Group - Glacial lake outburst flood

A glacial lake outburst flood (GLOF) can occur when a lake contained by a glacier (called Jökulhlaup if it was a subglacial lake, marginal lake drainage if it was dammed between ice and the ground) or a terminal moraine dam fails. This can happen due to erosion, a buildup of water pressure, an avalanche of rock or heavy snow, an earthquake or cryoseism, volcanic eruptions under the ice, or if a large enough portion of a glacier breaks off and massively displaces the waters in a glacial lake at its base. A glacial lake outburst flood is created when water dammed by a glacier or a moraine is released. A water body that is dammed by the front of a glacier is called a marginal lake, and a water body that is capped by the glacier is called a sub-glacial lake. When the former bursts it may also be called a marginal lake drainage, and when the latter bursts it may be called a jökulhlaup. A jökulhlaup is thus a sub-glacial outburst flood. Jökulhlaup is an Icelandic term that has been adapted into the English language, and originally only referred to glacial outburst floods from Vatnajökull, which are triggered by volcanic eruptions, but now is accepted to describe any abrupt and large release of sub-glacial water.