Lava delta

Lava deltas are found mainly associated with volcanic islands, particularly those formed at hotspots as they produce the necessary effusive basaltic flows. The largest lava delta systems known are associated with formation of volcanic type passive margins. Just prior to break-up along the northern Atlantic in the late Paleocene, massive eruptions occurred along the eventual line of break-up. This volcanism, part of the North Atlantic Igneous Province, led to the formation of two extensive lava escarpments, interpreted as deltas, extending from the Faeroes onto the More Margin (the Faeroe-Shetland escarpment) and the Vøring escarpment on the Vøring margin, a combined distance of approximately . As these deltas were prograding into water of relatively constant depth, they were able to extend as much as from their original vents. ==Formation==

When a sub-aerial lava flow reaches the ocean (or other large body of water), contact with the water causes both rapid cooling of the lava and steam explosions that fragment it. The glassy fragments that are formed, known as hyaloclastites, fall down to the seabed forming foresets. As the seabed topography becomes infilled, the subaerial flow is able to build out. The process continues as long as the lava supply is maintained, creating a lava bench. A lava bench is a volcanic landform with a horizontal surface raised above the level of the surrounding area. The Hawaiian islands are an example of land that was formed this way, and the Big Island is currently still expanding due to lava benches. ==Hazards==

Collapse of the frontal part of lava deltas is common during their formation, representing a hazard for any people that are watching from a solidified part of the delta and such areas are normally marked as dangerous. If a newly formed lava bench rests on sediments, it may pose hazards due to its extremely unstable structure. Oftentimes, these benches are so unstable that they collapse into the sea, exposing the water to the hot lava on the interior of the bench and releasing acres of land into the ocean. People standing too close to the edge of an active delta are not only at risk from being thrown in the water but from the steam explosions and the accompanying acidic clouds (laze) that result from the collapse as seawater comes into contact with the active lava tube system. ==Uses==

On steep-sided volcanic islands, lava deltas make attractive sites for building and many villages and towns are located on old lava deltas, such as Garachico on Tenerife. ==See also==