Category: Monitoring

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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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Typical geophone station that I run

Here is a picture of a typical geophone station that I run in Iceland. This is the computer and other needed hardware on the Böðvarshólar geophone station that I am running. This hardware used to be the Hvammstangi geophone station until December 2012 when I had to move it.


Click on the image for full size. This image is released under Creative Commons licence. Please see the CC licence page for more details.

What is not shown in this picture is the geophone it self. But it is in the white box on the table. The readings from all my geophone stations can be found here.

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Earthquake swarm in Katla volcano caldera

Yesterday (14.12.2012) from 20:50 UTC until 22:52 UTC there was an minor earthquake swarm in Katla volcano caldera. The largest earthquake in this swarm was a magnitude 2,2 earthquake. With the depth of 0,1 km. So it was a shallow earthquake. This is not uncommon for this part of Katla volcano. This earthquake activity has its origin in hydrothermal activity or changes in hydrothermal systems in this area of Katla volcano caldera.


Earthquake swarm in Katla volcano. This area has had earthquakes swarms before. Copyright of this image belongs to Icelandic Meteorological Office.

I do not expect anything special to result from this earthquake swarm. Since it is highly unlikely that Katla volcano is going to erupt in December. It is also a when it comes to earthquakes. Katla volcano has a lot of them during the year and earthquake swarm as this one should be expected to happen every once in a while.

Blog post updated at 10:42 UTC on 15.12.2012.

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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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Interesting earthquake swarm in TFZ

Today (12.12.2012) there was a interesting earthquake swarm in south part of TFZ (close to a place called Ásbyrgi). This earthquake swarm did consist mostly of minor earthquakes. With magnitudes of from ML0.2 and up to magnitude ML2.6. This earthquake swarm is tectonic in nature. I do not believe it is volcanic in nature. But this earthquake swarm is inside Krafla volcano fissure swarm or TFZ-NVZ two volcanoes. I am not sure in this case here.


The earthquake swarm is in the corner of this image. Copyright of this image belongs to Icelandic Meteorological Office.

This earthquake swarm might not mean anything special as is. But earthquake activity in this area has been some for the past few years. But it has so far never resulted in any major events so far in this area.

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Harmonic tremor level drops in Grímsfjall volcano

During the night. Harmonic tremor levels started to drop in Grímsfjall volcano. The reason for this harmonic tremor level increase remain unknown and unclear. But no volcano related activity has been seen or recorded so far in Grímsfjall volcano.


Harmonic tremor levels in Grímsfjall volcano. This is high resolution image. Copyright of this image belongs to Icelandic Meteorological Office.


Harmonic tremor levels in Grímsfjall volcano. This is low resolution image. Copyright of this image belongs to Icelandic Meteorological Office.

Some earthquake activity has been taking place following this events. But the earthquakes have been small and do not suggest anything is about to take place in Grímsfjall volcano.


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

So far Grímsfjall volcano has remained quiet during this glacier flood. With nothing suggesting that it is going to change soon. As for the glacier flood it self. According to latest news it seems to have peaked and is now dropping. But this was a small glacier flood. With just rise about 153 cm. But that is quite small compared to many older glacier floods from Grímsfjall volcano.

Icelandic News about this glacier flood

Hlaupið í Grímsvötnum virðist hafa náð hámarki (Vísir.is)
Hlaupið í Gígjukvísl í rénun (Rúv.is)

Blog post updated at 12:48 UTC on 27.11.2012

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Minor glacier flood has started from Grímsfjall volcano glacier lake

A minor glacier flood has started from Grímsfjall volcano glacier lake. This glacier flood is expected to be extremely small. Since last glacier flood from Grímsfjall volcano took place earlier this year. That glacier flood was also small. Minor harmonic tremor changes have been taking place on Grímsfjall SIL stations. But they are not strong and can easily drown in wind noise. But it has been a stormy few weeks in Iceland.


Harmonic tremor changes on Grímsfjall SIL station. Copyright of this image belongs to Icelandic Meteorological Office.

I do not expect any volcano activity to take place following this glacier flood. As last eruption in Grímsfjall volcano took place last year and that eruption was the largest one in 140 years at least. But I am going to keep monitoring this activity and post updates if anything changes.

Icelandic News about this glacier flood

Lítið hlaup hafið í Grímsvötnum (Rúv.is)
Vatnamælingamenn á leið austur (Rúv.is)
Hlaup að hefjast í Grímsvötnum (Vísir.is)
Lítið hlaup hafið í Grímsvötnum (mbl.is)

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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 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.