheer precipice of immense height, so as to produce a glowing cascade exceeding (in breadth and perpendicular descent) the celebrated Niagara Falls. The Niagara Falls are massive Waterfalls on the Niagara River, straddling the international border separating the Canadian province of Ontario In other cases, the lava, instead of at once flowing down the sides of the mountain, has been first thrown up into the air as a fiery fountain several hundred feet in height (see Volcanic cone). Volcanic cones are among the simplest Volcano formations in the world
Lava lakes
Rarely, a volcanic cone may fill with lava but not erupt. Lava lakes are large volumes of molten Lava, usually Basaltic, contained in a vent Volcanic crater, or broad depression Lava which pools within the caldera is known as a lava lake. Lava lakes do not usually persist for long, either draining back into the magma chamber once pressure is relieved (usually by venting of gases through the caldera), or by draining via eruption of lava flows or pyroclastic explosion.
There are only a few sites in the world where permanent lakes of lava exist. These include:
- Mount Erebus, Antarctica
- Pu'u 'Ō'ō and formerly Kīlauea volcanoes, Hawaiʻi
- Erta Ale, Ethiopia
- Nyiragongo, Democratic Republic of Congo
Unusual lavas
Four types of unusual volcanic rocks have been recognised as erupting onto the surface of the Earth:
- Carbonatite and natrocarbonatite lavas are known from Ol Doinyo Lengai volcano in Tanzania, which is the sole example of an active carbonatite volcano. The United States Geological Survey ( USGS) is a scientific agency of the United States government. Carbonatites (kɑrˈbɒnətaɪt are Intrusive or extrusive Igneous rocks defined by mineralogy that comprises more than 50 volume-% Carbonate Natrocarbonatite is a rare Carbonatite Lava which erupts from the Ol Doinyo Lengai Volcano in Tanzania and is part of the volcanic Ol Doinyo Lengai is a Volcano located in the north of Tanzania and is part of the volcanic system of the Great Rift Valley in Eastern Africa Tanzania ˌtænzəˈniːə officially the United Republic of Tanzania (Jamhuri ya Muungano wa Tanzania is a country in East Africa bordered by Kenya [4]
- Copper sulfide bearing lavas have been recognised from Chile and Bolivia[5]
- Iron oxide lavas are thought to be the source of the iron ore at Kiruna, Sweden, erupted in the Proterozoic, and in Chile associated with highly alkaline igneous rocks[6]
- Olivine nephelinite lavas are a unique type of lava that is thought to have come from much deeper in the mantle of the Earth. The term sulfide ( sulphide in British English) refers to several types of Chemical compounds containing Sulfur in its lowest Oxidation Chile, officially the Republic of Chile ( Spanish:) is a country in South America occupying a long and narrow Coastal strip wedged between the The Republic of Bolivia (República de Bolivia) named after Simón Bolívar, is a Landlocked country in central South America. Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Iron ores are rocks and Minerals from which Metallic Iron can be economically extracted Kiruna is the northernmost city of Sweden, situated in Lappland province with roughly inhabitants "Sverige" redirects here For other uses see Sweden (disambiguation and Sverige (disambiguation. The Proterozoic (ˌproʊtərəˈzoʊɪk is a geological eon representing a period before the first abundant complex life on Earth. Nephelinite is a fine-grained or Aphanitic Igneous rock made up almost entirely of Nepheline and Clinopyroxene (variety Augite) The mantle is a part of an Astronomical object. The interior of the Earth, similar to the other Terrestrial planets, is Chemically divided EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 [7]
The term "lava" can also be used to refer to molten "ice mixtures" in eruptions on the icy satellites of the Solar system's gas giants[8].
Hazards
Lava flows are enormously destructive to property in their path but generally move slowly enough for people to get out of their way, so casualties caused directly by active lava flows are rare. Nevertheless injuries and deaths have occurred, either because people had their escape route cut off, because they got too close to the flow[9] or, more rarely, if the lava flow front travelled too quickly.
This notably happened during the eruption of Nyiragongo in Zaire (now Democratic Republic of Congo) on 10 January 1977 when the crater wall was breached during the night and the fluid lava lake in it drained out in less than an hour. Mount Nyiragongo is a Stratovolcano in the Virunga Mountains associated with the Great Rift Valley. The Democratic Republic of the Congo (République démocratique du Congo often referred to as DR Congo, DRC or RDC, and formerly known or referred to Events 49 BC - Julius Caesar crosses the Rubicon, signaling the start of civil war. Also 1977 (album by Ash. Year 1977 ( MCMLXXVII) was a Common year starting on Saturday (link displays Flowing down the steep slopes of the volcano at up to 60 miles per hour (100 km/h), the lava swiftly overwhelmed several villages whilst their residents were asleep. As a result of this disaster, the mountain was designated a Decade Volcano in 1991[10]. The Decade Volcanoes are 16 Volcanoes identified by the International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI as being worthy
Deaths attributed to volcanoes frequently have a different cause, for example volcanic ejecta, pyroclastic flow from a collapsing lava dome, lahars, poisonous gases that travel ahead of lava, or explosions caused when the flow comes into contact with water[9]. A pyroclastic flow (also known as a pyroclastic density current) is a common and devastating result of some volcanic eruptions. A lahar is a type of Mudflow / Landslide composed of Pyroclastic material and Water that flows down from a Volcano, typically
Towns destroyed by lava flows
- Kaimū, Hawaiʻi Destroyed by the eruption of the Kīlauea volcano in 1990. Kaimū was a small town on the Island of Hawai{{okina}}i in the Hawaiian Islands that was completely destroyed by an eruptive flow of Lava from the Kīlauea (kiːlauea is an active Volcano in the Hawaiian Islands, one of five Shield volcanoes that together form the Island of Hawai{{okina}}i (abandoned)
- Kalapana, Hawaiʻi Destroyed by the eruption of the Kīlauea volcano in 1990. Kalapana is a town on the Island of Hawai{{okina}}i in the Hawaiian Islands that was completely destroyed and partly buried by the eruptive flow of Lava Kīlauea (kiːlauea is an active Volcano in the Hawaiian Islands, one of five Shield volcanoes that together form the Island of Hawai{{okina}}i (abandoned)
- Kapoho, Hawaiʻi Destroyed by a lava flow from an eruption of Kīlauea on January 28, 1960. Kapoho Hawaii was a town in Puna district, Hawai{{okina}}i County, Hawai{{okina}}i, located near the eastern tip of the island of Hawai{{okina}}i Kīlauea (kiːlauea is an active Volcano in the Hawaiian Islands, one of five Shield volcanoes that together form the Island of Hawai{{okina}}i Events 1077 - Walk to Canossa: The Excommunication of Henry IV Holy Roman Emperor is lifted Year 1960 ( MCMLX) was a Leap year starting on Friday (link will display full calendar of the Gregorian calendar. (abandoned)
- Keawaiki, Hawaiʻi (abandoned)
- Koaʻe, Hawaiʻi (abandoned)
- San Sebastiano al Vesuvio, Italy Destroyed in 1944 by the most recent eruption of Mount Vesuvius during the Allies' occupation of southern Italy. San Sebastiano al Vesuvio is a commune in the Province of Naples, located on the western slopes of Mount Vesuvius. Mount Vesuvius (in Italian Monte Vesuvio and in Latin Mons Vesuvius) is an active Stratovolcano east of Naples Italy (Italia officially the Italian Republic, (Repubblica Italiana is located on the Italian Peninsula in Southern Europe, and on the two largest (rebuilt)
- Cagsawa, Philippines [11]
Towns partially destroyed by lava flows
- Catania, Italy, in the eruption Mount Etna in 1669 (rebuilt)
- Goma, Democratic Republic of Congo, in the eruption of Nyiragongo in 2002
- Heimaey, Iceland, in the 1973 Eldfell eruption (rebuilt)
- Royal Gardens, Hawaiʻi, by the eruption of Kilauea in 1986-87 (abandoned)
- Parícutin (village after which the volcano was named) and San Juan Parangaricutiro, Mexico, by Parícutin from 1943-1952. Daraga is also another name for Albreda in The Gambia. Daraga is a 1st class municipality in the province of The Philippines ( Filipino: Pilipinas, officially known as the Republic of the Philippines (fil ''Republika ng Pilipinas'' RP Catania ( Greek: &ndash Katánē; Latin: Catăna and Catĭna; Arabic: Goma is a City in the eastern Democratic Republic of the Congo, on the northern shore of Lake Kivu, next to the Rwandan city of Gisenyi Mount Nyiragongo is a Stratovolcano in the Virunga Mountains associated with the Great Rift Valley. Heimaey (pronounced HAY-mah-ay or ˈheɪmaeɪ is the largest island (13 Eldfell is a Cinder cone Volcano just over 200 metres (650 ft high on the Icelandic island of Heimaey. Kīlauea (kiːlauea is an active Volcano in the Hawaiian Islands, one of five Shield volcanoes that together form the Island of Hawai{{okina}}i Parícutin (or Volcán de Parícutin also accented Paricutín by locals to more closely match the pronunciation of the native Purepecha name Parhicutini or spelled unaccented Nuevo San Juan Parangaricutiro, Michoacán, Mexico is a small village near the Parícutin volcano Parícutin (or Volcán de Parícutin also accented Paricutín by locals to more closely match the pronunciation of the native Purepecha name Parhicutini or spelled unaccented
Towns destroyed by tephra
- Pompeii, Italy in the eruption Mount Vesuvius in 79 AD
- Herculaneum, Italy in the eruption Mount Vesuvius in 79 AD
References
- ^ Merriam-Webster OnLine dictionary
- ^ Dictionary.com
- ^ Vesuvius Erupts, 1738
- ^ http://www.geology.sdsu.edu/how_volcanoes_work/Unusual%20lava.html Vic Camp, How volcanoes work, Unusual Lava Types, San Diego State University, Geology
- ^ Guilbert, John M. Pompeii is a ruined and partially buried Roman town-city near modern Naples and Caserta in the Italian region of Campania, in Mount Vesuvius (in Italian Monte Vesuvio and in Latin Mons Vesuvius) is an active Stratovolcano east of Naples Herculaneum (in modern Italian Ercolano) is an ancient Roman town located in the territory of the current commune of Ercolano. Mount Vesuvius (in Italian Monte Vesuvio and in Latin Mons Vesuvius) is an active Stratovolcano east of Naples and Charles F. Park, Jr. ; 1986, The Geology of Ore Deposits, W. H. Freeman, pp556-557, ISBN 0-7167-1456-6
- ^ Guilbert, John M. and Charles F. Park, Jr. ; 1986, The Geology of Ore Deposits, W. H. Freeman, pp404-405, ISBN 0-7167-1456-6
- ^ Catelogue of Canadian volcanoes - Stikine Volcanic Belt: Volcano Mountain Retrieved on 2007-11-23
- ^ McBride and Gilmore (Ed. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 800 - Charlemagne arrives at Rome to investigate the alleged crimes of ); 2007, An introduction to the Solar System, Cambridge University Press, p. 392
- ^ a b Lava Flows and Their Effects USGS
- ^ Nyiragongo -- Could it happen here? USGS Hawaiian Volcano Observatory
- ^ Philippines Government Tourism website
External links
- USGS definition of ʻAʻā
- USGS definition of Pāhoehoe
- Volcanic landforms of Hawaiʻi
- USGS hazards associated with lava flows
- Hawaiian Volcano Observatory Volcano Watch newsletter article on Nyiragongo eruptions, 31 January 2002
- Google Maps Plot of World Volcanoes
- National Geographic lava video Retrieved 23 August 2007
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