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Lava
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10-metre (33 ft) high fountain of pahoehoe lava, Hawaii, United States
Lava flow during a rift eruption at Krafla, Iceland in 1984.
Lava is the molten rock expelled by a volcano during an eruption. The resulting rock after solidification and cooling is also called lava. The molten rock is formed in the interior of some planets, including Earth, and some of their satellites. The source of the heat that melts the rock within the earth is geothermal energy. When first erupted from a volcanic vent, lava is a liquid at temperatures from 700 to 1,200 °C (1,292 to 2,192 °F). 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. 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.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. 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.
^ Pinkerton, H.; Bagdassarov, N. "Transient phenomena in vesicular lava flows based on laboratory experiments with analogue materials". Journal of Volcanology and Geothermal Research. doi:10.1016/s0377-0273(03)00341-x. Retrieved 19 June 2008.
^ "Rheological properties of basaltic lavas at sub-liquidus temperatures: laboratory and field measurements on lavas from Mount Etna". cat.inist.fr. Retrieved 19 June 2008.
^ "Lava". Merriam-Webster Online Dictionary. 2012-08-31. Retrieved 2013-12-08.
^ "Lava". Dictionary.reference.com. 1994-12-07. Retrieved 2013-12-08.
^ "Vesuvius Erupts, 1738". Lindahall.org. Retrieved 21 October 2015.
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