Fissure vent

A fissure vent, also known as a volcanic fissure, eruption fissure or simply a fissure, is a linear volcanic vent through which lava erupts, usually without any explosive activity. The vent is often a few metres wide and may be many kilometres long. Fissure vents can cause large flood basalts which run first in lava channels and later in lava tubes. After some time the eruption builds up spatter cones and may concentrate on one or some of them. Small fissure vents may not be easily discernible from the air, but the crater rows (see Laki) or the canyons (see Eldgjá) built up by some of them are.

The dikes that feed fissures reach the surface from depths of a few kilometers and connect them to deeper magma reservoirs, often under volcanic centers. Fissures are usually found in or along rifts and rift zones, such as Iceland and the East African Rift. Fissure vents are often part of the structure of shield volcanoes.[1]

Iceland

In Iceland, volcanic vents, which can be long fissures, often open parallel to the rift zones where the Eurasian and the North American Plate lithospheric plates are diverging, a system which is part of the Mid-Atlantic Ridge.[2] Renewed eruptions generally occur from new parallel fractures offset by a few hundred to thousands of metres from the earlier fissures. This distribution of vents and sometimes voluminous eruptions of fluid basaltic lava usually builds up a thick lava plateau, rather than a single volcanic edifice. But there are also the central volcanoes, composite volcanoes, often with calderas, which have been formed during thousands of years, and eruptions with one or more magma reservoirs underneath controlling their respective fissure system.[3]

The Laki fissures, part of the Grímsvötn volcanic system, produced one of the biggest effusive eruptions on earth in historical times, in the form of a flood basalt of 12–14 km3 of lava in 1783.[4] During the Eldgjá eruption A.D. 934-40, another very big effusive fissure eruption in the volcanic system of Katla in South Iceland, ~18 km3 (4.7 mi3) of lava were released.[5] In September 2014, a fissure eruption is ongoing on the site of the 18th century lava field Holuhraun. The eruption is part of an eruption series in the Bárðarbunga volcanic system.[6]

Hawaii

The radial fissure vents of Hawaiian volcanoes also produce “curtains of fire” as lava fountains erupting along a portion of a fissure. These vents build up low ramparts of basaltic spatter on both sides of the fissure. More isolated lava fountains along the fissure produce crater rows of small spatter and cinder cones. The fragments that form a spatter cone are hot and plastic enough to weld together, while the fragments that form a cinder cone remain separate because of their lower temperature.

List of fissure vents

NameElevationLocationLast eruption
metresfeetCoordinates
Quetena57301879922.25°S 67.42°W / -22.25; -67.42 (Quetena)Unknown
Ray Mountain2050673052.23°N 120.12°W / 52.23; -120.12 (Ray Mountain)Pleistocene
Cordón Caulle1798589940.46°S 72.25°W / -40.46; -72.25 (Cordón Caulle)2011
Manda-Inakir600+196812.38°N 42.20°E / 12.38; 42.20 (Manda-Inakir)1928
Alu429140713.82°N 40.55°E / 13.82; 40.55 (Alu)Unknown
Bishoftu Volcanic Field1850+60698.78°N 38.98°E / 8.78; 38.98 (Bishoftu Volcanic Field)Unknown
Hertali90029539.78°N 40.33°E / 9.78; 40.33 (Hertali)Unknown
Eldgjá800262563.88°N 18.77°W / 63.88; -18.77 (Eldgjá)934
Holuhraun730239564.87°N 16.83°W / 64.87; -16.83 (Nornahraun)2014
Krafla1984
Lakagígar (Laki)620203464.07°N 18.23°W / 64.07; -18.23 (Laki)1783
Banda Api64021004.525°S 129.871°E / -4.525; 129.871 (Banda Api)1988
Komaga-take1996
Kuchinoerabu1980
Singu Plateau507166322.70°N 95.98°E / 22.70; 95.98 (Singu Plateau)Unknown
Estelí899294913.17°N 86.40°W / 13.17; -86.40 (Estelí)Unknown
Pagan1981
Nejapa Miraflores360118112.12°N 86.32°W / 12.12; -86.32 (Nejapa Miraflores)Unknown
Tor Zawar[7]2237733930°28′45″N 67°28′30″E2010
São Jorge Island1053345538.65°N 28.08°W / 38.65; -28.08 (São Jorge Island)1907
Tolbachik1975
Lanzarote670219829.03°N 13.63°W / 29.03; -13.63 (Lanzarote)1824
Butajiri Silti Field228174848.05°N 83.85°E / 8.05; 83.85 (Butajiri Silti Field)Unknown

References

  1. V. Camp, Dept. of Geologic Sciences, Univ. of San Diego: How volcanoes work. Eruption types. Fissure eruptions.
  2. Einarsson, Páll (2008). "Plate boundaries, rifts and transforms in Iceland" (PDF). Jökull. 58 (12): 35–58.
  3. Thordarson, Thorvaldur; Höskuldsson, Ármann (2008). "Postglacial volcanism in Iceland" (PDF). Jökull. 58 (198): e228.
  4. Institute of Earth Sciences, University of Iceland: Grímsvötn. Received 9/24, 2014.
  5. Institute of Earth Sciences, University of Iceland: Katla. Received 9/24, 2014.
  6. Institute of Earth Sciences, University of Iceland: Bardarbunga 2014
  7. Kerr, A. C; Khan, M; McDonald, I (2010). "Eruption of basaltic magma at Tor Zawar, Balochistan, Pakistan on 27 January 2010: Geochemical and petrological constraints on petrogenesis". Mineralogical Magazine. 74 (6): 1027–36. doi:10.1180/minmag.2010.074.6.1027.

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