Two earthquake swarms in Tjörnes Fracture Zone (TFZ)

Over the last few days there has been small earthquake swarm activity in Tjörnes Fracture Zone. The activity has been in two locations, west of Kópasker village and east of Grímsey island (ongoing swarm). Both earthquake swarms are small for now and only few earthquakes larger than magnitude 2,0 have happened. Total number of earthquakes is around 146 for the whole Tjörnes Fracture Zone when this article is written.


Current earthquake activity on the Tjörnes Fracture Zone. Copyright of this image belongs to Icelandic Met Office.

The earthquake swarm east of Grímsey island is not over as it has not yet peaked based on what I am seeing. It is more difficult to know about the earthquake swarm west of Kópasker village. As of writing of this article both earthquake swarms are ongoing.

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Update on the earthquake swarm east of Grímsey island in Nafir volcano

This is a short update on the earthquake swarm east of Grímsey island in the Nafir volcano (no Global Volcanism Program profile). Yesterday (19-March-2019) a magnitude 3,2 earthquake happened. Other earthquakes both before and after it are smaller in magnitude. In total over 200 earthquakes appear to have taken place in this earthquake swarm.


Earthquake activity yesterday (19-March-2019) in Nafir volcano. Copyright of this image belongs to Icelandic Met Office.

Earthquake activity has currently stopped. Based on the pattern in the earthquake swarm last year this might not be over and this might be going on for weeks until a peak is reached in earthquake swarm activity. It is impossible to know for sure what happens next in this earthquake activity in this area.

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Earthquake swarm east of Grímsey island (Tjörnes Fracture Zone)

During the night of 18-March-2019 an earthquake swarm started east of Grímsey island in a volcano called Nafir (no Global Volcanism Program profile). The only GVP profile that exists is about the volcano south of this one (GVP profile can be found here). The volcano in this area doesn’t have any documented eruption history in recent 10.000+ years. This might be wrong due to lack of research. In 2018 there was a strong earthquake swarm in this area. Articles connected to that earthquake swarm can be read here. Top of the earthquake activity on 19th of February 2018 looked like this as I wrote in a article last year. Current earthquake activity suggests a repeat of last year activity, only time is going to show if this does happen, but clues are strong in that direction. Earthquake activity in this area is complex and this is a rift valley it is taking place in.


The earthquake swarm east of Grímsey island in Tjörnes Fracture Zone. Copyright of this image belongs to Icelandic Met Office.

Largest earthquake so far has the magnitude of 3,3 and other earthquakes are smaller in magnitude. Currently around 55 earthquakes have been recorded. The earthquake swarm is ongoing even if current rate of earthquakes is low.

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Nafir volcano (TFZ) update at 17:45 UTC on 20-February-2018

Information in this article is going to get outdated quickly.

Currently there activity in Nafir volcano in the TFZ has quieted down since yesterday. Only one earthquake with the magnitude 3,0 has been detected since midnight. This earthquake swarm is ongoing as is even if it is just making smaller earthquakes at the moment. There has not been many earthquakes with magnitude above 2,0 since midnight. Most earthquakes currently happening are earthquakes with magnitudes below 2,0.


Current earthquake activity in Nafir volcano, TFZ. Copyright of this image belongs to Icelandic Met Office.


Current earthquake activity is not that dense at the moment. Copyright of this image belongs to Icelandic Met Office.

Currently there is extremely bad weather on the way to Iceland. That weather might have an effect on detection of small earthquakes in Tjörnes Fracture Zone and other parts of Iceland.

If anything happens I’ll update this article.

Nafir volcano update (TFZ) at 21:50 UTC

Information in this article are going go outdated quickly.

Here are the latest magnitude updates from the earthquakes this morning as reported by Icelandic Met Office and USGS.

Magnitude 4,9 at 05:34 UTC. USGS reports this as mb4,8.
Magnitude 5,2 at 05:38 UTC. USGS reports this as mb5,0.
Magnitude 4,0 at 06:32 UTC. USGS reports this as mb4,5.

In the last 48 hours 68 earthquakes larger than magnitude 3,0 have happened in Nafir volcano east of Grímsey island. In total 1497 earthquakes have been detected in the last 48 hours.


Current earthquake activity in Nafir volcano east of Grímsey island (TFZ). Copyright of this image belongs to Icelandic Met Office.


The current earthquake activity seems to be dropping a little for the moment. Copyright of this image belongs to Icelandic Met Office.

Currently the weather forecast in Iceland is really bad and that is going to prevent any proper detection of smaller earthquakes. Larger earthquakes are going to go above the wind noise threshold (possibly) and be properly detected. Large enough earthquakes are going be detected by monitoring networks outside of Iceland where weather is not a factor.

Next update is going to be tomorrow about this earthquake swarm. Unless something major happens in Nafir volcano.

Update at 12:03 UTC on earthquake swarm in Nafir volcano, TFZ, 19-February-2018

Information in this article is going to go outdated quickly.

Uncertainty level has been declared in Grímsey island and nearby area due to the strong earthquake activity in the night. Largest earthquake during the night was a magnitude 5,2 the second largest earthquake had the magnitude of 4,5 at the moment. Based on how it appeared on my geophone it possibly close to being a magnitude 5,0 earthquake. Revision takes time when a large earthquake swarm like this happens. The largest earthquake was felt over a wide area in north, north-east and north-west Iceland according to reports by Icelandic Met Office.


Current earthquake swarm in Nafir volcano east of Grímsey island in the TFZ. Copyright of this image belongs to Icelandic Met Office.


Earthquake activity is high at the moment. Copyright of this image belongs to Icelandic Met Office.

There is currently no end in sight for this earthquake swarm. It remains unclear if this is due to a possible volcano event in the making or just tectonic activity. Currently there is no eruption happening at this location. Unlike what appears on the live updated maps all of the earthquake activity is located east of Grímsey island. The SIL network has problems properly locating the earthquakes automagically when a large earthquake swarm like this happens.

Status of the earthquake swarm in Nafir volcano east of Grímsey island in Tjörnes Fracture Zone (TFZ) at 15:53 UTC on 18-February-2018

Welcome to the longest article title (this might be like this for a while). Information here might go outdated quickly as the situation changes.

Currently the earthquake swarm is smaller today (18-February-2018) then yesterday (17-February-2018) with mostly small earthquakes happening. Largest earthquakes since midnight had the magnitude of 3,4 at 12:14 UTC. It remains unclear if this earthquake swarm is going to increase again, but at the moment it is currently ongoing.


The earthquake swarm east of Grímsey island. Copyright of this image belongs to Icelandic Met Office.


The earthquake activity is less dense today than yesterday. Copyright of this image belongs to Icelandic Met Office.

It is difficult to know what happens next in this area due to the fact that this area is under the ocean and is really complex due to mixture of tectonic earthquakes (strike-slip activity) and volcano earthquake activity. What seems to be going on now is a volcanic earthquake activity. There is no magma signature at the moment because magma has not started to flow to the surface. It remains a question if it is just a question of time now if that happens. There is no documented eruption history in this area and that makes everything little bit more difficult.

This article is going to be updated if needed.

Article updated at 16:22 UTC. Text fixes.