The Icelandic Met Office reports that a glacial outburst flood, or jökulhlaup, is expected to occur underneath Vatnajökull glacier. Water is draining from Grímsvötn subglacial lake, located underneath the glacier. RÚV reported first.
The ice shelf above the lake has subsided approximately 5 metres, another indication that a flood is likely. The flood is expected to be of similar size to floods in recent years and therefore should not be disruptive or dangerous.
Glacial outburst floods are usually a result of geothermal heating, but can also be triggered by subglacial eruptions.