Category: Swarm

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Earthquake swarm in Hofsjökull volcano

Today (28. June 2023) an earthquake swarm started in Hofsjökull volcano. At the writing of this article it seems to be over, but I am uncertain if that’s the case. This was not a large earthquake swarm, with just around eight earthquakes happening. All where below Mw3,0 magnitude in size.

Red dots in western part of Hofsjökull volcano caldera. Time on map is 28. June. 23, 09:30 Icelandic time.
Earthquake activity in Hofsjökull volcano. Copyright of this image belongs to Icelandic Met Office.

Largest earthquake in this swarm had a magnitude of Mw2,6. While other earthquakes where smaller in magnitude. I am not sure what is happening in Hofsjökull volcano. There have not been any eruptions in Hofsjökull volcano in the last 8000 to 12000 years. There might not have been any eruption in Hofsjökull volcano for more than 12000 years, how much longer is information I do not have.

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Earthquake with magnitude of Mw3,6 in Katla volcano

Today (27. June 2023) at 07:42 UTC an earthquake with magnitude of Mw3,6 took place in Katla volcano. This earthquake was part of a earthquake swarm that had started few moments earlier. There is no change in harmonic tremor at the writing of this article and earthquake activity has slowed down again. This earthquake was felt in nearby areas.

Green star and red dots in Katla volcano caldera, along with older earthquakes from yesterday shown as blue and yellow dots. Time on map is 27. june. 23, 09:20 (Icelandic time).
Earthquake activity in Katla volcano caldera. Copyright of this image belongs to Icelandic Met Office.

This earthquake activity seems to happen in active time periods with quiet period between them, when there are few to no earthquake activity. This activity is ongoing at the writing of this article.

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Renewed earthquake activity in Katla volcano

Today (26. June 2023) the earthquake activity in Katla volcano increased again for few hours. Largest earthquake this time had a magnitude of Mw2,5. This earthquake activity has slowed down again. This earthquake activity is ongoing, even if there is no activity at the writing of this article.

A lot of orange dots and blue dots showing earthquake activity in Katla volcano caldera. Time on image is 26. June. 23, 19:55 Icelandic time.
Earthquake activity in Katla volcano. Copyright of this image belongs to Icelandic Met Office.

Its is still unclear what is going on in Katla volcano. There was no change in harmonic tremor following this earthquake activity. Showing that magma did not move in any obvious way when this earthquake activity took place.

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Earthquake swarm in Reykjanes volcano

Today (26. June 2023) an earthquake swarm took place in Reykjanes volcano. This earthquake swarm is in a location in Reykjanes volcano that has been having repeated earthquake activity over the last few months. This strongly suggest that at this location there’s an active dyke that might erupt in the future.

Earthquake swarm out in the ocean close to Reykjanestá in the Reykjanes volcano. A lot of red dots piled on top of each other. Blue to orange dots located elsewhere on the Reykjanes peninsula. Time on map 26. June. 23. 16:05 (Icelandic Time).
Earthquake swarm in Reykjanes volcano. Copyright of this image belongs to Icelandic Met Office.

Largest earthquake in this swarm at the writing of this article had a magnitude of Mw3,0. Other earthquakes have been smaller in magnitude. I am unclear on how many earthquakes have happened in Reykjanes volcano at the writing of this article. This earthquake swarm is ongoing at the writing of this article.

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Earthquake swarm in Katla volcano

Today (24. June 2023) an earthquake swarm started in Katla volcano. Largest earthquakes had magnitude of Mw3,8 and Mw3,3. Other earthquakes have been smaller. This earthquake swarm is ongoing but has slowed down since this morning.

Two green stars in Katla volcano caldera along with blue and red dots that show this earthquake activity. It is spread over some area in the caldera. Time on image is 24. june 23, 13:45.
Earthquake activity in Katla volcano. Copyright of this image belongs to Icelandic Met Office.

At the writing of this article there is no clear sign that an eruption is about to happen. That might change without a warning. This earthquake activity might stop and nothing more is going to happen until next time. That is what has been going on for the last few months and years.

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Increase in earthquake activity in Reykjanes and Fagradalsfjall volcano

During the night of 3. June 2023 an earthquake swarm took place in Reykjanes volcano, at location called Reykjanestá. Largest earthquake in that swarm had a magnitude of Mw3,0. Other earthquakes where smaller. This earthquake swarm suggests a magma movement, but it is difficult to be sure if that is what happened now.

Earthquake swarm out in the ocean next to Reykjanestá and there's also an earthquake activity in Fagradalsfjall volcano. Time on map is 03. june. 23 12:35 (Iceland time)
Earthquake activity in Reykjanes volcano and Fagradalsfjall volcano. Copyright of this image belongs to Icelandic Met Office.

Its been ten months since last eruption took place in Fagradalsfjall volcano. It is likely that a new eruption is going to happen soon, but it is impossible to know when. In last few weeks earthquake activity has been increasing in Fagradalsfjall volcano and that suggests that magma pressure inside the volcano is increasing. It just has not reached the levels to start a new eruption.

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Earthquake swarm in Krýsuvík-Trölladyngja volcano

Yesterday an earthquake swarm started in Krýsuvík-Trölladyngja volcano. This earthquake swarm doesn’t appear (it might be connected, but it is difficult to know currently) to be connected to the inflation that is happening at Fagradalsfjall volcano. Largest earthquake in this earthquake swarm had a magnitude of Mw3,0. This earthquake swarm took place just south-west of Kleifarvatn lake.

Green star just south-west of Kleifarvatn lake in Krýsuvík volcano. Where few smaller earthquakes have been taking place in a small location in Krýsuvík volcano.
Earthquake activity in Krýsuvík volcano. Copyright of this image belongs to Icelandic Met Office.

This earthquake swarm doesn’t seems to indicate an magma movement. There has not been any indicators (clear) that Krýsuvík-Trölladyngja volcano has gone active. It remains a dormant volcano.

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Earthquake swarm east of Grímsey island

Yesterday (23. May 2023) at 19:22 UTC an earthquake swarm started east of Grímsey island. Largest earthquake had a magnitude of Mw3,8 at the writing of this article. This earthquake swarm is ongoing. The largest earthquake was felt in Akureyri and other nearby towns.

Green star, red and yellow dots east of Grímsey island. With other red and yellow dots and blue dots on other places on the map. Time of the map is 24. May. 23. 18:40 (Icelandic time)
Earthquake activity east of Grímsey island. Copyright of this image belongs to Icelandic Met Office.

Around 130 earthquakes have happened in this earthquake swarm so far. This area of Iceland has frequent earthquake activity. This earthquake swarm might increase, as they sometimes do in this area. It is impossible to know when this activity is going to stop. It took me a little longer to write this article, because this is a frequent earthquake area and I was also trying to get a little break (I also have to do other things outside of this) in next few days from geology. How that goes is to be seen.

I also want to point people out that I have set-up a website that shows Icelandic Met Office harmonic tremor charts and other information for that area.

Harmonic tremor on SIL stations in Iceland

I also have a webicorder website with an earthquake recording that I run. I am trying to figure out how to install and run seismometer in Iceland again. Its a slow work in progress for me because of the technical problems I am dealing with.

Webicorders

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Earthquake swarm in Þórðarhyrna volcano

Today (11. May 2023) there was a earthquake swarm in Þórðarhyrna volcano. This are small earthquakes, but their location and depth suggest that this is a dyke intrusion taking place at this location.

Earthquake swarm in south-west part of Þórðarhyrna volcano. This volcano is located in Vatnajökull glacier, just few km south of Grímsfjall volcano, is part of the Grímsfjall volcano fissure swarm. Time on image 11. May. 23 13:10.
Earthquake activity in Þórðarhyrna volcano. Copyright of this image belongs to Icelandic Met Office.

Þórðarhyrna volcano is part of Grímsfjall volcano fissure swarm, that connects to Laki eruption fissures. Last eruption in Þórðarhyrna volcano was in the year 1902 to 1904 and had the VEI=4 according to Global Volcanism Program report that can be read here.

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Earthquake swarm in Reykjanes volcano (out in the ocean)

During the night of 4. May 2023 an earthquake swarm took place in the Reykjanes volcano out in the ocean. This was not a large earthquake swarm. Largest earthquake recorded had a magnitude of Mw3,4. Other earthquakes where smaller in magnitude.

Green star and a cluster of earthquakes on down and west part of this image. Showing the Reykjanes peninsula. Few other earthquakes are dotted on the map in other volcanoes on the Reykjanes peninsula.
Earthquake swarm in Reykjanes volcano. Copyright of this image belongs to Icelandic Met Office.

This earthquake activity suggests an dyke intrusion in this area. This is part of Reykjanes volcano, but that volcano is in part out in the ocean. The Reykjanes volcano has been having regular dyke intrusion in recent years without it resulting in an eruption. That is most likely what is going to happen now.