Category: Magma

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Comparison of volcano eruptions

When there is nothing going on in Iceland. It is good to prepare for the future by checking out what has happened in the past. Here is a comparison of harmonic tremor data from few past eruptions. I only have limited set of data to work with here.

Grímsfjall volcano eruptions 2004 and 2011

Harmonic tremor indicates how strong the eruption is when it is happening. This is clearly visible on the harmonic tremor plots from the Grímsfjall volcano eruptions in the year 2004 and compared to the eruption in Grímsfjall volcano eruption in the year 2011.


Harmonic tremor in Grímsfjall volcano eruption in the year 2004. Copyright of this image belongs to Icelandic Meteorological Office.

This harmonic tremor plot is from the early start of the eruption. It clearly shows when the eruption starts and how it progressed during it’s first few hours.


Here is the volcano eruption start in Grímsfjall volcano on 23. May 2011. This is the start of the eruption. It clearly shows the difference from the eruption that took place in the year 2004. Both is that starts sharper. But is also a lot more powerful then the eruption in the year 2004. Copyright of this image belongs to Icelandic Meteorological Office.

Eyjafjallajökull volcano and Katla volcano

Sometimes it is useful to compare two eruptions of two different volcanoes. This is useful when you really don’t have anything else to compare with.


Harmonic tremor in Eyjafjallajökull volcano eruption back in the year 2010. This is from the second phase of the eruption. But I seems to have misplaced or not saved harmonic tremor data from the first phase of the eruption (at least I cannot find them for the moment). Copyright of this image belongs to Icelandic Meteorological Office.


Harmonic tremor connected to a minor eruption in Katla volcano in July 2011. This eruption was minor. But created a flood that took out a bridge. Copyright of this image belongs to Icelandic Meteorological Office.


Diffrent SIL stations from the same minor eruption in Katla volcano in July 2011. This clearly shows that this minor eruption in Katla volcano was possibly larger then eruption in Eyjafjallajökull volcano year earlier (2010). But it did not manage to break the ice of Mýrdalsjökull glacier. Copyright of this image belongs to Icelandic Meteorological Office.

Past data show and are useful to learn what happens in a volcano. For this reason I now save important information on what is happening in a volcano. So I can compare it with future activity when it takes place.

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Earthquake swarm north of Kolbeinsey Island

During the night (on 15.12.2012) there was a swarm of earthquakes far north of Kolbeinsey Island. The distance from Kolbeinsey Island is about 100 to 200 km. What exactly is taking place at this location is impossible to know for now. Since this is far from Iceland and the SIL network. Last eruption is believed to have taken place around this area back in the year 1999, or at least there was an large dike intrusion at that time. What did happen exactly is not known.


The earthquake activity north of Kolbeinsey Island at midnight (00:00 UTC) 15.12.2012. Copyright of this image belongs to Icelandic Meteorological Office.


Earthquake activity at 09:00 UTC this morning (15.12.2012). More earthquakes have taken place since midnight. Copyright of this image belongs to Icelandic Meteorological Office.

There is a chance of more earthquakes in this area. It can also be expected that not all earthquake activity in this area is being detected by the SIL network. Due to distance, weather and ocean activity.

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Dike intrusion in Askja volcano

Today (14.12.2012) around 12:00 UTC Askja volcano had dike intrusion. This dike intrusion was not in the main volcano it self. But a good distance away from it. But this is in a area that has erupted before in distant past in a fissure style eruption (just lava, no volcano ash). What is the case now I am not sure at the moment. But this dike intrusion was at the depth of 25 to 22 km. So it has long way to go before any eruption takes place. This dike intrusion did also not show any sign of moving upwards according to Rúv News of this event.


Earthquake map from IMO showing the dike intrusion clearly. Copyright of this image belongs to Icelandic Meteorological Office.

What this means in the long term is impossible to know at this point. But this is one event in a long series of events that started in March 2010. This is going to end with a eruption. Large or small is impossible to know until it happens. What is also impossible to know is when and where such eruption might take place. As is always the case with active volcanoes. There is at least no reason to panic about this. Not now, not ever.

Donations: I am still needing donations to cover my cost of buying 3G hardware for upcoming geophone stations Böðvarshólar (total cost around 1300 DKK, or 29900 ISK). I have got some donations already. But they just cover the cost of UPS and USB card for Skeiðflöt geophone station. But I was fixing technical problems with it. Thanks for the support.

Icelandic News about this

Á annan tug skjálfta austur af Öskju (Rúv.is)

Blog post updated at 23:29 UTC on 14.12.2012

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Unclear what is going on in Grímsfjall volcano

It is unclear what is going on in Grímsfjall volcano at this moment. Harmonic tremor level continue to rise. They are currently way above what is normal for minor glacier floods from Grímsfjall volcano. This might be a minor eruption, or it might just be glacier on the move inside caldera. Whatever it is. This is not a strong event. As it only appears so far on only one SIL station. The one located on top of Grímsfjall volcano. Other SIL stations do not show any change so far. There is no earthquake activity in Grímsfjall volcano so far following this activity.


Grímsfjall volcano tremor levels this morning at 09:20 UTC. This is high resolution image. Copyright of this image belongs to Icelandic Meteorological Office.


Tremor levels at Grímsfjall SIL station (low resolution). The spike is maybe an earthquake. Copyright of this image belongs to Icelandic Meteorological Office.

So far nothing there is no word from Icelandic Meteorological Office on what is going on in Grímsfjall volcano. I am also uncertain what is going on in Grímsfjall volcano at present time. But I am sure that is going to get clearer in the next few hours. The harmonic tremor level appears to be continue to rise. So it might get confirmed in the next few hours if there is an eruption in Grímsfjall volcano or not.

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Earthquake activity update on 16.11.2012

Here is a short update on earthquake activity in Iceland. It has been stormy few weeks so recorded earthquake activity has not been a lot in Iceland.

Tjörnes Fracture Zone

Earthquake activity continues in TFZ. A bit less then when it did start on 20. October 2012. But it still moves along. The risk of large earthquake area remains for this area. When, where and how big remains unknown factors so far.


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

Herðubreiðarfjöll volcano

Herðubreiðarfjöll volcano is a small volcano (no GVP entry that I know of) just north of Askja volcano. But Herðubreiðarfjöll volcano are in fact part of Askja volcano fissure swarm. But I do not think they are part of Askja volcano as such.


Earthquake activity in Herðarbreiðarfjöll volcano (the blue dots). Copyright of this image belongs to Icelandic Meteorological Office.

The earthquake activity in Herðurbreiðarfjöll volcano was most likely a minor dike intrusion into the volcano. What that means is too early to say at this moment. But most likely it does not mean anything for now at least.

There has been some minor ice-quake activity in Iceland when the temperature drops below 0 degrees in Iceland.

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Earthquake swarm in TFZ continues, little earthquake activity in Katla voclano, new earthquake activity in Askja volcano

Here is a short update on activity in Iceland for the past few days.

Tjörnes Fracture Zone

Earthquake activity continues in Tjörnes Fracture Zone. But this earthquake activity has been ongoing since 20 October, 2012. Every once in a while a magnitude 3.0 earthquake takes place, or larger. The risk of large earthquake taking place in this area remains. General alert for this area is also in effect because of this danger of large earthquake taking place in this area.


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

Katla volcano

Winter has come. At least when it comes to earthquake activity in Katla volcano. But little to none earthquake activity is now taking place in Katla volcano. Earthquake activity is now well below background level. It can be expected that current status is going to remain in Katla volcano until next summer.


Earthquake activity in Katla volcano for the past few days. Nothing important is taking place in Katla volcano as this image clearly shows. Copyright of this image belongs to Icelandic Meteorological Office.

Askja volcano

While Katla volcano is getting quiet. It seems that Askja volcano is getting slightly more active. But earthquake activity in Askja volcano during the past few weeks suggests a minor magma intrusion (dike intrusion) might have taken place. But none of the earthquakes that took place where above magnitude 2.0 in size.


Earthquakes in Askja volcano during the past few days. Copyright of this image belongs to Icelandic Meteorological Office.

I do not think this earthquake activity in Askja volcano means it is getting close for an eruption. Since there are no signs in that direction at the moment. But this earthquake activity is interesting. What ever it means in the short term for Askja volcano. It is also common that volcanoes have earthquake activity without anything happening at all following such earthquake activity.

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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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Earthquake activity update on 20.10.2012 at 14:51 UTC

Today (20.10.2012) has been busy in terms of earthquake activity in Iceland. So I am expecting to write a second update later today on this activity.

Hekla volcano

At 05:28 UTC there was an earthquake in Hekla volcano. This earthquake had the magnitude of ML1.1 with the depth of 0.6 km. No other earthquakes have followed this single earthquake. What this means is impossible to know at this time. But so far everything remains quiet in Hekla volcano.


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

Kverkfjöll volcano

Earthquake activity continues in Kverkfjöll volcano. This earthquake activity is the result of dike intrusion into Kverkfjöll volcano. So far this earthquake activity is taking place in short burst of earthquake swarm.


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

Tjörnes Fracture Zone

At 02:07 UTC earthquake activity did start in TFZ. Just off the coast of Iceland. This earthquake activity is taking place in area that last had earthquake swarm in September. I did cover that earthquake activity in details on this blog. So far the largest earthquakes in this area of TFZ have had the magnitude of ML2.9. This is purely tectonic earthquake activity.

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

It is difficult to know what happens next in TFZ earthquake activity. But it likely going to continue for the next few hours to days like earlier. It is best to keep an eye on this earthquake activity. This earthquake activity also sometimes stops for few hours before it continues again. Most of this earthquake activity can be seen on my geophone network web page.

If anything major happens in this earthquake activity. I am going to post new blog post with updated information on that activity.

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Earthquake swarm in Kverkfjöll volcano

At 20:03 UTC an earthquake swarm started in Kverkfjöll volcano. The strongest earthquake so far has the magnitude of ML2.6, the depth is 1.1 km according to automatic estimate. Both size and depth of this earthquake are expected to change once it has been reviewed by Icelandic Meteorological Office. So far no harmonic tremor has been detected following this earthquake swarm. The most likely explanation for this earthquake swarm is that dike intrusion of magma has started in Kverkfjöll volcano. This has been happening on regular basis now for several years.


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

The earthquake swarm is currently ongoing. It is hard to know what happens in Kverkfjöll volcano following this earthquake swarm. But Kverkfjöll volcano are among Iceland most active volcanoes. With last eruption being in the year 1968 (small I think). This is clearly magma on the move inside Kverkfjöll volcano. But I do not know if this is going to result in a eruption or not. At the moment. It is my estimate that eruption is unlikely to happen. But that might change without warning at any time. But changes in Kverkfjöll volcano might be rapid and without warning. I am going to continue to monitor this activity and post new blog post if there are any major changes in activity in Kverkfjöll volcano.