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A volcanic fissure and lava channel
Lava channel on Hawaii
Eruption fissure with spatter cones, Holuhraun, Iceland, 2014
Mauna Loa with different lava flows and fissure vent
Crater row of Laki
Eldhraun, a lava field produced by the Laki craters
Cinder cones on Etna

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]

Contents

IcelandEdit

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]

HawaiiEdit

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 ventsEdit

Name Elevation Location Last eruption
metres feet Coordinates
  Quetena 5730 18799 22°15′S 67°25′W / 22.25°S 67.42°W / -22.25; -67.42 (Quetena) Unknown
  Ray Mountain 2050 6730 52°14′N 120°07′W / 52.23°N 120.12°W / 52.23; -120.12 (Ray Mountain) Pleistocene
  Cordón Caulle 1798 5899 40°28′S 72°15′W / 40.46°S 72.25°W / -40.46; -72.25 (Cordón Caulle) 2011
  Manda-Inakir 600+ 1968 12°23′N 42°12′E / 12.38°N 42.20°E / 12.38; 42.20 (Manda-Inakir) 1928
  Alu 429 1407 13°49′N 40°33′E / 13.82°N 40.55°E / 13.82; 40.55 (Alu) Unknown
  Bishoftu Volcanic Field 1850+ 6069 8°47′N 38°59′E / 8.78°N 38.98°E / 8.78; 38.98 (Bishoftu Volcanic Field) Unknown
  Hertali 900 2953 9°47′N 40°20′E / 9.78°N 40.33°E / 9.78; 40.33 (Hertali) Unknown
  Eldgjá 800 2625 63°53′N 18°46′W / 63.88°N 18.77°W / 63.88; -18.77 (Eldgjá) 934
  Holuhraun 730 2395 64°52′N 16°50′W / 64.87°N 16.83°W / 64.87; -16.83 (Nornahraun) 2014
  Krafla 1984
  Lakagígar (Laki) 620 2034 64°04′N 18°14′W / 64.07°N 18.23°W / 64.07; -18.23 (Laki) 1783
  Banda Api 640 2100 4°31′30″S 129°52′16″E / 4.525°S 129.871°E / -4.525; 129.871 (Banda Api) 1988
  Komaga-take 1996
  Kuchinoerabu 1980
  Singu Plateau 507 1663 22°42′N 95°59′E / 22.70°N 95.98°E / 22.70; 95.98 (Singu Plateau) Unknown
  Estelí 899 2949 13°10′N 86°24′W / 13.17°N 86.40°W / 13.17; -86.40 (Estelí) Unknown
  Pagan 1981
  Nejapa Miraflores 360 1181 12°07′N 86°19′W / 12.12°N 86.32°W / 12.12; -86.32 (Nejapa Miraflores) Unknown
  Tor Zawar[7] 2237 7339 30°28′45″N 67°28′30″E / 30.47917°N 67.47500°E / 30.47917; 67.47500 (Tor Zawar) 2010
  São Jorge Island 1053 3455 38°39′N 28°05′W / 38.65°N 28.08°W / 38.65; -28.08 (São Jorge Island) 1907
  Tolbachik 1975
  Lanzarote 670 2198 29°02′N 13°38′W / 29.03°N 13.63°W / 29.03; -13.63 (Lanzarote) 1824
  Butajiri Silti Field 2281 7484 8°03′N 83°51′E / 8.05°N 83.85°E / 8.05; 83.85 (Butajiri Silti Field) Unknown

ReferencesEdit

  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.

External linksEdit