Category: Dyke intrusions

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The earthquake activity in Skaftafellsfjöll mountain (part under Vatnajökull glacier)

Since May 2011 there has been an earthquake activity in mountain called Saftafellsfjöll. This is slightly north of Öræfajökull volcano and south of Grímsfjall volcano. This earthquake activity is now permanent in this area it seems. Some of it might be glacier quakes, but most of the earthquake activity there is not, because of the depth this earthquake activity is happening at.

Earthquake activity in Skaftafell in Skaftafellsfjöll mountain. Shown as blue, orange and yellow dots on the map of Vatnajökull glacier. Also on this map is earthquake activity in Askja volcano and Herðubreið shown with red dots.
Earthquake activity in Skaftafellsfjöll mountain. Copyright of this image belongs to Icelandic Met Office.
One year worth of earthquake data from Skjalftalísa program on Icelandic Met Office. It shows a clear concentration of earthquakes in Skaftafellsfjöll mountain over this time.
Earthquake activity in Skaftafellsfjöll mountain for 365 days. Picture is from Skjálftalísa on Icelandic Met Office website. Copyright of this image belongs to Icelandic Met Office.

I don’t know for sure what is going on. This earthquake activity clearly shows that something is going on in this part of Vatnajökull glacier. It is my unverified opinion that there is a volcano there. Its not documented and map only show a extinct volcano in this area. This is unlikely to be earthquake activity in extinct volcano, its not impossible, what makes this unlikely is that this earthquake activity happens regularly and has been going on since May 2011. There is ice quake activity in this same area, but some of this earthquake activity is both deep and being located in areas with no glacier. If those are not measuring errors or something like that (I find that unlikely in many cases). I don’t think there’s going to be an eruption in this area, at least not for a long time if it ever happens. This earthquake activity might have been going on for a lot longer then from May 2011.

– This is not an registered or confirmed volcano in this area. Unless there’s an eruption, it might be a long time until a confirmation happens.

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Earthquake swarm close to Geirfugladrangur on Reykjanes ridge

Today (21. February 2023) an earthquake swarm started close to Geirfugladrangur on Reykjanes ridge. This is possibly in another volcano than Reykjanes volcano that is just east of this location, this is because of distance and its unlikely that Reykjanes volcano extends this far south. It has no other name than Geirfugladrangur. Largest earthquake in this swarm had a magnitude of Mw3,1 and this earthquake swarm is ongoing and stronger earthquakes are a possibility.

Earthquake swarm on the Reykjanes ridge, marked by orange and green star were the largest earthquake took place. A lot of yellow dots close to Reykjanestá area.
Earthquake swarm on Reykjanes ridge. Copyright of this image belongs to Icelandic Met Office.

This earthquake pattern seems to indicate that a magma dyke intrusion is taking place. This area of the Reykjanes ridge last erupted in 16th to 18th century and has been quiet since.

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Strong earthquake swarm in Reykjanes volcano on Reykjanes ridge / Reykjanes peninsula

This earthquake swarm is ongoing at the writing of this article and information can change without warning. The largest earthquake recorded by automatic magnitude of Mw3,7 at the writing of this article. Around 30 to 40 earthquakes have happened so far, but that number might change quickly. This earthquake activity has some signs that it might be happening because of magma intrusion in the area, out in the ocean but signals are not clear.

Three green stars and red dots on the left down side on the map of Reykjanes peninsula, the earthquake activity is happening out in the ocean on the Reykjanes ridge.
The current earthquake activity on Reykjanes ridge. Copyright of this image belongs to Icelandic Met Office.

This earthquake activity is in the volcano Reykjanes, that volcano goes into the ocean and is on dry land. Making possible future eruptions both explosive and flowing magma at the same time. To date, Reykjanes volcano only has had earthquake swarms and no eruption. When that is going to change is impossible to know.

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Earthquake swarm 3 km north of Grindavík town

Today (19. December 2022) and yesterday (18. December 2022) an earthquake swarm took place 3 km north of Grindavík town in the Reykjanes volcano. Largest earthquake had a magnitude of Mw2,9 and was felt in Grindavík. Earthquakes with magnitude Mw2,0 are felt in Grindavík, possibly even smaller earthquakes. At the writing of this article, this earthquake swarm is ongoing but weather is blocking almost all of the automatic earthquake detection.
Continue reading “Earthquake swarm 3 km north of Grindavík town”

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Earthquake swarm in Reykjanes volcano (3-December-2022)

Today (03-December-2022) at 12:49 UTC an earthquake with magnitude of Mw3,5 at 7,0 km depth. This was the largest earthquake in the swarm. Around of 40 earthquakes took place at the writing of this article. There are no reports about the largest earthquake was felt in nearby populated areas.

Green star on the left down corner of the image with orange dots showing smaller earthquakes. With few red dots in the same area.
Earthquake activity in the Reykjanes peninsula. Copyright of this image belongs to Icelandic Met Office.

This earthquake activity suggest that a new inflation period is about to start in this part of the Reykjanes peninsula and Reykjanes ridge. There has been rather quiet time in Fagradalsfjall volcano and Reykjanes volcano since August when last eruption took place in Fagradalsfjall volcano. Reykjanes volcano has not erupted so far, but has continued activity of magma injection into the crust. When that is going to result in a eruption is impossible to know.

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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.

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Change in the earthquake activity in close to Herðubreið mountain

Sometime yesterday (24-October-2022) a change happened in the earthquake swarm close to Herðubreið mountain. I am not sure when that change happened and it probably took few hours to happen before I detected it. But the change seems to be that now the earthquake swarm is at two locations and not just one. The second change is that the earthquake swarm is now getting more intense. The earthquakes at the writing of this article are minor, only magnitude Mw0,0 to Mw2,7 at the strongest. Nothing above Mw3,0 so far, but that might change without warning. Depth of this earthquake swarm is around 2 to 3 km at the writing of this article.

Two swarms of red dots show the location of the earthquake swarm east of Askja volcano and south of Herðurbreiðartögl volcano. The earthquake swarm is now west and north of Herðubreið mountain
Earthquake activity close to Herðubreið mountain. Picture from Icelandic Met Office.

What is going to happen next is impossible to know. An eruption in this area has not happened for at least 12.000 years or even longer. I don’t know if stronger earthquake activity is required for this area for an eruption to happen. It already is rather fractured from older earthquake activity and rift activity, that makes it possible for magma to have easier paths to the surface without much earthquake activity. That is at least one idea on the situation in this area. I might be wrong on this, since I don’t have information on the finer details of the crust around Herðubreið mountain.