Category: Monitoring

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Earthquake activity in Hofsjökull volcano

Yesterday (12. August 2023) an small earthquake swarm took place in Hofsjökull volcano. Largest earthquake had a magnitude of Mw3,0 and the second largest earthquake had a magnitude of Mw2,5. The area is remote and there are no reports of this earthquakes being felt.

Dots in Hofsjökull volcano, that is at the center of this image. Between Langjökull to the west and Vatnajökull to the south-east. One earthquake is located at the caldera rim in the south part of Hofsjökull volcano. Other earthquakes are located on a line in north part of the volcano.
Earthquake activity in Hofsjökull volcano. Copyright of this image belongs to Icelandic Met Office.

According to Morgunblaðið news there where report of smelling gas after this earthquake activity. There is a risk of gas pockets around Hofsjökull volcano, probably mostly to the north in the area closest to the earthquake area.

I don’t have any other information about Hofsjökull volcano. Because it last erupted more than 12.000 years ago. At most there might have been smaller eruptions that resulted in lava flows sometimes in the last 12.000 years. I don’t expect an eruption now, this earthquake activity might signal a long term change in Hofsjökull volcano. How long that is going to be is anyone guess. It might be in the next 100 to 500 years or maybe never. Hofsjökull volcano is on its own rift zone that is slowly dying off. Along with Kerlingafjöll volcano to the south of Hofsjökull volcano. This are the only two (?) active volcanoes on this old dying rift zone (its around 5 to 10 million years old).

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Earthquake swarm in Torfajökull volcano

Today (30. July 2023) an earthquake swarm took place in Torfajökull volcano. This volcano is located north of Katla volcano (Mýrdalsjökull glacier). This area has had regular earthquake swarms over the year. Why is not clear. There is no clear signal of magma movement in this area. Torfajökull erupts highly Felsic magma that’s mostly explosive and some type of magma that can flow as a lava flow (maybe in later stage of an eruption, I don’t know for sure).

Green star north of Katla volcano (Mýrdalsjökull glacier) and in Torfajökull volcano caldera rim to the north. Time on map is 30. July 2023 at 19:40 (Iceland time)
Earthquake activity in Torfajökull volcano. Copyright of this image belongs to Icelandic Met Office.

The largest earthquake in this swarm had a magnitude of Mw3,2. It was felt in nearby tourist areas and caused few rock slides. Icelandic Met Office is still warning against rock slides because of this earthquakes close to the earthquake swarm location. There is a ongoing risk of more stronger earthquakes in this area of the volcano at the writing of this article.

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Eruption at Litli-Hrútur might end in two weeks

Rúv News and Earth Science at University of Iceland is reporting that the eruption in Fagradalsfjall at Litli-Hrútur might end in one or two weeks time. This is based on how much the lava flow from the crater is currently decreasing. This would also be mostly in line with the eruption in Meradalir valley in 2021, that lasted for two weeks. This eruption has been slightly longer than that eruption, since it has been slightly larger in volume of magma erupting.

Icelandic reporting on this

Eru goslok handan við hornið? (Rúv.is, Icelandic)
Facebook post reporting on the details of the eruption for 29. July 2023 (Facebook, Icelandic, Possible English)

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Two strong earthquakes in Bárðarbunga volcano

Yesterday (28. July 2023) at 23:42 UTC and 23:55 UTC two earthquakes with magnitude of Mw3,2 and Mw3,6 took place in Bárðarbunga volcano. EMSC is reporting the earthquake at 23:55 as Mw4,7 and that information can be found here.

Two green stars in Bárðarbunga volcano in Vatnajökull glacier. Time on map is 29. july 2023 at 13:05 (UTC).
Earthquake activity in Bárðarbunga volcano. Copyright of this image belongs to Icelandic Met Office.

There where few smaller earthquakes following this larger earthquakes. This is normal inflation activity in Bárðarbunga volcano and this is going to continue for next 30 to 70 years (based on earlier history).

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Earthquake in Katla volcano (Mýrdalsjökull glacier)

Yesterday (23. July 2023) at 23:17 UTC an earthquake with magnitude of Mw3,5 took place in Katla volcano. This earthquake was felt to Hvolsvellir town in south Iceland.

Green star on Katla volcano caldera rim in the south-west part of the caldera. Time on image is 24. july, 23 at 14:50 UTC.
Earthquake in Katla volcano. Copyright of this image belongs to Icelandic Met Office.

No other earthquake or activity took place following this earthquake. Katla volcano remains quiet at the writing of this article.

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Update on the eruption close to Litli-Hrútur on 23. July 2023 at 21:22 UTC

This is a short update. Since there is not a lot of information about this.

  • The crater might collapse at any time without warning. Geologists that monitor the eruption have noticed that the crater has started to get larger and is now full of lava. This means it is going to collapse. What direction is not known. It is my view that it is going to collapse to the east because of least resistance in that direction.
  • When the crater collapses the lava is going to flow more than 100m/s in whatever direction it flows.
  • Tourists are in high danger close the crater because of this collapse risk.
  • Dyke intrusion has been detected east of Keilir mountain. Along with increased ground temperature, that means the magma is at shallow depth in the crust. This area might erupt soon in similar way as is now happening close to Litli-Hrútur.

This is all the information I have now and only thing that has changed in the eruption in the last 13 days.

Icelandic News

Veggir gígsins muni hrynja innan skamms (Vísir.is)

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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.

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Update on the eruption at Litli-Hrútur on 11th July 2023 at 17:18 UTC

This article is short. The eruption is mostly stable at the writing of this article but the situation can change quickly without warning.

  • The eruption has changed in last few hours. It seems to be in only one crater that is slowly forming. The eruption has stopped at the north most end of the eruption fissure. At the writing of this article.
  • The dyke now extends 1 km under Keilir mountain in the direction of north-east. This might be a new dyke intrusion and not connected to the dyke that started the current eruption. This might result in a second eruption soon, but its too early to know for sure at the writing of this article.
  • The eruption started large fires in the moss and other plants in this area around Litli-Hrútur. This has resulted in massive toxic smoke in this area.
  • There’s a high risk of the volcano gas from the eruption, along with the toxic smoke from all the plants and moss burning.
  • Interestingly, while earthquake activity has dropped it has not stopped. Why that has happened is a bit of a mystery, it might be connected to the possible new dyke that has formed under Keilir mountain.
  • Yesterday (10. July 2023) the longest the fissure extent was at 1500 meters or 1,5 km. Since then it has gone down to one erupting crater that seems to be 50 meters to 100 meters long.
Map of the magma dyke and the eruption fissures on a map from Icelandic Met Office and others. Orange area between Keilir and to Meradalir valley show the danger area around the eruption area.
Map of the danger area around the eruption. The orange area is the danger zone that people should not travel over. Copyright of this image belongs to Icelandic Met Office and others.

 

It is impossible to know how long this eruption is going to last. Since dyke intrusions are poor magma containers this eruption might be a short one if there isn’t a constant supply of fresh magma from the deep mantle. Its too early to know if that is the case here. I have also noticed that once the eruption ends in any area, that area is not going to erupt again. When the eruption ends, it ends forever and that makes this a single eruption activity or crater rows. This area might be Monogenetic volcanic field (Wikipedia).

Since this type of eruptions are mostly uneventful and just continue. I plan on only posting updates when there are some news or changes to the eruption happen.

Update at 17:41 UTC

ISOR is reporting that their station called FAF (Fagradalsfjall) has to be moved because the lava is flowing directly at it. They are going to find a new location for this station. This report can be seen here on Facebook in Icelandic.

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Update on the eruption at Litli-Hrútur on 10th July 2023 at 18:41 UTC

This is a short update because events are changing quickly.

  • Length of the eruption fissure is uncertain, reports are conflicting. The numbers I’ve seen are from 200 meters to 900 meters long. This also might be a case of growing fissure eruption.
  • Harmonic tremor on the SIL station Fagradalsfjall continues to grow. Suggesting that the eruption is increasing in power since it started. This sometimes happens in lava eruptions.
  • The lava is flowing to the south. It might reach Meradalir valley in about one  week to three weeks. Some of the lava is flowing to the north, but a lot of less of it and is only expected to flow in the nearby area. There is no risk at current time for any damage to infrastructure or property.
  • There’s a risk of new fissures opening up in this area without warning.
  • This area is remote and difficult to go towards. Police has closed roads for the time being for safety reasons.

I’ll post new update soon as I have any new information or if anything changes. Experience has shown that this type of eruptions are rather uneventful for a longer time periods. I’ll adjust my updates in accordance with that.