Category: Earthquakes

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Earthquake activity update for Iceland and TFZ

This is update for TFZ over the past few days. Along with update for earthquake activity in Iceland during the past few days.

Tjörnes Fracture Zone

Earthquake swarm in TFZ continues. In the past days the largest earthquakes have had the magnitude of ML3.2. A second earthquake swarm is also taking place west of the village of Kópasker. That area also had an earthquake with the magnitude of ML3.2. That earthquake swarm is unrelated to the earthquake swarm taking place off north of Siglufjörður village. Earlier today an earthquake with the magnitude 3.8 took place. More earthquakes are expected to take place. This latest earthquake was clearly felt in Siglufjörður village. This earthquake swarm started on 20th of October. So it has been ongoing now for almost two weeks.


The latest earthquake in TFZ. Copyright of this image belongs to Icelandic Meteorological Office.


Earthquake tracker from Icelandic Meteorological Office showing the earthquakes during the past 48 hours in TFZ. Copyright of this image belongs to Icelandic Meteorological Office.

Earthquake activity is expected to continue in this part of TFZ. The risk of large earthquake in this area has not yet passed. Most of the earthquakes appears clearly on my geophone in Hvammstangi.

Iceland activity

Other the earthquake activity in TFZ. It has been generally quiet in Iceland. For the past four days there has been really bad winter storm taking place in Iceland. With wind up to 40m/s and wind gust up to 70m/s or more. This means that fewer earthquakes are being detected by the SIL network in Iceland due to increased wind noise. But earthquake activity has been low in Iceland for the past few weeks (besides TFZ). So I am not sure if that changes anything. There is no volcano activity taking place in Iceland at the moment.

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TFZ earthquake swarm ongoing after 10 days

The earthquake swarm that started in TFZ on 20.10.2012 continues. It has slowed down a little bit. But is still making earthquakes with the magnitude above 3.0 every few hours to days as it currently stands. This earthquake swarm at current time does not show any signs of stopping. Uncertainty level is in effect for north part of Iceland at the moment.


The earthquake activity from the start in this area of TFZ. Copyright of this image belongs to Icelandic Meteorological Office.


Current activity in TFZ. Copyright of this image belongs to Icelandic Meteorological Office.

It is hard to know for sure what happens next in this earthquake swarm. But I am sure it is going to continue as is. But as I sad above. This earthquake swarm does not show any signs of stopping for now. This earthquake swarm does not drop the risk of a large earthquake in this area of Iceland. At least while it is ongoing. Regardless of what happens later.

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TFZ earthquake swarm update on 26.10.2012 at 16:12 UTC

The earthquake activity in TFZ continues today, as it has done so for the past six days. Yesterday there was little change in earthquake activity in TFZ. General alert for the risk of earthquake larger then Mw6.0 is still in place and is going to remain in place for at least few more days.


The earthquake activity in TFZ on 26.10.2012. Copyright of this image belongs to Icelandic Meteorological Office.

It is impossible to know for sure what happens next in TFZ. But the stress is high in this area of Iceland according to GPS measurements. As some of the fault lines in TFZ are locked in place, while the whole system remains on the move otherwise. This builds up stress levels on the fault lines that are locked and unable to move in accordance with other tectonic movements in the area. This lock is then released in large earthquakes in TFZ that happen once to twice a century in this area. Now it is possible that it is time for new large earthquake in this area. But when is impossible to know for sure at the moment.

Some rock collapse has happened following the Mw5.6 earthquake on TFZ. This has been reported in local news media in Skagafjörður.

Icelandic news of rock collapse

Hrun í kjölfar skjálfta (Icelandic, pictures) Note that second picture is from the year 2006. The newest picture is the smaller frame and shows two blocks of rock that is at least 80 to 200 tons that broke loose in the largest earthquake on 20.10.2012.

Update 1: Icelandic Meteorological Office has issued this information this earthquake swarm. It can be found here on there web page.

Blog post updated at 20:59 UTC on 26.10.2012

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Uncertainty level is declared in north Iceland due to risk of large earthquake from TFZ

Uncertainty level has been declared in north Iceland due to risk of large earthquake taking place in TFZ. This is done after consulting scientists that have been monitoring this area for the past few days since the earthquake swarm started in TFZ. It is still impossible to know when a large earthquake might take place in TFZ. But the earthquake swarm is still ongoing with little change.

The Civil Protection of Iceland announcement

Óvissustigi almannavarna lýst yfir vegna jarðskjálftahrinu úti fyrir Norðurlandi (Icelandic)

Icelandic news about this

Óvissustigi almannavarna lýst yfir (Rúv.is)
Lýsa yfir óvissustigi almannavarna vegna jarðskjálftahrinu (mbl.is)

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Earthquake update on TFZ at 19:00 UTC on 24.10.2012

There is little change in the earthquake activity at TFZ today. The amount of earthquake activity on TFZ is about the same today as it was yesterday. But when this is written there have been about 100 earthquakes. But that number is going to change soon, as new earthquakes continue to happen.


The earthquake swarm in TFZ as it is today at 24.10.2012. Copyright of this image belongs to Icelandic Meteorological Office.


The trace of the earthquake activity during the past 48 hours. Copyright of this image belongs to Icelandic Meteorological Office.

Earthquake activity has moved a bit to the south. In the area what is called Flatey-Húsavíkur fault. This fault is known for making up to Mw7.0 earthquakes. If that is going to happen now is impossible to know at current time. But IMO has told of this risk in an news bit from yesterday (see yesterday blog post). For the moment however. The only thing that can be done is to wait and see what happens next in TFZ.

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Large amount of stress in Tjörnes fracture zone

According to a news by Icelandic Meteorological Office. There is enough stress in the Tjörnes Fracture Zone for magnitude 6.8 earthquake. This is based on a study (Metzger o.fl., 2011). When and where this stress, or if it is going to be released in one 6.8 magnitude earthquake is impossible to know for sure. As it is impossible to predict behavior of this type of earthquake activity.


The circle shows the odd earthquake swarm on 22.10.2012 that where more east then the main earthquake swarm in TFZ. Copyright of this image belongs to Icelandic Meteorological Office.

For the time being, at least while the earthquake swarm is currently ongoing. It is best to keep an eye out for it and any sudden changes in it. But as I sad before. It is impossible to predict this events. All that can be done is to wait and hope for the best when this earthquake activity do starts to happen.

Current earthquake swarm in TFZ is still ongoing. But earthquake activity so far continues to drop at the same rate as before.

Icelandic Meteorological Office news

Earthquake activity offshore North Iceland continues (en.vedur.is)

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Earthquake swarm update for TFZ and Kverkfjöll volcano at 12:55 UTC

Earthquake swarm in TFZ continues. But earthquake activity continues to drop at fast rate. The largest earthquake so far from midnight has the magnitude of 4.0 (reviewed magnitude). Several smaller earthquakes have taken place during the night in TFZ. But no larger earthquakes have so far taken since midnight. Current earthquake activity has moved little bit east since it started on 21.10.2012.


Current earthquake activity in TFZ for the past few months. Copyright of this image belongs to Icelandic Meteorological Office.

Kverkfjöll volcano

Earthquake activity has continues since it started again in Kverkfjöll volcano. The strongest earthquake so far had the magnitude 3.3. This earthquake activity in Kverkfjöll volcano has it source in magma movements inside Kverkfjöll volcano. This is most likely not going to start an eruption. But it is worth keeping an eye on.


Earthquake activity in Kverkfjöll volcano. Copyright of this image belongs to Icelandic Meteorological Office.

Earthquake activity has been slow in Kverkfjöll volcano. This is normal. As this is not tectonic movements, as in TFZ. But magma often moves slower and makes fewer earthquakes then just pure tectonic movements.

Blog post updated at 14:06 UTC on 23.10.2012
Blog post updated at 14:14 UTC on 23.10.2012

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New earthquake swarm in Kverkfjöll volcano

It seems that earthquake activity has started again in Kverkfjöll volcano. So far this is just small earthquakes. But earthquake activity started in Kverkfjöll volcano on 20.10.2012. That was also just small earthquakes. This is most likely minor dike intrusion taking place in Kverkfjöll volcano.


Earthquake in Kverkfjöll volcano. Copyright of this image belongs to Icelandic Meteorological Office.

It is impossible to know what this activity means. But I do think it is going to remain as is for now. At least it is unlikely for the time being that something bigger is going to happen in Kverkfjöll volcano. But it is worth keeping an eye on this activity. As this might be a clue that Kverkfjöll volcano are waking up from there dormancy. But it might just be minor earthquake activity that happens occasionally in volcanoes, without any other activity taking place in them following such activity.

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TFZ earthquake swarm update at 11:03 UTC on 22.10.2012

The earthquake swarm in TFZ continues at slowed rate then before. But number of earthquakes has dropped more then half since yesterday. During the night the strongest earthquake was ML4.1. With several earthquakes with the magnitude of 3.0 to 3.9. Many smaller earthquakes have taken place. Most of them with the magnitude around 2.0.


The area of earthquake activity in TFZ. The green stars mark earthquakes that where larger then ML3.0. Copyright of this image belongs to Icelandic Meteorological Office.


Trace showing the earthquake activity in TFZ during past 48 hours. Copyright of this image belongs to Icelandic Meteorological Office.


Tremor plot showing the earthquake activity. This is Hraun á Skaga SIL station. Copyright of this image belongs to Icelandic Meteorological Office.


Tremor plot showing the earthquake activity. This is Siglufjörður SIL station. Copyright of this image belongs to Icelandic Meteorological Office.

Earthquake activity is currently ongoing and is not expected to stop any time soon. But it might slowly decrease if there are no large earthquakes in this area in next few hours to days. But there is always more earthquake activity following stronger earthquakes in this area. The largest earthquakes in this earthquake swarm have been felt in the town of Siglufjörður and at times in other nearby towns in the area.

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Earthquake traces of the magnitude Mw5.6 earthquake

Here are the earthquake traces of the magnitude Mw5.6 earthquake that took place in TFZ on 21.10.2012 at 01:24 UTC. I did detect this earthquake in all of my geophone stations in Iceland.


The Mw5.6 earthquake in TFZ. This is the Z trace. This image is released under Creative Commons licence. See licence page for more details.


The Mw5.6 earthquake in TFZ. This is the E-W trace. This image is released under Creative Commons licence. See licence page for more details.


The Mw5.6 earthquake in TFZ. This is the N-S trace. This image is released under Creative Commons licence. See licence page for more details.

The interesting thing about this earthquake is how stronger the N-S,E-W trace is compared to the Z (vertical). This shows that this earthquake movement was strongest on E-W and N-S then vertical (Z).


The Mw5.6 earthquake in TFZ. This is Heklubyggð geophone station. This image is released under Creative Commons licence. See licence page for more details.


The Mw5.6 earthquake in TFZ. This is Eyrarbakki geophone station. This image is released under Creative Commons licence. See licence page for more details.


The Mw5.6 earthquake in TFZ. This is Skeiðflöt geohone station. This image is released under Creative Commons licence. See licence page for more details.

Earthquake activity is currently ongoing in TFZ. With earthquakes often reaching magnitude 3.0 in size. But many smaller earthquakes have taken place in the past 10 hours in TFZ. But overall the earthquake activity has slowly been dropping down since the large Mw5.6 took place at 01:24 UTC. If the earthquake activity is going to increase again is impossible to know for sure at current time.