Deep earthquakes in Fagradalsfjall mountain

Today (21-July-2021) few deep earthquakes took place in Fagradalsfjall mountain that is part of Krýsuvík-Trölladyngja volcano system.

This earthquake activity was not big and the largest magnitude recorded was a magnitude of Mw0,8. Most depth that appeared had a depth of 13,4km.

Earthquake activity in Fagradalsfjalli mountain shown by a red dot, orange dots and few blue dots on Reykjanes peninsula.
The earthquake activity in Fagradalsfjall mountain on Reykjanes peninsula. Copyright of this image belongs to Icelandic Met Office.

It is difficult to know what this means. What is possibly happening is that more magma is pushing up in the magma feeding that now exist where the eruption has been happening. If that is happening, it can result in new craters or fissure opening up and start erupting. At the writing of this article this earthquake activity seems to be ongoing, but at slow rate and small earthquakes only so far.

Fog continues to block view to the crater and Fagradalsfjall mountain. But harmonic tremor data shows that the Fagradalsfjall mountain eruption is currently not erupting.

Update on the eruption in Fagradalsfjall on Saturday 17-July-2021

This is going to be shortest update to the eruption in Fagradalsfjall mountain that is part of Krýsuvík-Trölladyngja volcano system.

  • Since 9th July the eruption has been unstable. Between 10th July and 15th of July the eruption continued as before with pulsing activity.
  • On 15th of July at 05:00 the eruption stopped and it didn’t start again until around 10:00 on 16th of July.
  • At the writing of this article it seems that the eruption has stopped again based on the harmonic tremor.
  • The lava flows is down in Meradalir when the lava flow happens. At current rate it is going to take 1 to 4 weeks until Merdalir overflows with lava into next valley.
  • The east side of the crater has collapsed and that allows the lava flow direct flow down into Meradalir.

It is unclear why the eruption stops and starts again. One of my ideas is that the deep feeder system of the eruption is now empty and needs time to refill. The eruption stops when the feeder system is empty. The more empty it is the longer the eruption stops since it takes more time for the magma to fill up the magma chamber that seems to be there at 20km depth or more. How long this is going to go on I don’t know but I don’t think this can go on for many months or years. Current crater is at one point going to seal it self and the eruption is going to stop because of that.

Earthquake activity north of Grindavík town in Reykjanes volcano

Early morning of 11-July-2021 an earthquake swarm took place north of Grindavík town. Largest earthquake in this swarm had a magnitude of Mw2,5. Most of the other earthquakes had a magnitude of Mw0,0 to Mw1,0. There was also an earthquake swarm on Reykjanestá area that is part of Reykjanes volcano.

Earthquake activity north of Grindavík town show as cluster of small orange dots on Icelandic Met Office image.
Earthquake activity on Reykjanes peninsula in Reykjanes volcano. Copyright of this image belongs to Icelandic Met Office.

It is difficult to know for sure what this earthquake activity means for this volcano. Since it has already been proven that eruption activity can start on Reykjanes peninsula without any warning or earthquake activity. Currently there are no clear indicators that suggest anything is about to happen but that can change without warning.

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Update on Fagradalsfjall mountain eruption on 9-July-2021

This is a short update on the eruption in Fagradalsfjall mountain that is part of Krýsuvík-Trölladyngja volcano system (currently, this might change in the future).

  • Since 23:00 UTC on 5-July-2021 the eruption has been on the low side and no lava has been seen leaving the crater when the fog is less dense in the eruption area. This is the longest break in the eruption activity since it started in 19-March-2021.
  • Small amounts of lava has been seen in the crater and it is speculated that it might be flowing from the crater in tubes in the lava field. This remains unconfirmed at the writing of this article.
  • Currently the eruption is not over. It is ongoing as is.

The following is a speculation on my part.

This lack of activity and amount of lava in the crater suggests that the deep system that has been feeding the eruption is for now close to being empty or is completely empty. That system of magma chambers needs time to fill up. This lack of activity is also common for this type of volcano and magma system. Since eruptions go trough a cycles of high and low activity. This might result in the eruption starting in a new fissure in next few weeks to months along with continuing in the current crater. There is also a equal chance of the eruption just continuing in the current crater once the eruption starts at full energy again. But that might be weeks until that happens.

End of speculations

Summer is fog season in Iceland when there is no strong wind and this has been a problem for monitoring the eruption on Reykjanes peninsula in recent days. This is going to continue until September or October depending on the weather pattern.

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Fagradalsfjall mountain eruption refuses to stop (2-July-2021)

In a surprise move the activity in Fagradalsfjall mountain (part of Krýsuvík-Trölladyngja volcano system) started to increase again around 16:00 UTC and around that time the first lava was seen in the crater after it had emptied it self out during the night as was mentioned in last article.

I have been following eruptions for a long time and this is the first time that I see this happen in a crater eruption. Normally when they collapse in this way the eruption is normally over. In this case the magma cleared out the rock from the collapse over few hours (it just goes down the stream with the lava) and the eruption started as the pressure did build up again in the deep magma system. Harmonic tremor has increased again since 16:00 UTC. I don’t know if it has reached its maximum yet. That is possible, but difficult to be sure.

Red hot lava from the crater flows down on Rúv web camera. Small drown is in frame of the shot.
The eruption as it appeared on Rúv web camera. Copyright of this image belongs to Rúv ohf.

It is impossible to know for sure what this eruption does next. Since this eruption seems to be breaking a lot of the normal rules that happens during an eruption.

Harmonic tremor going almost vertical up on the SIL station Fagradalsfjall.
The harmonic tremor on the SIL station Fagradalsfjall. Copyright of this image belongs to Icelandic Met Office.

Currently there is a lot of lava flowing into Nátthagi and possibly also into Geldingadalir that is already full of lava and is about to overflow at lowest points in next few days.

Possible end of the eruption in Fagradalsfjall mountain (2-July-2021)

At the writing of this article the eruption in Fagradalsfjall mountain has possibly ended (please note that Icelandic Met Office has not officially called the end of this eruption). This is part of Krýsuvík-Trölladyngja volcano system.

Around 03:43 UTC on 2-July-2021 the crater started erupting a cloud of volcano ash. What was unclear until earlier today was that the eruption had ended in the crater. The reason for the ash cloud was the the crater was collapsing in on it self and sealing up.

Cloud of volcano ash from the crater at around 03:43 UTC.
The volcano ash cloud as it appeared on Rúv web camera during the night. Copyright of this image belongs to Rúv ohf.

The harmonic tremor has also dropped at the same time as there is no lava flowing from the crater.

Harmonic tremor on SIL station Fagradalsfjall. The lines are showing up and down pattern and in last few hours the lines drop down to background noise. Few spikes have appeared in the last few hours but unclear what they mean.
The harmonic tremor noise on SIL station Fagradalsfjall mountain. Copyright of this image belongs to Icelandic Met Office.

What happens next is unclear. It is unlikely that eruption is going to start in the crater that stopped erupting. Normally they almost never erupt again. Magma is going to find it self a new path to erupt once a pressure has build up again in the deep crust. Once the pressure is enough it is highly possible that new earthquake swarm is going to start before an new eruption happens on the Reykjanes peninsula. How long this is going to take is impossible to know for sure.

This is the last article about Fagradalsfjall until an earthquake or a new eruption starts in Fagradalsfjalli mountain.

Changes in the eruption in Fagradalsfjall mountain

This is the short update on the eruption in Fagradalsfjall mountain. That is part of Krýsuvík-Trölladyngja volcano system.

From 22-June to 29-June the eruption in Fagradalsfjall mountain changed. It started to from being stable output of magma to intermittence magma output. That phase lasted from 22-June to 29-June until around 19:30 when activity started to increase again. The magma output seems to have more than doubled based on what I am seeing on the web cameras (when not blinded by fog).

It is unclear but there might have a new crater opened up just south of the main crater. Right next to him and that location is making confirmation on this difficult. There has been splatter activity seen from that location. It is also possible that this crater has already shut down in the latest changes. I don’t know yet.

Some lava fountain activity has been seen on web cameras in the last hour. As the lava activity continues to increase. The flow of lava seems to be increasing from before and is now flowing out on all sides of the crater. That did not happen before. Activity seems to drop to almost nothing between lava flows. If this is permanent or just temporary phase of the eruption I don’t know. This might take weeks to change into stable lava flow again.

It has also been reported in the news that most of the lava flow happens underground and goes directly into the lava field where it collects into lava ponds before it goes into Meradalir, Geldingadalir (already full of lava) or Nátthagi valleys.

Update on the eruption in Fagradalsfjall mountain on 18-June-2021

This is a short update on the eruption in Fagradalsfjall mountain. It is still classified as Krýsuvík-Trölladyngja volcano eruption. That might change in the future.

  • There is no sign of the eruption is about to stop.
  • Most of the week the lava was flowing in lava tubes that where invisible from the surface. Today (Friday 18-June-2021) that changed and lava is now again overflowing over the crater.
  • The crater remains unstable and collapses from the inside walls are frequents, or used to be. It is possible that for now the amount of lava in the crater is holding the walls up.
  • Nátthagi is now flooded with lava and the lava is on its way out of Nátthagi in next few hours to days. There won’t be any attempt made to stop the lava reaching the road or the ocean.
  • Geldingadalir valley is now full of lava and has overflowed a little. Lava might flow into Nátthagakriki in next few days, but small dirt walls where pushed up to try and delay that from happening. It is unclear if that worked. But for now the lava has not flowed into that direction.
Yellow lava flows out of the crater into a lava field and creates a new lava river.
The crater overflowing with lava. Copyright of this image belongs to Rúv.
A lot of smoke blocks the clear view into Nátthagi where the lava field is and is about to leave Nátthagi. Car can be seen at the end of the lava field.
View into Nátthagi but is in part blocked by gas pollution from the eruption. Copyright of this image belongs to Rúv.

Currently there are no other news about this eruption. Next update should be on 25-June.

Update on the eruption in Fagradalsfjall mountain on 11-June-2021

This is not going to be a long update since there has not been a lot of change during the last week. There has been some and this is what happened. This is part of Krýsuvík-Trölladyngja volcano system (until the studies are updated).

  • The main crater is slowly closing and lava fountain activity has almost or has ended at the writing of this article.
  • The main crater is now around 100 meters high. Lava depth is from 10 to 70 meters thick depending on a location. There is a map but for copyright reasons I can’t show it here.
  • Lava flow is now permanent and does not happen between overflows necessary.
  • Lava lake might be forming in the crater, but the status of that remains unclear at the writing of this article.
  • There are overflows happening in the crater but according to the news the main lava flow happens underground in large dykes that go from the main crater into the lava field. Creating lava ponds that regularly break and expand the lava field at random.
  • Today (11-June-2021) people that are idiots where seen walking on the fresh lava that has a surface temperature from 50C to 100C in order to get to the viewing area (blocked by fresh lava flows) and one did even go as far walking on the slopes of the crater and almost ending up as part of the lava field him self. Video of that can be seen here on mbl.is website. As can be seen the lava flows them self are human height and can bury a person in a few seconds time.
  • Fresh lava in Fagradalsfjall is hot. While it is only 100C on the surface it can be 900C just few centimetres down and can go as high as 1100C if a surface of a lava tube is broken.
  • Yesterday (10-June-2021) a change happened in the eruption and that resulted in a change in the harmonic tremor that continues. Suggesting a permanent or a long term change to the eruption. What this mean is unclear currently.

There are no other updates as is. Next update should be on 18-June-2021 unless something happens in this eruption. Other parts of Iceland are quiet at the writing of this article.

Blue, green and purple show the harmonic tremor from the eruption in Fagradalsfjall. The change on 10-June shows a sharp edged harmonic tremor plot.
The harmonic tremor on nearby SIL station to the eruption in Fagradalsfjall mountain. Copyright of this image belongs to Icelandic Met Office.

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Update on the eruption in Fagradalsfjall mountain on 5-June-2021

There has not been a lot of change in the eruption during this week (28-May to 5-June) in the eruption of Fagradalsfjall mountain that might be part of Krýsuvík-Trölladyngja volcano system.

  • The crater continues to get bigger. The crater grows by collapsing on the inside and expanding it walls following that it seems. Current height of the crater is 300 to 500 meters. This is a bad estimate based on web camera views.
  • The main viewing area is now cut off from walking people because lava has flowed over the lowest point on the walking path.
  • There is now a risk because of the overflow over the walking path that the western barrier is going to be breached soon.
  • In general the lava doesn’t travel far but it builds up close to the erupting crater and is now at locations hundreds of meters thick.
  • If the eruption continues as it has been doing the whole area is going to go under lava in next 6 to 10 months. As the lava just keeps building up.
  • There are no signs that this eruption is ending.

There are no other news about this eruption that I know of. It continues as it has been doing since 19-March-2021. In other parts of Iceland it has also been quiet or minimal activity not worthy of reporting.

This article is a little late because I was dealing with headache issue for the last 12 hours.

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