Category: TFZ

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Update on Tjörnes Fracture Zone earthquake swarm

Donation note: I still need donations to survive this month as any other months while I am just on social welfare from Iceland as I have explained here. This month I just have around 24 DKK (3.21€) for food this month after paying all the bills and my debt. I have already got some donation, but they just allow me to buy food for about one and half week if I am smart. Thanks for the help.

The earthquake swarm on Tjörnes Fracture Zone continues. The earthquakes are getting stronger, with the largest one today having the magnitude 3.8 (automatic results) and five other earthquakes with the magnitude 3.0 to 3.2. Currently the depth is around the same, it remains at 5 to 15 km and at the moment it doesn’t seems to be changing. Rate of earthquakes is around the same today (02-October-2013) as it was yesterday (01-October-2013), with no major changes in earthquake rate from what I can see currently taken place.

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Earthquake activity in Tjörnes Fracture Zone. Green star show earthquakes larger than magnitude 3.0. Copyright of this image belongs to Icelandic Meteorological Office.

All earthquakes above magnitude 3.0 have been felt in Siglufjöður and Ólafsfjörður towns and other populated areas that are close to this earthquake swarm. There are no signs of this earthquake swarm slowing down as is. It still has not been confirmed if this earthquake activity is connected to magma injection at depth, or if this is just normal tectonic earthquake activity in this area. It’s going to remain difficult to confirm this idea until an eruption starts in this area and that simply might just not happen at all. The largest earthquakes appear on my webicorders website here, on the geophone station named Böðvarshólar.

Blog post updated at 22:33 UTC on 02-October-2013.
Blog post updated at 22:39 UTC on 02-October-2013.

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More earthquake activity in Tjörnes Fracture Zone

Donation note: Please donate. This month as past several months before that are difficult for me. Due to poor exchange range from ISK to DKK and the fact that I generally have low income. This website and writing on it is my job, along with other writing jobs that I attend to. Older posts on donations can be found here.

Today (01-October-2013) there has been a lot of earthquake activity in Tjörnes Fracture Zone. Current area of activity is same as for the past week, what is now changing is the rate and magnitude of earthquakes. This morning an magnitude 3.2 earthquake took place in this area. That earthquake and at least two other smaller ones where felt in Ólafsfirði, the town closest to this earthquake swarm. Earthquake activity is currently ongoing and with no signs of stopping.

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

It has been reported by Rúv and other news media in Iceland that this might be an dike intrusion in this area. This is what geologist at Icelandic Meteorological Office are theorising at the moment. I do not know if this is true or not. What I do know is that at this location there is no known volcano and if there is an volcano at this location it is currently unknown and not documented at all (such things happen). If this is magma and if it finds an path to the surface we are going to see an eruption. I do not know if that would create an new island if that was the case, such speculations have to wait until an eruption started. If it ever gets that far. If this is magma then it is still at great depth, since the depth of this earthquake swarm is at the moment around 5 to 15 km and does not seem to change that much at the moment.

It is possible to watch this earthquake activity here on my webicorder website. The closest geophone station that I have to this earthquake swarm is the one named “Böðvarshólar”. It is already showing many of the strongest earthquakes in this swarm clearly. It is located in the country side far from any major traffic source.

I am going to post updates about this earthquake swarm when needed.

Blog post updated at 20:26 UTC on 01-October-2013.
Blog post updated at 23:53 UTC on 01-October-2013.

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Update on Tjörnes Fracture Zone earthquake swarm

It has been almost a week since the earthquake swarm started in Tjörnes Fracture Zone. Today (30-September-2013) this activity continues. Since this earthquake swarm just around 1000 earthquakes (according to news) have so far been recorded by Icelandic Meteorological Office (when this words are written). The largest earthquakes have had the magnitude of 2.8, but no earthquake so far has reached the magnitude above 3.0.

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

Currently there is no sign of this earthquake swarm ending. So far it has not been felt by anyone and so far. I do not know how this earthquake swarm is going to develop. It’s however important to keep an eye on this earthquake swarm, since it’s impossible to know what happens next in this area.

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Earthquake activity continues on Tjörnes Fracture Zone

The earthquake swarm that started two days ago (wrote about it here) in Tjörnes Fracture Zone continues and appears to be growing in the past few hours. So far the largest earthquakes have not been stronger then magnitude 2.6 or 2.7 (automatic and reviewed results).

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

None of this earthquakes have been felt that I know. Since they are good distance (~20 km) from populated areas and are small at the moment. That might change if larger earthquakes start to happen in Tjörnes Fracture Zone. Currently this earthquake swarm activity is mostly continuous with just few stops in it, no stop has so far not lasted more than 1 to 3 hours so far. Currently this earthquake swarm activity is ongoing and I do not expect it to stop at the moment.

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Earthquake swarm in Tjörnes Fracture Zone

Today (25-September-2013) an earthquake swarm started in Tjörnes Fracture Zone. This earthquake swarm started slowly and was mostly making small earthquakes early on. The largest earthquake today had the magnitude of 2.8 according to automatic results from Icelandic Meteorological Office. Currently the earthquake swarm is ongoing.

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Earthquake swarm in Tjörnes Fracture Zone. Copyright of this image belongs to Icelandic Meteorological Office.

I am expecting this earthquake swarm to continue for the next hours at least. TFZ is highly active when it comes to earthquake activity so this earthquake swarm is no surprise. If any major earthquake take place in TFZ it’s possible to see them here on my webicorder website.

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Earthquake swarm in Tjörnes Fracture Zone

Yesterday (31-July-2013) a earthquake swarm started in TFZ, the south end of it, not far from a village named Kópasker. This earthquake swarm was small most of yesterday, but after midnight this earthquake swarm started to pick up in activity and magnitude of earthquakes. Around 07:09 UTC this morning (1-August-2013) a magnitude 3.7 earthquake took place, this earthquake was felt in Kópasker along with few magnitude 3.0 earthquake that took place after it. The epicenter of this earthquake swarm is out in the ocean, so no population is any major danger if this earthquake swarm continues as is.

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

This earthquake swarm is currently ongoing and there are no signs that is going to end soon, current activity is not continuous, it drops regularly and then it resumes again. It is impossible to know for sure how long this earthquake swarm is going to continue. The largest earthquakes appear clearly on my geophone and can be seen here.

Blog post updated at 18:11 UTC on 01-August-2013.

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More frequent earthquake swarms expected in Tjörnes Fracture Zone

According to a news on Rúv.is, there is now a risk of more frequent earthquake swarms in Tjörnes Fracture Zone. This is due to the tension that has been building up in Tjörnes Fracture Zone for the past 200 years, with the last large earthquake taking place 37 years ago (Kópasker magnitude 6.5 earthquake in January 1976). This short and small earthquake swarms in TFZ are not going to release the tension that has been building up there for the past 200 years (in some areas), for that too happen. It takes one or more earthquakes that are stronger than magnitude 6.0 to take place before tension starts to drop in the Tjörnes Fracture Zone.

Icelandic news about this

Útlit fyrir tíða skjálfta fyrir norðan (Rúv.is)

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Earthquake activity in Hekla, Askja volcanoes and TFZ

Before I start. I want to remind people that donations are import to me. Since they help me keeping this blog and my earthquake web page up and running.

Hekla volcano earthquake activity

A minor earthquake activity took place in Hekla volcano yesterday. None of the earthquake was larger then ML1.2. The depth of this earthquake activity was around 8.4 km. This earthquake activity took place outside the main volcano. But was in the connected fissure swarms that extends from Hekla volcano.

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Earthquake activity in Hekla volcano system. The earthquakes are the orange dots just south-west of Hekla volcano. Copyright of this image belongs to Icelandic Meteorological Office.

Earthquakes have been taking place in this area for few years now. I do not know what they mean. This might just be a earthquake activity and nothing else. Uncertainty level has been canceled for few weeks now due to lack of any more activity in the main Hekla volcano.

Askja volcano

There has been minor earthquake activity in Askja volcano this past weeks. All of the earthquakes have been smaller then magnitude 1.5. Depth of this earthquakes is around 18 to 22 km. Suggesting that current earthquake activity has its source in magma movements rather then tectonic earthquakes.

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Earthquakes in Askja volcano. Askja volcano is the volcano north-east of Vatnajökull glacier. Copyright of this image belongs to Icelandic Meteorological Office.

Tjörnes Fracture Zone

Activity in Tjörnes Fracture Zone has slowed down since 2. April when a large earthquake swarm started in it. But earthquake activity remains as is. Even if the earthquakes are smaller and fewer. This means the earthquake activity has been continuous for the past three weeks.

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Earthquake activity in Tjörnes Fracture Zone. It remains in two areas as of now. New activity has also been taking place. Copyright of this image belongs to Icelandic Meteorological Office.

It is difficult to know for sure what happens next in TFZ. But tension in it remains as before and so does the risk for larger earthquake in this area. For the moment however, it remains rather quiet. When that might change is impossible to know for sure.

Blog post updated at 18:16 UTC on 24.04.2013.

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Less earthquake activity in Tjörnes Fracture Zone

Yesterday (09.April 2013) there has been less activity in Tjörnes Fracture Zone. The largest earthquakes yesterday did have the magnitude 4.0 and 3.3. A smaller earthquake with the magnitude 3.1 also took place. Many other smaller earthquakes also took place as is normal for this type of earthquake swarm. There are no signs of any volcano activity in the area during this earthquake activity.

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Earthquake activity in Tjörnes Fracture Zone during the past 48 hours. Copyright of this image belongs to Icelandic Meteorological Office.

This earthquake swarm does not appear to be over. Even if it has slowed down from its peak one week ago following the magnitude 5.5 earthquake. This type of slowdown are common in this type of earthquake swarms. In many cases the activity stops altogether and starts again after some time. I now believe that current earthquake swarm is connected (not sure how yet) to the earthquake swarm that took place in TFZ in October 2012 and started view few smaller earthquakes and had one magnitude 5.6 earthquake. For now however the earthquake activity is dropping. But it is impossible to know for sure what happens next in TFZ area.

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Update on the TFZ earthquake swarm at 01:01 UTC

This is a short update on the earthquake swarm in TFZ. This is going to be a long earthquake swarm from the looks of it (currently).

The earthquake swarm in TFZ continues as it has been doing for the past six days now. The strongest earthquakes for the past 24 hours have had the magnitude 3.5, 3.6 and now 3.3 (automatic magnitude). This is a extremely complex earthquake swarm. Over a period of 48 hours there have been around 368 earthquakes. That is a drop in activity, but in the first few hours after the magnitude 5.5 earthquake in TFZ there where recorded over 500 earthquakes.

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Earthquake activity in TFZ for the past 48 hours. Copyright of this image belongs to Icelandic Meteorological Office.

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The trace plot that shows the earthquake activity for the past 48 hours in TFZ. Copyright of this image belongs to Icelandic Meteorological Office.

This earthquake swarm is complex due to three factors. There is a both slip fault and normal fault taking place there. There also appears to be a volcano in the area. But it not properly understood and is extremely poorly studied. It is unclear at present time if this volcano is connected to this earthquakes swarms at present time. Since so little is known about it. It is also not known if the current earthquake swarm is going to start something in the volcano. The second volcano that is in this area last erupted in the year 1868 following an earthquake swarm in this area. Why that did happen is also not known. But it has a Global Volcanism profile here. The volcano that is closer to Grímsey Island is currently unnamed. There is also almost no studies or documentation on it. But from the little I did find

Please note that the earthquake swarm information is always changing so this information here do get outdated fast. This mostly applies the maps and number of earthquakes.

Scientific data on Tjörnes Fracture Zone

As I did say here above. The Tjörnes Fracture Zone is complex and that is making this earthquake swarm extremely complex as it is taking place.

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The rift fault lines in TFZ. This is the simple version. It is from a science study that can be found here. Copyright of this image belongs to Icelandic Meteorological Office/Hjorleifur Sveinbjornsson.

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More complex nature of the fault systems in TFZ. Copyright of this image belongs to Agust Gudmundsson. From study Infrastructure and evolution of ocean-ridge discontinuities in Iceland.

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More complex image showing the fault lines in TFZ. Copyright Ragnar Stefansson, Gunnar B. Gudmundsson, Pall Halldorsson. From the study Tjörnes fracture zone. New and old seismic evidences for the link between the North Iceland rift zone and the Mid-Atlantic ridge.

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The most detailed picture that I was able to find of Tjörnes Fracture Zone and the ocean floor. Copyright of this image belongs to many people. Please see the list of copyright holders in the following link. From the study First observations of high-temperature submarine hydrothermal vents and massive anhydrite deposits off the north coast of Iceland.

It is clearly worth watching this earthquake activity. Since it might have interesting effects on the volcano where this earthquake activity is taking place. Even on the second volcano just north of Þeystareykjabunga volcano.