Aviation Code for Fagradalsfjall Lowered to Yellow, 18 October 2021

Good Afternoon!

The eruption at Fagradalsfjall has halted.  No lava has been erupted in the period 18 September to 18 October 2021 (or to the time of writing).  The seismic swarm at Kelir has lessened.  Gas emissions have decreased. The aviation code has therefore been lowered.

Fig 1: Image of Kelir cropped from Keilir (mountain) – Wikipedia, published under CC BY 2.0

The eruption will not be declared over for some time.  It is not possible to tell if this is a temporary lull or the eruption has ended; the eruption may resume at the same location in Fagradalsfjall or at a new fissure.   As the authorities have pointed out, this can only be determined in retrospect. 

The volcanic hazards are currently: gas, high temperatures both in the area and the lava field, earthquakes and rockfalls.

It’s been a few days since we looked at the latest earthquake swarm at Kelir, which is on-going.  Here are the updated plots.

Fig 2:  Count by day in the confirmed earthquakes reported by IMO; plot by the author.  © Copyright remains with the author; all rights reserved, 2021.
Fig 3:  Depths and magnitudes by day  of  the confirmed earthquakes reported by IMO; plot by the author. Blue columns are minimum depth (deepest); orange columns are average depth; grey columns are maximum depth (shallowest); yellow columns are average magnitude; and, light blue columns are maximum magnitude.  © Copyright remains with the author; all rights reserved, 2021.

From the plots we see a slow decrease in average depth.  This is borne out by the scatter plots. Let’s look at them.

Fig 4: Video by the author of geoscatter plots and scatter plots by day of the earthquake swarm at Kelir  from day 1 (27.09.2021) to day 25 (21.10.2021).  Note: day 25 is not a complete day.  © Copyright remains with the author; all rights reserved, 2021.,

Whether or not the eruption will resume and where, only time will tell.

Armchair Volcanologist

© Copyright remains with the author; all rights reserved, 2021

Sources

Raw earthquake data:  IMO

IMO: The Civil protection crisis level lowered from alert to uncertainty phase | News | Icelandic Meteorological office (vedur.is)