Category: Magma

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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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Earthquake activity increasing in Katla volcano again

For the last 24 hours (15 and 16.02.2017) earthquake activity has been increasing in Katla volcano. If it follows earlier pattern, a swarm of earthquakes with magnitude 3,0 or stronger might happen in Katla volcano in next few days or next week at the latests. Please note that there is no good way to say when this might happen and time estimates are just guesses (based on current best data).


Earthquake activity in Katla volcano. Copyright of this image belongs to Icelandic Met Office.

Current earthquake activity was not strong, the largest earthquake that happened had a magnitude of 2,0. All other earthquakes had smaller magnitude (at the moment). Earlier pattern have been that small earthquake swarm starts, a break happens for several hours for up to several days and then a swarm of activity happens with one or more earthquake with magnitude above 3,0. I’m expecting this pattern to repeat it self now, but what actually happens remains to be seen.

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Deep earthquake activity in Öræfajökull volcano

I haven’t written many articles about Öræfajökull volcano, since most of the time nothing happens in it. Öræfajökull volcano is located outside the main activity area in Iceland, like Esjufjöll and Snæfell (east Iceland). This three volcanoes form a volcano “arch” in south to east Iceland. Research suggests that old continental crust is possibly melting under Öræfajökull volcano and maybe Esjufjöll volcano (unclear). Research into that can be found here. This research shows a possible volcano directly east of Esjufjöll, I don’t have it on my maps so I don’t have a name for it (it might be unconfirmed volcano in that area, some maps show it, other don’t. I don’t know why).


Earthquake activity in Öræfajökull volcano. Öræfajökull volcano is in the right-south corner. Copyright of this image belongs to Icelandic Met Office.

The magnitude of the earthquakes in question is only 1,1 and up to 1,8. What makes them interesting and might be a signal about something is about to happen in Öræfajökull volcano is the depth of earthquakes in question. The earthquake (magnitude 1,1) with the most depth has the depth of 21,2 km. The rest of the earthquakes has the depth of 19,0 to 20,7 km. View on the tremor plot suggest that this earthquake activity is magma related, rather than being driven by tectonic forces.

This activity started in the year 2011 with few earthquakes, no earthquakes happened in 2012 according to my data. Since then few earthquakes have been happening each year. How long the process is from just minor earthquake activity until an eruption starts in Öræfajökull volcano is something I don’t know and far as I know historical documents about the known eruptions are limited at best. Last known eruptions took place in the years 1362 June 5th until 1362 October 15 +-45 days, the other known eruption was in the year 1727 on August 3 and it lasted until May 1st 1728 +-30 days.

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Strong earthquake swarm in Bárðarbunga volcano

Yesterday (30.01.2017) there was exactly one week (article here) since last earthquake activity in Bárðarbunga volcano. In this weekly activity there is an emerging pattern, that pattern is that earthquake magnitude is growing. Number of earthquakes happening in each swarm has not increased that I have noted (at the moment at least). Magnitude 4,3 earthquake moves the fault few mm upward in this case. Those millimetres have now started to add up. I don’t know what the inflation currently is due to lack of GPS data at the moment.


The earthquake activity in Bárðarbunga volcano. Copyright of this image belongs to Icelandic Met Office.

Latest earthquake swarm had magnitude (in the order they happened), magnitude 4,3, magnitude 4,1, magnitude 3,4. Depth of this earthquake swarm was also slightly different, being from 9,4 – 8,3 km. It is difficult to know for sure what is going on at this depth, magma might be creating path for it in the crust on its way to the surface or this simply might just be the fault inside the caldera moving upward at slow phase. Earthquake activity happens when fresh magma is injected into Bárðarbunga volcano. This is going to continue to happen for a long time, maybe until next eruption.

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Katla volcano has magnitude 4,3 earthquake

Today (26.01.2017) at 15:14 UTC a magnitude 4,3 earthquake took place in Katla volcano. This earthquake was felt in Vík í Mýrdal (village) and nearby area. A second earthquake with the magnitude of 3,0 took place few moments after the largest earthquake, a magnitude 2,9 earthquake (3rd largest) took place soon after the magnitude 3,0 earthquake. Other earthquakes have been smaller in magnitude (at the moment).


The earthquake in Katla volcano, green star is the magnitude 4,3 earthquake. Copyright of this image belongs to Icelandic Met Office.


The magnitude 4,3 earthquake in Katla volcano as it appeared on my geophone in Heklubyggð (distance ~53 km). This image is under Creative Commons licence, please see CC Licence website for more details.

No major change has happened in tremor plots around Katla volcano following this earthquake. Unclear signals on one SIL stations suggest that hydrothermal areas might have gotten exited just before the main earthquake, but that is unconfirmed and unclear if it can be confirmed at all.

This article is going to be updated as new activity happens (if there is a reason to do so).

Update 27.01.2017

Science council of the Civil protection agency in Iceland (Almannavarnir) has issued the following statement. This is a rude translation of that statement since none has been issued in English yet.

Increased risk of eruption in Katla

Earthquake activity in Katla has been unusually high since August 2016, with three earthquakes larger than magnitude 4,0 and many more earthquakes with magnitude 3,0. Earthquake activity is shallow and spread around the caldera. No harmonic tremor has been detected following this earthquake activity. Following this increase in activity small increase in geothermal heat has been observed. GPS station show that small inflation has been taking place since 2010 in the top kilometres of the crust. When activity increases in Katla, as has been the case now, the risk of eruption grows and that has to be considered by the emergency response teams.

(The rest is about Bárðarbunga, just the basic translation of it.)

Since September 2015 Bárðarbunga has been inflating slowly under the caldera. It might be many years until the next eruption, until magma pressure is at the same levels before the eruption started in 2014. It is impossible to exclude new eruptions in next few years. Limited measurements are on geothermal activity in Bárðarbunga, to the best knowledge little has changed in last few months. It is important to monitor geothermal activity due to risk of water collection in the caldera.

My note: Water collection increases the risk of sudden glacier flood from Bárðarbunga.

The news announcement in Icelandic

Fundur í Vísindaráði almannavarna
Auknar líkur á eldgosi í Kötlu (Rúv News)

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Article updated on 27.01.2017 at 18:53 UTC.

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Sharp increase in earthquake activity in Katla volcano

In the last 24 hours there has been a sharp increase of earthquakes in Katla volcano. This started yesterday with few minor earthquakes swarms with long quiet period between activity happening. This is what happens when magma is trying to push it self out of a volcano, but doesn’t have the energy to do so just yet. It is not fully understood why most of the earthquakes happen at 0,1 km depth, but it has been theorised (not proven) that Katla volcano is already so hot in the magma tubes that no further earthquakes are possible (for now at least). Details can be found here and here (pdf).


The earthquake activity in Katla volcano during the last 24 hours. Copyright of this image belongs to Icelandic Met Office.

Largest earthquake so far had the magnitude of 3,3. Other earthquakes that have happened are smaller in magnitude at the moment. Current earthquake count is 74 earthquakes, I think that number is going to increase if this earthquake activity continues. I suspect that it is going to do so, there might however be a drop in activity for few hours, days and up to several weeks at the time. Why that happens is something I don’t know. It is also worth noticing that there has been a lot of negative value earthquakes taking place. Those don’t show up on the new Icelandic Met Office website, just the old one.

There is a good chance of conductivity changes in glacier rivers from Mýrdalsjökull glacier. That data can be viewed here, just click on station to view its data. Please note that linking to a station here (in the comment) doesn’t work, I don’t know why that is.

Update 25.01.2017

On 24.01.2017 at 11:13 UTC a magnitude 3,1 earthquake took place in Katla volcano caldera. This earthquake was close to the area where considerable earthquake swarm had taken place. Since then the earthquake activity has quieted down a bit.


The earthquake activity in Katla volcano during the last 24 hours. Copyright of this image belongs to Icelandic Met Office.

Currently there is a quiet in the earthquake activity, since it happens in pulses with drop or no activity between them. The earthquakes that have been happening and I have recorded are hybrid earthquakes (details here). I don’t know if there have been any low frequency earthquakes or very low frequency earthquakes. I expect this earthquake activity to continue.

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Article updated on 25.01.2017 at 04:38 UTC.

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Earthquake swarms in Katla volcano

Since Saturday 21 of January 2017 there has been unusual earthquake activity taking place in Katla volcano (for this time of the year). Small earthquake swarms have been scattered all over the caldera, largest earthquakes so far have only reached magnitude of 2,4. Other earthquakes have been smaller in magnitude.


The earthquake activity in Katla volcano. Copyright of this image belongs to Icelandic Met Office.

This earthquake activity is unusual since normally Katla volcano is quiet in January and until June and often until mid-July when earthquake activity starts again. Current activity is unusual since snow has been adding on the glacier since it started snowing in Iceland this winter (November I think it was). Higher areas get snow sooner then lower areas, so it started earlier on Mýrdalsjökull glacier that is on top of Katla volcano. Currently the earthquake activity is ongoing, even if it has slowed down a little for the past few hours.

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Weekly earthquake in Bárðarbunga volcano happens

On 19-January-2017 a magnitude 3,5 earthquake happened in Bárðarbunga volcano. This is a normal earthquake activity for Bárðarbunga volcano at the moment and happens just about weekly at the moment.


The earthquake activity in Bárðarbunga volcano. Copyright of this image belongs to Icelandic Met Office.

I don’t expect any activity outside of what has been happening for the last several months.

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Magma inflow results in earthquake activity in Bárðarbunga volcano

On Friday 6th of January 2017 it was noted by one of my readers that a deep earthquake activity had happen in Bárðarbunga volcano, the earthquake in question was a magnitude 1,6 at depth of 25 km. At that depth the only earthquakes that happen are due to magma movement, at that depth the pressure is such tectonic (as explained by Icelandic geologists) earthquakes do not commonly happen at this depth. Today, 8th of January 2017 a magnitude 3,3 earthquake happened in Bárðarbunga volcano at the depth of 7,3 km and the earthquake had the magnitude of 3,5.


The earthquake activity in Bárðarbunga volcano. Copyright of this image belongs to Icelandic Met Office.

The inflation of Bárðarbunga volcano is now at considerable levels, it is not known if or when an next eruption happens. It appears, based on historical data that eruption cycles in Bárðarbunga volcano last for up to 20 years (depending), during such time there is an eruption every few years. At the moment there is also a rifting taking place in this area, making already a complex situation a lot more complex and harder to figure out. Since besides the main volcano, a volcano named Hamarinn can also erupt during this cycles. It has already erupted and did so in July-2011 when it had a 8 – 12 hour long eruption resulting a massive glacier flood, but it did not break the surface of the glacier (Vatnajökull).

Good example of this cycle and repeated eruption pattern can be found in historical data on Global Volcanism Program website (link above).

The last eruption cycle took place in the late 19th century and ended in early 20th century. The following eruptions happened (documented, there is a good chance that some eruption might have been missed due to how remote Bárðarbunga volcano is),

1862 June 30 – 1864 October 15 (error margin +- 45 days). Area of eruption was Tröllagígar.
1872 – Date not know nor eruption site, Dyngjuhals suspected.
1902 December – 1903 June. Eruption site not known, Dyngjuhals also suspected.
1910 June 18 – 1910 October, Loki-Fögrufjöll (East loki Cauldron). This is also known as Hamarinn volcano.

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Earthquakes in Bárðarbunga volcano

On the 4th and 6th of January 2017 earthquakes took place in Bárðarbunga volcano. The earthquake on 4th of January had the magnitude of 3,3 (I think) and the earthquake on the 6th of January had the magnitude of 3,5. Both earthquakes where inside the crater of Bárðarbunga volcano, along the fault rims. The reason for this earthquake activity is the inflation of Bárðarbunga volcano, that appears to be rather rapid and mostly steady process. Influx of magma happens in pulses and those pulses are in different size and how long they last.


The earthquake activity in Bárðarbunga volcano. Copyright of this image belongs to Icelandic Met Office.

This type of earthquake activity is a regular feature of Bárðarbunga volcano at the moment. I don’t expect that to change any time soon. What might change is the magnitude of the earthquakes happening, I suspect that with time they are going to get more rare but larger in magnitude instead.

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