More earthquake activity in Katla volcano

Today (28-July-2021) at 12:36 UTC an earthquake with magnitude of Mw3,1 took place in Katla volcano caldera. Few smaller earthquakes have followed the largest earthquake.

Green star in north-east part of the Katla volcano caldera where the magnitude 3,1 earthquake took place. One red dot in the same location shows a new earthquake that has happened there.
Earthquake activity in Katla volcano. Copyright of this image belongs to Icelandic Met Office.

This looks like a normal summer earthquake activity in Katla volcano. If that changes is impossible to know. There is no change in harmonic tremor on SIL stations around Katla volcano.

Strong earthquake activity in Bárðarbunga volcano

After a long while of not writing about Bárðarbunga volcano it is now time for new article.

On 27-July-2021 at 19:02 UTC an earthquake with magnitude of Mw3,9 took place in Bárðarbunga volcano. At 22:12 UTC an earthquake with magnitude of Mw4,5 took place in eastern part of Bárðarbunga volcano.  EMSC is reporting this earthquake as mb4,8. That information can be found here.

Earthquake activity in Bárðarbunga voclano shown by two green stars. One little to the west and the second one to the east in the rim of the main caldera.
Earthquake activity in Bárðarbunga volcano. Copyright of this image belongs to Icelandic Met Office.

This earthquake activity in Bárðarbunga volcano is because there is now inflation going on in Bárðarbunga volcano. This inflation is going to continue until there is a new eruption. When that happens is impossible to know.

Earthquake activity in Ljósufjöll volcano

Today (26-July-2021) at 16:35 UTC an earthquake with magnitude of Mw3,0 took place in Ljósufjöll volcano. Earlier earthquake with magnitude of Mw2,2 also took place at 15:44 UTC.

Red dot on western Iceland shows the earthquake activity in Ljósufjöll volcano.
Earthquake activity in Ljósufjöll volcano. Copyright of this image belongs to Icelandic Met Office.

In this area there is also a fault zone that is between Langjökull and Snæfellsnes. That fault zone normally doesn’t have many earthquakes. With only activity happening every few decades and sometimes even less frequency. The area where the earthquake activity is inside the volcano named Ljósufjöll. Earthquake activity in this area started in May-2021. Currently its too early to know if this means anything, since this might just be earthquake activity and nothing more might happen, even if this earthquake activity is happening in a volcano.

More earthquake activity in Katla volcano

Since yesterday (24-July-2021) and until today (25-July-2021) there has been rather strong earthquake activity in Katla volcano. The earthquakes are not strong with largest earthquakes having a magnitude of Mw2,6. It is unclear what is going on.

Earthquake activity in Katla volcano caldera. A lot of yellow dots showing the locations of the earthquakes from south to north and then turn to east direction.
Earthquake activity in Katla volcano. Copyright of this image belongs to Icelandic Met Office.

One of the reasons this earthquake activity is happening is that cauldron might be emptying in the Mýrdalsfjökull glacier. That creates a drop in pressure that can start earthquake activity. I don’t know if that is what happened now. If that is what is going on it is going to take the melt water few hours to reach the rivers in Mýrdalssandur sand area. There has not been any change in harmonic tremor activity following this earthquake activity.

Earthquake activity in Katla volcano

Since 22-July-2021 there has been an earthquake activity in Katla volcano. This earthquake activity has been mostly located to the east of the caldera and largest earthquake so far detected had a magnitude of Mw3,0.

Earthquake activity to the east of Katla volcano caldera shown on the image by ring line. A second smaller cluster of earthquakes is the west and little bit inside the caldera of Katla.
Earthquake activity in Katla volcano. Copyright of this image belongs to Icelandic Met Office.

There has not been any change in harmonic tremor activity following this earthquake activity. That strongly suggest that this is normal summer earthquake activity for Katla volcano. Earthquake activity is also far too low for it to signal any eruption risk. That might change if earthquake activity changes and grows in size.

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.