Category: Dyke intrusions

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Strong earthquake swarm in Reykjanes volcano

This is a short article. It might get outdated quickly.

Around midnight of 9. November 2023 an strong earthquake started close to Þorbjörn mountain, in the same area that has been having an earthquake and dyke intrusion since 25. October 2023. At the writing of this article, the largest earthquake had a magnitude of Mw5,0 and with a lot of smaller earthquakes taking place.

A lot of green stars and red dots close to Grindavík town on the Reykjanes peninsula in the volcano Reykjanes.
Strong earthquake activity in Reykjanes volcano. Copyright of this image belongs to Icelandic Met Office.

It is unclear if this earthquake activity is the start of the eruption or just normal inflation related earthquake activity. The magma is still at depth of 5 km. If it has started to move upwards trough the crust, it is going to take several hours to reach the surface. That means nothing might happen on the surface until late tomorrow or on 10. November at the earliest. Depending on how quickly the magma goes up through the crust.

I’ll post updates tomorrow if anything more happens.

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Update on Reykjanes volcano activity

This is a short update and this information can go out of date quickly and without warning.

  • Earthquake activity continues in Svartsengi and close to Þorbjörn mountain. This earthquake activity is either tension earthquakes because of the dyke on either side (north-east and south-west) or in the dyke it self.
  • Inflation in Svartsengi and nearby area is extremely high and has been increasing much as 10mm a day in last few days.
  • There has been magma building up in the crust in the Reykjanes volcano since at least year 2020. It might have started few years earlier at more depth, but that is unclear.
  • There’s a risk of large eruption in this area, that might go on for few months in the worst case.
  • Largest earthquakes so far have had the magnitude of Mw4,7. Larger earthquakes remain a possibility.
  • It is impossible to know when a eruption starts or if it starts. But the likelihood of an eruption is extremely high.
  • Morgunblaðið reported that ground heat has been seen on thermal cameras. The news can be found about this here in Icelandic. There’s a YouTube video of this in both Icelandic and English (with more footage).

I’ll post new information about what is going on when it happens. As is, the situation does not change a lot from one day to another so I don’t have a lot to report on.

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Magma movement close to Þorbjörn mountain this morning

Today (31. October 2023) at around 08:00 UTC an magma movement was detected by Icelandic Met Office. This started an earthquake swarm that had a largest earthquake with magnitude of Mw3,7. The magma seems to be at depth of 1,5 km where it is the shallowest. Few days ago, that magma was at depth of 5 to 8 km. This change is rather quick movement of magma, that suggests higher pressure compared the magma that erupted in Fagradalsfjall volcano. This might result in a larger eruption when it happens. The inflation at Fagradalsfjall volcano, south part of it has not lowered. The only thing that has happened there is that earthquake activity has dropped to almost nothing. Earthquake activity has moved to western part of Fagradalsfjall volcano. Eruption also happening in Fagradalsfjall volcano should not be ruled out, but the events close to Þorbjörn mountain might delay the progress of that magma.

Red dots and green stars north of Grindavík town, close to Þorbjörn mountain. There's also red dots west of Þorbjörn mountain and Grindavík town. Blue dots close to Reykjanestá on this map. Time on map is 31. Okt. 23 at 16:55 UTC.
Earthquake activity because of magma movements in Reykjanes volcano. Copyright of this image belongs to Icelandic Met Office.

It is difficult to know what is going to happen next. But an eruption is highly likely, when and where is almost impossible to know even if GPS data gives good clues on where it might happen. This situation is complex and it is uncertain what is going to happen next with this activity in Reykjanes volcano and Fagradalsfjall volcano.

I’ll post information soon as I know something. A list of web cameras of Icelandic volcanoes can be found on the YouTube page that I set up a while ago.

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Reykjanes volcano placed on Yellow warning level

The Reykjanes volcano has been placed on yellow warning level. This is because of sudden inflation that is now taking place north-west of Þorbjörn mountain. In slightly less than 24 hours the inflation did reach 30mm. This is the fifth time (as reported by Morgunblaðið) that inflation has happened in this area since the year 2020. This inflation now is a lot faster than earlier when this has happened.

Yellow triangle on the Reykjanes volcano on the Reykjanes peninsula. Other triangles, showing other volcanoes in Iceland are green.
The alert status for Reykjanes volcano is now yellow. Copyright of this image belongs to Icelandic Met Office.

This inflation in the Reykjanes volcano has the risk of creating stronger earthquakes in new locations on the Reykjanes peninsula and on the Reykjanes ridge in next few days to weeks. There is a ongoing inflation in Fagradalsfjall volcano and that has not stopped or slowed down since it started on 25. October 2023. It is not possible to know when or if an eruption in going to start in Reykjanes volcano, but how quickly this inflation is happening suggests that might happen. The location is not that good, if it erupts where the inflation is happening. The blue lagoon is nearby along with power plant and hot water energy plant in this area. Eruption in this location can result in major damage to infrastructure in this area.

Only thing that can be done now is to wait and monitor what is happening in this area.

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New earthquake swarm in Fagradalsfjall volcano and in Þorbjörn mountain (Reykjanes volcano)

This article is going to get outdated quickly.

Current activity is also complicated and might not behave in the same way as earlier eruptions did. Largest earthquakes at writing of this article have had magnitude of Mw3,5 and Mw4,5. Larger earthquakes can be expected without warning. There have been around 1000 smaller earthquakes at the writing of this article.

Green stars close to Þorbjörn mountain and a lot of red dots in south part of Fagradalsfjall volcano. There is also green to west of Þorbjörn mountain.
Earthquake activity in Fagradalsfjall volcano and Þorbjörn mountain. Copyright of this image belongs to Icelandic Met Office.

There is a good chance this events are not going to behave the same way as happened in earlier eruptions, because the location is little bit difference and that can result in a lot of change on what happens when magma pushes it self up through the crust. The earthquake activity close to Þorbjörn might be a mixed earthquake activity of tension breaking earthquakes and magma pushing it self up. GPS data doesn’t show any inflation close to Þorbjörn mountain at the writing of this article.

Earthquake activity is increasing in south part of Fagradalsfjall volcano, this is area in Nátthagi, Nátthagakriki and other nearby area. There is a dyke intrusion in that area and has been a while. That dyke intrusion might be about to erupt. There is a lot of uncertainty going on at the writing of this article. There is also a pattern of high and low in the earthquake activity, this has been the pattern in the earthquake activity before the earlier eruptions.

I’ll write updates about this activity as needed. It might take a while, since I always try to figure out what is going on before an article is written.

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Next eruption in Fagradalsfjall volcano might happen at Christmas or sooner

Icelandic Met Office reported today (14. October 2023) that an new eruption in Fagradalsfjall volcano or nearby is now expected to happen before or close to Christmas. After the end of the eruption on 6th August 2023 the inflation that has been happening is now faster then before earlier eruptions. At the writing of this article, an earthquake with magnitude of Mw2,7 took place north of Grindavík town and was felt in Grindavík.

A lot of of red dots showing new earthquakes north of Grindavík town and in Fagradalsfjall volcano. This are small earthquakes and often happen before an eruption starts.
Earthquake activity north of Grindavík town and in Fagradalsfjall volcano. Copyright of this image belongs to Icelandic Met Office.

In the last two eruptions, after the first eruption ended. There have been around ten months between eruption. That does not seem to be the case now. Since it seems that next eruption is going to happen at four to six months time. A half or close to it from when the last eruption took place. This situation is dangerous, because this means that an eruption can start without much warning and not a lot of earthquake activity. Icelandic Met Office advice is that people travel around and in Fagradalsfjall volcano carefully.

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Two earthquakes connected to Fagradalsfjall volcano

Today (5. October 2023) two earthquakes took place that are connected to Fagradalsfjall volcano inflation. The first one was a magnitude Mw3,3 in Krýsuvík-Trölladyngja volcano. This was a tectonic earthquake because of inflation in Fagradalsfjall volcano. The second earthquake was north of Grindavík town and had a magnitude of Mw3,2. That earthquake was part of an earthquake swarm and dyke intrusion in that area. That area north of Grindavík town has been seeing a lot of earthquake activity in recent weeks, all connected to dyke intrusion activity.

Two green stars on Reykjanes peninsula that are connected to inflation in Fagradalsfjall volcano.
Two green stars on Reykjanes peninsula. Copyright of this image belongs to Icelandic Met Office.

The increase in activity in recent weeks strongly suggests that an eruption is going to happen soon. When is impossible to know and earthquake activity is too low at the writing of this article for an eruption to be happening today. This might change without warning, as has happened in the last two eruptions. There is a possibility that something has changed after the last eruption, but the answer to that question won’t happen until next eruption. All that can be done now is to wait and see what happens.

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Earthquake swarm in Reykjanes volcano (ongoing)

Today (27. September 2023) an earthquake swarm took place in Reykjanes volcano on Reykjanes peninsula. This earthquake swarm is ongoing at the writing of this article. At the writing of this article, the largest earthquake had a magnitude of Mw3,3 and the second largest earthquake had a magnitude of Mw3,1.

Green star on the Reykjanes peninsula in the Reykjanes volcano, there's also a green star at Reykjanestá that is next to the ocean. A lot of orange and red dots at this same location.
Earthquake activity in Reykjanes volcano. Copyright of this image belongs to Icelandic Met Office.

The source of this earthquake swarm seems to be magma intrusion into this part of Reykjanes volcano. I don’t know if this is going to result in a eruption, this earthquake activity seems to be too low for that to happen. That might change without warning, as sometimes happens with volcanoes. This is at least highly active time period now and what is going to happen is unclear.

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Earthquake swarm north of Grindavík town

Today (18. September 2023) there was an earthquake swarm north of Grindavík town. Largest earthquake had a magnitude of Mw2,7 and was felt in Grindavík town according to Icelandic Met Office. This earthquake activity has the direction of SW to NE and is under the road to Grindavík town.

Earthquake activity north of Grindavík town. Shown with orange dots on this map from today.
Earthquake swarm activity north of Grindavík town. Copyright of this image belongs to Icelandic Met Office.

This is clearly a dyke intrusion taking place at this location. This location is bad, because this area has infrastructure that is important to Grindavík town. In this area both hot and cold water is transported along with electricity wires (I think, they might have a different path, but it is at most nearby). Eruption at this location would be a major hazard and a problem. Currently there are no signs that this magma is looking for a path to the surface.

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High earthquake activity in Fagradalsfjall volcano

Yesterday (15. September 2023) an earthquake swarm took place on Fagradalsfjall volcano. This earthquake swarm wasn’t in the news because it was only small earthquakes, that is earthquakes with magnitude less of Mw1,0. It was not even felt by the people standing on the volcano because of depth. If this earthquake swarm has stopped I don’t know. Since most of this earthquakes don’t show up in the automatic earthquake list at Icelandic Met Office website. They only appear after a manual review by Icelandic Met Office.

A lot of orange dots on Fargradalsfjall volcano showing high level of earthquake activity in the volcano.
High earthquake activity in Fagradalsfjall volcano. Copyright of this image belongs to Icelandic Met Office.

In my view, this means that next eruption might happen between November to February 2024 if this earthquake activity and dyke intrusion activity continues as it is currently doing. It has happened before earlier eruptions that a high period of activity is followed by a period of quiet until an eruption happens. Why that is I don’t know, that is a pattern I’ve observed. I don’t know if there has been change after last eruption in Fagradalsjall volcano. That is a possibility that should not be ruled out.