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 kilometers 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 diver