Largest recorded glacial meltwater flood

Between late September and mid-October 1996, a volcanic eruption led to an unusually large lake (called Grimsvötn) developing beneath Iceland’s largest ice cap, Vatnajökull. This lake burst through the ice margin on the morning of 5 November and over the course of 40 hours achieved a peak meltwater discharge of at least 45,000 cubic metres (1,590 cubic feet) per second, the largest ever recorded for a glacial flood.

The 1918 eruption of the Katla volcano, beneath the much smaller Myrdalsjökull ice cap in Iceland, generated one of the world’s more recent largest glacial floods, and reconstructions based on displaced sediments and landforms indicate that its peak discharge rate may have been as high as 100,000 to 400,000 cubic metres (3.53 million–14.12 million cubic feet) per second, however this is more speculative than the better documented Grimsvötn event.