Volcano and earthquake activity in Iceland
During the night and today on 5-Augustu-2021 an earthquake swarm took place in the Reykjanes volcano.
Largest earthquake in this swarm had a magnitude of Mw3,0 and other earthquakes at the writing of this article have been smaller. That can change without warning. Currently there is a possibly that this earthquake swarm is over.
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During the night of 5-August-2021 an earthquake swarm took place in Tjörnes Fracture Zone (TFZ). At the writing of this article this earthquake swarm is ongoing.
Largest earthquake in this swarm had a magnitude of Mw3,0. Other earthquakes where smaller in magnitude. No earthquake has been felt in Grímsey island.
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At midnight on 1-August-2021 an earthquake swarm seems to have started deep on the Reykjanes ridge. The current distance seems to be around 220 km away from Reykjavík or 190 km from Grindavík town. At this distance the location from Icelandic Met Office are not accurate. At the writing of this article the earthquake swarm seems to be ongoing.
Largest earthquake recorded at the writing of this article had a magnitude of Mw5,2 and the rest of the earthquakes have magnitude between Mw4,0 and Mw4,8. Overview of this earthquake activity can be found here on EMSC website. This links works as I publish this article. How long it is going to work I don’t know.
The current distance makes it impossible to know for sure what is going on at this location. The pattern of this earthquake activity suggests that this might be earthquake activity because of magma movement in the crust, but there is not any way to confirm this because of the location. Even if there is an eruption at this location it won’t make any difference to the surface of the ocean, since depth of the ocean at this location is more than 1 km. I don’t know the exact depth.
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.
I don’t have anything to say about the earthquake that took place (on 29-July-2021 at 06:15 UTC) in Alaska, United States since I don’t know the area geology features. I am going to show the trace of this earthquake as it did appear on my geophone in Iceland.
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.
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.
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.
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.
On 24-May-2021 at 21:36 UTC an earthquake took place in Brennisteinfjöll volcano. The magnitude of this earthquake was Mw3,6 and this earthquake was felt in Reykjavík area.
There have been few smaller earthquakes in this area since the largest earthquake, but other than that it has been quiet. This earthquake is believed to have happened because of stress changes on the Reykjanes peninsula because of the eruption in Fagradalsfjall mountain.