Aviation Alert Level for The Krýsuvík Volcanic System raised to Orange

3 March 2021 (Updated 07.03.2021 – new plots added).

The earthquake swarm which started on 24 February 2021 between Kleifarvatn and Svartsengi on the Reykjanes Peninsula is continuing.

This image has an empty alt attribute; its file name is capture-keilir.png — *Fig 1: Keilir. Image cropped from one taken by Michal Klajban, published under CC BY-SA 4.0. Keilir is the dark cone in the background; Spákonuvatn lake is in the foreground.*

IMO have raised the aviation code for Krýsuvík to Orange and report a tremor pulse south of Keilir. At the time of writing, no eruption has been confirmed; however, visibility of the area is hampered by weather.

*Fig 2: Drumplot showing the onset of the tremor pulse. Source: IMO.*

If magma does reach the surface, the most likely scenario is a fissure eruption, which would produce effusive basaltic lava flows and toxic gases, rather than an explosive ashy eruption. If lava meets a significant amount of water, some tephra may be produced.

The likely impact from any eruption is expected to be disruption of air traffic and also road traffic access to and from Keflavík International Airport, if lava flows cross the access road.

Keilir, itself, is a subglacial mound near Krýsuvík formed during the Pleistocene during a fissure eruption. The mound is built of tephra formed when melting ice met magma, topped by lava. Fagradalsfjall, another location associated with the earthquake swarm, is a Pleistocene table-mountain. As lava prefers to take the easy route out, it is unlikely to emerge via these two volcanoes whose lavas would be fairly solid – hence the expectation of a new fissure swarm.

*Fig 3: Current aviation codes for Iceland. Source: IMO.*

For status updates, please consult IMO.

A local news service that is also providing updates in English is the Reykjavik Grapevine.

Life is not easy for the research scientists monitoring events. Two had to be rescued after having been separated from the main party while studying gas emissions. Spare a thought for the risks they take.

The public have been advised to stay clear of the area at least until it is known where and how lava emerges and where it would be safe to observe the eruption.

In our excitement at the thought of a possible eruption we overlooked the very real risk of larger earthquakes, if the intensity of the swarm continues: up to 6.0 M near Fagradalsfjall and up to 6.5 M in the Brennisteinfjöll range. Be careful if you are in the area.

Update 05.03.2021 23:29

We have plotted the earthquakes with a quality of 99.0 from IMO’s page showing the earthquakes for the last 48 hours for the Reykjanes Peninsula for the period 2 March 2021 to 5 March 2021 (23:29) (we were too slow to capture 1 March 2021). Here are the results. Colour coding in the scatter plots is by day and size reflects magnitude. The geodensity plot is weighted by magnitude.