Vestari-Skaftárketill 12.08.2013. Ljósmynd: Jón Grétar Sigurðsson, Atlantsflugi.

Impending outburst flood in Skaftá: Likely hazards

15.8.2013

An outburst flood is expected in the Skaftá river, which drains from western Vatnajökull. The timing of the flood is unknown but it could occur within days to several weeks. Here is an outline of the hazards that are likely to occur during the course of the flood.

Possible hazards

• Flood conditions are possible in Skaftá. Some flooding of unpaved roads close to Skaftá is possible.
• The flood could drain partly from Síðujökull, which would cause flooding in Hverfisfljót, particularly at the bridge over Highway 1.
• Hydrogen sulphide would be released from the floodwater as it drained from the Vatnajökull ice-cap. The gas is particularly potent at the ice margin, where concentrations will reach poisonous levels. If flood occurs, travellers must stay away from the edge of Skaftárjökull, Tungnaárjökull and Síðujökull.
• Crevasses will develop rapidly around the ice cauldron, so travellers on Vatnajökull should stay away from the region, including the lower part of Skaftárjökull and Tungnárjökull, where floodwater could burst through the surface.

Background

Floods in Skaftá are sourced from two ice cauldrons, formed due to persistent geothermal activity beneath Vatnajökull ice-cap. On average, the cauldrons drain every two years, producing floods of up to 1,500 cubic metres per second. When the interval between floods is short the flood tends to be smaller. The eastern cauldron is responsible for the largest floods.

A study of a jökulhlaup from the Western Skaftá cauldron was published by IMO in 2009.