Notification of change in aviation color code

Grímsvötn

Time: 11. Jan 2024, 12:17 GMT

Color code:  Yellow 

Volcano id: 373010

Activity summary:
This morning at 06:53, a magnitude 4.3 earthquake occurred in Grímsvötn. This is the largest earthquake in Grímsvötn since the beginning of measurements in 1991. In recent days, a slow and gradual increase in tremor has been detected on Grímsfjall, and the water level in Gígjukvísl has been increasing since yesterday night. Therefore, a glacial flood (jökulhlaup) has started from Grímsvötn. It is likely that the earthquake this morning is due to pressure release following the onset of the glacial flood. Due to the ongoing flood and increase in seismicity the aviation color code for Grímsvötn volcano is raised to yellow as the likelihood of an eruption has slightly increased.

Cloud height:
NA

Other cloud information:
NA

Remarks:
There are past examples of Grímsvötn eruptions starting, following a flood. The drainage of the water from Grímsvötn lake reduces the pressure on top of the volcano and this can result in an eruption. This happened in 2004, and before that in 1934 and in 1922. However, twelve glacial floods have occurred since 2004 without triggering an eruption. Seismicity over the past 4 months has been above background.