Tag Archives: VEI 4

A Quick Update for Grímsvötn: Alert level: Yellow

The Icelandic Met Office (IMO) has updated the aviation alert for Grímsvötn from green to yellow today (30.09.2020) because the volcano’s activity is above background level, now at a level comparable to that which preceded previous eruptions.  They note:

  • Above average seismicity for September 2020;
  • Deepening cauldrons in the ice-cap round the caldera from geothermal activity;
  • Surface deformation exceeding that which preceded the 2011 eruption;
  • Magmatic gases detected in the summer of 2020.

An eruption is not considered imminent.

Water levels in the sub-glacial lake are high indicating possible jökulhlaups in the coming months.   Draining of the lake by a jökulhlaup depressurised the system before the 2011 eruption, so an eruption is considered possible in the event of a jökulhlaup.

Activity may decrease without an eruption in this instance; only time will tell.

Jumping the gun a bit on our next post in the volcanic risk mitigation series, the IMO’s alert is an example of using alert levels to highlight the increased risk of an eruption to those who need to know, without being unduly alarmist – a straightforward statement of the facts supporting the current status. For the exact wording of the alert, please follow the link below.

Fig 1: Eruption column 3 hours after the onset of the 2011 eruption of Grímsvötn. Source: Sigurjónsson, O. (2011 May 21). Grímsvötn: photo 10 of 14. Retrieved from http://icelandicvolcanoes.is/?volcano=GRV

Grímsvötn is located under the Vatnajökull ice-cap in an active rift zone of the Eastern Volcanic Zone, Iceland. She erupts frequently; her last in 2011 was a large VEI 4, which impacted local farmers and livestock and aviation in Europe.

Update (02/10/2020)

Googling around a bit more, I note that Iceland’s Department of Civil Protection and Emergency Management, Almannavarnir, have reported in their 25 September 2020 bulletin that an eruption is considered likely this Autumn (use Google Translate or other tool, if you need to, as it is in Icelandic).

For more information, please visit IMO.

The Armchair Volcanologist

30 September 2020

Source and Further Reading:

Icelandic Met Office: https://en.vedur.is/   &  https://en.vedur.is/about-imo/news/the-aviation-color-code-for-grimsvotn-changed-from-green-to-yellow

Almannavarnir: https://www.almannavarnir.is/frettir/

Google Translate: https://translate.google.com/