Yesterday, The Icelandic Met Office raised the aviation color code for Grímsvötn volcano from green to yellow. Several monitored geophysical and geochemical parameters have shown a gradual increase for the past months, thus the activity at Grímsvötn is now considered to be above the known background level:

• The seismicity during the past month has been above average
• Geothermal activity has increased over the past months with clear signs of deepening cauldrons in several places around the caldera
• The surface deformation has exceeded the level it was at prior to the 2011 eruption
• Magmatic gases were measured in the geothermal emissions this summer   

Furthermore, the water level in the subglacial lake is comparable to the level prior to the floods in 2004 and 2010, increasing the likelihood for a flood in the coming months. 

Multiple datasets now indicate that Grímsvötn volcano has reached a level of unrest, comparable to that observed prior to historic eruptions.  

For the above mentioned reasons, the aviation color code has changed from green to yellow. This does not mean that an eruption is imminent. However, an eruption could be triggered by depressurization if the subglacial lake inside the caldera will drain and cause a flood or occur regardless, possibly with very weak precursory activity and short warning time, as seen in the eruption of 2011.  

The conditions at the volcano may change at any given time and the volcano may return to normal background conditions without further escalation.  

The Civil Protection meets regularly with the Icelandic Meteorological Office and is informed about the situation. So far, there are no reasons to change the alert level of civil protection due to Grímsvötn. 

This information and updates are posted on en.vedur.is