Ice and fire

Iceland is characterized by numerous ice-sheets, among which the vast  Vatnajökull (jökull  means glacier in Icelandic); with a surface area of  8,300 km2, is the largest in Europe. Glaciers are resting on basalt plateaux formed by a number of volcanoes that are still active today. Where the two worlds meet, the one of ice and the one of fire, an incredible, extraordinary landscape  forms, and it is as fascinating as it is risky and dangerous. In fact  the effects of the heat of the volcanic activity on the ice above are easy to guess : the most spectacular forms are the gigantic systems of enormous galleries  running along the glacier base, through which large quantities of melted water are drained. In these systems of caves, whose  vaults are dug in the ice and whose floor is a hot rock surface, and in the ice above them, at times large lakes form. These are the greatest risks of these glaciers. The walls supporting them in fact can crumble suddenly, instantly freeing enormous quantities of  subglacial water and provoking frightening outbursts: due to the large amounts of water that are accumulated because of the volcanic activity, these kind of flood has no comparison with the outbursts in “normal” glaciers. It is not surprising that these jökulhlaup   phenomena have an Icelandic name. In fact it was the Vatnajökull, in 1996, that gave rise to one of the most impressive jökulhlaup ever seen. Between 29th September and 13th October 1996 the eruption, from one of the numerous volcanic vents below the glacier, provoked the formation of an enormous amount of melt water, which initially filled the caldera of Grimsvötn, a subglacial volcano, and then overflowed, provoking a frightful flooding. The volcanic activity that preceded the flooding created a plume of ashes over 3,000 m high, which immediately warned the researchers who started the “count-down” for the foreseen outburst. The liberation of  4 billion m3 of water, imprisoned below the ice,  was monitored and observed also by the media all over the world due to its spectacular nature. With a discharge, during the maximum phase, of 45,000 m3/s, which can be compared to that of the Congo river, the flood wave  spread 50 km downstream, provoking damages amounting to over 30 million dollars, fortunately without any victims thanks to the immediate forecasts and the sparse population.


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