Lava is molten rock generated by geothermal energy and expelled through fractures in planetary crust or in an eruption, usually at temperatures from 700 to 1,200 °C (1,292 to 2,192 °F). The structures resulting from subsequent solidification and cooling are also sometimes described as lava. The molten rock is formed in the interior of some planets, including Earth, and some of their satellites, though such material located below the crust is referred to by other terms.

A lava flow is a moving outpouring of lava created during a non-explosive effusive eruption. When it has stopped moving, lava solidifies to form igneous rock. The term lava flow is commonly shortened to lava. Although lava can be up to 100,000 times more viscous than water, lava can flow great distances before cooling and solidifying because of its thixotropic and shear thinning properties.[1][2]

Explosive eruptions produce a mixture of volcanic ash and other fragments called tephra, rather than lava flows. The word lava comes from Italian, and is probably derived from the Latin word labes which means a fall or slide.[3][4] 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 in 1737.[5] 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.

Pahoeoe fountain edit2
10-metre-high (33 ft) fountain of pāhoehoe lava, Hawaii, United States
Lava flow at Krafla, 1984
Lava flow during a rift eruption at Krafla, Iceland in 1984

Lava composition

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

The composition of almost all lava of the Earth's crust is dominated by silicate minerals, mostly feldspars, olivine, pyroxenes, amphiboles, micas and quartz.

Silicate lavas

Igneous rocks, which form lava flows when erupted, can be classified into three chemical types: felsic, intermediate, and mafic (four if one includes the super-heated ultramafic). 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 lava

Felsic or silicic lavas such as rhyolite and dacite typically form lava spines, lava domes or "coulees" (which are thick, short lava flows) and are associated with pyroclastic (fragmental) deposits. Most silicic 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, and thus has a higher viscosity than other magma types. Felsic magmas can erupt at temperatures as low as 650 to 750 °C (1,202 to 1,382 °F). 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.

Intermediate lava

Intermediate or andesitic lavas are lower in aluminium and silica, and usually somewhat richer in magnesium and iron. Intermediate lavas form andesite domes and block lavas, and may occur on steep composite volcanoes, such as in the Andes. Poorer in aluminium and silica than felsic lavas, and also commonly hotter (in the range of 750 to 950 °C (1,380 to 1,740 °F)), 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. Higher iron and magnesium tends to manifest as a darker groundmass, and also occasionally amphibole or pyroxene phenocrysts.

Mafic lava

Mafic or basaltic lavas are typified by their high ferromagnesian content, and generally erupt at temperatures in excess of 950 °C (1,740 °F). 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 higher 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 to produce low-profile shield volcanoes or "flood basalt fields", because the fluidal lava flows for long distances from the vent. 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 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.

Ultramafic lava

Ultramafic lavas such as komatiite and highly magnesian magmas that form boninite take the composition and temperatures of eruptions to the extreme. 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 no polymerization of the mineral compounds, creating a highly mobile liquid.[6] Most if not all ultramafic lavas are no younger than the Proterozoic, with a few ultramafic magmas known from the Phanerozoic. No modern komatiite lavas are known, as the Earth's mantle has cooled too much to produce highly magnesian magmas.

Unusual lavas

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

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.[11] (See cryovolcanism).

Lava behavior

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

In general, the composition of a lava determines its behavior more than the temperature of its eruption. 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.

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. 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

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.

Lava flow speeds vary based primarily on viscosity and slope. In general, lava flows slowly (0.25 mph), with maximum speeds between 6–30 mph on steep slopes. An exceptional speed of 20–60 mph was recorded following the collapse of a lava lake at Mount Nyiragongo.[12]

Lava morphology

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

The physical behavior 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.

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 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 flow is commonly 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 flow 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). 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.

Discriminating between an intrusive sill and a lava flow in ancient rock sequences can be difficult. 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 practice to identify these metamorphic phenomena 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.


Aa large
Glowing ʻaʻā flow front advancing over pāhoehoe on the coastal plain of Kilauea in Hawaii, United States

ʻAʻā 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 Hawaiian word was introduced as a technical term in geology by Clarence Dutton.[13]

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.

Accretionary lava balls as large as 3 metres (10 feet) 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).[14]

ʻAʻā lavas typically erupt at temperatures of 1,000 to 1,100 °C (1,830 to 2,010 °F).

The word is also spelled aa, aʻa, ʻaʻa, and a-aa, and pronounced /ˈɑː(ʔ)ɑː/. It originates from Hawaiian where it is pronounced [ʔəˈʔaː],[15] meaning "stony rough lava", but also to "burn" or "blaze".


Ropy pahoehoe
Pāhoehoe lava from Kīlauea volcano, Hawaii, United States

Pāhoehoe (/pəˈhoʊiˈhoʊi/ or /pɑːˈhoʊeɪhoʊeɪ/; from Hawaiian [paːˈhoweˈhowe],[16] meaning "smooth, unbroken lava"), also spelled pahoehoe, 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.[13]

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. Pahoehoe lavas typically have a temperature of 1,100 to 1,200 °C (2,010 to 2,190 °F).

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.[17]

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

Block lava flows

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. Like in ʻaʻā flows, the molten interior of the flow, which is kept insulated by the solidified blocky surface, overrides the rubble that falls off the flow front. They also move much more slowly downhill and are thicker in depth than ʻaʻā flows.

Domes and coulées

Lava domes and coulées are associated with felsic lava flows ranging from dacite to rhyolite. The very viscous nature of these lava cause them to not flow far from the vent, causing the lava to form a lava dome at the vent. 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 kilometers from the vent.

Pillow lava

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. However, pillow lava can also form when lava is erupted beneath 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 water covers the majority of Earth's surface and most volcanoes are situated near or under bodies of water, pillow lava is very common.

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.


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.

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. 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. 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.


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.

Lava domes

Valle Grande 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, 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.

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

Lava tubes

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.

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 (9 miles).

Lava fountains

Lava fountain at Kilauea
450m-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 fountains recorded were during the 1999 eruption of Mount Etna in Italy, which reached heights of 2,000 m (6,562 ft).[18] However, lava fountains observed during Mount Vesuvius' 1779 eruption are believed to have reached at least 3,000 m (9,843 ft).[18][19] Lava fountains may occur as a series of short pulses, or a continuous jet of lava. They are commonly associated with Hawaiian eruptions.

Lava lakes

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. 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

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.


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[20] 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.[21]

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.[20] 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 'a'a 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.[22]

Towns destroyed by lava flows

Kalapana house destroyed by lava
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 volcanic ash, lapilli, volcanic bombs or volcanic blocks.

See also

  • Laze (geology), acid rains and air pollution arising from steam explosions and large plume clouds containing extremely acid condensate that occur when molten lava flows enter oceans.
  • Vog, volcanic smog originating from volcanic vents.


  1. ^ 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. doi:10.1016/s0377-0273(03)00341-x.
  2. ^ "Rheological properties of basaltic lavas at sub-liquidus temperatures: laboratory and field measurements on lavas from Mount Etna". Retrieved 19 June 2008.
  3. ^ "Lava". Merriam-Webster Online Dictionary. 2012-08-31. Retrieved 8 December 2013.
  4. ^ "Lava". 1994-12-07. Retrieved 8 December 2013.
  5. ^ "Vesuvius Erupts, 1738". Retrieved 21 October 2015.
  6. ^ Arndt, N.T. (1994). "Archean komatiites". In Condie, K.C. (ed.). Archean Crustal Evolution. Amsterdam: Elsevier. p. 19. ISBN 978-0-444-81621-4.
  7. ^ Vic Camp, How volcanoes work, Unusual Lava Types, San Diego State University, Geology
  8. ^ a b Harlov, D.E.; et al. (2002). "Apatite–monazite relations in the Kiirunavaara magnetite–apatite ore, northern Sweden". Chemical Geology. 191 (1–3): 47–72. doi:10.1016/s0009-2541(02)00148-1.
  9. ^ a b 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.
  10. ^ Catalogue of Canadian volcanoes – Stikine Volcanic Belt: Volcano Mountain Archived 2009-03-07 at the Wayback Machine Retrieved on 23 November 2007
  11. ^ McBride and Gilmore (Ed.); 2007, An introduction to the Solar System, Cambridge University Press, p. 392
  12. ^ "Lava Flows" (PDF). UMass Department of Geosciences. University of Massachusetts Amherst. 11 February 2004. p. 19. Retrieved 5 June 2018.
  13. ^ a b James Furman Kemp: A handbook of rocks for use without the microscope : with a glossary of the names of rocks and other lithological terms. 5. Aufl., New York: D. Van Nostrand, 1918, pp. 180, 240: C. E. Dutton, 4th Annual Report U.S. Geological Survey, 1883, S. 95; Bulletin of the Geological Society of America, Volume 25 / Geological Society of America. 1914, p. 639
  14. ^ McGounis-Mark, Peter. "Radar Studies of Lava Flows". Volcanic Features of Hawaii and Other Worlds. Lunar and Planetary Institute. Retrieved 18 March 2017.
  15. ^ Hawaiian Dictionaries Archived 2012-12-28 at
  16. ^ Hawaiian Dictionaries Archived 2012-09-18 at
  17. ^ "Types and Processes Gallery: Lava Flows". Global Volcanism Program. Smithsonian Institution. 2013. Retrieved 1 December 2015.
  18. ^ a b Klemetti, Erik. "Stunning Lava Fountains From Italy's Etna". Retrieved 2013-12-08.
  19. ^ "ERTH15: Most Significant Eruptions at Mt. Vesuvius". Archived from the original on 2013-01-16. Retrieved 2013-12-08.
  20. ^ a b Lava Flows and Their Effects USGS
  21. ^ Nyiragongo – Could it happen here? USGS Hawaiian Volcano Observatory
  22. ^ Sonstroem, Eric (14 September 2010). "Vestmannaeyjar, The Town That Fought A Volcano And Won". Indiana Public Media. Retrieved 24 November 2017.
  23. ^ "Article – Our Volcanic History by Gladys Flanders". 1959-11-15. Retrieved 2013-12-08.
  24. ^ "Tourist attractions of Albay Province, Philippines". Archived from the original on 2017-12-22. Retrieved 2013-12-08.
  25. ^ 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.
  26. ^ "Global Volcanism Program - Nyiragongo".
  27. ^ Thomas, Pierre (23 June 2008). "Église et gendarmerie envahies mais non détruites par la coulée d'avril 1977 de Piton Sainte Rose, île de La Réunion". Planet Terre (in French). ENS de Lyon. Retrieved 26 May 2018.
  28. ^ Bundschuh, J. and Alvarado, G. E (editors) (2007) Central America: Geology, Resources and Hazards, volume 1, p. 56, London, Taylor and Francis

External links


Basalt (US: , UK: ) is a mafic extrusive igneous rock formed from the rapid cooling of magnesium-rich and iron-rich lava exposed at or very near the surface of a terrestrial planet or a moon. More than 90% of all volcanic rock on Earth is basalt. Basalt lava has a low viscosity, due to its low silica content, resulting in rapid lava flows that can spread over great areas before cooling and solidification. Flood basalt describes the formation in a series of lava basalt flows.


Kīlauea (, US: ; Hawaiian: [kiːlɐwˈwɛjə]) is an active shield volcano in the Hawaiian Islands, and the most active of the five volcanoes that together form the island of Hawaiʻi. Located along the southerneastern shore of the island, the volcano is between 210,000 and 280,000 years old and emerged above sea level about 100,000 years ago.

It is the second youngest product of the Hawaiian hotspot and the current eruptive center of the Hawaiian–Emperor seamount chain. Because it lacks topographic prominence and its activities historically coincided with those of Mauna Loa, Kīlauea was once thought to be a satellite of its much larger neighbor. Structurally, Kīlauea has a large, fairly recently formed caldera at its summit and two active rift zones, one extending 125 km (78 mi) east and the other 35 km (22 mi) west, as an active fault of unknown depth moving vertically an average of 2 to 20 mm (0.1 to 0.8 in) per year.

Kīlauea erupted nearly continuously from 1983 to 2018, causing considerable property damage, including the destruction of the towns of Kalapana in 1990, and Vacationland Hawaii and Kapoho in 2018. During the 2018 lower Puna eruption, which began on May 3, two dozen lava vents erupted downrift from the summit in Puna. The eruption was accompanied by a strong earthquake on May 4 of Mw 6.9, and nearly 2,000 residents were evacuated from the rural Leilani Estates subdivision and nearby areas.

On May 17, 2018 at 4:17 AM, the volcano explosively erupted at the summit in Halemaumau Crater, throwing ash 30,000 feet into the air. Continued explosive activity at the summit caused a months-long closure of the Kīlauea section of Hawaii Volcanoes National Park, while vigorous eruptive activity in lower Puna, sent lava into the ocean in three places, destroyed Hawaii's largest natural freshwater lake, covered substantial portions of Leilani Estates and Lanipuna Gardens, and completely inundated Vacationland Hawaii and all but three houses in the Kapoho Beach Lots. Lava also filled Kapoho Bay and extended new land nearly a mile into the sea. The County of Hawaii reported that 716 dwellings were destroyed by lava. By early August the eruption subsided substantially, and the last active lava was reported at the surface on September 4, 2018. Portions of Hawaii Volcanoes National Park reopened to the public on September 22. On December 5, 2018, after 90 days of inactivity from the volcano, the eruption that started in 1983 was declared to be over.

Lava Beds National Monument

Lava Beds National Monument is located in northeastern California, in Siskiyou and Modoc counties. The monument lies on the northeastern flank of Medicine Lake Volcano and has the largest total area covered by a volcano in the Cascade Range.

The region in and around Lava Beds National Monument lies at the junction of the Sierra-Klamath, Cascade, and the Great Basin physiographic provinces. The monument was established as a national monument on November 21, 1925, and includes more than 46,000 acres (190 km2).

Lava Beds National Monument has numerous lava tubes, with 25 having marked entrances and developed trails for public access and exploration. The monument also offers trails through the high Great Basin xeric shrubland desert landscape and the volcanic field. In 1872 and 1873, the area was the site of the Modoc War, involving a band led by Kintpuash (also known as Captain Jack). The area of Captain Jack's Stronghold was named in his honor.

Lava dome

In volcanology, a lava dome or volcanic dome is a roughly circular mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano. Dome-building eruptions are common, particularly in convergent plate boundary settings. Around 6% of eruptions on earth are lava dome forming. The geochemistry of lava domes can vary from basalt (e.g. Semeru, 1946) to rhyolite (e.g. Chaiten, 2010) although the majority are of intermediate composition (such as Santiaguito, dacite-andesite, present day) The characteristic dome shape is attributed to high viscosity that prevents the lava from flowing very far. This high viscosity can be obtained in two ways: by high levels of silica in the magma, or by degassing of fluid magma. Since viscous basaltic and andesitic domes weather fast and easily break apart by further input of fluid lava, most of the preserved domes have high silica content and consist of rhyolite or dacite.

Existence of lava domes has been suggested for some domed structures on the Moon, Venus, and Mars, e.g. the Martian surface in the western part of Arcadia Planitia and within Terra Sirenum.

Lava lamp

A lava lamp (or astro lamp) is a decorative lamp, invented in 1963 by British entrepreneur Edward Craven Walker the founder of the British lighting company Mathmos. The lamp consists of a bolus of a special coloured wax mixture inside a glass vessel, the remainder of which contains clear or translucent liquid; the vessel is then placed on a box containing an incandescent light bulb whose heat causes temporary reductions in the density of the wax and surface tension of the liquid. The warmed wax rises through the surrounding liquid, cools, loses its buoyancy, and falls back to the bottom of the vessel in a cycle that is visually suggestive of pāhoehoe lava, hence the name. The lamps are designed in a variety of styles and colours.


Mafic is an adjective describing a silicate mineral or igneous rock that is rich in magnesium and iron, and is thus a portmanteau of magnesium and ferric. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include basalt, diabase and gabbro. Mafic rocks often also contain calcium-rich varieties of plagioclase feldspar.

Chemically, mafic rocks are enriched in iron, magnesium and calcium and typically dark in color. In contrast the felsic rocks are typically light in color and enriched in aluminium and silicon along with potassium and sodium. The mafic rocks also typically have a higher density than felsic rocks. The term roughly corresponds to the older basic rock class.

Mafic lava, before cooling, has a low viscosity, in comparison with felsic lava, due to the lower silica content in mafic magma. Water and other volatiles can more easily and gradually escape from mafic lava. As a result, eruptions of volcanoes made of mafic lavas are less explosively violent than felsic-lava eruptions. Most mafic-lava volcanoes are shield volcanoes, like those in Hawaii.

Martian lava tube

Martian lava tubes are volcanic caverns on Mars that are believed to form as a result of fast-moving, basaltic lava flows associated with shield volcanism. Lava tubes usually form when the external surface of the lava channels cools more quickly and forms a hardened crust over subsurface lava flows. The flow eventually ceases and drains out of the tube, leaving a conduit-shaped void space which is usually several meters below the surface. Lava tubes are typically associated with extremely fluid pahoehoe lava. Gravity on mars is about 38% that of Earth's, allowing Martian lava tubes to be much larger in comparison.

Newberry Volcano

Newberry Volcano is a large active shield-shaped stratovolcano located about 20 miles (32 km) south of Bend, Oregon, United States, 35 miles (56 km) east of the major crest of the Cascade Range, within the Newberry National Volcanic Monument. Its highest point is Paulina Peak. The largest volcano in the Cascade Volcanic Arc, Newberry has an area of 1,200 square miles (3,100 km2) when its lava flows are taken into account. From north to south, the volcano has a length of 75 miles (121 km), with a width of 27 miles (43 km) and a total volume of approximately 120 cubic miles (500 km3). It was named for the geologist and surgeon John Strong Newberry, who explored central Oregon for the Pacific Railroad Surveys in 1855. The surrounding area has been inhabited by Native American populations for more than 10,000 years.

The volcano contains a large caldera, 4 by 5 miles (6.4 km × 8.0 km) in diameter, known as the Newberry Caldera. Within the caldera are two lakes: Paulina Lake and East Lake. The volcano and its vicinity include many pyroclastic cones, lava flows and lava domes; Newberry has more than 400 vents, the most of any volcano in the contiguous United States. Glaciers may have once been present at the volcano, though this remains contested. The area has a dry climate with low precipitation levels and little surface runoff.

The origin of the volcano remains somewhat unclear; while some scientists believe it originated from an independent hotspot, most evidence indicates that it formed from the subduction of the oceanic Juan de Fuca and Gorda tectonic plates under the continental North American Plate. Eruptive activity at Newberry Volcano began about 600,000 years ago and has continued into the Holocene, the last eruption taking place 1,300 years ago. Unlike other shield-shaped volcanoes, which often erupt basaltic lavas only, Newberry Volcano has also erupted andesitic and rhyolitic lavas. A popular destination for hiking, fishing, boating, and other recreational activities, the volcano lies within 19 miles (31 km) of 16,400 people and within 62 miles (100 km) of nearly 200,000 people, and it continues to pose a threat to life. Still considered an active volcano, it could erupt and produce lava flows, pyroclastic flows, lahars (volcanically induced mudslides, landslides, and debris flows), ashfall, earthquakes, avalanches, and floods. To track this threat, the volcano and its surroundings are closely monitored with sensors by the United States Geological Survey.

Nisga'a Memorial Lava Bed Provincial Park

Nisga'a Memorial Lava Bed Provincial Park (Nisga'a: Anhluut'ukwsim Laxmihl Angwinga'asankswhl Nisga'a) is a provincial park in the Nass River valley in northwestern British Columbia, Canada, about 80 kilometres north of Terrace, and near the Nisga'a Villages of Gitlakdamix and Gitwinksihlkw.

The park was established by Order in Council on April 29, 1992, expanded in 1995, included in the Nisga'a Treaty in 2000, and is the first park in the province to be jointly managed by the government and a First Nation. An interpretive centre in a traditional Nisga'a longhouse informs visitors about the Nisga'a legend that accounts for the lava as well as geological causes.

The park has waterfalls, pools, cinder cones, tree moulds, lava tubes, spatter cones, a lava-dammed lake, caves and other features created by lava flows. The park aims to protect moose, goats, marmots, bears and many other species of wildlife.

The park covers 178.93 square kilometres in area.


Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock.Obsidian is produced when felsic lava extruded from a volcano cools rapidly with minimal crystal growth. It is commonly found within the margins of rhyolitic lava flows known as obsidian flows, where the chemical composition (high silica content) causes a high viscosity which, upon rapid cooling, forms a natural glass from the lava. The inhibition of atomic diffusion through this highly viscous lava explains the lack of crystal growth. Obsidian is hard, brittle, and amorphous; it therefore fractures with very sharp edges. In the past it was used to manufacture cutting and piercing tools and it has been used experimentally as surgical scalpel blades.

Olympus Mons

Olympus Mons ( ; Latin for Mount Olympus) is a very large shield volcano on the planet Mars. The volcano has a height of nearly 22 km (13.6 mi or 72,000 ft) as measured by the Mars Orbiter Laser Altimeter (MOLA). Olympus Mons is about two and a half times Mount Everest's height above sea level. It is the largest volcano, the tallest planetary mountain, and the second tallest mountain currently discovered in the Solar System, comparable to Rheasilvia on Vesta. It is the youngest of the large volcanoes on Mars, having formed during Mars's Hesperian Period. It had been known to astronomers since the late 19th century as the albedo feature Nix Olympica (Latin for "Olympic Snow"). Its mountainous nature was suspected well before space probes confirmed its identity as a mountain.The volcano is located in Mars's western hemisphere at approximately 18.65°N 226.2°E / 18.65; 226.2, just off the northwestern edge of the Tharsis bulge. The western portion of the volcano lies in the Amazonis quadrangle (MC-8) and the central and eastern portions in the adjoining Tharsis quadrangle (MC-9).

Two impact craters on Olympus Mons have been assigned provisional names by the International Astronomical Union. They are the 15.6 km (9.7 mi)-diameter Karzok crater (18°25′N 131°55′W) and the 10.4 km (6.5 mi)-diameter Pangboche crater (17°10′N 133°35′W). The craters are notable for being two of several suspected source areas for shergottites, the most abundant class of Martian meteorites.

Prabhu Deva

Prabhu Deva (born 3 April 1973) is an Indian dance choreographer, film director, producer and actor, who has worked in Tamil, Telugu, Hindi, Malayalam and Kannada films. In a career spanning 25 years, he has performed and designed a wide range of dancing styles and has garnered two National Film Awards for Best Choreography.He was also awarded the Padma Shree award in 2019 for his contributions to the art.Beginning with a series of acting roles in the 1990s and early 2000s, Prabhu Deva featured in several commercially successful films including Kadhalan (1994), Minsara Kanavu (1997) and VIP (1997). After further critically acclaimed performances in the comedy Kaathala Kaathala (1998) and the family drama Vanathai Pola (2000), Deva then failed to recreate the success of his earlier films and his box office value began to decline and he subsequently made appearances in supporting roles and low budget Telugu language films. He then successfully ventured into direction with the 2005 Telugu film Nuvvostanante Nenoddantana, and the success of the project prompted further offers for Deva as a director. He then went on to make highly profitable films in Telugu, Hindi and Tamil languages such as Pokkiri (2007), Wanted (2009), Rowdy Rathore (2012) and Singh is Bling (2015).


Rhyolite is an igneous, volcanic rock, of felsic (silica-rich) composition (typically > 69% SiO2 – see the TAS classification). It may have any texture from glassy to aphanitic to porphyritic. The mineral assemblage is usually quartz, sanidine and plagioclase (in a ratio > 2:1 – see the QAPF diagram). Biotite and hornblende are common accessory minerals. It is the extrusive equivalent to granite.

Shield volcano

A shield volcano is a type of volcano usually composed almost entirely of fluid lava flows. It is named for its low profile, resembling a warrior's shield lying on the ground. This is caused by the highly fluid (low viscosity) lava erupted, which travels farther than lava erupted from a stratovolcano, and results in the steady accumulation of broad sheets of lava, building up the shield volcano's distinctive form.


A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava, tephra, pumice and ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and periodic intervals of explosive eruptions and effusive eruptions, although some have collapsed summit craters called calderas. The lava flowing from stratovolcanoes typically cools and hardens before spreading far, due to high viscosity. The magma forming this lava is often felsic, having high-to-intermediate levels of silica (as in rhyolite, dacite, or andesite), with lesser amounts of less-viscous mafic magma. Extensive felsic lava flows are uncommon, but have travelled as far as 15 km (9.3 mi).Stratovolcanoes are sometimes called "composite volcanoes" because of their composite stratified structure built up from sequential outpourings of erupted materials. They are among the most common types of volcanoes, in contrast to the less common shield volcanoes. Two famous examples of stratovolcanoes are Krakatoa in Indonesia, known for its catastrophic eruption in 1883 and Vesuvius in Italy, whose catastrophic eruption in AD 79 ruined the Roman cities of Pompeii and Herculaneum. Both eruptions claimed thousands of lives. In modern times, Mount Saint Helens and Mount Pinatubo have erupted catastrophically, with fewer deaths.

The possible existence of stratovolcanoes on other terrestrial bodies of the Solar System has not been conclusively demonstrated. The one feasible exception are the existence of some isolated massifs on Mars, for example the Zephyria Tholus.

The Adventures of Sharkboy and Lavagirl in 3-D

The Adventures of Sharkboy and Lavagirl (also known simply as Sharkboy and Lavagirl) is a 2005 American adventure film written and directed by Robert Rodriguez and originally released in the United States on June 10, 2005 by Miramax Films, Columbia Pictures and Dimension Films. The film uses the anaglyph 3-D technology, similar to the one used in Spy Kids 3-D: Game Over (2003). The film stars Taylor Lautner, Taylor Dooley, Cayden Boyd, David Arquette, Kristin Davis and George Lopez. Many of the concepts and much of the story were conceived by Rodriguez's children. The special effects were done by Hybride Technologies, CafeFX, The Orphanage, Post Logic, Hydraulx, Industrial Light & Magic, R!ot Pictures, Tippett Studio, Amalgamated Pixels, Intelligent Creatures and Troublemaker Digital. The film received negative reviews from critics with much of the criticism directed at the decision to post-convert the film into 3-D which many said damaged the film's visual look. The film also underperformed at the box office earning just $39 million in the United States and $69.4 million worldwide on a $50 million budget.

Types of volcanic eruptions

Several types of volcanic eruptions—during which lava, tephra (ash, lapilli, volcanic bombs and volcanic blocks), and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior has been observed. Some volcanoes may exhibit only one characteristic type of eruption during a period of activity, while others may display an entire sequence of types all in one eruptive series.

There are three different types of eruptions. The most well-observed are magmatic eruptions, which involve the decompression of gas within magma that propels it forward. Phreatomagmatic eruptions are another type of volcanic eruption, driven by the compression of gas within magma, the direct opposite of the process powering magmatic activity. The third eruptive type is the phreatic eruption, which is driven by the superheating of steam via contact with magma; these eruptive types often exhibit no magmatic release, instead causing the granulation of existing rock.

Within these wide-defining eruptive types are several subtypes. The weakest are Hawaiian and submarine, then Strombolian, followed by Vulcanian and Surtseyan. The stronger eruptive types are Pelean eruptions, followed by Plinian eruptions; the strongest eruptions are called "Ultra-Plinian." Subglacial and phreatic eruptions are defined by their eruptive mechanism, and vary in strength. An important measure of eruptive strength is Volcanic Explosivity Index (VEI), an order of magnitude scale ranging from 0 to 8 that often correlates to eruptive types.

Volcanic rock

Volcanic rock (often shortened to volcanics in scientific contexts) is a rock formed from lava erupted from a volcano. In other words, it differs from other igneous rock by being of volcanic origin. Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and metamorphic rocks and constitute an important element of some sediments and sedimentary rocks. For these reasons, in geology, volcanics and shallow hypabyssal rocks are not always treated as distinct. In the context of Precambrian shield geology, the term "volcanic" is often applied to what are strictly metavolcanic rocks. Volcanic rocks and sediment that form from magma erupted into the air are called "volcaniclastics," and these are technically sedimentary rocks.

Volcanic rocks are among the most common rock types on Earth's surface, particularly in the oceans. On land, they are very common at plate boundaries and in flood basalt provinces. It has been estimated that volcanic rocks cover about 8% of the Earth's current land surface.


A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.

Earth's volcanoes occur because its crust is broken into 17 major, rigid tectonic plates that float on a hotter, softer layer in its mantle. Therefore, on Earth, volcanoes are generally found where tectonic plates are diverging or converging, and most are found underwater. For example, a mid-oceanic ridge, such as the Mid-Atlantic Ridge, has volcanoes caused by divergent tectonic plates whereas the Pacific Ring of Fire has volcanoes caused by convergent tectonic plates. Volcanoes can also form where there is stretching and thinning of the crust's plates, e.g., in the East African Rift and the Wells Gray-Clearwater volcanic field and Rio Grande Rift in North America. This type of volcanism falls under the umbrella of "plate hypothesis" volcanism. Volcanism away from plate boundaries has also been explained as mantle plumes. These so-called "hotspots", for example Hawaii, are postulated to arise from upwelling diapirs with magma from the core–mantle boundary, 3,000 km deep in the Earth. Volcanoes are usually not created where two tectonic plates slide past one another.

Erupting volcanoes can pose many hazards, not only in the immediate vicinity of the eruption. One such hazard is that volcanic ash can be a threat to aircraft, in particular those with jet engines where ash particles can be melted by the high operating temperature; the melted particles then adhere to the turbine blades and alter their shape, disrupting the operation of the turbine. Large eruptions can affect temperature as ash and droplets of sulfuric acid obscure the sun and cool the Earth's lower atmosphere (or troposphere); however, they also absorb heat radiated from the Earth, thereby warming the upper atmosphere (or stratosphere). Historically, volcanic winters have caused catastrophic famines.

Types of basalts
Basalts by tectonic setting
Basalts by form and flow
Basalts by chemistry
Important minerals

This page is based on a Wikipedia article written by authors (here).
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.