A lava spine (or lava spire) is a vertical growth of solid
lava
Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...
that is forced from a
volcanic vent
A volcano is commonly defined as a vent or fissure 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.
On Earth, volcanoes are most often fo ...
. A lava spine can either be formed by viscous lava slowly being pushed out of the vent, or by magma that has solidified within the vent before being pushed out.
In February 1983, the dome activity of
Mount St. Helens culminated in a spine that reached a height of about before collapsing after two weeks, but in 2005 another lava spine (called the ''Whaleback'') lasted until it collapsed in July 2005. In November 2005, a new spine, called "the slab" grew continuously until late 2006, though it continually collapsed under its own weight; the growth finally stopped in January 2008, when Mount St. Helens' eruption ended. Another example is a spine that appeared on the lava dome of the
Soufrière Hills Volcano in
Montserrat
Montserrat ( , ) is a British Overseas Territories, British Overseas Territory in the Caribbean. It is part of the Leeward Islands, the northern portion of the Lesser Antilles chain of the West Indies. Montserrat is about long and wide, wit ...
prior to the volcano's eruption in 1997.
Gallery
File:Soufriere Hills Lava Dome Spire1.jpg, A spire of lava on top of the lava dome of Soufrière Hills volcano
File:Pelee 1902 6.jpg, A lava spine at the summit of Mount Pelée
Mount Pelée or Mont Pelée ( ; , ; ), meaning "bald mountain" or "peeled mountain" in French, is an active volcano at the northern end of Martinique, an island and French overseas department in the Lesser Antilles Volcanic Arc of the Caribbean ...
in 1902
File:Whaleback, Mount St Helens volcanic crater (February 22 2005).jpg, "Whaleback", Mount St. Helens
See also
*
Volcanic plug
A volcanic plug, also called a volcanic neck or lava neck, is a volcano, volcanic object created when magma hardens within a Volcanic vent, vent on an active volcano. When present, a plug can cause an extreme build-up of high gas pressure if risi ...
References
Volcanic landforms
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