Update on Fagradalsfjall mountain eruption on 9-April-2021

This is a short article about the eruption in Fagradalsfjall mountain that is part of Krýsuvík-Trölladyngja volcano system.

This week has been busy and please read the older articles about what happened earlier in this week.

  • Lava output is now 50% more according to University of Iceland measurements compared to start of the eruption (19-March-2021). Gas output is also more then in start of the eruption. It has resulted in problems depending on wind direction.
  • There is a high risk that an eruption might start south of Geldingadalir valley eruption. There is also a high risk that new eruption is going to start north of the 5-April-2021 eruption.
  • There is no change in inflation in the area. It has slowed down but remains the same.
  • There continues to be low level earthquake activity along the dyke from Keili to Fagradalsfjall mountain.

Any change that is going to happen without warning and might not happen without any earthquake or little earthquake activity.

Next update is going to be on 16-April-2021 unless something major happens. This eruption is always changing and this weekend and next week might get interesting. If anything happens I am going to write new article soon as possible.

Update at 22:43 UTC

Icelandic Met Office released this map and press release (in Icelandic only) about the risk new fissures can open up both north and south the the current craters that are erupting. This page is updated regularly so if you are looking at this later than 9 to 10 April 2021 you might have to look for this information.

Map showing marked area that goes little south and north of the current erupting fissures in Fagradalsfjall. That area has been marked as dangerous by Icelandic Met Office. The map also shows the lava fields in purple.
The new area that has a risk of new fissures opening up without warning. Copyright of this image belongs to Icelandic Met Office.

The map shows the area that is now at risk of new fissures opening up without warning.

Update 10-April-2021 at 15:20 UTC

Around 03:14 UTC on 10-April-2021 fissure number 4 did open up between fissure number 2 (5-April-2021) and fissure number 3. The eruption from this crater doesn’t seem to be large but it did happen under a new lava that had flowed over that same area few days before from fissure 2. In fissure/crater 1 the amount of erupting lava did drop a little just before the new eruption.

I am noticing that it seems new fissures are opening up more frequently then before. This seems to have changed after opening up of fissure 3.

Timeline of fissure openings so far.

1st fissure 19-March-2021
2nd fissure opened 5-April-2021
3rd fissure opened 7-April-2021
4th fissure opened 10-April-2021

Time period between new fissures opening up currently seems to be 3 to 4 days. I suspect that this is going to change soon and it is possible that new fissure that opens up might get larger as the eruption goes on. There seems to be phase in this eruption that is happening in Fagradalsfjall mountain. I am not perfectly sure what that phase is now since I’ve never seen this before and I don’t have any data on this type of eruption behaviour from other volcanoes outside of Iceland. That I know of.

Video of the eruption fissure 4 opening up.

Nátt­úr­an er óút­reikn­an­leg og ófyr­ir­sjá­an­leg (mbl.is)


Article updated at 22:48 UTC.

Article updated at 15:39 UTC on 10-April-2021.
Article updated at 15:54 UTC on 10-April-2021.

Update on the eruption in Fagradalsfjall mountain on 6-April-2021 (2nd update)

This is a short update and second update for 6-April-2021 for Fagradalsfjall mountain that is part of Krýsuvík-Trölladyngju volcano system.

  • During the night a new fissure was discovered between the new eruption and the old eruption. The fissure is about 150 meters long and there is hot air coming up from it.
  • There are reports of a new fissure north of the new eruption and land has been sinking down at that location. No other changes have been reported at the writing of this article.
  • The lava going down into Meradalir valley slows down once it is there because it cools down quickly once it is there. There is a lava river going down in the Meradalir valley and that lava is moving quickly.
  • It is now estimated that this is a start of a long volcano activity period on Reykjanes peninsula that is going to last for centuries with breaks of 10 to 20 years between active periods of 30 to 50 years.

The situation is currently changes often during the day and the night and the risk of a new eruptions starting without any warning is now extremely high.

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Update on the eruption in Fagradalsfjall (including Geldingadalir valley) on 6-April-2021

This is a short update on the eruption in Fagradalsfjall mountain as it is part of Krýsuvík-Trölladyngja volcano.

There has been a slight increase in micro-earthquake activity along the dyke after the new fissures opened up in Fagradalsfjall mountain. Most of them are interestingly forced on a area close to Keilir mountain.

Earthquake activity on the Reykjanes peninsula many earthquakes form a direct line with the magma dyke that formed in February and March. Few red dots close to Keilir mountain
The earthquake activity on the Reykjanes peninsula. Copyright of this image belongs to Icelandic Met Office.
  • It has been reported that lava flow from the new and old eruption site is now more than what was most at the old eruption site (Geldingadalir valley). It is now estimated to be total 10m3/second.
  • Craters are building up at the new eruption site. That might change the lava flow long term and there is a risk that it is going to flow towards Geldingadalir valley when that change in lava flow happens.
  • There is a high risk of new fissures opening up both north and south of Geldingadalir valley (1st eruption) and north of Fagradalsfjall mountain eruption (2nd eruption).
  • Lava is now flowing into Meradalir valley. That valley is far larger then Geldingadalir valley and won’t be filled up easily. There seems to be more water in this valley and that might result in lava explosions if the lava gets that far down into the valley.

Currently there are no other new information that I can find. Next update should be on Friday 9th April 2021 unless something major happens.