A fissure vent, also known as a volcanic fissure, eruption fissure or simply a fissure, is a linear

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 ...

through which

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 ...

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 basalt A flood basalt (or plateau basalt) is the result of a giant volcanic eruption or series of eruptions that covers large stretches of land or the ocean floor with basalt lava. Many flood basalts have been attributed to the onset of a hotspot (geolo ...

s which run first in

lava channel A lava channel is a stream of fluid lava contained within zones of static (i.e., solid and stationary) lava or lava levees. The initial channel may not contain levees per se, until the parental flow solidifies over what develops into the channel a ...

s and later in

lava tube A lava tube, more rarely called a pyroduct, is a 'roofed conduit through which molten lava travels away from its vent'. If lava in the tube drains out, it will leave an empty cave. Lava tubes are common in low-viscosity volcanic systems. La ...

s. After some time, the eruption tends to become focused at one or more

spatter cone Volcanic cones are among the simplest volcano, volcanic landforms. They are built by ejecta from a volcanic vent, piling up around the vent in the shape of a cone (geometry), cone with a central crater. Volcanic cones are of different types, depen ...

Volcanic cone Volcanic cones are among the simplest volcanic landforms. They are built by ejecta from a volcanic vent, piling up around the vent in the shape of a cone with a central crater. Volcanic cones are of different types, depending upon the nature and s ...

s and their craters that are aligned along a fissure form a crater row. Small fissure vents may not be easily discernible from the air, but the crater rows (see

Laki Laki () or Lakagígar (, ''Craters of Laki'') is a volcanic fissure in the western part of Vatnajökull National Park, Iceland, not far from the volcanic fissure of Eldgjá and the small village of Kirkjubæjarklaustur. The fissure is proper ...

) or the canyons (see

Eldgjá Eldgjá (, "fire canyon") is a volcano and a canyon in Iceland. Eldgjá is part of the Katla volcano; it is a segment of a long chain of volcanic craters and fissure vents that extends northeast away from Katla volcano almost to the Vatnajök ...

) built up by some of them are. The

dikes Dyke or dike may refer to: General uses * Dyke (slang), a slang word meaning "lesbian" * Dike (geology), formations of magma or sediment that cut through and across the layering of adjacent rocks * Dike (mythology), ''Dikē'', the Greek goddess ...

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

rift In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-graben ...

s and

rift zone A rift zone is a feature of some volcanoes, especially shield volcanoes, in which a set of linear cracks (or rifts) develops in a volcanic edifice, typically forming into two or three well-defined regions along the flanks of the vent. Believed ...

s, such as

Iceland Iceland is a Nordic countries, Nordic island country between the Atlantic Ocean, North Atlantic and Arctic Oceans, on the Mid-Atlantic Ridge between North America and Europe. It is culturally and politically linked with Europe and is the regi ...

and the

East African Rift The East African Rift (EAR) or East African Rift System (EARS) is an active continental rift zone in East Africa. The EAR began developing around the onset of the Miocene, 22–25 million years ago. It was formerly considered to be part of a l ...

. Fissure vents are often part of the structure of

shield volcano A shield volcano is a type of volcano named for its low profile, resembling a shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more viscous lava ...

es.

Iceland

In Iceland, volcanic vents, which can be long fissures, often open parallel to the rift zones where the Eurasian and the

North American North America is a continent in the Northern and Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Caribbean Sea, and to the sou ...

lithospheric

plates Plate may refer to: Cooking * Plate (dishware), broad, mainly flat vessel commonly used to serve food * Plates, tableware, dishes or dishware used for setting a table, serving food and dining * Plate, the content of such a plate (for example: ...

are diverging, a system which is part of the

Mid-Atlantic Ridge The Mid-Atlantic Ridge is a mid-ocean ridge (a Divergent boundary, divergent or constructive Plate tectonics, plate boundary) located along the floor of the Atlantic Ocean, and part of the List of longest mountain chains on Earth, longest mountai ...

. 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 volcano A central volcano is a type of volcano formed by basalts and silica-rich volcanic rocks. They contain very few or no volcanic rocks of intermediate composition, such that they are chemically bimodal volcanism, bimodal. Large silicic eruptions at c ...

es,

composite volcano A stratovolcano, also known as a composite volcano, is a typically conical volcano built up by many alternating layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a ...

es, often with

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the str ...

s, which have been formed during thousands of years, and eruptions with one or more magma reservoirs underneath controlling their respective fissure system. The

fissures, part of the

Grímsvötn Grímsvötn (; ''vötn'' = "waters", singular: ) is an active volcano with a (partially subglacial) fissure system located in Vatnajökull National Park, Iceland. The central volcano is completely subglacial and located under the northwestern side ...

volcanic system, produced one of the biggest

effusive eruption An effusive eruption is a type of volcanic eruption in which lava steadily flows out of a volcano onto the ground. Overview There are two major groupings of eruptions: effusive and explosive. Effusive eruption differs from explosive eruption ...

s on earth in historical times, in the form of a flood basalt of 12–14 km³ of lava in 1783. During the

eruption A.D. 934–40, another very big effusive fissure eruption in the volcanic system of Katla in South Iceland, ~ of lava were released. In September 2014, a fissure eruption was ongoing on the site of the 18th century lava field Holuhraun. The eruption is part of an eruption series in the

Bárðarbunga Bárðarbunga (, alternative name Veiðivötn), is an active and productive stratovolcano located under Vatnajökull in Vatnajökull National Park which is Iceland's most extensive glacier. The second highest mountain in Iceland, above sea le ...

volcanic system.

Hawaii

The radial fissure vents of Hawaiian volcanoes also produce "curtains of fire" as

lava fountain Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or unde ...

s erupting along a portion of a fissure. These vents build up low ramparts of

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

ic spatter on both sides of the fissure. More isolated lava fountains along the fissure produce crater rows of small spatter and

cinder cone A cinder cone or scoria cone is a steep, volcanic cone, conical landform of loose pyroclastic rock, pyroclastic fragments, such as volcanic ash, clinkers, or scoria that has been built around a volcanic vent. The pyroclastic fragments are forme ...

s. The fragments that form a

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

References

External links

*
Detailed list and KML files for Fissure Vents
{{Volcanoes Lists of coordinates