Category: Swarm

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Strong earthquake swarm in Bárðarbunga volcano

Yesterday (30-January-2018) Bárðarbunga volcano had strongest earthquake since 27-October-2017. That earthquake had the magnitude of Mw4,9 (at 19:24 UTC). Two earlier earthquakes had happened but they had smaller magnitude of 3,7 (at 17:47 UTC) and magnitude 3,8 (at 18:00 UTC).


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

Earthquake activity seems to have stopped with last earthquake happening at 21:29 UTC. There is no change in harmonic tremor from Bárðarbunga volcano and that means no eruption. The north-east part of the Bárðarbunga volcano seems to be getting unstable with each earthquake swarm that happens. Magnitude of earthquakes happening has also increased but it is now longer between earthquake swarm. The time between earthquake swarms now can go up to several weeks. Soon after this earthquake activity started in September-2015 this type of activity happened weekly.

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Strong earthquake swarm on Tjörnes Fracture Zone (TFZ)

Yesterday (28-January-2018) a earthquake swarm started in Tjörnes Fracture Zone (TFZ). This earthquake swarm is ongoing and current numbers might change and magnitudes of earthquakes from what they currently are. At the moment largest earthquake that has been recorded happened yesterday and had a magnitude of 4,1 (at 07:49 UTC) and the second strongest earthquake so far had the magnitude of 3,4 (at 08:11 UTC). The stronger earthquake woke people up from their sleep and was felt over a wide area. That was not reported with the second earthquake.


The earthquake swarm in TFZ. Strongest earthquakes are marked by green stars. Copyright of this image belongs to Icelandic Met Office.

All other earthquakes so far have been smaller than magnitude 3,0 at the moment. Over 130 earthquakes have happened so far. This earthquake swarm is currently ongoing. This earthquake swarm is only tectonic in nature and at the moment there is nothing suggesting that this activity is connected to magma movements.

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Magnitude 3,5 earthquake 2,6 km from Grindavík village

Yesterday (21-January-2018) at 21:15 UTC an earthquake with magnitude of 3,5 took place 2,5 km from Grindavík village. This earthquake was clearly felt in Grindavík village. This earthquake was at depth of 5,0 km.


The magnitude 3,5 earthquake (green star) on the Reykjanes peninsula. Copyright of this image belongs to Icelandic Met Office.

Largest aftershock had the magnitude of 2,8 and all other earthquakes where smaller in magnitude. This earthquake swarm does seems to be over for now. There is always a risk of more earthquakes on the Reykjanes peninsula due to tectonic forces at work in this area.

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Dyke intrusion south-east of Bárðarbunga volcano

On Sunday (21-January-2018) a dyke intrusion took place south-east of Bárðarbunga volcano. The area is question is slightly outside of Bárðarbunga volcano fissure swarm but seems to be connected to the main volcano.


The earthquakes south-east of Bárðarbunga volcano. Copyright of this image belongs to Icelandic Met Office.

Largest earthquake only had magnitude 1,2 and the shallowest depth was only 13,9 km with a magnitude 0,8 earthquake. The risk of an eruption in this area is increasing, but it is not possible to know when a eruption might happen. This area has been active for some time now with regular dyke intrusions at the same location.

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Earthquake swarm in Tungnafellsjökull volcano

In the last 24 hours (20-January-2018) an earthquake swarm started in Tungnafellsjökull volcano. All earthquakes that have happened so far are small and no earthquakes have so far reached magnitude 1,0.


The earthquakes in Tungnafellsjökull volcano (red dots), north of Bárðarbunga volcano. Copyright of this image belongs to Icelandic Met Office.

At the moment there is nothing suggesting that magma is reaching the surface of this volcano. At the moment the earthquakes appear to be tectonic in nature. If they are due to influence of Bárðarbunga volcano (crustal stress changes) is unclear at the moment. Tungnafellsjökull volcano has not erupted in last 12.000 years and little data is on eruptions that are older than 12.000 years.

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Article updated at 20:00 UTC. Added text that was forgotten.

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Magnitude 3,1 earthquake in Öræfajökull volcano

A magnitude 3,1 earthquake took place on 18-January-2018 at 02:14 UTC in Öræfajökull volcano. This earthquake was followed by one magnitude 2,0 earthquake and one magnitude 1,8 earthquake. All other earthquakes where smaller in magnitude.


Earthquake activity in Öræfajökull volcano (green star). Copyright of this image belongs to Icelandic Met Office.

This earthquake activity was followed by an increase in higher frequency noise on the tremor plots around Öræfajökull volcano. This possibly was the swarm of small earthquakes detected in Öræfajökull volcano at the same time. I am not sure at this moment, but I do hope it gets clearer what is happening as more data is collected with increasing activity.


The change in the tremor plot at Fagurhólsmýri SIL station. The change is at the blue line close the end (spikes). Copyright of this image belongs to Icelandic Met Office.

At the moment everything is quiet in Öræfajökull volcano.

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Earthquake activity in Bárðarbunga volcano (Week 03-2018)

Today (15-January-2018) a earthquake swarm activity took place in Bárðarbunga volcano. This is a regular event at this point and has been for some time now. Today’s earthquakes had the magnitude of 3,5 (09:39 UTC) and 3,3 (09:47 UTC). The location suggests that stronger earthquakes are going to happen soon in Bárðarbunga volcano in the north-east part of the caldera of Bárðarbunga volcano.


Earthquake activity in Bárðarbunga volcano (green stars). Copyright of this image belongs to Icelandic Met Office.

This earthquake activity shows that Bárðarbunga volcano continues to inflate after the end of the eruption in Holuhrauni in Februar-2015. Currently it is clear that Bárðarbunga volcano is preparing for an eruption. When next eruption might happen is impossible to know.

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Strong earthquake swarm deep on the Reykjanes ridge

Yesterday (11-January-2018) at 09:46 and 09:50 UTC two strong earthquakes took place around 780 km deep south west of Iceland. The earlier earthquake had a magnitude of Mw5,4 (EMSC information here) and the second earthquake had a magnitude of mb4,9 (EMSC information here).


Earthquake activity deep south of Iceland (green stars). Copyright of this image belongs to Icelandic Met Office.

Icelandic Met Office reports in total 7 earthquakes, including the two largest ones that EMSC did record but with lower magnitude. The EMSC magnitude is the correct one. This earthquake swarm starts at 08:37 UTC with a magnitude 4,0 earthquake. It ends at 11:11 UTC with a magnitude 3,6 earthquake. The exact location of this swarm is difficult to know due to the distance it is from any earthquake monitoring network. It is also difficult to know for sure what is going on at this location but the earthquake data suggests that this was just a normal earthquake swarm and not connected to any volcano activity. At this distance smaller earthquakes are not detected (below magnitude of Mw3,6).

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Sharp increase in earthquakes in Katla volcano

Yesterday (05-January-2018) a warning was issued about higher conductivity in glacier rivers from Mýrdalsjökull glacier. This is due to increased activity in Katla volcano. At the moment the conductivity is around 613 µS/cm according to Icelandic Met Office (I can’t find that number on their website for unknown reasons). Volcano gas has also been registered at Láguhvolar SIL station (a gas measurement takes place there). Last time this happened was in November-2017 when a slightly larger glacier flood took place.


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

Following the glacier flood was a sharp increase in earthquake activity. It is unclear why that happened as glacier flood do not require special earthquake activity to happen. There are no clear sign of minor eruptions happening on SIL stations around Katla volcano. I have not seen any change in tremor plots from SIL stations around Katla volcano. As it now stands I am expecting more earthquake activity and more glacier flood activity if this follows earlier pattern. That might not happen and it is difficult to know for sure what is going to happen next. Largest earthquake in current activity had the magnitude of 2,1 and all other earthquakes have so far been smaller in magnitude. All earthquakes have depth shallower than 1 km.

Sorry if my English is bit off. I did travel for good 14 hours (start time at ~04:10 and got home at ~18:40) on 4th of January-2018. This is the time it takes me to travel home (Denmark) from Iceland. I was completely exhausted once I got home.

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Small earthquake swarm in Katla volcano

Today (30-December-2017) a small earthquake swarm took place in Katla volcano. This earthquake activity was a minor one and the largest earthquake only had a magnitude of 1,4 and all other earthquakes where smaller.


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

It is difficult to know if more earthquake activity is going to happen in Katla volcano. Winter months are normally quiet when it comes to earthquake activity in Katla volcano.

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