Fissure vent

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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

A fissure vent, also known as a volcanic fissure or eruption fissure, is a linear volcanic vent through which lava erupts, usually without any explosive activity. The vent is often a few meters wide and may be many kilometers 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 resp. ash 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 dykes 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[edit]

In Iceland, volcanic vents, which can be long fissures, often open parallel to the rift zones where the Eurasian and the Northamerican 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 build 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 undeneath controlling their resp. 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.[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[edit]

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[edit]

Name Elevation Location Last eruption
metres feet Coordinates
Iceland Laki 1725 5659 64°25′N 17°20′W / 64.42°N 17.33°W / 64.42; -17.33 (Laki) 1783
Spain Lanzarote 670 2198 29°02′N 13°38′W / 29.03°N 13.63°W / 29.03; -13.63 (Lanzarote) 1824
Chile Cordón Caulle 1798 5899 40°28′S 72°15′W / 40.46°S 72.25°W / -40.46; -72.25 (Cordón Caulle) 2011?
Portugal 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
Iceland Vatnafjöll 1235 4052 63°55′N 19°40′W / 63.92°N 19.67°W / 63.92; -19.67 (Vatnafjöll) 1200 BP
Bolivia Quetena 5730 18799 22°15′S 67°25′W / 22.25°S 67.42°W / -22.25; -67.42 (Quetena) Unknown
Nicaragua Nejapa Miraflores 360 1181 12°07′N 86°19′W / 12.12°N 86.32°W / 12.12; -86.32 (Nejapa Miraflores) Unknown
Eritrea Manda-Inakir 600+ 1968 12°23′N 42°12′E / 12.38°N 42.20°E / 12.38; 42.20 (Manda-Inakir) 1928
Ethiopia Hertali 900? 2953 9°47′N 40°20′E / 9.78°N 40.33°E / 9.78; 40.33 (Hertali) Unknown
Nicaragua Estelí 899 2949 13°10′N 86°24′W / 13.17°N 86.40°W / 13.17; -86.40 (Estelí) Unknown
Sri Lanka 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
Ethiopia 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
Ethiopia Alu 429 1407 13°49′N 40°33′E / 13.82°N 40.55°E / 13.82; 40.55 (Alu) Unknown
Burma Singu Plateau 507 1663 22°42′N 95°59′E / 22.70°N 95.98°E / 22.70; 95.98 (Singu Plateau) Unknown
Canada Ray Mountain 2050 - 52°14′N 120°07′W / 52.23°N 120.12°W / 52.23; -120.12 (Ray Mountain) Pleistocene
Iceland Eldgjá 800 2625 63°53′N 18°46′W / 63.88°N 18.77°W / 63.88; -18.77 (Eldgjá) 934

References[edit]

  1. ^ See e.g. http://www.geology.sdsu.edu/how_volcanoes_work/index.html V. Camp, Dept. of Geologic Sciences, Univ. of San Diego: How volcanoes work. Eruption types. Fissure eruptions.
  2. ^ http://jardvis.hi.is/sites/jardvis.hi.is/files/Pdf_skjol/Jokull58_pdf/jokull58-einarsson.pdf P. Einarsson: Plate boundaries, rifts and transforms in Iceland. Jökull No.28, 2008
  3. ^ http://www.geo.mtu.edu/~raman/papers2/Thordarson%20and%20Hoskuldsson%202008%20Postglacial%20volcanism.pdf Th. Thordarson, etal.: Postglacial volcanism in Iceland. Jökull no. 58, 2008
  4. ^ http://earthice.hi.is/grimsvotn_volcano Institute of Earth Sciences, University of Iceland: Grímsvötn. Received 9/24, 2014.
  5. ^ http://earthice.hi.is/katla_volcano Institute of Earth Sciences, University of Iceland: Katla. Received 9/24, 2014.
  6. ^ See: http://earthice.hi.is/bardarbunga_2014 Institute of Earth Sciences, University of Iceland: Bardarbunga 2014

External links[edit]