Category: Dyke intrusions

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Update on Reykjanes peninsula earthquake swarm (Fagradalsfjall mountain)

Since 26-July-2017 there has been a earthquake swarm on Reykjanes peninsula close to a mountain called Fagradalsfjall. This earthquake swarm has been one of the larger ones in the area in recent years. Total number of earthquakes that have been detected so far is well over 600 at the writing of this article. There is some magma involved in this earthquake swarm, it has stayed deep in the crust and there are currently no signs of it moving upwards more then it already has at this point. This makes an eruption extremely unlikely, unlike what some news reports about this earthquake swarm might suggest an eruption is not imminent in this area of Iceland.


Earthquake activity close to Fagradalsfjall mountain for the last 48 hours. Copyright of this image belongs to Icelandic Met Office.

Largest earthquake during the last 24 hours is a magnitude 3,2 earthquake that took place at 05:56 UTC. In 1968 a magnitude 6,0 earthquake took place in this same area. I don’t know if that is going to happen now, what is a risk is this earthquake swarm increasing again from current drop in activity. This area is in part a rift valley and plate interaction can get complicated and last for a long time. With quiet period between high periods of activity. At this moment the earthquake activity in this area is decreasing, that does not mean it is over yet, just that a decreasing in activity is currently happening.

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Ongoing earthquake activity north-east of Flatey in Skjálfanda fjord (north-east Iceland)

Earthquake activity that started in March 2017 in TFZ (Tjörnes Fracture Zone) is ongoing. I don’t know yet how many earthquakes have happened so far, but at last check Icelandic Met Office reported that the mark was at 800 and that was more then a month ago. The fluid that is pressuring up at this location between fault lines is most likely a magma in my view. If that results in a eruption is harder to say, at the moment the magma seems to be stuck at 10 km depth (in or around that depth).


The current earthquake at Flatey in Skjálfanda fjord. The location is where the yellow and orange dots mix (slightly east of Eyjafjörður fjord). Copyright of this image belongs to Icelandic Met Office.

The earthquake activity at this location continues with little signs of stopping. What is also interesting is the fact the magma doesn’t seems to be making any progress up the crust at the moment. With fault line already in place the path to the surface is almost direct in this area if nothing is preventing the magma from moving upwards (impossible to know). At the moment this earthquake activity is limited to minor earthquakes and this magma seems to be lacking pressure to reach the surface at the moment. At this location there are no known volcanoes.

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Earthquake activity in Öræfajökull volcano (13-June-2017)

Today (13-June-2017) a magnitude 2.6 earthquake took place in Öræfajökull volcano. This is the largest earthquake in this volcano for a long time now and it is worth noting that Öræfajökull volcano normally doesn’t have any earthquake activity. This suggests that something might be up if it doesn’t start to quiet down in next few years. Earthquake activity in Öræfajökull volcano is not high as can be seen in this science paper that covers the years 1994 – 2007 in earthquake activity in Iceland.


Earthquake activity in Öræfajökull volcano (to the south on this image). Some of the activity might be glacier quakes due to summer heat or rain. Copyright of this image belongs to Icelandic Met Office.

Tectonic settings in this area don’t allow for a lot of crustal-tension earthquakes and that suggests that the source of current earthquake activity in Öræfajökull volcano can be explained by magma movements. If this is going to end in a eruption remains to be seen. At the moment current low level activity rules that out, since a lot more and stronger earthquake activity needs to happen before magma can reach the surface.

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Weekly earthquake in Bárðarbunga volcano (12-June-2017)

Today (12-June-2017) a magnitude 3,6 earthquake took place in Bárðarbunga volcano. This earthquake activity is mostly normal for Bárðarbunga volcano, there has been slight increase in earthquake activity in Bárðarbunga volcano during the past few days (minor earthquakes), why that increase is taking place is unclear at the moment. This increased happened at the same time as a sharp increase in earthquake activity took place in Tungnafellsjökull volcano (read the article about that for more information).


The earthquake activity in Bárðarbunga volcano and Tungnafellsjökull volcano. The green star shows the magnitude 3,6 earthquake. Copyright of this image belongs to Icelandic Met Office.

Currently the activity in Bárðarbunga volcano is mostly what is now considered ‘normal’ after the 2014 – 2015 eruption. I don’t know if that status is about to change, but there are clues in current activity suggesting that might be about to happen. This increased activity however might slow down again and go back to normal background levels.

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Deep earthquake activity in Trölladyngja (volcano)

Today (08-June-2017) there have been deep earthquakes in Trölladyngja (volcano). This earthquake swarm was shallower than last earthquake swarm that took place in Trölladyngja. Several months ago the earthquakes in Trölladyngja where happening at 28 km depth, but now they are at the depth range of 18,6 – 23,3 km, this means that the magma under Trölladyngja is migrating upwards at fast phase, a lot faster then I thought was possible. Earthquake swarm in November-2015 where slight off to the side, those earthquakes had the depth of 15 – 18 km as I wrote about here. Since November-2015 here has been other activity in Trölladyngja, but that has been in the form of one or two earthquakes so I have not written about it (I never bother with just one or two earthquakes at location due to the amount that happens daily in Iceland).


Earthquake activity in Trölladyngja (volcano), north-east of Bárðarbunga volcano fissure swarm. Copyright of this image belongs to Icelandic Met Office.

Last eruption in Trölladyngja was according to GVP (under Bárðarbunga volcano history) was 7000 years ago. Since then nothing has happened. There has been a lot more eruption in Dyngjuháls area and that area is also having deep earthquakes. That area is also covered with ~200 meters of glacier. It remains to be seen what happens next in the Bárðarbunga volcano saga.

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Earthquake swarm in Kolbeinsey island

Yesterday (24-May-2017) and today (during the night of 25-May-2017) there was an earthquake swarm in Kolbeinsey island. Largest earthquakes had the magnitude of 3,6 (x2) and one magnitude 3,5 earthquake took place. Other earthquakes where smaller in magnitude. No harmonic tremor where detected during this activity, that does not rule out that this activity is due to dyke intrusion taking place in Kolbeinsey island. It just didn’t reach the surface this time. Kolbeinsey island is far away from the SIL network, with the closest station being in Grímsey island (~25 km) with other SIL station at ~60 km distance. If an eruption starts in Kolbeinsey Island, a harmonic tremor signal is going to appear in Grímsey island SIL station.


Green star mark the area where the earthquake swarm took place in Kolbeinsey island. Copyright of this image belongs to Icelandic Met Office.

Last eruption in this area took place in the year 1755, but that eruption might not actually have been in Kolbeinsey Island, but in a other unnamed volcano north of it (where is not known). Last confirmed eruption in Kolbeinsey island took place in the year 1372, it was closer to land somewhere north-west of Grímsey island (suggesting that fissure swarm of Kolbeinsey island comes close to Grímsey island).

At the moment the activity has quieted down and no earthquakes are being detected by the SIL network.

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Possible dyke intrusion in Þórðarhyrna volcano

Tonight (05.03.2017) an possible dyke intrusion has taken place in Þórðarhyrna volcano. It’s a small volcano south-west of Grímsfjall volcano and on Global Volcanism Program website it is counted with Grímsfjall volcano eruptions. Last eruption in Þórðarhyrna took place in 1902 at the same time there was an eruption in Grímsfjall volcano (size VEI=4). Before that eruption, the earlier eruption in Þórðarhyrna took place in the year (August 15th) 1887 and lasted for two years (ended in 1889).


Possible dyke intrusion in Þórðarhyrna volcano (south-west of Grímsfjall volcano). Copyright of this image belongs to Icelandic Met Office.

Largest earthquake in this swarm had the magnitude of 2,5 and the second largest earthquake in this swarm had the magnitude of 2,4. Other earthquakes where smaller. It is not possible to know how this is going to evolve since there is a lack of data on Þórðarhyrna volcano due the fact no eruption has happened since the year 1902. That means for now, it is just more wait and see what happens next.

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RSS feed

If people want to keep up with articles in real time (in case of an eruption), it is possible to do so with an RSS feed that WordPress supports. Both for new articles and new comments as they appear. Its an alternative with the email list I currently support.

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Continued and strong earthquake activity north of Kolbeinsey Island

For the past few weeks something has been going on in the deep ocean far north of Kolbeinsey Island. The area north of Kolbeinsey Island has been having strong earthquake swarms for several weeks now, what is creating them is less clear.


The earthquake activity north of Kolbeinsey Island (blue dots). Copyright of this image belongs to Icelandic Met Office.

All magnitudes are under-estimated at this location. I managed to record the last earthquake swarm (largest earthquakes) and it was clear by this activity that something was going on. Five earthquakes that where at least magnitude 3,2 (estimate) took place in the space of 4 – 8 minutes. This where only the earthquakes that I was able to record, distance from my geophone to this area is ~230 km at shortest distance. Making it difficult for me to record earthquakes on my simple geophone. Icelandic Met Office SIL network is not having much better luck recording earthquakes at this location, due to distance the SIL network underestimates the magnitude and location of the earthquakes has higher than normal error margins (up to several dozen of km at most).

There is a possibility that an eruption is taking place at this location now. There was a possible eruption or dyke injection at this location in October of the year 1999, the Global Volcanism Program report on that activity can be found here.

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Deep earthquakes in Bárðarbunga volcano

Over the past few hours a sequence of deep earthquakes has been taking place in Bárðarbunga volcano. The depth of those earthquakes is from 19 km and up to 11 km, how they spread out suggesting a dyke intrusion in Bárðarbunga volcano fissure swarm or on the edge of the volcano.

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The deep earthquakes taking place almost south of the main caldera in Bárðarbunga volcano (few blue/yellow dots). Copyright of this image belongs to Icelandic Met Office.

Deep earthquake activity suggests that fresh magma is pushing into the volcano at more pressure than in past few days. The clues about this happening have been the stronger earthquake activity in Bárðarbunga volcano over the past few weeks. New dykes can also form without warning and start an eruption if the pressure is enough in them, such eruption might not last long, not even a whole day in some cases.

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Increased activity in Öræfajökull volcano noticed

It has been noticed that earthquake activity in Öræfajökull volcano is slowly increasing. At the moment this increase is just in the form of minor earthquakes taking place in the volcano at 5 – 10 km depth (at the moment). This was covered in a Icelandic news two days ago (when this is written), the volcanologist in the news (Páll Einarsson) says this is nothing to worry about at the moment, that I agree with, mostly, he also put forward that idea this process, if it evolves into an eruption might take up to 18 years from start to finish, as was the case with Eyjafjallajökull volcano. This is where I disagree with the professor Páll Einarsson, the reason being that this process already started good 10 years ago, I also suspect that Öræfajökull volcano to be a volcano that erupts suddenly and with a lot of force once it does erupt.

The eruption in the year 1362 had the VEI of 5 and the eruption in 1727 had the explosive force of VEI=4. Both eruptions lasted several months. Öræfajökull volcano only makes ash rich, explosive eruptions, based on latest historical data and studies into the volcano history. The processes that power Öræfajökull volcano might also be different, since there is an slab of old continental crust (study: Continental crust beneath southeast Iceland) under Öræfajökull volcano, that is slowly melting due the nearby hotspot. This means the magma is mostly silica, not far from the magma found in volcanoes found at subduction zones around the world.

There is also a second volcano this same area that has been showing sign of increased activity. That volcano is called Esjufjöll, it has even less understood activity (if any) since people moved to Iceland ~1300 years ago. There is a chance of an unconfirmed eruption in the year 1927, but it didn’t last long, maybe up to five days, it was mostly noted due a glacier flood from the area this volcano is located (small according to historical documents).