Warning - glacial outburst flood at Skaftá
Jökulhlaup in progress
Within the past 24 hours* the level of the Skaftá river at Sveinstindur has risen. Additionally electrical conductivity readings from the same location have increased. These observations signify that a glacial outburst flood (jökulhlaup) is in progress. It is likely that the flood originated from the western Skaftá ice cauldron, which last drained in January 2014; however this is unconfirmed until visual observations are made. The discharge of Skaftá at Sveinstindur is presently 150 m³/s.
Possible hazards
- Flood conditions are expected in Skaftá over the next two to three days. Some flooding of unpaved roads close to Skaftá is possible.
- Hydrogen sulphide is released from the floodwater as it drains from the Vatnajökull ice-cap. The gas is particularly potent at the ice margin, where concentrations will reach poisonous levels. Travellers must stay away from the edges of Skaftárjökull, Tungnaárjökull and Síðujökull while the flood occurs.
- 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 Tungnaárjökull, 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. 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.
Further information
* This warning was issued 17.6.2015 at 16:00. Specialists on duty were Hilmar Björn Hróðmarsson og Gunnar Sigurðsson. The situation will be watched closely at IMO. A map shows the source of the flooding, which rivers are affected, and the location of water level gauges.
