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Lava

January 07, 2023

"Lava flow" redirects here. For the programming anti-pattern, see Lava flow (programming). For other uses, see Lava (disambiguation).

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 800 to 1,200 °C (1,470 to 2,190 °F). The volcanic rock resulting from subsequent cooling is also often called lava.

10-metre-high (33 ft) lava fountain in Hawaii, United States
Lava fountains and flow at Piton de la Fournaise, 2016
Satellite image of a lava flow erupted from SP Crater, Arizona

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.[1]

The word lava comes from Italian and is probably derived from the Latin word labes, which means a fall or slide.[2][3] An early use of the word in connection with extrusion of magma from below the surface is found in a short account of the 1737 eruption of Vesuvius, written by Francesco Serao, who described "a flow of fiery lava" as an analogy to the flow of water and mud down the flanks of the volcano (a lahar) after heavy rain.[4][5]

Properties of lava

Composition

 
Pāhoehoe and ʻaʻā lava flows side by side in Hawaii, September 2007

Solidified lava on the Earth's crust is predominantly silicate minerals: mostly feldspars, feldspathoids, olivine, pyroxenes, amphiboles, micas and quartz.[6] Rare nonsilicate lavas can be formed by local melting of nonsilicate mineral deposits[7] or by separation of a magma into immiscible silicate and nonsilicate liquid phases.[8]

Silicate lavas

Silicate lavas are molten mixtures dominated by oxygen and silicon, the most abundant elements of the Earth's crust, with smaller quantities of aluminium, calcium, magnesium, iron, sodium, and potassium and minor amounts of many other elements.[6] Petrologists routinely express the composition of a silicate lava in terms of the weight or molar mass fraction of the oxides of the major elements (other than oxygen) present in the lava.[9]

The physical behavior of silicate magmas is dominated by the silica component. Silicon ions in lava strongly bind to four oxygen ions in a tetrahedral arrangement. If an oxygen ion is bound to two silicon ions in the melt, it is described as a bridging oxygen, and lava with many clumps or chains of silicon ions connected by bridging oxygen ions is described as partially polymerized. Aluminium in combination with alkali metal oxides (sodium and potassium) also tends to polymerize the lava.[10] Other cations, such as ferrous iron, calcium, and magnesium, bond much more weakly to oxygen and reduce the tendency to polymerize.[11] Partial polymerization makes the lava viscous, so lava high in silica is much more viscous than lava low in silica.[10]

Because of the role of silica in determining viscosity and because many other properties of a lava (such as its temperature) are observed to correlate with silica content, silicate lavas are divided into four chemical types based on silica content: felsic, intermediate, mafic, and ultramafic.[12]

Felsic lava

Felsic or silicic lavas have a silica content greater than 63%. They include rhyolite and dacite lavas. With such a high silica content, these lavas are extremely viscous, ranging from 108 cP (105 Pa⋅s) for hot rhyolite lava at 1,200 °C (2,190 °F) to 1011 cP (108 Pa⋅s) for cool rhyolite lava at 800 °C (1,470 °F).[13] For comparison, water has a viscosity of about 1 cP (0.001 Pa⋅s). Because of this very high viscosity, felsic lavas usually erupt explosively to produce pyroclastic (fragmental) deposits. However, rhyolite lavas occasionally erupt effusively to form lava spines, lava domes or "coulees" (which are thick, short lava flows).[14] The lavas typically fragment as they extrude, producing block lava flows. These often contain obsidian.[15]

Felsic magmas can erupt at temperatures as low as 800 °C (1,470 °F).[16] Unusually hot (>950 °C; >1,740 °F) rhyolite lavas, however, may flow for distances of many tens of kilometres, such as in the Snake River Plain of the northwestern United States.[17]

Intermediate lava

Intermediate or andesitic lavas contain 52% to 63% silica, and are lower in aluminium and usually somewhat richer in magnesium and iron than felsic lavas. Intermediate lavas form andesite domes and block lavas and may occur on steep composite volcanoes, such as in the Andes.[18] They are also commonly hotter than felsic lavas, in the range of 850 to 1,100 °C (1,560 to 2,010 °F). Because of their lower silica content and higher eruptive temperatures, they tend to be much less viscous, with a typical viscosity of 3.5 × 106 cP (3,500 Pa⋅s) at 1,200 °C (2,190 °F). This is slightly greater than the viscosity of smooth peanut butter.[19] Intermediate lavas show a greater tendency to form phenocrysts.[20] Higher iron and magnesium tends to manifest as a darker groundmass, including amphibole or pyroxene phenocrysts.[21]

Mafic lava

Mafic or basaltic lavas are typified by relatively high magnesium oxide and iron oxide content (whose molecular formulas provide the consonants in mafic) and have a silica content limited to a range 52% to 45%. They generally erupt at temperatures of 1,100 to 1,200 °C (2,010 to 2,190 °F) and at relatively low viscosities, around 104 to 105 cP (10 to 100 Pa⋅s). This is similar to the viscosity of ketchup,[22] although it is still many orders of magnitude higher than that of water. Mafic lavas tend to produce low-profile shield volcanoes or flood basalts, because the less viscous lava can flow for long distances from the vent. The thickness of a solidified basaltic lava flow, particularly on a low slope, may be much greater than the thickness of the moving molten lava flow at any one time, because basaltic lavas may "inflate" by a continued supply of lava and its pressure on a solidified crust.[23] Most basaltic lavas are of ʻaʻā or pāhoehoe types, rather than block lavas. Underwater, they can form pillow lavas, which are rather similar to entrail-type pahoehoe lavas on land.[24]

Ultramafic lava

Ultramafic lavas, such as komatiite and highly magnesian magmas that form boninite, take the composition and temperatures of eruptions to the extreme. All have a silica content under 45%. Komatiites contain over 18% magnesium oxide and are thought to have erupted at temperatures of 1,600 °C (2,910 °F). At this temperature there is practically no polymerization of the mineral compounds, creating a highly mobile liquid.[25] Viscosities of komatiite magmas are thought to have been as low as 100 to 1000 cP (0.1 to 1 Pa⋅s), similar to that of light motor oil.[13] Most ultramafic lavas are no younger than the Proterozoic, with a few ultramafic magmas known from the Phanerozoic in Central America that are attributed to a hot mantle plume. No modern komatiite lavas are known, as the Earth's mantle has cooled too much to produce highly magnesian magmas.[26]

Alkaline lavas

Some silicate lavas have an elevated content of alkali metal oxides (sodium and potassium), particularly in regions of continental rifting, areas overlying deeply subducted plates, or at intraplate hotspots.[27] Their silica content can range from ultramafic (nephelinites, basanites and tephrites) to felsic (trachytes). They are more likely to be generated at greater depths in the mantle than subalkaline magmas.[28] Olivine nephelinite lavas are both ultramafic and highly alkaline, and are thought to have come from much deeper in the mantle of the Earth than other lavas.[29]

Examples of lava compositions (wt%)[30]
Component Nephelinite Tholeiitic picrite Tholeiitic basalt Andesite Rhyolite
SiO2 39.7 46.4 53.8 60.0 73.2
TiO2 2.8 2.0 2.0 1.0 0.2
Al2O3 11.4 8.5 13.9 16.0 14.0
Fe2O3 5.3 2.5 2.6 1.9 0.6
FeO 8.2 9.8 9.3 6.2 1.7
MnO 0.2 0.2 0.2 0.2 0.0
MgO 12.1 20.8 4.1 3.9 0.4
CaO 12.8 7.4 7.9 5.9 1.3
Na2O 3.8 1.6 3.0 3.9 3.9
K2O 1.2 0.3 1.5 0.9 4.1
P2O5 0.9 0.2 0.4 0.2 0.0

Tholeiitic basalt lava

  SiO2 (53.8%)
  Al2O3 (13.9%)
  FeO (9.3%)
  CaO (7.9%)
  MgO (4.1%)
  Na2O (3.0%)
  Fe2O3 (2.6%)
  TiO2 (2.0%)
  K2O (1.5%)
  P2O5 (0.4%)
  MnO (0.2%)

Rhyolite lava

  SiO2 (73.2%)
  Al2O3 (14%)
  FeO (1.7%)
  CaO (1.3%)
  MgO (0.4%)
  Na2O (3.9%)
  Fe2O3 (0.6%)
  TiO2 (0.2%)
  K2O (4.1%)
  P2O5 (0.%)
  MnO (0.%)

Non-silicate lavas

See also: Cryovolcano

Some lavas of unusual composition have erupted onto the surface of the Earth. These include:

  • Carbonatite and natrocarbonatite lavas are known from Ol Doinyo Lengai volcano in Tanzania, which is the sole example of an active carbonatite volcano.[31] Carbonatites in the geologic record are typically 75% carbonate minerals, with lesser amounts of silica-undersaturated silicate minerals (such as micas and olivine), apatite, magnetite, and pyrochlore. This may not reflect the original composition of the lava, which may have included sodium carbonate that was subsequently removed by hydrothermal activity, though laboratory experiments show that a calcite-rich magma is possible. Carbonatite lavas show stable isotope ratios indicating they are derived from the highly alkaline silicic lavas with which they are always associated, probably by separation of an immiscible phase.[32] Natrocarbonatite lavas of Ol Doinyo Lengai are composed mostly of sodium carbonate, with about half as much calcium carbonate and half again as much potassium carbonate, and minor amounts of halides, fluorides, and sulphates. The lavas are extremely fluid, with viscosities only slightly greater than water, and are very cool, with measured temperatures of 491 to 544 °C (916 to 1,011 °F).[33]
  • Iron oxide lavas are thought to be the source of the iron ore at Kiruna, Sweden which formed during the Proterozoic.[8] Iron oxide lavas of Pliocene age occur at the El Laco volcanic complex on the Chile-Argentina border.[7] Iron oxide lavas are thought to be the result of immiscible separation of iron oxide magma from a parental magma of calc-alkaline or alkaline composition.[8]
  • Sulfur lava flows up to 250 metres (820 feet) long and 10 metres (33 feet) wide occur at Lastarria volcano, Chile. They were formed by the melting of sulfur deposits at temperatures as low as 113 °C (235 °F).[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.[34]

Rheology

 
Toes of a pāhoehoe advance across a road in Kalapana on the east rift zone of Kīlauea Volcano in Hawaii, United States

The behavior of lava flows is mostly determined by the lava's viscosity. While the temperature of common silicate lava ranges from about 800 °C (1,470 °F) for felsic lavas to 1,200 °C (2,190 °F) for mafic lavas,[16] its viscosity ranges over seven orders of magnitude, from 1011 cP (108 Pa⋅s) for felsic lavas to 104 cP (10 Pa⋅s) for mafic lavas.[16] Lava viscosity is mostly determined by composition but also depends on temperature[13] and shear rate.[35]

Lava viscosity determines the kind of volcanic activity that takes place when the lava is erupted. The greater the viscosity, the greater the tendency for eruptions to be explosive rather than effusive. As a result, most lava flows on Earth, Mars, and Venus are composed of basalt lava.[36] On Earth, 90% of lava flows are mafic or ultramafic, with intermediate lava making up 8% of flows and felsic lava making up just 2% of flows.[37] Viscosity also determines the aspect (thickness relative to lateral extent) of flows, the speed with which flows move, and the surface character of the flows.[13][38]

When highly viscous lavas erupt effusively rather than their more common explosive form, they almost always erupt as high-aspect flows or domes. These flows take the form of block lava rather than ʻaʻā or pāhoehoe. Obsidian flows are common.[39] Intermediate lavas tend to form steep stratovolcanoes, with alternating beds of lava from effusive eruptions and tephra from explosive eruptions.[40] Mafic lavas form relatively thin flows that can move great distances, forming shield volcanoes with gentle slopes.[41]

In addition to melted rock, most lavas contain solid crystals of various minerals, fragments of exotic rocks known as xenoliths, and fragments of previously solidified lava. The crystal content of most lavas gives them thixotropic and shear thinning properties.[42] In other words, most lavas do not behave like Newtonian fluids, in which the rate of flow is proportional to the shear stress. Instead, a typical lava is a Bingham fluid, which shows considerable resistance to flow until a stress threshold, called the yield stress, is crossed.[43] This results in plug flow of partially crystalline lava. A familiar example of plug flow is toothpaste squeezed out of a toothpaste tube. The toothpaste comes out as a semisolid plug, because shear is concentrated in a thin layer in the toothpaste next to the tube and only there does the toothpaste behave as a fluid. Thixotropic behavior also hinders crystals from settling out of the lava.[44] Once the crystal content reaches about 60%, the lava ceases to behave like a fluid and begins to behave like a solid. Such a mixture of crystals with melted rock is sometimes described as crystal mush.[45]

Lava flow speeds vary based primarily on viscosity and slope. In general, lava flows slowly, with typical speeds for Hawaiian basaltic flows of 0.40 km/h (0.25 mph) and maximum speeds of 10 to 48 km/h (6 to 30 mph) on steep slopes.[37] An exceptional speed of 32 to 97 km/h (20 to 60 mph) was recorded following the collapse of a lava lake at Mount Nyiragongo.[37] The scaling relationship for lavas is that the average speed of a flow scales as the square of its thickness divided by its viscosity.[46] This implies that a rhyolite flow would have to be about a thousand times thicker than a basalt flow to flow at a similar speed.

Temperature

 
Columnar jointing in Giant's Causeway in Northern Ireland

The temperature of most types of molten lava ranges from about 800 °C (1,470 °F) to 1,200 °C (2,190 °F).[16] depending on the lava's chemical composition. This temperature range is similar to the hottest temperatures achievable with a forced air charcoal forge.[47] Lava is most fluid when first erupted, becoming much more viscous as its temperature drops.[13]

Lava flows quickly develop an insulating crust of solid rock as a result of radiative loss of heat. Thereafter the lava cools by very slow conduction of heat through the rocky crust. For instance, geologists of the United States Geological Survey regularly drilled into the Kilauea Iki lava lake, formed in an eruption in 1959. After three years, the solid surface crust, whose base was at a temperature of 1,065 °C (1,949 °F), was still only 14 m (46 ft) thick, even though the lake was about 100 m (330 ft) deep. Residual liquid was still present at depths of around 80 m (260 ft) nineteen years after the eruption.[16]

A cooling lava flow shrinks, and this fractures the flow. Basalt flows show a characteristic pattern of fractures. The uppermost parts of the flow show irregular downward-splaying fractures, while the lower part of the flow shows a very regular pattern of fractures that break the flow into five- or six-sided columns. The irregular upper part of the solidified flow is called the entablature, while the lower part that shows columnar jointing is called the colonnade. (The terms are borrowed from Greek temple architecture.) Likewise, regular vertical patterns on the sides of columns, produced by cooling with periodic fracturing, are described as chisel marks. Despite their names, these are natural features produced by cooling, thermal contraction, and fracturing.[48]

As lava cools, crystallizing inwards from its edges, it expels gases to form vesicles at the lower and upper boundaries. These are described as pipe-stem vesicles or pipe-stem amygdales. Liquids expelled from the cooling crystal mush rise upwards into the still-fluid center of the cooling flow and produce vertical vesicle cylinders. Where these merge towards the top of the flow, they form sheets of vesicular basalt and are sometimes capped with gas cavities that sometimes fill with secondary minerals. The beautiful amethyst geodes found in the flood basalts of South America formed in this manner.[49]

Flood basalts typically crystallize little before they cease flowing, and, as a result, flow textures are uncommon in less silicic flows.[50] On the other hand, flow banding is common in felsic flows.[51]

Lava morphology

 
Lava entering the sea to expand the big island of Hawaii, Hawaii Volcanoes National Park

The morphology of lava describes its surface form or texture. More fluid basaltic lava flows tend to form flat sheet-like bodies, whereas viscous rhyolite lava flows form knobbly, blocky masses of rock. Lava erupted underwater has its own distinctive characteristics.

 
Lava enters the Pacific at the Big Island of Hawaii

ʻAʻā

The following subsection is about the types of lava flow. For the sculpture of a god from the Pacific island of Rurutu, see Statue of A'a from Rurutu.
 
Glowing ʻaʻā flow front advancing over pāhoehoe on the coastal plain of Kilauea in Hawaii, United States

ʻAʻā (also spelled aa, aʻa, ʻaʻa, and a-aa, and pronounced [ʔəˈʔaː] or /ˈɑː(ʔ)ɑː/) is one of three basic types of flow lava. ʻAʻā is basaltic lava characterized by a rough or rubbly surface composed of broken lava blocks called clinker. The word is Hawaiian meaning "stony rough lava", but also to "burn" or "blaze";[52] it was introduced as a technical term in geology by Clarence Dutton.[53][54]

The loose, broken, and sharp, spiny surface of an ʻaʻā flow makes hiking difficult and slow. 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.[55]

Accretionary lava balls as large as 3 metres (10 feet) are common on ʻaʻā flows.[56] ʻAʻā is usually of higher viscosity than pāhoehoe. Pāhoehoe can turn into ʻaʻā if it becomes turbulent from meeting impediments or steep slopes.[55]

The sharp, angled texture makes ʻaʻā a strong radar reflector, and can easily be seen from an orbiting satellite (bright on Magellan pictures).[57]

ʻAʻā lavas typically erupt at temperatures of 1,050 to 1,150 °C (1,920 to 2,100 °F) or greater.[58][59]

Pāhoehoe

 
Pāhoehoe lava from Kīlauea volcano, Hawaii, United States

Pāhoehoe (also spelled pahoehoe, from Hawaiian [paːˈhoweˈhowe][60] meaning "smooth, unbroken lava") is basaltic lava that has a smooth, billowy, undulating, or ropy surface. These surface features are due to the movement of very fluid lava under a congealing surface crust. The Hawaiian word was introduced as a technical term in geology by Clarence Dutton.[53][54]

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. 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.[24] Experiments suggest that the transition takes place at a temperature between 1,200 and 1,170 °C (2,190 and 2,140 °F), with some dependence on shear rate.[61][35] Pahoehoe lavas typically have a temperature of 1,100 to 1,200 °C (2,010 to 2,190 °F).[16]

On the Earth, most lava flows are less than 10 km (6.2 mi) long, but some pāhoehoe flows are more than 50 km (31 mi) long.[62] Some flood basalt flows in the geologic record extend for hundreds of kilometres.[63]

The rounded texture makes pāhoehoe a poor radar reflector, and is difficult to see from an orbiting satellite (dark on Magellan picture).[57]

Block lava flows

 
Block lava at Fantastic Lava Beds near Cinder Cone in Lassen Volcanic National Park

Block lava flows are typical of andesitic lavas from stratovolcanoes. They behave in a similar manner to ʻaʻā flows but their more viscous nature causes the surface to be covered in smooth-sided angular fragments (blocks) of solidified lava instead of clinkers. As with ʻaʻā flows, the molten interior of the flow, which is kept insulated by the solidified blocky surface, advances over the rubble that falls off the flow front. They also move much more slowly downhill and are thicker in depth than ʻaʻā flows. [15]

Pillow lava

Main article: Pillow lava
 
Pillow lava on the ocean floor near Hawaii

Pillow lava is the lava structure typically formed when lava emerges from an underwater volcanic vent or subglacial volcano or a lava flow enters the ocean. 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 water covers the majority of Earth's surface and most volcanoes are situated near or under bodies of water, pillow lava is very common.[64]

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

Main article: Volcano
 
Arenal Volcano, Costa Rica, is a stratovolcano.

Volcanoes are the primary landforms built by repeated eruptions of lava and ash over time. 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.[65]

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 itself afterwards.[66] Such features may include volcanic crater lakes and lava domes after the event.[67] However, calderas can also form by non-explosive means such as gradual magma subsidence. This is typical of many shield volcanoes.[68]

Cinder and spatter cones

Main article: Volcanic cone

Cinder cones and spatter cones are small-scale features formed by lava accumulation around a small vent on a volcanic edifice. Cinder cones are formed from tephra or ash and tuff which is thrown from an explosive vent. Spatter cones are formed by accumulation of molten volcanic slag and cinders ejected in a more liquid form.[69]

Kīpukas

Main article: Kīpuka

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. 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.[70]

Lava domes and coulées

Main article: Lava dome
 
A forested lava dome in the midst of the Valle Grande, the largest meadow in the Valles Caldera National Preserve, New Mexico, United States

Lava domes are formed by the extrusion of viscous felsic magma. They can form prominent rounded protuberances, such as at Valles Caldera. As a volcano extrudes silicic lava, it can form an inflation dome or endogenous 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.[71]

Examples of lava dome eruptions include the Novarupta dome, and successive lava domes of Mount St Helens.[72]

When a dome forms on an inclined surface it can flow in short thick flows called coulées (dome flows). These flows often travel only a few kilometres from the vent.[39]

Lava tubes

Main article: Lava tube

Lava tubes are formed when a flow of relatively fluid lava cools on the upper surface sufficiently to form a crust. Beneath this crust, which 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.[73]

Lava tubes are known from the modern day eruptions of Kīlauea,[74] and significant, extensive and open lava tubes of Tertiary age are known from North Queensland, Australia, some extending for 15 kilometres (9 miles).[75]

Lava lakes

Main article: Lava lake
 
Shiprock, New Mexico, United States: a volcanic neck in the distance, with a radiating dike on its south side

Rarely, a volcanic cone may fill with lava but not erupt. Lava which pools within the caldera is known as a lava lake.[76] 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:

Lava delta

Main article: Lava delta

Lava deltas form wherever sub-aerial flows of lava enter standing bodies of water. The lava cools and breaks up as it encounters the water, with the resulting fragments filling in the seabed topography such that the sub-aerial flow can move further offshore. Lava deltas are generally associated with large-scale, effusive type basaltic volcanism.[80]

Lava fountains

 
450 m-high lava fountain at Kilauea

A lava fountain is a volcanic phenomenon in which lava is forcefully but non-explosively ejected from a crater, vent, or fissure. The highest lava fountain recorded was during the 23 November 2013 eruption of Mount Etna in Italy, which reached a stable height of around 2,500 m (8,200 ft) for 18 minutes, briefly peaking at a height of 3,400 m (11,000 ft).[81] Lava fountains may occur as a series of short pulses, or a continuous jet of lava. They are commonly associated with Hawaiian eruptions.[82]

Hazards

Lava flows are enormously destructive to property in their path. However, casualties are rare since flows are usually slow enough for people and animals to escape, though this is dependent on the viscosity of the lava. Nevertheless, injuries and deaths have occurred, either because they had their escape route cut off, because they got too close to the flow[83] or, more rarely, if the lava flow front travels too quickly. This notably happened during the eruption of Nyiragongo in Zaire (now Democratic Republic of the Congo). On the night of 10 January 1977 a crater wall was breached and a fluid lava lake drained out in under an hour. The resulting flow sped down the steep slopes at up to 100 km/h (62 mph), and overwhelmed several villages while residents were asleep. As a result of this disaster, the mountain was designated a Decade Volcano in 1991.[84]

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.[83] A particularly dangerous area is called a lava bench. This very young ground will typically break off and fall into the sea.

Areas of recent lava flows continue to represent a hazard long after the lava has cooled. Where young flows have created new lands, land is more unstable and can break off into the sea. Flows often crack deeply, forming dangerous chasms, and a fall against ʻaʻā lava is similar to falling against broken glass. Rugged hiking boots, long pants, and gloves are recommended when crossing lava flows.

Diverting a lava flow is extremely difficult, but it can be accomplished in some circumstances, as was once partially achieved in Vestmannaeyjar, Iceland.[85] The optimal design of simple, low-cost barriers that divert lava flows is an area of ongoing research.[86][87]

Towns destroyed by lava flows

 
Lava can easily destroy entire towns. This picture shows one of over 100 houses destroyed by the lava flow in Kalapana, Hawaii, United States, in 1990.

Towns damaged by lava flows

Towns destroyed by tephra

Tephra is lava in the form of volcanic ash, lapilli, volcanic bombs or volcanic blocks.

See also

  • Laze (geology) – Acid haze formed when molten lava enters the cold ocean
  • Vog – Air pollution resulting from volcanic gases reacting with the atmosphere
  • Blue lava – Optical phenomenon resulting from burning sulfur

References

  1. ^ Philpotts, Anthony R.; Ague, Jay J. (2009). Principles of igneous and metamorphic petrology (2nd ed.). Cambridge, UK: Cambridge University Press. pp. 53–55. ISBN 9780521880060.
  2. ^ "Lava". Merriam-Webster Online Dictionary. 2012-08-31. Retrieved 8 December 2013.
  3. ^ "Lava". Dictionary.reference.com. 1994-12-07. Retrieved 8 December 2013.
  4. ^ Serao, Francesco (1778). Istoria dell' incendio del Vesuvio accaduto nel mese di maggio dell'anno MDCCXXXVII. Naples: Presso Il De Bonis. Retrieved 6 August 2022.
  5. ^ "Vesuvius Erupts, 1738". Linda Hall Library of Science, Engineering & Technology. Retrieved 6 August 2022.
  6. ^ a b Philpotts & Ague 2009, p. 19.
  7. ^ a b c Guijón, R.; Henríquez, F.; Naranjo, J.A. (2011). "Geological, Geographical and Legal Considerations for the Conservation of Unique Iron Oxide and Sulphur Flows at El Laco and Lastarria Volcanic Complexes, Central Andes, Northern Chile". Geoheritage. 3 (4): 99–315. doi:10.1007/s12371-011-0045-x. S2CID 129179725.
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  9. ^ Philpotts & Ague 2009, pp. 132–133.
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External links

 
Look up lava, aa, or pahoehoe in Wiktionary, the free dictionary.
 
Wikimedia Commons has media related to:
lava (category)
  • USGS definition of ʻAʻā
  • USGS definition of Pāhoehoe
  • USGS definition of Ropy Pāhoehoe
  • USGS hazards associated with lava flows
  • Hawaiian Volcano Observatory Volcano Watch newsletter article on Nyiragongo eruptions, 31 January 2002
  • National Geographic lava video 2016-03-03 at the Wayback Machine Retrieved 23 August 2007

January 07, 2023
lava, flow, redirects, here, programming, anti, pattern, flow, programming, other, uses, disambiguation, molten, partially, molten, rock, magma, that, been, expelled, from, interior, terrestrial, planet, such, earth, moon, onto, surface, erupted, volcano, thro. Lava flow redirects here For the programming anti pattern see Lava flow programming For other uses see Lava disambiguation 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 800 to 1 200 C 1 470 to 2 190 F The volcanic rock resulting from subsequent cooling is also often called lava 10 metre high 33 ft lava fountain in Hawaii United States Lava fountains and flow at Piton de la Fournaise 2016 Satellite image of a lava flow erupted from SP Crater Arizona 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 1 The word lava comes from Italian and is probably derived from the Latin word labes which means a fall or slide 2 3 An early use of the word in connection with extrusion of magma from below the surface is found in a short account of the 1737 eruption of Vesuvius written by Francesco Serao who described a flow of fiery lava as an analogy to the flow of water and mud down the flanks of the volcano a lahar after heavy rain 4 5 Contents 1 Properties of lava 1 1 Composition 1 1 1 Silicate lavas 1 1 1 1 Felsic lava 1 1 1 2 Intermediate lava 1 1 1 3 Mafic lava 1 1 1 4 Ultramafic lava 1 1 1 5 Alkaline lavas 1 1 2 Non silicate lavas 1 2 Rheology 1 3 Temperature 2 Lava morphology 2 1 ʻAʻa 2 2 Pahoehoe 2 3 Block lava flows 2 4 Pillow lava 3 Lava landforms 3 1 Volcanoes 3 2 Cinder and spatter cones 3 3 Kipukas 3 4 Lava domes and coulees 3 5 Lava tubes 3 6 Lava lakes 3 7 Lava delta 4 Lava fountains 5 Hazards 6 Towns destroyed by lava flows 7 Towns damaged by lava flows 8 Towns destroyed by tephra 9 See also 10 References 11 External linksProperties of lavaComposition Pahoehoe and ʻaʻa lava flows side by side in Hawaii September 2007 Solidified lava on the Earth s crust is predominantly silicate minerals mostly feldspars feldspathoids olivine pyroxenes amphiboles micas and quartz 6 Rare nonsilicate lavas can be formed by local melting of nonsilicate mineral deposits 7 or by separation of a magma into immiscible silicate and nonsilicate liquid phases 8 Silicate lavas Silicate lavas are molten mixtures dominated by oxygen and silicon the most abundant elements of the Earth s crust with smaller quantities of aluminium calcium magnesium iron sodium and potassium and minor amounts of many other elements 6 Petrologists routinely express the composition of a silicate lava in terms of the weight or molar mass fraction of the oxides of the major elements other than oxygen present in the lava 9 The physical behavior of silicate magmas is dominated by the silica component Silicon ions in lava strongly bind to four oxygen ions in a tetrahedral arrangement If an oxygen ion is bound to two silicon ions in the melt it is described as a bridging oxygen and lava with many clumps or chains of silicon ions connected by bridging oxygen ions is described as partially polymerized Aluminium in combination with alkali metal oxides sodium and potassium also tends to polymerize the lava 10 Other cations such as ferrous iron calcium and magnesium bond much more weakly to oxygen and reduce the tendency to polymerize 11 Partial polymerization makes the lava viscous so lava high in silica is much more viscous than lava low in silica 10 Because of the role of silica in determining viscosity and because many other properties of a lava such as its temperature are observed to correlate with silica content silicate lavas are divided into four chemical types based on silica content felsic intermediate mafic and ultramafic 12 Felsic lava Felsic or silicic lavas have a silica content greater than 63 They include rhyolite and dacite lavas With such a high silica content these lavas are extremely viscous ranging from 108 cP 105 Pa s for hot rhyolite lava at 1 200 C 2 190 F to 1011 cP 108 Pa s for cool rhyolite lava at 800 C 1 470 F 13 For comparison water has a viscosity of about 1 cP 0 001 Pa s Because of this very high viscosity felsic lavas usually erupt explosively to produce pyroclastic fragmental deposits However rhyolite lavas occasionally erupt effusively to form lava spines lava domes or coulees which are thick short lava flows 14 The lavas typically fragment as they extrude producing block lava flows These often contain obsidian 15 Felsic magmas can erupt at temperatures as low as 800 C 1 470 F 16 Unusually hot gt 950 C gt 1 740 F rhyolite lavas however may flow for distances of many tens of kilometres such as in the Snake River Plain of the northwestern United States 17 Intermediate lava Intermediate or andesitic lavas contain 52 to 63 silica and are lower in aluminium and usually somewhat richer in magnesium and iron than felsic lavas Intermediate lavas form andesite domes and block lavas and may occur on steep composite volcanoes such as in the Andes 18 They are also commonly hotter than felsic lavas in the range of 850 to 1 100 C 1 560 to 2 010 F Because of their lower silica content and higher eruptive temperatures they tend to be much less viscous with a typical viscosity of 3 5 106 cP 3 500 Pa s at 1 200 C 2 190 F This is slightly greater than the viscosity of smooth peanut butter 19 Intermediate lavas show a greater tendency to form phenocrysts 20 Higher iron and magnesium tends to manifest as a darker groundmass including amphibole or pyroxene phenocrysts 21 Mafic lava Mafic or basaltic lavas are typified by relatively high magnesium oxide and iron oxide content whose molecular formulas provide the consonants in mafic and have a silica content limited to a range 52 to 45 They generally erupt at temperatures of 1 100 to 1 200 C 2 010 to 2 190 F and at relatively low viscosities around 104 to 105 cP 10 to 100 Pa s This is similar to the viscosity of ketchup 22 although it is still many orders of magnitude higher than that of water Mafic lavas tend to produce low profile shield volcanoes or flood basalts because the less viscous lava can flow for long distances from the vent The thickness of a solidified basaltic lava flow particularly on a low slope may be much greater than the thickness of the moving molten lava flow at any one time because basaltic lavas may inflate by a continued supply of lava and its pressure on a solidified crust 23 Most basaltic lavas are of ʻaʻa or pahoehoe types rather than block lavas Underwater they can form pillow lavas which are rather similar to entrail type pahoehoe lavas on land 24 Ultramafic lava Ultramafic lavas such as komatiite and highly magnesian magmas that form boninite take the composition and temperatures of eruptions to the extreme All have a silica content under 45 Komatiites contain over 18 magnesium oxide and are thought to have erupted at temperatures of 1 600 C 2 910 F At this temperature there is practically no polymerization of the mineral compounds creating a highly mobile liquid 25 Viscosities of komatiite magmas are thought to have been as low as 100 to 1000 cP 0 1 to 1 Pa s similar to that of light motor oil 13 Most ultramafic lavas are no younger than the Proterozoic with a few ultramafic magmas known from the Phanerozoic in Central America that are attributed to a hot mantle plume No modern komatiite lavas are known as the Earth s mantle has cooled too much to produce highly magnesian magmas 26 Alkaline lavas Some silicate lavas have an elevated content of alkali metal oxides sodium and potassium particularly in regions of continental rifting areas overlying deeply subducted plates or at intraplate hotspots 27 Their silica content can range from ultramafic nephelinites basanites and tephrites to felsic trachytes They are more likely to be generated at greater depths in the mantle than subalkaline magmas 28 Olivine nephelinite lavas are both ultramafic and highly alkaline and are thought to have come from much deeper in the mantle of the Earth than other lavas 29 Examples of lava compositions wt 30 Component Nephelinite Tholeiitic picrite Tholeiitic basalt Andesite RhyoliteSiO2 39 7 46 4 53 8 60 0 73 2TiO2 2 8 2 0 2 0 1 0 0 2Al2O3 11 4 8 5 13 9 16 0 14 0Fe2O3 5 3 2 5 2 6 1 9 0 6FeO 8 2 9 8 9 3 6 2 1 7MnO 0 2 0 2 0 2 0 2 0 0MgO 12 1 20 8 4 1 3 9 0 4CaO 12 8 7 4 7 9 5 9 1 3Na2O 3 8 1 6 3 0 3 9 3 9K2O 1 2 0 3 1 5 0 9 4 1P2O5 0 9 0 2 0 4 0 2 0 0 Tholeiitic basalt lava SiO2 53 8 Al2O3 13 9 FeO 9 3 CaO 7 9 MgO 4 1 Na2O 3 0 Fe2O3 2 6 TiO2 2 0 K2O 1 5 P2O5 0 4 MnO 0 2 Rhyolite lava SiO2 73 2 Al2O3 14 FeO 1 7 CaO 1 3 MgO 0 4 Na2O 3 9 Fe2O3 0 6 TiO2 0 2 K2O 4 1 P2O5 0 MnO 0 Non silicate lavas See also Cryovolcano Some lavas of unusual composition have erupted onto the surface of the Earth These include Carbonatite and natrocarbonatite lavas are known from Ol Doinyo Lengai volcano in Tanzania which is the sole example of an active carbonatite volcano 31 Carbonatites in the geologic record are typically 75 carbonate minerals with lesser amounts of silica undersaturated silicate minerals such as micas and olivine apatite magnetite and pyrochlore This may not reflect the original composition of the lava which may have included sodium carbonate that was subsequently removed by hydrothermal activity though laboratory experiments show that a calcite rich magma is possible Carbonatite lavas show stable isotope ratios indicating they are derived from the highly alkaline silicic lavas with which they are always associated probably by separation of an immiscible phase 32 Natrocarbonatite lavas of Ol Doinyo Lengai are composed mostly of sodium carbonate with about half as much calcium carbonate and half again as much potassium carbonate and minor amounts of halides fluorides and sulphates The lavas are extremely fluid with viscosities only slightly greater than water and are very cool with measured temperatures of 491 to 544 C 916 to 1 011 F 33 Iron oxide lavas are thought to be the source of the iron ore at Kiruna Sweden which formed during the Proterozoic 8 Iron oxide lavas of Pliocene age occur at the El Laco volcanic complex on the Chile Argentina border 7 Iron oxide lavas are thought to be the result of immiscible separation of iron oxide magma from a parental magma of calc alkaline or alkaline composition 8 Sulfur lava flows up to 250 metres 820 feet long and 10 metres 33 feet wide occur at Lastarria volcano Chile They were formed by the melting of sulfur deposits at temperatures as low as 113 C 235 F 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 34 Rheology Toes of a pahoehoe advance across a road in Kalapana on the east rift zone of Kilauea Volcano in Hawaii United States The behavior of lava flows is mostly determined by the lava s viscosity While the temperature of common silicate lava ranges from about 800 C 1 470 F for felsic lavas to 1 200 C 2 190 F for mafic lavas 16 its viscosity ranges over seven orders of magnitude from 1011 cP 108 Pa s for felsic lavas to 104 cP 10 Pa s for mafic lavas 16 Lava viscosity is mostly determined by composition but also depends on temperature 13 and shear rate 35 Lava viscosity determines the kind of volcanic activity that takes place when the lava is erupted The greater the viscosity the greater the tendency for eruptions to be explosive rather than effusive As a result most lava flows on Earth Mars and Venus are composed of basalt lava 36 On Earth 90 of lava flows are mafic or ultramafic with intermediate lava making up 8 of flows and felsic lava making up just 2 of flows 37 Viscosity also determines the aspect thickness relative to lateral extent of flows the speed with which flows move and the surface character of the flows 13 38 When highly viscous lavas erupt effusively rather than their more common explosive form they almost always erupt as high aspect flows or domes These flows take the form of block lava rather than ʻaʻa or pahoehoe Obsidian flows are common 39 Intermediate lavas tend to form steep stratovolcanoes with alternating beds of lava from effusive eruptions and tephra from explosive eruptions 40 Mafic lavas form relatively thin flows that can move great distances forming shield volcanoes with gentle slopes 41 In addition to melted rock most lavas contain solid crystals of various minerals fragments of exotic rocks known as xenoliths and fragments of previously solidified lava The crystal content of most lavas gives them thixotropic and shear thinning properties 42 In other words most lavas do not behave like Newtonian fluids in which the rate of flow is proportional to the shear stress Instead a typical lava is a Bingham fluid which shows considerable resistance to flow until a stress threshold called the yield stress is crossed 43 This results in plug flow of partially crystalline lava A familiar example of plug flow is toothpaste squeezed out of a toothpaste tube The toothpaste comes out as a semisolid plug because shear is concentrated in a thin layer in the toothpaste next to the tube and only there does the toothpaste behave as a fluid Thixotropic behavior also hinders crystals from settling out of the lava 44 Once the crystal content reaches about 60 the lava ceases to behave like a fluid and begins to behave like a solid Such a mixture of crystals with melted rock is sometimes described as crystal mush 45 Lava flow speeds vary based primarily on viscosity and slope In general lava flows slowly with typical speeds for Hawaiian basaltic flows of 0 40 km h 0 25 mph and maximum speeds of 10 to 48 km h 6 to 30 mph on steep slopes 37 An exceptional speed of 32 to 97 km h 20 to 60 mph was recorded following the collapse of a lava lake at Mount Nyiragongo 37 The scaling relationship for lavas is that the average speed of a flow scales as the square of its thickness divided by its viscosity 46 This implies that a rhyolite flow would have to be about a thousand times thicker than a basalt flow to flow at a similar speed Temperature Columnar jointing in Giant s Causeway in Northern Ireland The temperature of most types of molten lava ranges from about 800 C 1 470 F to 1 200 C 2 190 F 16 depending on the lava s chemical composition This temperature range is similar to the hottest temperatures achievable with a forced air charcoal forge 47 Lava is most fluid when first erupted becoming much more viscous as its temperature drops 13 Lava flows quickly develop an insulating crust of solid rock as a result of radiative loss of heat Thereafter the lava cools by very slow conduction of heat through the rocky crust For instance geologists of the United States Geological Survey regularly drilled into the Kilauea Iki lava lake formed in an eruption in 1959 After three years the solid surface crust whose base was at a temperature of 1 065 C 1 949 F was still only 14 m 46 ft thick even though the lake was about 100 m 330 ft deep Residual liquid was still present at depths of around 80 m 260 ft nineteen years after the eruption 16 A cooling lava flow shrinks and this fractures the flow Basalt flows show a characteristic pattern of fractures The uppermost parts of the flow show irregular downward splaying fractures while the lower part of the flow shows a very regular pattern of fractures that break the flow into five or six sided columns The irregular upper part of the solidified flow is called the entablature while the lower part that shows columnar jointing is called the colonnade The terms are borrowed from Greek temple architecture Likewise regular vertical patterns on the sides of columns produced by cooling with periodic fracturing are described as chisel marks Despite their names these are natural features produced by cooling thermal contraction and fracturing 48 As lava cools crystallizing inwards from its edges it expels gases to form vesicles at the lower and upper boundaries These are described as pipe stem vesicles or pipe stem amygdales Liquids expelled from the cooling crystal mush rise upwards into the still fluid center of the cooling flow and produce vertical vesicle cylinders Where these merge towards the top of the flow they form sheets of vesicular basalt and are sometimes capped with gas cavities that sometimes fill with secondary minerals The beautiful amethyst geodes found in the flood basalts of South America formed in this manner 49 Flood basalts typically crystallize little before they cease flowing and as a result flow textures are uncommon in less silicic flows 50 On the other hand flow banding is common in felsic flows 51 Lava morphology Lava entering the sea to expand the big island of Hawaii Hawaii Volcanoes National Park The morphology of lava describes its surface form or texture More fluid basaltic lava flows tend to form flat sheet like bodies whereas viscous rhyolite lava flows form knobbly blocky masses of rock Lava erupted underwater has its own distinctive characteristics Lava enters the Pacific at the Big Island of Hawaii ʻAʻa The following subsection is about the types of lava flow For the sculpture of a god from the Pacific island of Rurutu see Statue of A a from Rurutu Glowing ʻaʻa flow front advancing over pahoehoe on the coastal plain of Kilauea in Hawaii United States ʻAʻa also spelled aa aʻa ʻaʻa and a aa and pronounced ʔeˈʔaː or ˈ ɑː ʔ ɑː is one of three basic types of flow lava ʻAʻa is basaltic lava characterized by a rough or rubbly surface composed of broken lava blocks called clinker The word is Hawaiian meaning stony rough lava but also to burn or blaze 52 it was introduced as a technical term in geology by Clarence Dutton 53 54 The loose broken and sharp spiny surface of an ʻaʻa flow makes hiking difficult and slow 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 ʻaʻa 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 ʻaʻa flow 55 Accretionary lava balls as large as 3 metres 10 feet are common on ʻaʻa flows 56 ʻAʻa is usually of higher viscosity than pahoehoe Pahoehoe can turn into ʻaʻa if it becomes turbulent from meeting impediments or steep slopes 55 The sharp angled texture makes ʻaʻa a strong radar reflector and can easily be seen from an orbiting satellite bright on Magellan pictures 57 ʻAʻa lavas typically erupt at temperatures of 1 050 to 1 150 C 1 920 to 2 100 F or greater 58 59 Pahoehoe Pahoehoe lava from Kilauea volcano Hawaii United States Pahoehoe also spelled pahoehoe from Hawaiian paːˈhoweˈhowe 60 meaning smooth unbroken lava is basaltic lava that has a smooth billowy undulating or ropy surface These surface features are due to the movement of very fluid lava under a congealing surface crust The Hawaiian word was introduced as a technical term in geology by Clarence Dutton 53 54 A pahoehoe 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 The surface texture of pahoehoe flows varies widely displaying all kinds of bizarre shapes often referred to as lava sculpture With increasing distance from the source pahoehoe flows may change into ʻaʻa flows in response to heat loss and consequent increase in viscosity 24 Experiments suggest that the transition takes place at a temperature between 1 200 and 1 170 C 2 190 and 2 140 F with some dependence on shear rate 61 35 Pahoehoe lavas typically have a temperature of 1 100 to 1 200 C 2 010 to 2 190 F 16 On the Earth most lava flows are less than 10 km 6 2 mi long but some pahoehoe flows are more than 50 km 31 mi long 62 Some flood basalt flows in the geologic record extend for hundreds of kilometres 63 The rounded texture makes pahoehoe a poor radar reflector and is difficult to see from an orbiting satellite dark on Magellan picture 57 Block lava flows Block lava at Fantastic Lava Beds near Cinder Cone in Lassen Volcanic National Park Block lava flows are typical of andesitic lavas from stratovolcanoes They behave in a similar manner to ʻaʻa flows but their more viscous nature causes the surface to be covered in smooth sided angular fragments blocks of solidified lava instead of clinkers As with ʻaʻa flows the molten interior of the flow which is kept insulated by the solidified blocky surface advances over the rubble that falls off the flow front They also move much more slowly downhill and are thicker in depth than ʻaʻa flows 15 Pillow lava Main article Pillow lava Pillow lava on the ocean floor near Hawaii Pillow lava is the lava structure typically formed when lava emerges from an underwater volcanic vent or subglacial volcano or a lava flow enters the ocean 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 water covers the majority of Earth s surface and most volcanoes are situated near or under bodies of water pillow lava is very common 64 Lava landformsBecause 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 Main article Volcano Arenal Volcano Costa Rica is a stratovolcano Volcanoes are the primary landforms built by repeated eruptions of lava and ash over time 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 65 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 itself afterwards 66 Such features may include volcanic crater lakes and lava domes after the event 67 However calderas can also form by non explosive means such as gradual magma subsidence This is typical of many shield volcanoes 68 Cinder and spatter cones Main article Volcanic cone Cinder cones and spatter cones are small scale features formed by lava accumulation around a small vent on a volcanic edifice Cinder cones are formed from tephra or ash and tuff which is thrown from an explosive vent Spatter cones are formed by accumulation of molten volcanic slag and cinders ejected in a more liquid form 69 Kipukas Main article Kipuka Another Hawaiian English term derived from the Hawaiian language a kipuka denotes an elevated area such as a hill ridge or old lava dome inside or downslope from an area of active volcanism New lava flows will cover the surrounding land isolating the kipuka so that it appears as a usually forested island in a barren lava flow 70 Lava domes and coulees Main article Lava dome A forested lava dome in the midst of the Valle Grande the largest meadow in the Valles Caldera National Preserve New Mexico United States Lava domes are formed by the extrusion of viscous felsic magma They can form prominent rounded protuberances such as at Valles Caldera As a volcano extrudes silicic lava it can form an inflation dome or endogenous 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 71 Examples of lava dome eruptions include the Novarupta dome and successive lava domes of Mount St Helens 72 When a dome forms on an inclined surface it can flow in short thick flows called coulees dome flows These flows often travel only a few kilometres from the vent 39 Lava tubes Main article Lava tube Lava tubes are formed when a flow of relatively fluid lava cools on the upper surface sufficiently to form a crust Beneath this crust which 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 73 Lava tubes are known from the modern day eruptions of Kilauea 74 and significant extensive and open lava tubes of Tertiary age are known from North Queensland Australia some extending for 15 kilometres 9 miles 75 Lava lakes Main article Lava lake Shiprock New Mexico United States a volcanic neck in the distance with a radiating dike on its south side Rarely a volcanic cone may fill with lava but not erupt Lava which pools within the caldera is known as a lava lake 76 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 77 Erta Ale Ethiopia 78 Nyiragongo Democratic Republic of Congo 79 Ambrym Vanuatu 77 Lava delta Main article Lava delta Lava deltas form wherever sub aerial flows of lava enter standing bodies of water The lava cools and breaks up as it encounters the water with the resulting fragments filling in the seabed topography such that the sub aerial flow can move further offshore Lava deltas are generally associated with large scale effusive type basaltic volcanism 80 Lava fountains 450 m high lava fountain at Kilauea A lava fountain is a volcanic phenomenon in which lava is forcefully but non explosively ejected from a crater vent or fissure The highest lava fountain recorded was during the 23 November 2013 eruption of Mount Etna in Italy which reached a stable height of around 2 500 m 8 200 ft for 18 minutes briefly peaking at a height of 3 400 m 11 000 ft 81 Lava fountains may occur as a series of short pulses or a continuous jet of lava They are commonly associated with Hawaiian eruptions 82 HazardsLava flows are enormously destructive to property in their path However casualties are rare since flows are usually slow enough for people and animals to escape though this is dependent on the viscosity of the lava Nevertheless injuries and deaths have occurred either because they had their escape route cut off because they got too close to the flow 83 or more rarely if the lava flow front travels too quickly This notably happened during the eruption of Nyiragongo in Zaire now Democratic Republic of the Congo On the night of 10 January 1977 a crater wall was breached and a fluid lava lake drained out in under an hour The resulting flow sped down the steep slopes at up to 100 km h 62 mph and overwhelmed several villages while residents were asleep As a result of this disaster the mountain was designated a Decade Volcano in 1991 84 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 83 A particularly dangerous area is called a lava bench This very young ground will typically break off and fall into the sea Areas of recent lava flows continue to represent a hazard long after the lava has cooled Where young flows have created new lands land is more unstable and can break off into the sea Flows often crack deeply forming dangerous chasms and a fall against ʻaʻa lava is similar to falling against broken glass Rugged hiking boots long pants and gloves are recommended when crossing lava flows Diverting a lava flow is extremely difficult but it can be accomplished in some circumstances as was once partially achieved in Vestmannaeyjar Iceland 85 The optimal design of simple low cost barriers that divert lava flows is an area of ongoing research 86 87 Towns destroyed by lava flows Lava can easily destroy entire towns This picture shows one of over 100 houses destroyed by the lava flow in Kalapana Hawaii United States in 1990 The Nisga a villages of Lax Ksiluux and Wii Lax K abit in northwestern British Columbia Canada were destroyed by thick lava flows during the eruption of Tseax Cone in the 1700s Garachico on the island of Tenerife was destroyed by the eruption of Trevejo 1706 rebuilt Cagsawa Philippines buried by lava erupted from Mayon Volcano in 1814 88 Keawaiki Hawaii 1859 abandoned San Sebastiano al Vesuvio Italy Destroyed in 1944 by the most recent eruption of Mount Vesuvius during the Allies occupation of southern Italy rebuilt Koae and Kapoho Hawaii were both destroyed by the same eruption of Kilauea in January 1960 89 abandoned Kalapana Hawaii was destroyed by the eruption of the Kilauea volcano in 1990 abandoned Kapoho Hawaii was largely inundated by lava in June 2018 with its subdivision Vacationland Hawaii being completely destroyed Towns damaged by lava flowsCatania Italy in the 1669 Etna eruption 90 rebuilt Sale aula Samoa by eruptions of Mt Matavanu between 1905 and 1911 Mascali Italy almost completely destroyed by the eruption of Mount Etna in 1928 rebuilt 91 Paricutin village after which the volcano was named and San Juan Parangaricutiro Mexico by Paricutin from 1943 to 1952 Heimaey Iceland in the 1973 Eldfell eruption rebuilt Piton Sainte Rose Reunion island in 1977 92 Royal Gardens Hawaii by the eruption of Kilauea in 1986 87 abandoned Goma Democratic Republic of Congo in the eruption of Nyiragongo in 2002 93 Los Llanos de Aridane Todoque neighbourhood and El Paso El Paraiso neighbourhood on La Palma in the 2021 Cumbre Vieja volcanic eruption 94 95 96 Towns destroyed by tephraTephra is lava in the form of volcanic ash lapilli volcanic bombs or volcanic blocks Pompeii Italy in the eruption of Mount Vesuvius in 79 AD Herculaneum Italy in the eruption of Mount Vesuvius in 79 AD Ceren El Salvador in the eruption of Ilopango between 410 and 535 AD 97 Sumbawa Island Indonesia in the eruption of Mount Tambora in 1815 Plymouth Montserrat in 1995 Plymouth was the capital and only port of entry for Montserrat and had to be completely abandoned along with over half of the island It is still the de jure capital See also Volcanoes portal Geology portalLaze geology Acid haze formed when molten lava enters the cold ocean Vog Air pollution resulting from volcanic gases reacting with the atmosphere Blue lava Optical phenomenon resulting from burning sulfurReferences Philpotts Anthony R Ague Jay J 2009 Principles of igneous and metamorphic petrology 2nd ed Cambridge UK Cambridge University Press pp 53 55 ISBN 9780521880060 Lava Merriam Webster Online Dictionary 2012 08 31 Retrieved 8 December 2013 Lava Dictionary reference com 1994 12 07 Retrieved 8 December 2013 Serao Francesco 1778 Istoria dell incendio del Vesuvio accaduto nel mese di maggio dell anno MDCCXXXVII Naples Presso Il De Bonis Retrieved 6 August 2022 Vesuvius Erupts 1738 Linda Hall Library of Science Engineering amp Technology Retrieved 6 August 2022 a b Philpotts amp Ague 2009 p 19 a b c Guijon R Henriquez F Naranjo J A 2011 Geological Geographical and Legal Considerations for the Conservation of Unique Iron Oxide and Sulphur Flows at El Laco and Lastarria Volcanic Complexes Central Andes Northern Chile Geoheritage 3 4 99 315 doi 10 1007 s12371 011 0045 x S2CID 129179725 a b c Harlov D E et al 2002 Apatite monazite relations in the Kiirunavaara magnetite apatite ore northern Sweden Chemical Geology 191 1 3 47 72 Bibcode 2002ChGeo 191 47H doi 10 1016 s0009 2541 02 00148 1 Philpotts amp Ague 2009 pp 132 133 a b Philpotts amp Ague 2009 p 25 Schmincke Hans Ulrich 2003 Volcanism Berlin Springer p 38 ISBN 9783540436508 Casq R A F Wright J V 1987 Volcanic Successions Unwin Hyman Inc p 528 ISBN 978 0 04 552022 0 a b c d e Philpotts amp Ague 2009 p 23 Philpotts amp Ague 2009 pp 70 77 a b Schmincke 2003 p 132 a b c d e f Philpotts amp Ague 2009 p 20 Bonnichsen B Kauffman D F 1987 Physical features of rhyolite lava flows in the Snake River Plain volcanic province southwestern Idaho Geological Society of America Special Paper Geological Society of America Special Papers 212 119 145 doi 10 1130 SPE212 p119 ISBN 0 8137 2212 8 Schmincke 2003 pp 21 24 132 143 Philpotts amp Ague 2009 pp 23 611 Takeuchi Shingo 5 October 2011 Preeruptive magma viscosity An important measure of magma eruptibility Journal of Geophysical Research 116 B10 B10201 Bibcode 2011JGRB 11610201T doi 10 1029 2011JB008243 Philpotts amp Ague 2009 pp 1376 377 Philpotts amp Ague 2009 pp 23 25 Philpotts amp Ague 2009 p 53 55 59 64 a b Schmincke 2003 pp 128 132 Arndt N T 1994 Archean komatiites In Condie K C ed Archean Crustal Evolution Amsterdam Elsevier p 19 ISBN 978 0 444 81621 4 Philpotts amp Ague 2009 pp 399 400 Philpotts amp Ague 2009 pp 139 148 Philpotts amp Ague 2009 pp 606 607 Stikine Volcanic Belt Volcano Mountain Catalogue of Canadian volcanoes Archived from the original on 2009 03 07 Retrieved 23 November 2007 Philpotts amp Ague 2009 p 145 Vic Camp How volcanoes work Unusual Lava Types Archived 2017 10 23 at the Wayback Machine San Diego State University Geology Philpotts amp Ague 2009 pp 396 397 Keller Jorg Krafft Maurice November 1990 Effusive natrocarbonatite activity of Oldoinyo Lengai June 1988 Bulletin of Volcanology 52 8 629 645 Bibcode 1990BVol 52 629K doi 10 1007 BF00301213 S2CID 129106033 McBride Gilmore eds 2007 An introduction to the Solar System Cambridge University Press p 392 a b Sonder I Zimanowski B Buttner R 2006 Non Newtonian viscosity of basaltic magma Geophysical Research Letters 330 2 L02303 Bibcode 2006GeoRL 33 2303S doi 10 1029 2005GL024240 Schmincke 2003 p 128 a b c Lava Flows PDF UMass Department of Geosciences University of Massachusetts Amherst 11 February 2004 p 19 Retrieved 5 June 2018 Peterson Donald W Tilling Robert I May 1980 Transition of basaltic lava from pahoehoe to aa Kilauea Volcano Hawaii Field observations and key factors Journal of Volcanology and Geothermal Research 7 3 4 271 293 Bibcode 1980JVGR 7 271P doi 10 1016 0377 0273 80 90033 5 a b Schmincke 2003 pp 132 138 Schmincke 2003 pp 143 144 Schmincke 2003 pp 127 128 Pinkerton H Bagdassarov N 2004 Transient phenomena in vesicular lava flows based on laboratory experiments with analogue materials Journal of Volcanology and Geothermal Research 132 2 3 115 136 Bibcode 2004JVGR 132 115B doi 10 1016 s0377 0273 03 00341 x Schmincke 2003 pp 39 40 Philpotts amp Ague 2009 p 40 Philpotts amp Ague 2009 p 16 Philpotts amp Ague 2009 p 71 Cheng Zhilong Yang Jian Zhou Lang Liu Yan Wang Qiuwang January 2016 Characteristics of charcoal combustion and its effects on iron ore sintering performance Applied Energy 161 364 374 doi 10 1016 j apenergy 2015 09 095 Philpotts amp Ague 2009 pp 55 56 Philpotts amp Ague 2009 pp 58 59 Philpotts amp Ague 2009 p 48 Philpotts amp Ague 2009 p 72 ʻaʻa Hawaiian Dictionary Hwn to Eng Archived from the original on 28 December 2012 a b Kemp James Furman 1918 A handbook of rocks for use without the microscope with a glossary of the names of rocks and other lithological terms Vol 5 New York D Van Nostrand pp 180 240 a b Dutton C E 1883 Hawaiian volcanoes Annual Report U S Geological Survey 4 95 240 a b Schmincke 2003 pp 131 132 Macdonald Gordon A Abbott Agatin T Peterson Frank L 1983 Volcanoes in the sea the geology of Hawaii 2nd ed Honolulu University of Hawaii Press p 23 ISBN 0824808320 a b McGounis Mark Peter Radar Studies of Lava Flows Volcanic Features of Hawaii and Other Worlds Lunar and Planetary Institute Retrieved 18 March 2017 Pinkerton Harry James Mike Jones Alun March 2002 Surface temperature measurements of active lava flows on Kilauea volcano Hawai i Journal of Volcanology and Geothermal Research 113 1 2 159 176 Bibcode 2002JVGR 113 159P doi 10 1016 S0377 0273 01 00257 8 Cigolini Corrado Borgia Andrea Casertano Lorenzo March 1984 Intra crater activity aa block lava viscosity and flow dynamics Arenal Volcano Costa Rica Journal of Volcanology and Geothermal Research 20 1 2 155 176 Bibcode 1984JVGR 20 155C doi 10 1016 0377 0273 84 90072 6 pahoehoe Hawaiian Dictionary Hwn to Eng Archived from the original on 18 September 2012 Sehlke A Whittington A Robert B Harris A Gurioli L Medard E 17 October 2014 Pahoehoe to a a transition of Hawaiian lavas an experimental study Bulletin of Volcanology 76 11 876 doi 10 1007 s00445 014 0876 9 S2CID 129019507 Types and Processes Gallery Lava Flows Global Volcanism Program Smithsonian Institution 2013 Retrieved 1 December 2015 Philpotts amp Ague 2009 p 53 Lewis J V 1914 Origin of pillow lavas Bulletin of the Geological Society of America 25 1 639 Bibcode 1914GSAB 25 591L doi 10 1130 GSAB 25 591 Philpotts amp Ague 2009 pp 59 73 Schmincke 2003 pp 147 148 Schmincke 2003 pp 132 286 Schmincke 2003 pp 149 151 Macdonald Abbott amp Peterson 1983 pp 26 17 Macdonald Abbott amp Peterson 1983 pp 22 23 Schmincke 2003 pp 132 138 152 153 Schmincke 2003 pp 132 134 Macdonald Abbott amp Peterson 1983 pp 23 26 29 Macdonald Abbott amp Peterson 1983 p 27 Atkinson A Griffin T J Stephenson P J June 1975 A major lava tube system from Undara Volcano North Queensland Bulletin Volcanologique 39 2 266 293 Bibcode 1975BVol 39 266A doi 10 1007 BF02597832 S2CID 129126355 Schmincke 2003 p 27 a b Lev Einat Ruprecht Philipp Oppenheimer Clive Peters Nial Patrick Matt Hernandez Pedro A Spampinato Letizia Marlow Jeff September 2019 A global synthesis of lava lake dynamics Journal of Volcanology and Geothermal Research 381 16 31 Bibcode 2019JVGR 381 16L doi 10 1016 j jvolgeores 2019 04 010 S2CID 182844266 Philpotts amp Ague 2009 p 61 Burgi P Y Darrah T H Tedesco D Eymold W K May 2014 Dynamics of the Mount Nyiragongo lava lake DYNAMICS OF THE MT NYIRAGONGO LAVA LAKE Journal of Geophysical Research Solid Earth 119 5 4106 4122 doi 10 1002 2013JB010895 Bosman Alessandro Casalbore Daniele Romagnoli Claudia Chiocci Francesco Latino July 2014 Formation of an a a lava delta insights from time lapse multibeam bathymetry and direct observations during the Stromboli 2007 eruption Bulletin of Volcanology 76 7 838 Bibcode 2014BVol 76 838B doi 10 1007 s00445 014 0838 2 S2CID 129797425 Bonaccorso A Calvari S Linde A Sacks S 28 July 2014 Eruptive processes leading to the most explosive lava fountain at Etna volcano The 23 November 2013 episode Geophysical Research Letters 41 14 4912 4919 Bibcode 2014GeoRL 41 4912B doi 10 1002 2014GL060623 S2CID 129813334 To the best of our knowledge it reached the highest value ever measured for a lava fountain on Earth Macdonald Abbott amp Peterson 1983 p 9 a b Lava Flows and Their Effects USGS Nyiragongo Could it happen here USGS Hawaiian Volcano Observatory Sonstroem Eric 14 September 2010 Vestmannaeyjar The Town That Fought A Volcano And Won indianapublicmedia org Indiana Public Media Archived from the original on 23 February 2017 Retrieved 24 November 2017 Dietterich Hannah Cashman Katherine Rust Alison Lev Einat 2015 Diverting lava flows in the lab Nature Geoscience 8 7 494 496 Bibcode 2015NatGe 8 494D doi 10 1038 ngeo2470 Hinton Edward Hogg Andrew Huppert Herbert 2020 Viscous free surface flows past cylinders Physical Review Fluids 5 84101 084101 Bibcode 2020PhRvF 5h4101H doi 10 1103 PhysRevFluids 5 084101 hdl 1983 f52f7078 5936 4e37 9d79 be456f08eb5c S2CID 225416948 Tourist attractions of Albay Province Philippines Nscb gov ph Archived from the original on 2016 09 21 Retrieved 2013 12 08 Article Our Volcanic History by Gladys Flanders Vhca info 1959 11 15 Archived from the original on 2016 03 03 Retrieved 2013 12 08 Bonaccorso A et al eds 2004 Mount Etna Volcano Laboratory Washington D C American Geophysical Union Geophysical Monograph 143 p 3 ISBN 978 0 87590 408 5 Duncan A M Dibben C Chester D K Guest J E 1996 The 1928 Eruption of Mount Etna Volcano Sicily and the Destruction of the Town of Mascali Disasters 20 1 1 20 doi 10 1111 j 1467 7717 1996 tb00511 x PMID 8867507 Thomas Pierre 23 June 2008 Eglise et gendarmerie envahies mais non detruites par la coulee d avril 1977 de Piton Sainte Rose ile de La Reunion Planet Terre in French ENS de Lyon Retrieved 26 May 2018 Global Volcanism Program Nyiragongo volcano si edu La Palma volcano Visual guide to what happened BBC News 2021 09 25 Retrieved 2021 09 25 Inge y Rainer los duenos de la casa milagro de La Palma Aunque no podemos ir nos alivia que siga en pie El Mundo in Spanish 2021 09 23 Retrieved 2021 09 25 en El Paraiso justo la pedania mas afectada hasta la fecha por el rio de lava del volcan Mas de la mitad de las casas incluido el colegio local ya han sido devoradas por la ceniza in El Paraiso just the district most affected to date by the river of lava from the volcano More than half of the houses including the local school have already been consumed by ash Sagrera Berto 10 October 2021 El barrio de Todoque desaparece totalmente bajo la lava del volcan de La Palma elnacional cat in Spanish Barcelona Retrieved 18 January 2022 Bundschuh J and Alvarado G E editors 2007 Central America Geology Resources and Hazards volume 1 p 56 London Taylor and FrancisExternal links Lava Encyclopaedia Britannica Vol 16 11th ed 1911 pp 289 290 Look up lava aa or pahoehoe in Wiktionary the free dictionary Wikimedia Commons has media related to lava category USGS definition of ʻAʻa USGS definition of Pahoehoe USGS definition of Ropy Pahoehoe Volcanic landforms of Hawaii USGS hazards associated with lava flows Hawaiian Volcano Observatory Volcano Watch newsletter article on Nyiragongo eruptions 31 January 2002 National Geographic lava video Archived 2016 03 03 at the Wayback Machine Retrieved 23 August 2007 Retrieved from https en wikipedia org w index php title Lava amp oldid 1130938797, wikipedia, wiki, book, books, library,

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