Volcano and earthquake activity in Iceland
Today (31-July-2021) at 12:53 UTC an earthquake with magnitude of Mw3,3 took place in Katla volcano. A swarm of smaller earthquakes continued after the largest earthquake, this earthquake activity seems to be ongoing at the writing of this article.
Summer earthquake activity in Katla volcano is common and that makes it less clear what is going on in Katla volcano at the writing of this article. There is now a chance of more earthquake activity in Katla volcano.
Yesterday (29-July-2021) there was an earthquake activity in Katla volcano. Two strongest earthquakes had the magnitude of Mw3,2 at 19:20 and 19:22 UTC. Third largest earthquake at 19:28 UTC had a magnitude of Mw2,8.
It is unclear if this earthquake activity is just summer activity or part of a larger activity. At this time I am not expecting an eruption since the earthquake activity is currently too low for such event to about to take place. There are going to be thousands of earthquakes in Katla volcano before an large eruption. Until that happens. I do not worry about this activity.
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.
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.
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.
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.
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.
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.
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.
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.
This is going to be shortest update to the eruption in Fagradalsfjall mountain that is part of Krýsuvík-Trölladyngja volcano system.
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.
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.
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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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).
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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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.
Currently there are no other news about this eruption. Next update should be on 25-June.