A so-called glacier run (literal translation of Icelandic "jökulhlaup") is due to the eruption of a volcano under a glacier. The ice over the volcano melts because of the heat, causing water to form a lake under the remaining ice-cap. Then the ice-cap collapses, or the water breaks through the barrier in front of it, and there follows a more or less disastrous flooding of the land below the mountain. A glacier run is a type of lahar.

It is not by chance that the term "glacier run" comes from the Icelandic, as the south of Iceland has very often been victim to such catastrophes. Lately, this was the case when in 1996 the volcano under the Grimsvötn lakes belonging to the Vatnajökull glacier erupted and the river Skeiðará flooded the land in front of Skaftafell National Park. The glacier run reached 45 000 m³s^-1 and destroyed parts of the Hringvegur (road no. 1). After the flooding some icebergs 10 m high could be seen on the banks of the river where the glacier run had left them behind (see also Mýrdalsjökull).

External links

• Volcanism at Grimsvötn lakes
• Formation and emptying of glacier lakes