Lava+ Lava is the molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling.
Laval University+ Laval University () is the oldest centre of education in Canada (4th oldest in North America), and was the first institution in North America to offer higher education in French.
Laval, Quebec+ Laval (; ) is a Canadian city located in southwestern Quebec, north of Montreal. It forms its own administrative region of Quebec.
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.
Lavandula+ Lavandula (common name lavender) is a genus of 39 species of flowering plants in the mint family, Lamiaceae.
Lava Records+ Lava Records is an American-based record label, owned by Universal Music Group, and operated through Republic Records.
Laval, Mayenne+ Laval () is a town in western France, about southwest of Paris, and the capital of the Mayenne department.
Laval Titan+ The Laval Titan was one of the names used by a junior ice hockey team in the Quebec Major Junior Hockey League franchise that played in Laval, Quebec, between 1971 and 1998.
Lava tube+ A lava tube is a natural conduit formed by flowing lava which moves beneath the hardened surface of a lava flow.
Laval Rouge et Or+ Rouge et Or (Red and Gold) is the name of Université Laval's varsity sports teams.

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'''Lava''' is the molten+ rock+ expelled by a volcano+ during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planet+s, including Earth+, and some of their satellite+s. The source of the heat that liquefies the rock within the earth is geothermal energy+. When first erupted from a volcanic vent, lava is a liquid+ at temperature+s from . Up to 100,000 times as viscous+ as water, lava can flow great distances before cooling and solidifying because of its thixotropic+ and shear thinning+ properties.

A ''lava flow'' is a moving outpouring of lava, which is 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''. Explosive eruption+s 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. The first use in connection with extruded magma+ (molten rock below the Earth's surface) was apparently in a short account written by Francesco Serao+ on the eruption of Vesuvius+ between May 14 and June 4, 1737. 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+.


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

Igneous rocks, which form lava flows when erupted, can be classified into three chemical types; ''felsic''+, ''intermediate''+, and ''mafic''+ (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+'' (or silicic) lavas such as rhyolite+ and da meaning "stony rough lava", but also to "burn" or "blaze") is one of three basic types of flow lava. okina: Aokina: ā 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+.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. , : 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.

The loose, broken, and sharp, spiny surface of an okina: aokina: ā 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 okina: aokina: ā 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 okina: aokina: ā flow.

Accretionary lava balls as large as 3 metres (10 feet) are common on okina: aokina: ā flows. okina: Aokina: ā is usually of higher viscosity than pāhoehoe. Pāhoehoe can turn into okina: aokina: ā if it becomes turbulent from meeting impediments or steep slopes.

The sharp, angled texture makes okina: aokina: ā a strong radar reflector, and can easily be seen from an orbiting satellite (bright on Magellan+ pictures).

okina: Aokina: ā lavas typically erupt at temperatures of 1000 to 1100 °C.

''Pāhoehoe'' (; from Hawaiian IPA-haw|paːˈhoweˈhowe|: , 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+.

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 tube+s 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 okina: aokina: ā flows in response to heat loss and consequent increase in viscosity. Pahoehoe lavas typically have a temperature of 1100 to 1200 °C.

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

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.

Lava domes+ and coulées are associated with felsic lava flows ranging from da However, lava fountains observed during Mount Vesuvius' 1779 eruption are believed to have reached at least . Lava fountains may occur as a series of short pulses, or a continuous jet of lava. They are commonly associated with Hawaiian eruption+s.



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:

* Mount Erebus+, Antarctica+
* Pu'u 'Ō'ō+ and Halemaʻumaʻu crater+ on Kīlauea+ volcano, Hawaiokina: i+
* Erta Ale+, Ethiopia+
* Nyiragongo+, Democratic Republic of Congo+
* Ambrym+, Vanuatu+.


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.

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.
* Copper sulfide+ bearing lavas have been recognised from Chile+ and Bolivia+.
* Iron+ oxide lavas are thought to be the source of the iron ore+ at Kiruna+, Sweden+, erupted in the Proterozoic+, and in Chile associated with highly alkaline igneous rocks
* Olivine nephelinite+ lavas are thought to have come from much deeper in the mantle+ of the Earth+ than other lavas.

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 giant+s. See cryovolcanism+.



Lava flows are enormously destructive to property in their path. However, casualties are rare since flows are usually slow enough for people to escape, though this is dependent on the viscosity of the lava. Nevertheless injuries and deaths have occurred, either because people had their escape route cut off, because they got too close to the flow USGS 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, and overwhelmed several villages while residents were asleep. As a result of this disaster, the mountain was designated a Decade Volcano+ in 1991. USGS+ Hawaiian Volcano Observatory+

Deaths attributed to volcanoes frequently have a different cause, for example volcanic ejecta, pyroclastic flow+ from a collapsing lava dome, lahar+s, poisonous gases that travel ahead of lava, or explosions caused when the flow comes into contact with water. 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 have deep cracks, and any fall against fresh lava is similar to falling against broken glass. Rugged hiking boots, long pants, and gloves are recommended when crossing lava flows. Special care should be taken whenever entering an isolated kipuka+ cut off by a lava flow. Wildlife, especially wild boar, can become trapped and concentrated within a kipuka. The chances of encountering boars in a Hawaiian kipuka is particularly high. Making a lot of noise is recommended and back away slowly if one holds ground.


* Kalapana, Hawaiokina: i+ Destroyed by the eruption of the Kīlauea volcano+ in 1990. (abandoned)
* Koae and Kapoho, Hawaiokina: i+ Were both destroyed by the same eruption of Kīlauea+ in January, 1960. (abandoned)
* Keawaiki, Hawaiokina: i 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)
* Cagsawa+, Philippines+ buried by lava erupted from Mayon Volcano+ in 1814.
* 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.

* Catania, Italy+, in the eruption Mount Etna+ in 1669 (rebuilt)
* Goma+, Democratic Republic of Congo+, in the eruption of Nyiragongo+ in 2002
* Heimaey, Iceland+, in the 1973 Eldfell+ eruption (rebuilt)
* Royal Gardens, Hawaiokina: i+, by the eruption of Kilauea+ in 1986–87 (abandoned)
* Parícutin+ (village after which the volcano was named) and San Juan Parangaricutiro+, Mexico, by Parícutin+ from 1943 to 1952.
* Sale'aula+, Samoa, by eruptions of Mt Matavanu+ between 1905 and 1911.

Tephra+ is volcanic ash+, lapilli+, volcanic bomb+s or volcanic block+s.

* Pompeii+, Italy in the eruption of Mount Vesuvius+ in 79 AD
* Herculaneum+, Italy in the eruption of Mount Vesuvius+ in 79 AD
* Sumbawa Island+, Indonesia in the eruption of Mount Tambora+ in 1815 AD
* Cerén+, El Salvador in the eruption of Ilopango+ between 410 and 535 AD
* 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.







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* Retrieved 23 August 2007

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