fissure vent

A fissure vent is the surface expression of a dike, which is an underground fracture filled with magma. These dikes typically measure between 0.5 to 2 meters wide and extend for several kilometers. Fissure vents are commonly found in places like Iceland and along the rift zones of shield volcanoes. In Iceland, eruptions often occur from new fissures that are parallel to and offset from earlier ones, leading to the formation of extensive lava plateaus rather than single volcanic cones. A notable example is the 1783 eruption in Iceland from the Laki fissure, which produced a long crater row and vast amounts of basaltic lava. Hawaiian volcanoes also feature radial fissure vents that create "curtains of fire" with lava fountains and low ramparts of spatter. A fissure can also be described as an irregular, narrow break in a surface caused by pressure, through which lava can flow.123