A minor jökulhlaup in river Gígjukvísl
Hazardous levels of gas at the outlet
A minor glacial outburst flood (jökulhlaup) is occurring in the river Gígjukvísl on Skeiðarársandur. The flood, which originates from subglacial lake Grímsvötn, became apparent on 6 May when the level of Gígjukvísl began to rise steadily. Additionally, the electrical conductivity of the river has increased markedly, signifying the presence of geothermal solutes. According to information from the Institute of Earth Sciences, University of Iceland, the volume of water available for drainage is 0.2 - 0.3 cubic kilometres. This volume is similar to floods from Grímsvötn in November 2012 and March 2014. The maximum discharge of the flood is therefore expected to be less than 700 cubic metres per second, occurring towards the middle of the week.
Potentially hazardous levels of hydrogen sulphide gas could be present at the location where floodwater bursts from Skeiðarárjökull. In the immediate vicinity of the outlet, gas concentrations could be high enough to cause respiratory problems and even damage to eyesight. For travellers on Skeiðarársandur, the ongoing flood poses no hazards. Elevated levels of seismic tremor have been recorded at IMO's seismic station on the edge of Grímsvötn. This signal is a measure of the amount of water draining from the lake. IMO continues to monitor the flood and any significant updates will be reported on the front page for hydrology.
The graphs below (enlarge) show the situation 5 - 9 May: water level, conductivity, water- and air temperature (combination graph) and the charge of the battery of the station.