Category: TFZ

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A ML3.4 earthquake 25 east of Grímsey Island (automatic size)

When things gets busy in Iceland, they mean it. At least that is the case now. This also the reason why I do not trust the quiet times in Iceland.

A earthquake with the size of ML3.4 took place 25 km east of Grímsey Island in the TFZ at 21:46 UTC. But that is an non-volcanic zone that bridges the eastern volcanic zone with the North-Atlantic rift zone. This earthquake had an earthquake with the size of ML2.9 taking place before the larger one. That was an pre-earthquake most likely. But it seems that an earthquake swarm is also starting in TFZ as it has done close to Krísuvík volcano on the Reykjanes Ridge. I do not know if this earthquake was felt or not.

I am going to update this blog post if I need to.

Update 1: The location of this earthquake. So far there have not been any aftershocks following the ML3.4 earthquake. Its depth was at 11.5 km. This earthquake does not appear clearly on my geophones due to the distance involved (over 200 km).


The location of the ML3.4 earthquake on TFZ. Copyright of this picture belongs to Iceland Met Office.

Blog post updated at 22:22 UTC.

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Earthquake swarm in Grímsey Island (TFZ)

Today there has been a earthquake swarm in Grímsey Island. But this tiny Island is off the north coast of Iceland. Around 100 people live on the Grímsey Island. This earthquake swarm is small. But its location makes sure that it is felt. But it is directly under the village on the Grímsey Island. So far the strongest earthquake recorded is a ML3.3 in size with the depth of 9.1 km.


The earthquake swarm in Grímsey Island. The Island is located where the earthquake swarm is on this map. Copyright of this picture belongs to Iceland Met Office.

The largest earthquake so far was recorded on my Hvammstangi geophone clearly.


The earthquake as recorded on my Hvammstangi geophone. This trace is filtered at 4Hz. This picture is released under Creative Commons licence. See top bar for more information.

The earthquake swarm appears to be ongoing. I am sure that this earthquake swarm is felt in the village because it is directly under it. But depth of the earthquakes might however play a role in it how well the earthquakes are felt in the village. So far there have not been any news reports on this earthquake swarm in Icelandic Media.

Blog post updated at 00:25 UTC on 25 November, 2011

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Earthquake swarm in Tjörnes Fracture Zone

Today (18 October, 2011) at 08:53 UTC a earthquake swarm started in TFZ. So far this earthquake swarm is small in nature, only about dozen earthquakes so far. But the largest earthquakes have been with the size of ML3.6 according to IMO automatic earthquake detection system (called SIL). There is a good chance that this earthquake swarm is going to continue for the next few hours. But it is hard to know that for sure at the moment.


The area with the earthquake activity in Tjörnes Fracture Zone (TFZ). Copyright of this picture belongs to Iceland Met Office.

There are no volcanoes in the area where this earthquake swarm is taking place.

Blog post was updated at 11:58 UTC on 18 October, 2011

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Earthquake swarms in Krýsuvík volcano, Tjörnes Fracture Zone and SPAR fracture zone (Kolbeinsey Ridge)

In the last few days there has been good earthquake activity in TFZ (Tjörnes Fracture Zone). The largest earthquakes have been up to ML3.0 in size. But this earthquakes swarm have mostly been small and lasted for a short time.

Last night a earthquake swarm started in Krýsuvík volcano. This was just a normal tectonic earthquake swarm that normally takes place in this area on regular basic. From what I can tell. But it is impossible to know if this earthquake swarm was created by magma movement or not.


The earthquake swarm as it did appear on my Heklubyggð geophone. This picture is released under Creative Common Licence, see the licence page for more details.


The location of the earthquake swarm. Copyright of this picture belongs to the Icelandic Met Office.

This earthquake swarm took place in and close to a lake called Kleifarvatn. The largest earthquake in this earthquake swarm was a ML2.9 (automatic size). Currently the earthquake swarm is ongoing. But it has slowed a lot down since it started last night. At the moment, it looks like this earthquake swarm in Krýsuvík volcano is over for now.

Some earthquake activity was also on the south part of the MAR SPAR fracture zone, south and north of Kolbeinsey Island. The largest earthquake there was a ML3.0 (automatic data). Earthquakes this area happen often also. Like on the Tjörnes Fracture Zone.

Blog post updated at 23:38 UTC.
Blog post updated at 22:06 UTC on 16. August 2011. Fixed a error in it.

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Earthquake swarm on the TFZ

There is currently a earthquake swarm taking place on the TFZ. This earthquake swarm appears to be rather small at the moment. The largest earthquake so far has been a ML3.2 according to the automatic earthquake list on Icelandic Met Office earthquake list.

There is no volcano activity connected to this earthquake swarm, as there are no volcanoes in this area off the coast of Iceland but there are volcanoes in part of what is considered part of TFZ. This area has its earthquakes from a slip faults. But they move in both north-east to north-west, but also in south-north direction in some cases.


The Tjörnes Fracture Zone. Copyright of this picture belongs to it’s owner. Picture found here.

Here is the latest earthquake image from Icelandic Met Office about this earthquake swarm.


Copyright of this picture belongs to Icelandic Met Office.

It is impossible to know how this earthquake swarm behaves. It is also known for the TFZ area that one earthquake swarm can start a new earthquake swarm nearby if a large enough earthquake happens. This happens sometimes, but not always. It is not a common thing to take place in the TFZ from what I remember about activity in TFZ.

I am going to update this blog post if this earthquake activity becomes something larger then it already is, or if a large earthquakes takes place in the TFZ.

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Earthquake swarm in South Langjökull volcano and Krýsuvík volcano

Today has been spotted with earthquake swarms in Iceland. This earthquake swarms have not been big so far in both terms of earthquakes and size of the earthquakes. With the biggest earthquakes in South Langjökull volcano (Presthnjúkar). The biggest earthquakes in South Langjökull volcano have been around ML2.5 in size. With the average depth of 10 to 5 km. Total number of earthquakes is something around 39 and that is an small earthquake swarm.

The area in question is known for earthquake activity. Few years ago there was an earthquake swarm in this area with several ML4.0+ earthquakes. This area did also see earthquake swarm earlier this year. So far nothing suggests that an eruption is close in this area.


Map from Icelandic Met Office showing the area with the earthquake swarm. Click on the picture to get full size. Copyright of this picture belongs to Icelandic Met Office.

Krýsuvík volcano did also have an minor earthquake swarm today. The largest earthquake in Krýsuvík volcano was ML2.1 with the depth of 3.9 km. So far this earthquake swarm has been an minor one. With just over 32 earthquakes happening today.

Other earthquake activity in Iceland is currently not an lot. A ML3.1 earthquake took place few days ago in TFZ in an area that commonly has earthquake swarms. That area does not have any volcanoes, so earthquakes there are only connected to faults in the fault lines in that area.

Blog post updated at 23:29 UTC on 7. June 2011.
Blog post updated at 23:35 UTC on 7. June 2011.

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Minor earthquake swarm east of Grímsey Island

Today there has been a minor earthquake swarm east of Grímsey Island (is in Tjörnes Fracture Zone). The number of earthquakes that have taken place at the moment is something around 20 to 30 earthquakes. All of the earthquakes so far are less then ML3.0 in size.

This earthquake swarm in TFZ is so far quiet and mostly small in size. It remains unclear as always if this earthquake swarm changes or starts a new earthquake swarm that is bigger. But this area is known for that one earthquake swarm starts a new one in the TFZ.

So far this does not appear to be happening in the TFZ. But it is worth mentioning that TFZ is highly active earthquake zone. But there are no volcanoes there. Except at the south and north end of the TFZ. Where the rift zone ends and where the rift zone starts again.

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Update on the quiet time

It currently is quiet in Iceland, both in volcano and earthquakes. But it is not all without earthquakes. Few earthquakes have taken place in Krísuvík volcano, the largest being ML2.6 and in Kverkfjöll volcano. Few earthquakes have also appeared in TFZ, but all of them where small.

Besides this small activity. Everything remains quiet.

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Last activity update before Christmas and Christmas stuff

Here is the last activity update before Christmas starts. As I did expect a deep earthquakes have started again under Eyjafjallajökull volcano. So far the main depth is about 10 to 15 km. So far nothing indicates a immanent eruption in Eyjafjallajökull volcano. But it is wise to keep watch on the deep earthquakes that have started to re-appear under Eyjafjallajökull volcano.

But Eyjafjallajökull volcano is not the only volcano making earthquakes. There are also earthquakes taking place in Grímsfjall volcano and in Esjufjöll volcano. The continues earthquake swarm in Krísuvík volcano. But this is the same that has been going on in previous weeks in that area.

There has also been some minor earthquake activity in Grímsfjall volcano. A signal that Grímsfjall volcano is getting ready for a eruption in the year 2011 maybe.

Non-volcanic earthquakes

There has been a lot of earthquakes in the Tjörnes Fracture Zone (TFZ). But the largest earthquakes in the last 24 hours did get the size ML3,0 according to the automatic SIL system that Icelandic Met Office runs. The size might be subject to a review later on.

But other then this it has been quiet in Iceland earthquake wise and volcano wise. But when the most frost was going on over Iceland there was a lot frost earthquakes taking place. But those events are false earthquakes and are due the fact that freezing water appears to crack the ground, sometimes with considerable force. The frost needed for this to happen has to be below -10C far as I understand.

Christmas stuff

I am going to take my Christmas break from 12:00 UTC on the 24th of December (2010) until the 27th of December (2010). While this break is on comments might be held longer in the moderation queue then normally. If anything major happens, I am going to post information about it when I can in this time. But unlike us humans nature doesn’t care about our days off. But I am hoping for a quiet Christmas in Iceland like everywhere else.

There is going to be special Christmas blog post tomorrow for all those Christmas greetings.