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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.

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Strong earthquake 1,4 km east of Keilir mountain

Today (9. July 2023) at 22:22 UTC an earthquake with magnitude of Mw5,2 happened 1,4 km east of Keilir mountain. This earthquake did shake Keilir mountain and resulting a small dust cloud. This earthquake is connected to inflation that is happening just south of Keilir mountain, rather than being connected directly to magma movements in this area.

A lot of green stars close to Keilir and Fagradalsfjall on Reykjanes peninsula map. Time on map is 9th July 2023 at 23:15 UTC.
Strong earthquake activity in Fagradalsfjall mountain and Keilir mountain. Copyright of this image belongs to Icelandic Met Office.

There’s a risk of more strong earthquakes like this in this area until an eruption starts.

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Update on activity in Fagradalsfjall – Keilir mountains on 9th July 2023 at 16:11 UTC

This is a short update, because there’s little to report.

  • Three earthquakes with magnitude above Mw4,0 took place north east of Keilir mountain in the last 24 hours.
  • Earthquake activity is increasing north-east and north of Keilir mountain. Why is unclear, it is a possibility that magma is creating a path for it self that way.
  • The magma seems stuck in the crust and there doesn’t seems to have stopped the inflow of magma from the deep mantle. This is going to result in increased pressure in the dyke until an eruption happens.
  • Risk of strong earthquakes is high and might get higher until an eruption starts.

 

Heavy earthquake activity remains in Fagradalsfjall - Keilir area. With the new activity area north-east of Keilir mountain. Time on map is 9 July 2023 at 15:55 UTC.
Heavy earthquake activity in Fagradalsfjall – Keilir mountain. Copyright of this image belongs to Icelandic Met Office.

Since the start of this activity, around 12000 earthquakes have been recorded by Icelandic Met Office according to the news. Strongest earthquake at the writing of this article is at magnitude Mw4,8.

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Stress related earthquake in Krýsuvík-Trölladyngja volcano system

Today (8. July 2023) at 17:57 UTC an earthquake with magnitude of Mw4,5 took place in Krýsuvík-Trölladyngja volcano system. This is a stress realted earthquake because of the inflation between Keilir and Fagradalsfjall mountain.

Difficult to see in all the activity, on the right there is a green star and a lot of red dots below it. That is where the earthquake took place. There's a lot of activity on this map because of Fagradalfjall mountain.
The earthquake activity in Krýsuvík is on the right on this map. A green star with a lot of red dots under it. Copyright of this image belongs to Icelandic Met Office.

More of this earthquakes are going to happen both east and west of the dyke between Keilir and Fagradalsfjall mountains. Both before an eruption and after it ends. This type of earthquakes can have magnitude above Mw5,0 and they can happen in areas that have been quiet so far.