Posted on by Jón Frímann

Tjörnes Fracture Zone (TFZ) earthquake update at 13:20 UTC on 17-February-2018

Information in this article are going to go outdated quickly.

As of the writing of this article total of 1593 earthquakes have happened in last 48 hours in Tjörnes Fracture Zone (TFZ). The reason for this earthquake swarm remains unclear at the moment. It is not clear if this is just tectonic earthquakes or have their origins in magma movements.


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


This earthquake swarm is dense. Copyright of this image belongs to Icelandic Met Office.

Largest earthquake since midnight has the magnitude of 3,7 so far. In the last 48 hours total of 27 earthquakes larger than magnitude 3,0 have happened east of Grímsey island. This earthquake swarm is happening in a volcano named Nafir (no GVP profile) and that volcano doesn’t have any documented eruption during the last 12.000 years that I know of (I might be wrong). It remains unclear at the moment if an eruption is going to happen at this location. At the moment there are no clear signs of magma movement, but ISOR (Icelandic article here) suggests that current earthquake swarm might be connected to magma movement in the area. If that is going to result in a eruption remains unclear in ISOR view.

I’ll update this article as needed today.

13 Replies to “Tjörnes Fracture Zone (TFZ) earthquake update at 13:20 UTC on 17-February-2018”

  1. The idea that the earthquake swarm in Tjörnes fracture zone is tectonic is ludicrous. This is the forming or reforming of a volcano in the middle of the Atlantic Ocean. We may not see a volcanic tremor, but if I compare it with the time before the Hohraun eruption, I see so many similarities. Our understanding in volcanology is too little to know what we can expect. So we don’t make predictions? We don’t have to make ONE prediction only. We may make more than one prediction, depending on the case before us. If it quaks like a duck, it flies like a duck and it walks like a duck: IT IS A DUCK. This is the emerging of a volcano under water. If the explosion occurs under water, we will have a mighty tsunami waiting to happen. Two possible scenarios: It will die down and no eruption. Or there will be an volcanic eruption either explosively or not. Even if there will be an explosive eruption, it may not be very violent. My intuition says that we are on the brink of a disaster. When? My intuition doesn’t say so. I am glad the tsunami is not in the direction of Europe but the Americas. But in Europe we may have the fall out of tephra. So much is happening now. Bardarbunga Oraefajakull, Katla, Hekla and who knows Nafir.

    1. Tsunami is not going to happen even if a eruption happens in this area. It is unclear if this a volcanic or tectonic event at the moment. Before the Holuhraun eruption there was a clear sign that magma was moving since the harmonic tremor did go trough the roof on most SIL stations on the lower bands. That has so far not yet happened.

      There are no known historical eruptions documented in this area so it is impossible to know what happens next. I hope that in the next 24 – 48 hours it becomes more clear what is happening in this area.

      The pulse like behaviour of the earthquake swarm suggests that magma is the reason for this earthquake swarm. There are strong hydrothermal systems in this area and they are only powered by magma at 1>km depth. This might not result in a eruption even if magma is on the move.

      This is on a rift zone and magma from any volcano in this area is basalt (thin flowing) and the only reason for an ash cloud if an eruption does happen is the ocean and water. That would only happen for as long as the ocean got into the eruption vent.

      2. It may not be clear what is happening, but I think if I lived on Grimsey, I would be visiting Aunt Tilly in Reykjavik for a few weeks.

  2. Thanks Jon
    Very clear this is not going to have the same impact that it would if it were happening on land. Any ash would have to come from some kind of surface eruption and we do not see that kind of vent above the surface of the Atlantic thus far. And Francis Marcel Vos it probably is a duck, but until we see it above the water its still not going to be the disaster your thinking of its more likely just a duckling under the water!

    1. I think this abstract of the article is very interesting. It is what i suspected, that this is a sign or cause of increasing volcanic activity along the volcanic Zones of Iceland. Maybe we will see more activity in for example Bardarbunga and Öræfajökull volcano after this has stopped and or underwater eruptions at Tjörnes fracture zones. Could this be a pat of the start of a once in a millennium thing. It is a pity that modern measurement equipment is just that: Modern!.

  4. Currently the earthquake activity is mostly just minor earthquakes below magnitude 2,0. That might change without warning during the night. This earthquake swarm is ongoing and shows no signs of stopping.

  6. Do you think its over or are it spreding inland to the bigg volcanos?is this having an effect on askja barda grims and the other bigg canons?

  9. Activity started to pick up again.
    Sunday
    18.02.2018 18:27:19 66.564 -17.716 15.8 km 3.8 99.0 13.2 km E of Grímsey

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