Earthquake swarm close to Skjaldbreið lava shield

Since 14. July 2023 there has been a minor earthquake swarm close to Skjaldbreið lava shield just south of Presthnjúkur volcano. Largest earthquake took place yesterday (20. July 2023), with a magnitude of Mw3,0.

Green star and red dots just south of Presthnjúkur volcano and south of Langjökull glacier. Few red dots outside of this. This earthquake swarm is next to Skjaldbreið lava shield
Earthquake activity close to Skjaldbreið lava shield. Copyright of this image belongs to Icelandic Met Office.

This is tectonic earthquake swarm and its just normal activity. Its not connected to eruption in Fagradalsfjall mountain, because its outside of that area influence. This earthquake swarm is ongoing at the writing of this article.

Strong earthquake swarm ongoing in Skjaldbreið shield volcano

Yesterday (10-12-2017) a earthquake swarm started in Skjaldbreið shield volcano (in Global Volcanism program this area is under Presthnjúkar area). Currently the earthquake swarm is ongoing. This activity started on Friday with few earthquakes and started in full force when the magnitude 3,5 earthquake happened. Largest earthquake so far had the magnitude of 3,8 and was felt as was the first earthquake that happened.

Earthquake activity in Skjaldbreið shield volcano. Copyright of this image belongs to Icelandic Met Office.

At the moment the number of earthquakes recorded is at 100 and that number is going to increase as this earthquake swarm continues, number of earthquakes happening has dropped considerably for the last few hours. This is the first large earthquake swarm in Skjaldbreið since 1992 according to Icelandic Met Office records (it goes back to 1706 can be viewed here (Icelandic only), locations are not accurate until late 20th century). This earthquake activity appears to be only tectonic in nature and there are no signs of magma movements at the moment.


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Earthquake activity intensifies in Skjaldbreið

The earthquake activity that started in Skjaldbreið yesterday continues. This earthquake activity has been picking up in number of earthquakes. But when this blog post is written no earthquake has been over magnitude 2.0. That however might change if this earthquake activity picks up more from the current activity level.

Earthquake activity in Skjaldbreið south of Langjökull glacier. Copyright of this image belongs to Icelandic Meteorological Office.

It is hard to know what is going to happen in this earthquake swarm. But earthquake activity in this area is often “slow”, in the terms it is slow to start and reaching its high point. If that is going to happen now is impossible to know. All that can be done is to watch and see how this earthquake swarm progresses and if any stronger earthquakes start to appear. Stronger earthquakes might not appear at all in this earthquake swarm. But they also cannot be ruled out.

Minor earthquake swarm in Skjaldbreið

During the night a small earthquake swarm started in Skjaldbreið south of Langjökull glacier (might be part of Presthnjúkar volcano). This earthquake swarm is minor. With largest earthquake only being magnitude 1.9. While this is an minor earthquake swarm there seems to be more activity taking place then appears on reviewed and automatic SIL map. The reason for that is the earthquakes in questions are small to be located by three or more SIL stations in the area. While this unseen earthquake activity does not appear on Icelandic Meteorological Office maps it can be seen on the SIL station closest to the earthquake locations.

Location of the earthquake swarm in Skjaldbreið. Copyright of this image belongs to Icelandic Meteorological Office.

Activity at the end of this tremor plot suggests more earthquakes are taking place. But they are not being located as they are not detected on three or more SIL stations. Copyright of this image belongs to Icelandic Meteorological Office.

Earthquake activity is common in this area. Since it is on the tectonic plate boundaries in Iceland. It is difficult to know how this earthquake swarm is going to behave in the next few hours. But so far it has stopped for few hours before continuing again.