Fissure vent

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A volcanic fissure and lava channel
Lava channel on Hawaii
Mauna Loa with different lava flows and fissure vent

A fissure vent, also known as a volcanic fissure or simply fissure, is a linear volcanic vent through which lava erupts, usually without any explosive activity. The vent is usually a few meters wide and may be many kilometres long. Fissure vents can cause large flood basalts and lava channels. This type of volcano is usually hard to recognize from the ground and from outer space because it has no central caldera and the surface is mostly flat. The volcano can usually be seen as a crack in the ground or on the ocean floor. Narrow fissures can be filled in with lava that hardens. As erosion removes its surroundings, the lava mass could stand above the surface as a dyke. The dykes that feed fissures reach the surface from depths of a few kilometers. Fissures are usually found in or along rifts and rift zones, such as Iceland and the East African Rift. Fissure vents are often found in shield volcanoes.

In Iceland, volcanic vents are often long fissures parallel to the rift zone where lithospheric plates are diverging. 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 voluminous eruptions of fluid basaltic lava usually build up a thick lava plateau rather than a single volcanic edifice. The Laki fissure system produced the biggest eruption on earth in historical times, in the form of a flood basalt, during the Eldgjá eruption A.D. 934, which released 19.6 km³ (4.7 mi³) of lava.

The radial fissure vents of Hawaiian volcanoes produce “curtains of fire” as lava fountains erupt along a portion of a fissure. These vents produce 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 Grímsvötn 1725 5659 64°15′N 17°12′W / 64.25°N 17.20°W / 64.25; -17.20 (Grímsvötn) 2011
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
Spain Gran Canaria 1950 6350 28°00′N 15°35′W / 28.00°N 15.58°W / 28.00; -15.58 (Gran Canaria) less than 1000 BP
Spain Fuerteventura 529 1736 28°21′29″N 14°01′12″W / 28.358°N 14.02°W / 28.358; -14.02 (Fuerteventura) 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
Myanmar 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

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