Minor earthquake swarm in Tjörnes Fracture Zone yesterday (30-August-2021)

Yesterday (30-August-2021) an small earthquake swarm took place east of Grímsey island in Tjörnes Fracture Zone. Two largest earthquakes had a magnitude of Mw3,2.

Earthquake swarm east of Grímsey island. Two green stars on top of each other.
Earthquakes east of Grímsey island. Copyright of this image belongs to Icelandic Met Office.

This earthquake swarm seems to have stopped for now. This area has frequent earthquake swarms and activity in this area of Tjörnes Fracture Zone might start again without warning.

Earthquake activity in Reykjanes volcano

During the night and today on 5-Augustu-2021 an earthquake swarm took place in the Reykjanes volcano.

Few dozen dots just out side in the ocean show the earthquake activity in Reykjanes volcano
Earthquake activity in Reykjanes volcano. Copyright of this image belongs to Icelandic Met Office.

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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Strong earthquake swarm ongoing on Reykjanes ridge

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.

Earthquake activity deep on the Reykjanes ridge. Many green stars are on the map that goes south along the Reykjanes ridge
The earthquake activity as it is shown on Icelandic Met Office map. Copyright of this image belongs to Icelandic Met Office.

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.

More earthquake activity in Katla volcano

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.

Earthquake activity in Katla volcano at 18:50 UTC this image shows three green stars, two of the stars are earthquakes from 29-July activity. New green star is from the earthquake today (31-July)
Earthquake activity in Katla volcano. Copyright of this image belongs to Icelandic Met Office.

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.

Earthquake activity in Katla volcano yesterday (29-July-2021)

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.

Cluster of smaller earthquakes in blue and red colours inside Katla volcano caldera. Two green stars on the north-east side of the caldera show the largest earthquakes.
Earthquake activity in Katla volcano. Copyright of this image belongs to Icelandic Met Office.

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.

Trace of the Mw8,2 earthquake in Alaska, United States

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.

The earthquake trace on north-south directed sensor that I have. It shows the P wave, the small S wave and the surface waves that I did record in Iceland.
The Mw8,2 earthquake as I did record it in Iceland.
Trace of the Mw8,2 earthquake in Alaska, shows the P wave that is strongest on the Z (vertical) line, along with the surface waves that I did record in a crude pattern
The Mw8,2 earthquake in Alaska, United States.
The Mw8,2 earthquake on a east-west direction. The P wave is the strongest followed by a small S wave and surface waves.
The Mw8,2 earthquake in Alaska, United States.

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.