Category: Swarm

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Small earthquake swarm on Reykjanes ridge

During the night of 30-August-2019 an earthquake swarm took place on Reykjanes ridge. Close to 69 earthquakes took place and largest earthquake had a magnitude of 3,0. Other earthquakes were smaller in magnitude.


The earthquake swarm on the Reykjanes ridge. Copyright of this image belongs to Icelandic Met Office.

Earthquake swarms are common in this area. This might result in a bigger earthquake swarm later or a new one at nearby location, that is also happens sometimes in this part of the Reykjanes ridge. This earthquake activity doesn’t appear to be connected to any volcano activity.

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Earthquake swarm in Krýsuvík volcano

At 01:27 UTC on 24-August-2019 an magnitude 3,4 earthquake took place in Krýsuvík volcano. This earthquake was felt in Hafnafjörður, Garðabæ and Kópavogi. This earthquake started a minor earthquake swarm in Krýsuvík volcano.


Earthquake swarm in Krýsuvík volcano. Copyright of this image belongs to Icelandic Met Office.

This earthquake swarm seems to be over when this article is written. Earthquake swarms like this are regular at this location.

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Earthquake swarm in Bárðarbunga volcano

A minor earthquake swarm took place in Bárðarbunga volcano today (21-august-2019). Largest earthquake had a magnitude of 3,5 and other earthquakes that happened are smaller in magnitude.


The earthquake in Bárðarbunga volcano (green star). Copyright of this image belongs to Icelandic Met Office.

This earthquake was in the north-east part of the caldera. In last few months earthquake activity has been increasing in that part of the caldera. Earthquake activity in Bárðarbunga volcano is due to magma inflating the volcano.

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Increase in earthquake activity in Hamarinn volcano (Bárðarbunga volcano)

Over the last few days there has been increase in earthquake activity in Hamarinn volcano (Bárðarbunga volcano). In Global Volcanism Program record this area is known as Loki-Fögrufjöll. Largest earthquakes today (12-August-2019) had a magnitude of 2,8 and 2,5 and other earthquakes have been smaller in magnitude.


The earthquake activity in Hamarinn volcano (red/blue dots at the edge of the glacier). Copyright of this image belongs to Icelandic Met Office.

Last time Hamarinn volcano had this type of earthquake activity it erupted for few months after it had started. That was on 12th July 2011. I wrote about those events here and here (glacier flood that followed, July 13th 2011). There were minor additional eruptions in August and November in 2011 according to the tremor data, those eruptions only lasted for ~4 hours at most. Since then this area has mostly been quiet and did drop down in activity after the eruption in Bárðarbunga volcano in 2014 to 2015.

It is unclear what is going on in Hamarinn volcano, for now there is no eruption taking place and any eruption is going to appear clearly on harmonic tremor data on the SIL network. It seems that eruptions in Hamarinn volcano start without any earthquake activity, I don’t know why that is. Last major eruption in Hamarinn volcano took place in the year 1910 from June 18 to October.

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New earthquake swarm in Tjörnes Fracture Zone

Early this morning (27-July-2019) a new earthquake swarm started north of Siglufjörður village. This earthquake swarm is in a different location than the magnitude Mw4,3 earthquake took place on 24-July-2019. This earthquake swarm is slightly more north of that location. That means this is a different fault that is creating this earthquake swarm. It is unclear if this is connected to the magnitude Mw4,3 earthquake that happened on 24-July-2019.


The earthquake swarm (green star) on Tjörnes Fracture Zone. Copyright of this image belongs to Icelandic Met Office.

The largest earthquakes at the writing of this article have the magnitude of Mw3,2. There is a lot suggesting that this earthquake swarm is ongoing as of writing of this article. Last earthquake to happen was at 20:07 UTC and had a magnitude of Mw2,7 (automatic). The risk of new earthquake swarms happening without warning and being bigger than what has happened so far remains high. The location of those earthquake swarm is going to be random and might be on land or out in the ocean. There is not any way to know were the next earthquake swarm is going to happen next.

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Earthquake swarm on north part of TFZ (north-west of Grímsey island)

Yesterday (24-July-2019) at 23:40 UTC and 23:42 UTC a magnitude Mw3,3 and Mw3,6 earthquake took place on the TFZ about 39 km west of Grímsey island. The two largest earthquakes were followed by a swarm of smaller earthquakes. Largest of those earthquake had a magnitude of Mw2,5. This earthquakes were not felt due to distance from populated areas.


The earthquakes 39 km north-west of Grímsey island. Copyright of this image belongs to Icelandic Met Office.

It is unclear if this earthquake activity is connected to the earthquake with the magnitude Mw4,3 that happened on 24-July-2019.

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Update on Tjörnes Fracture Zone earthquake (Siglufjörður village)

Today (24-July-2019) at 00:55 UTC an earthquake with the magnitude of 4,3 took place 20 km north-north-west of Siglufjörður village. The magnitude of the earthquake was downgraded from Mw4,6 to Mw4,3. This earthquake was felt over a wide area and minor damage was reported in Siglufjörður village, it was just items fallen off shelf. Largest aftershock had a magnitude of 2,7. There have been no major aftershocks at the writing of this article. This area had a earthquake swarm in 2012 with at least one earthquake with magnitude of Mw5,6 and one with magnitude of Mw5,5.


The Mw4,3 earthquake close to Siglufjörður village (green star). Copyright of this image belongs to Icelandic Met Office.


The earthquake as it appeared on my geophone in Böðvarshólar. Copyright Jón Frímann Jónsson.


The vertical (Z) movement on my geophone. Copyright Jón Frímann Jónsson.

There is a chance that a earthquake activity is increasing in Tjörnes Fracture Zone overall. Since its been a while since it had a major earthquake activity. With that I mean earthquakes with magnitude above Mw6,0.

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Earthquake in Torfajökull volcano

Today (20-Juli-2019) at 14:15 UTC an earthquake with the magnitude of 3,3 took place in Torfajökull volcano. This earthquake took place in south part of the caldera of Torfajökull volcano. This earthquake might have been felt by tourists in the area.


The earthquake activity in Torfajökull volcano. Copyright of this image belongs to Icelandic Met Office.

There has not been a lot of aftershocks following this earthquake for now. Last earthquake with magnitude above 3,0 took place on 12th of July and this means there might be a serious increase in earthquake activity in Torfajökull volcano. There are no obvious signs that Torfajökull volcano is about to erupt but it is also not known what is needed to make an eruption happen in Torfajökull volcano. Best action for now is to continue to monitor the activity in Torfajökull volcano.

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Earthquake swarm on the Reykjanes ridge

On Saturday (13-July-2019) earthquake swarm started off the coast of Reykjanes peninsula on Reykjanes ridge. The earthquake swarm is located 2 – 4 km south-west of Geirfulgadrangur rock. It is unclear if this earthquake swarm is over. Largest earthquakes in this swarm had a magnitude 3,1. Other earthquakes had smaller magnitude.


Earthquake swarm on the Reykjanes ridge. Copyright of this image belongs to Icelandic Met Office.

Activity in this area has the pattern of stopping and then starting again few hours to week later. This might result in stronger earthquake swarm next time this activity starts up again. There is a volcano in this area that last erupted in 18th or 19th of century. This volcano is not listed in Global Volcanism Program I think. I do not think this earthquake activity is volcano related but that is difficult to know fore sure due to how remote this area is and poorly known as such.

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Increase in earthquakes in Katla volcano

Since yesterday (13-July-2019) there has been a increase in earthquake activity in Katla volcano. There are no signs of anything more happening than just this increase of earthquakes.


Earthquake activity in Katla volcano. Copyright of this image belongs to Icelandic Met Office.

This increase in activity is something to keep a watch for but this has happened before without resulting in a eruption in Katla volcano. There have been reports on high volume of water level in the cauldrons in Mýrdalsjökull glacier. I don’t know if that is connected to this increase in earthquake activity. There is an expatiation that water is going to break out soon and the flood is going to be the largest since 2011. That might increase earthquake activity in Katla volcano once that happens. For now however nothing has been reported in the news of such a event.

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