Iceland, Reykjanes Peninsula

Fagradalsfjall: Update 02/01/2022

Good afternoon!

Updated Earthquake Plots, 2nd January 2022 13:50

Good afternoon!

We have updated the earthquake plots for Fagradalsfjall, Iceland, for the swarm which started on 21 December 2021. 

The swarm had an intense initial period while magma moved along a lateral dike, followed by a less intense period, accompanied by magma ascent.  The Icelandic Met Office, IMO, say that the swarm is following the same pattern as that which preceded the eruption in March 2021. 

Magma is ascending under Fagradalsfjall, itself.  The outlying earthquakes, e.g., at Svartsengi and Krýsuvík, are what Iceland calls triggered earthquakes.  Triggered earthquakes are tectonic in nature, arising as local faults respond to magma movement. 

Fig 4: Geodensity plot by the author of earthquakes at Fagradalsfjall the period 21.12.2021 to 02.01.2022.  © Copyright remains with the author; all rights reserved, 2021.
Fig 5: Geoscatter plot by the author of earthquakes at Fagradalsfjall the period 21.12.2021 to 02.01.2022.  Colour denotes age: red is the oldest and yellow the youngest. © Copyright remains with the author; all rights reserved, 2021.
Fig 6: Scatter plot by the author of earthquakes at Fagradalsfjall the period 21.12.2021 to 02.01.2022.  Colour denotes age: red is the oldest and yellow the youngest. © Copyright remains with the author; all rights reserved, 2021.
Fig 7: 2D Depth v Earthquake scatter plot by the author of earthquakes at Fagradalsfjall the period 21.12.2021 to 02.01.2022.  Colour denotes age: red is the oldest and yellow the youngest. © Copyright remains with the author; all rights reserved, 2021.

Armchair Volcanologist

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

Source

Raw earthquake data: https://skjalftalisa.vedur.is/#/page/map

Update 31/12/2021

Following a drop in seismicity over the past couple of days, visitors are now advised to avoid the area.

A similar drop in seismicity was observed immediately before the March 2021 eruption.

If the volcano does erupt again, this would be considered a new eruption in the same place; the earlier eruption was declared over three months after the cessation of activity on 19 September 2021.

Update 28/12/2021

The earthquake swarm at Fagradalsfjall, Iceland, is continuing.  While the swarm has slowed down a bit, 19,000 earthquakes have been recorded by the automatic SIL system since the swarm started.  14 earthquakes over 4.0 magnitude have occurred.  An alert for the risk of rockfall and landslides in the area has been raised; visitors are advised to stay away from the area.

We have plotted the confirmed earthquakes from 20 December 2021 to 28 December 12:50.  This shows the dike propagation south west of Geldingadalur, with additional activity near Kýsuvík and Svartsengi.

Fig 1: Geoscatter plot of the earthquake swarm between 20.12.2021 and 28.12.2021 12:50 by the author.  Red denotes oldest quakes and yellow the newest.  © Copyright remains with the author; all rights reserved, 2021
Fig 2: Scatter plot of the earthquake swarm between 20.12.2021 and 28.12.2021 12:50 by the author.  Red denotes oldest quakes and yellow the newest.  © Copyright remains with the author; all rights reserved, 2021
Fig 3: Geodensity plot of the earthquake swarm between 20.12.2021 and 28.12.2021 12:50 by the author.  © Copyright remains with the author; all rights reserved, 2021.

Only time will tell where and when lava will emerge.  In the meantime, if you are lucky enough to be in the area, be aware of the risk of rock fall and landslip.

Armchair Volcanologist

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

Sources:

Raw earthquake data: https://skjalftalisa.vedur.is/#/page/map

Icelandic Met Office: en.vedur.is