Possible dyke intrusion in Fagradalsfjall volcano

Early morning today (10-November-2022) an swarm of earthquakes took place slightly north of the place where the eruption in August 2022 took place in Fagradalsfjall volcano. This possible dyke intrusion was small and only lasted for about 1 hour before it stopped. Depth of the earthquakes was from 5 km to 7 km.

High resolution image of the earthquakes in Skjálfta-Lísa interactive earthquake map from Icelandic Met Office. It shows the dots line up in a fissure like location.
Skjálfta-lísa high resolution map of the earthquake activity. From Icelandic Met Office website.

This activity might give a clue on in what area next eruption is going to take place in Fagradalsfjall mountain. Based on earlier eruption there won’t be any warning before an eruption earthquake swarm starts. In August that eruption started with a minor earthquake swarm, created from a dyke intrusion that was happening. In the hours before an eruption starts there’s going to be a strong earthquake swarm, based on what happened just before the eruption in August. It is interesting if the eruption activity moves north-east, rather than south-west. Why that happens, if it does so, is not something I am clear on why happens.

Earthquake swarm in west part of Fagradalsfjall volcano

This morning on 23-October-2022 an earthquake swarm took place in west part of Fagradalsfjall volcano. Largest earthquake in this swarm so far had a magnitude of Mw3,0.

Green star just west of main Fagradalsfjall volcano. Few blue, yellow and red dots on the map showing earthquakes in other nearby volcanoes
Earthquake activity west of Fagradalsfjall volcano. Picture from Icelandic Met Office.

This earthquake activity is the result of magma pushing up into the crust at around 5 km depth. This is not a large dyke intrusion and possibly won’t result in a eruption, unless there’s a sharp increase in earthquake activity and that has happened (the August 2022 eruption started this way). This is currently a situation that requires monitoring for changes. If anything is going to happen is impossible to know.

Earthquake swarm in Brennisteinsfjöll volcano

Today (21-October-2022) an earthquake swarm took place in Brennisteinsfjöll volcano. Largest earthquake had a magnitude of Mw3,0 at 10:23 UTC. This earthquake swarm is possibly over, it is however difficult to be sure.

Red dots in Brennisteinsfjöll volcano on Reykjanes peninsula, located just south of Reykjavík city and east of Kleifarvatn lake. A lot of yellow and orange dots on the map in few volcanoes showing smaller earthquake activity
Earthquake activity in Brennisteinsfjöll volcano and other nearby volcanoes. Picture is from Icelandic Met Office.

This is probably just a tectonic earthquake activity. But it is worth noting that volcano activity as has been seen in Fagradalsfjall volcano (Iceland newest volcano) is going to move east on Reykjanes peninsula. How fast and how long that change is going to happen is not known because of lack of data and written records from 700 to 900 years ago are incomplete and vague on details at best.

Earthquake activity has started to increase in Fagradalsfjall and Reykjanes volcanoes

Since yesterday (06-October-2022) the earthquake activity has been increasing in the volcanoes Fagradalsfjall and Reykjanes volcanoes. Please note that Global Volcanism Program has updated the informations regarding Fagradalsfjall mountain and now classifies it as its own volcano, this is after a new report and information from Icelandic Met Office. From now on I am going to use that classification when updating on activity in Fagradalsfjall volcano. I’ll not update older articles (too much work), but this also applies to them as such.

This also means that Fagradalsfjall is a new volcano in Iceland.

Earthquake activity in Fagradalsfjall volcano, Krýsuvík-Trölladyngja and Reykjanes volcano. Shown with red, orange and blue dots
Earthquake activity in Fagradalsfjall volcano and Reykjanes volcano along with Krýsuvík-Trölladyngja volcano. Copyright of this image belongs to Icelandic Met Office.

Earthquake activity at start of an eruption cycle in Fagraldsfjall volcano are not large. They grow larger once magma has started to push into the crust, until then the earthquake activity only seems to happens with minor earthquake swarms.

Article updated with new information.


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Update on 1-August-2022 on the earthquake swarm in Fagradalsfjall mountain

This is a short update on the earthquake swarm in Fagradalsfjall mountain and nearby area. This is written on 1-August-2022 at 13:47 UTC.

The situation on Reykjanes peninsula is always updating so information in this article can be in part or in whole get obsolete quickly. Largest earthquake during the night had a magnitude of Mw4,7. This might not be the largest earthquake today, since larger earthquakes are always a possibility.

A lot of green stars on Reykjanes peninsula along with red dots that show the heavy earthquake activity that is now happening there
Strong earthquake activity on Reykjanes peninsula. Copyright of this image belongs to Icelandic Met Office.
Time trace of the strong earthquake activity in the last 48 hours. Dark blue dots, blue dots, yellow dots with a magnitude 5,4 earthquake line in it, orange dots and red dots show all the earthquakes. This earthquake activity is really dense
Time trace of the earthquake activity in the last 48 hours. Copyright of this image belongs to Icelandic Met Office.

GPS data have started to show a large displacement over the last 48 hours. The 24 hour GPS displacement can be found here and 8 hour GPS displacement data can be found here (find Reykjanes peninsula). This shows that magma is pushing its way though the crust at fast speed, but has not yet broken up trough the crust. When that happens is impossible to know, but this might not be a long wait based on the speed the magma is going. Current depth of the magma is around 2 to 4 km.

Earthquake swarm in Reykjanes volcano

This morning (12-July-2022) an earthquake swarm took place in Reykjanes volcano. This earthquake swarm has at the writing of this article around 30 earthquakes. Two largest earthquakes had a magnitude of Mw3,3 and Mw3,4. The second earthquake was felt in towns on Reykjanes peninsula.

Two green stars on the earthquake map from 10:00 clock this morning. Along with few red dots around the largest earthquakes
Earthquake swarm on the Reykjanes peninsula in the Reykjanes volcano. Copyright of this image belongs to Icelandic Met Office.

It has been rather quiet on the Reykjanes peninsula in last few months. There is always minor earthquake activity happening because of inflation of magma in this area. There has been lack of large earthquakes in recent months. I don’t know why that is. GPS data show that there has not been any notable inflation or deflation in Reykjanes volcano for the last few weeks. That translates into lack of earthquakes. If this earthquake swarm means that is changing is something to watch out for. Small earthquake swarm can mean change, what it means here is unclear. It is known that not every eruption starts with a big earthquake swarm in a volcano.


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Ongoing earthquake swarm north of Grindavík town wakes up people

Today (22-May-2022) at 09:53 and 09:57 UTC earthquakes with magnitude of Mw3,5 and Mw3,6 took place north-west of Grindavík town. This earthquake was felt and did wake up people according to the news.

Two green stars north-west of Grindavík town along with a green star north of Grindavík. A lot of orange and red dots around the area showing smaller earthquakes
Earthquake activity close to Grindavík town. Copyright of this image belongs to Icelandic Met Office.

There is no signs that this earthquake activity is slowing down. It does come in waves according to Icelandic Met Office. This means that there are period of high activity with low activity between. Currently, at the writing of this article, there is a low activity period ongoing.


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Deep inflation detected in Fagradalsfjall mountain

According to a news report today (16-November-2021) inflation has been detected deep under Fagradalsfjall mountain, that is part of Krýsuvík-Trölladyngja volcano system. This inflation suggests that an eruption might start again in Fagradalsfjall mountain, it remains impossible to know when such an eruption might start. Since there is a lot that suggest this inflation is because of magma collecting at depth under Fagradalsfjall mountain. When or if that results in a eruption in the future is impossible to know.

This inflation is now large enough to be seen on satellite images that monitors deformation in the upper crust. In the upper crust this deformation appears small, but that is not all the story in this.

Icelandic News (in Icelandic)

Gosið enn í dvala – Mæla litlar hreyfingar á miklu dýpi (Rúv.is)


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