Category: Dyke intrusions

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A ML3.2 earthquake (automatic size) happens in Katla volcano caldera

At 18:44 UTC a earthquake with the size ML3.2 and the depth of 2.9 km did happen in Katla volcano caldera (this size is based on automatic data and is going to be subject to a change).


The ML3.2 earthquake in Katla volcano. Copyright of this picture belongs to Iceland Met Office.

Currently there is strong wind around Katla volcano. This strong wind is interfering with IMO SIL network around Katla. But so far no harmonic tremor has been detected after this earthquake.

This earthquake appears to have be formed due to magma intrusion into the rock in Katla volcano caldera. It’s signature on my geophone shows that clearly.


The Z component unfiltered. This picture is released under Creative Commons licence.


The Z component filtered at 1Hz. This picture is released under Creative Commons licence.


All the component on my geophone. This is unfiltered data. This picture is released under Creative Commons licence.


All the component on my geophone. This is filtered data at 1Hz. This picture is released under Creative Commons licence.

This might just be part of normal Katla volcano activity. But it is a fact that it has more earthquakes during the summer and autumn then during the winter. But it is close to impossible to know if this just normal activity or something else. All that can be done is to wait and see what happens.

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Minor harmonic tremor in Katla volcano

There seems to have been minor harmonic tremor in Katla volcano this evening. This harmonic tremor seems to have started after a ML0.7 earthquake with the depth of ~3.7 km did happen inside the Katla volcano caldera. Last harmonic tremor spike did take place on the 24th of August according to the tremor plot on Icelandic Met Office web page.


Harmonic tremor mixed in with the earthquakes from Katla volcano on this tremor plot. Copyright of this image belongs to Icelandic Met Office.


Here is the harmonic tremor that I see on the tremor plot. It is the second spike. But the first spike is actually a earthquakes that did happen earlier today. Copyright of this image belongs to Icelandic Met Office.


This harmonic tremor can also be seen on this SIL station clearly. Copyright of this image belongs to Icelandic Met Office.

On other SIL stations around Katla volcano the signal is not so clear. But this is really a small event and unlikely a pre-eruption event. But it is hard to know it for sure, as Katla volcano has done this before and there was no eruption following this type of events. All that can be done now is to wait and see what happens next. It is also important to notice that Icelandic Met Office has not confirmed this harmonic tremor spike yet.

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Earthquake close to Hekla volcano. A earthquake swarm in Katla volcano

This has been a busy weekend in earthquakes, more then I was expecting. Here is a minor write up on the activity so far.

Hekla volcano:

A ML2.4 earthquake did happen close to Hekla volcano at 07:30 UTC. Depth of this earthquake was 3.7 km. The earthquake did happen on earthquake fault line that was created in a large earthquake in the year 1912. This fault line has been known since then and is well documented.


The SISZ earthquake this morning. This picture is released under Creative Common Licence. See Licence web page for more details.

Katla volcano:

Two new earthquake swarms took place in Katla volcano today. This earthquake started around 09:30 UTC this morning. Most of the earthquakes where smaller then ML1.0 in size. The depth was around 5.5 km on average. The largest earthquake was ML2.3 in size, with the depth of 5.5 km. That earthquake swarm was in Goðabunga area of Mýrdalsjökull glacier (Katla volcano). But here was also a minor earthquake swarm inside Katla volcano caldera. But in that earthquake swarm the earthquakes there where even smaller, most of those earthquake didn’t reach the size ML1.0. The earthquake swarm in Goðabunga area in Katla volcano might be due to dike intrusion in that area. I do not know if this might be something else. But given the data, this is the most likely the reason for this earthquake swarm in this area. The earthquake swarm did stop at 12:47 UTC. After that everything has been quiet so far.

Few earthquakes also did happen SE part of the Katla volcano caldera. But there have been earthquakes in this area since July. But this activity did start soon after the glacier flood from Mýrdalsjökull glacier.


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

All the earthquake swarms of today in Katla volcano, also the single earthquake close to Hekla volcano.

Icelandic news about this activity.

Mikið um smáskjálfta nærri Mýrdalsjökli (Vísir.is)
Jörð skelfur nálægt Hellu (Rúv.is)

Other: Short announcement. I have finally figured out how I am going to have my writing schedule. But my working period is going to be from 1. September to 1. June every year. This also means more activity on this blog and my other (Icelandic) blogs. During the summer time there is going to be reduced activity on all my blogs. But if something happens during the summer in earthquakes and volcanoes. I am going to write about it anyway or soon as I can do so.

Also note that I have started school to finish basic in electronic (house electronics and other basics in electronics). So I am busy during the day (most days). So my response might be slower then normal if anything happens in Iceland with earthquakes or volcano activity.

Other #2: I am having minor issues with uploading the gif images from my earthquake computer at the moment. So that is currently being done by the remote geophone computers at the moment. Because of this, there is no red colour if a large earthquakes happens in Iceland or close to a geophone station that I have up and running.

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Earthquakes in Öræfajökull volcano

I do not have a time for long blog post about this at the moment. But here is a short overview of earthquake activity in Öræfajökull volcano.

Since the year 1991 there have been total of three earthquake swarms (with the one in last week) in Öræfajökull volcano. The two earthquake swarms where in the year December 2005 and in September 2008. Total of 70 or so earthquakes have taken place in this earthquake swarms. But only 30 or so earthquakes in the main crater of Öræfajökull volcano.


Earthquake activity in Öræfajökull volcano between the year 1991 and to 2011. Copyright of this image belongs to Icelandic Met Office.


Earthquakes inside the main crater of Öræfajökull volcano from the year 1991 to 2011. Copyright of this image belongs to Icelandic Met Office.

All pictures are from here.

Currently the earthquake activity in Öræfajökull volcano is quite low. So I am not expecting anything for a long, long time now. The reason why earthquakes are taking place might be new magma. But this also might be due the glacier and pressure changes on the rock because of that. But I find the later idea less likely then the first one. But it hard to know for sure at the moment what actually is the real case now.

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Minor earthquake swarm in Öræfajökull volcano

Since early this morning there has been a minor earthquake swarm in Öræfajökull volcano. This earthquake swarm is so far just minor one, with the largest earthquake being ML2.0 at 4.3 km depth.

This earthquake swarm is most likely due to magma injection into Öræfajökull volcano. But this volcano is normally quiet and almost never has any earthquakes. But that has been changing during the past few years, but earthquake swarms have been getting more common in Öræfajökull volcano. Something that is in fact a big change from few years ago when no earthquakes where recorded from Öræfajökull volcano.

This increased activity in Öræfajökull volcano seems to be happening at the same time as there is increased activity in Esjufjöll volcano. The two volcanoes are not connected. But this might suggest a more inflow of magma under the general area. But that is just a speculation, based on rather limited amount of data.


Öræfajökull volcano is located to the south end of Vatnajökull glacier. Copyright of this image belongs to Icelandic Met Office.

The earthquakes in Öræfajökull volcano have been taking place in the main crater of the volcano. But it is important to know that currently there is nothing to suggest that a eruption is imminent in Öræfajökull volcano or in Esjufjöll volcano.

Interesting reading material on Öræfajökull volcano

The 1362 AD Öræfajökull eruption, Iceland: Petrology and geochemistry of large-volume homogeneous rhyolite (pdf)

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Earthquake activity in Katla volcano increases again

I was going to write about something else (TFZ and other earthquakes around Iceland in the last few days). But that just has to wait for a little longer.

It seems that Katla volcano earthquakes are increasing again. This increase appears to be similar to the increase in earthquakes before the glacier flood from the 9th to 17th of June and onwards until the glacier flood on 8th and 9th of July. The only difference now is that I am seeing this pattern earlier since I now know what to look for this time around when this is in its early stages.

How this is going to develop now is a wait and see process. But this might take as long time to get interesting as it did in June to July, to the event that ended with the glacier flood from Mýrdalsjökull glacier.


Current earthquake activity in Katla volcano. Copyright of this picture belongs to Icelandic Met Office.

It is also worth noticing that the earthquake activity is not as focused as it was in early June and in July. But I am fully expecting that to happen soon. But it remains to be seen if that actually happens or not.

The earthquake activity SSE in the Katla volcano caldera rim is still interesting. I do not know why it is taking place there. But if a eruption would take place at this location. There would be a short glacier flood and some period with volcano ash explosions. But after that it should be lava eruption in that location if it where to last long enough to remove all that water from the crater. But this is all just a speculation and nothing more.

For now. It is just wait and see what happens next.

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Overview of Hamarinn volcano current activity

Here is a short overview of the Hamarinn volcano activity this summer. From what I can gather in the current data this is most likely not over. During the past few days there have been at least suspected two minor eruption in Hamarinn volcano. But it hard to confirm it due to glacier that is covering this area.

This all starts on 12. July 2011 at 07:30 UTC with this event here.


The tremor spike on 12. July 2011 at 07:49 UTC. Copyright of this picture belongs to Icelandic Met Office.

When the clock is around 19:10 UTC the same day the tremor chart looks like this.


The tremor spikes are now three on 12. July 2011 at 19:09 UTC. Copyright of this picture belongs to Icelandic Met Office.

On the 13. July 2011 the tremor plot looks like this. But at that time the glacier flood had started and broken from the Vatnajökull glacier.


The tremor chart at 13. July 2011 at 01:10 UTC. Copyright of this picture belongs to Icelandic Met Office.


The tremor chart at 13. July 2011 at 12:59 UTC. Copyright of this picture belongs to Icelandic Met Office.

Then there was a short period of break when nothing interesting happened in Hamarinn volcano. That break did last until 16. July 2011 when a new, but smaller spike did appear on Skrokkalda SIL station.


The tremor at 16. July 2011 at 15:22 UTC. It is not fully clear what did happen at this time. But this was most likely a earthquake in Hamarinn volcano. But that is yet unconfirmed at this time. Copyright of this picture belongs to Icelandic Met Office.

Then there is a new break that lasts until 1. August when a earthquakes happens deep under Bárðarbunga volcano. But the deepest earthquake had the depth of 25.2 km. But it is also important to notice this earthquake that took place on 13. July 2011 and it is from Hamarinn volcano.


The earthquake from Hamarinn volcano. This picture is released under Creative Commons licence. Please see licence web page for more details.

On the 3. August 2011 around 02:00 UTC a new harmonic tremor spike starts to be visible on Skrokkalda SIL station.


The tremor plot at 01:55 UTC on 3. August 2011. Copyright of this picture belongs to Icelandic Met Office.

This day two minor harmonic tremor happens. A change in Skaftá glacier river is noticed. That is higher conductivity and slightly more water. It was announced in the news that a Skaftá glacier river flood was about to start from the eastern glacier cauldron that is formed above the Hamarinn volcano. Today however that does not seem to be the case. As no glacier flood has taken place so far.

Today (5. August 2011) there was a new harmonic tremor spike on Skrokkalda SIL station. It did follow the same pattern as before. It started and lasted for about 20 to 60 minutes or about that long.


The tremor chart 5. August 2011 at 17:38 UTC. Copyright of this image belongs to Icelandic Met Office.

So far today only one harmonic tremor has been detected. But given the past experience that is unlikely to hold for a long time now. But it is impossible to know when a new event starts or how big it is going to be.

The original event on 12. July 2011 did create new cauldron in the glacier. This map from Icelandic Met Office shows the location of those new cauldrons. But it has been marked with a star on the map. The coloured dots are earthquakes in this area over the past few years.


Map of the area that is currently active in Hamarinn volcano. Copyright of this image belongs to Icelandic Met Office.

Given the current data I am expect a full scale eruption in this area soon. When is hard to know for sure. But until that happens there are going to be more smaller eruptions in this area. I do not know why there is a lack of earthquakes following this events. I cannot explain it. But because of that this can only be seen after it has started on the tremor charts.

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Small glacier flood from Mýrdalsjökull glacier (Katla volcano)

During the night (and when I had unstable power) there was a small glacier flood from Mýrdalsjökull volcano. Some minor harmonic tremor change was detected following this glacier flood. This even was small one, many times smaller then what did happen on the 8 to 9 July 2011. Due to security concerns the Civil Emergency Authority did close the main road in Iceland for this area. Since they never know how big the flood can actually be. The main road was closed for about one hour. This glacier flood was detected around midnight 20 to 21 July 2011.

This flood is actually so small it is hard to see it on the harmonic tremor plot from the SIL stations around Katla volcano.


Tremor plot from 07:50 UTC this morning. It is hard to see the harmonic tremor from this minor glacier flood. Copyright of this image belongs to Icelandic Met Office.


Tremor plot from 07:50 UTC this morning. It is hard to see the harmonic tremor from this minor glacier flood. Copyright of this image belongs to Icelandic Met Office.


Tremor plot from 07:50 UTC this morning. It is hard to see the harmonic tremor from this minor glacier flood. Copyright of this image belongs to Icelandic Met Office.

What happens next is impossible to know for now. But it seems that activity continues to be high in Katla volcano. All that can be done is to wait and see what happens. But I am going to continue to monitor the changes in Katla volcano as best that I can do until I finish my summer job (29. July).

Icelandic News about this.

Aukin leiðni í Múlakvísl og órói í Mýrdalsjökli (Vísir.is, Icelandic)
Náið fylgst með Mýrdalsjökli (mbl.is, Icelandic)
Hringvegurinn opinn á ný (Rúv.is, Icelandic)
Breytingar í Múlakvísl (Rúv.is, Icelandic)

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New cauldrons forms in Mýrdalsjökull glacier (Katla volcano)

According to the news here in Iceland there have been a formation of at least three new cauldrons in Mýrdalsjökull glacier, where they have not been before in the glacier. But this means that the hydrothermal areas under the glacier are growing in size due to new magma pushing up into the crust and warming it up.

This has been revealed after a daily checking of the status on the glacier. But the current cauldrons that formed on the 8 and 9th July have also deepened according to the same news. A lot of deep cracks are also forming in Mýrdalsjökull glacier. Making the south part of the glacier extremely dangerous at current moment.

There is also risk of minor glacier flood from water collecting under the glacier (both really small and slightly larger ones). But water might be collecting in ice-caves under the glacier and break free without any warning at all. The Civil Emergency Authority in Iceland warn against travelling in this area on Mýrdalsjökull glacier.

The reason why this is happening is the fact that hydrothermal activity is increasing under Mýrdalsjökull glacier in Katla volcano. But this is a clear sign that Katla volcano is warming up to a eruption. When that might happen is still a question with no answers.

Currently there is no good way to know what happens in regards to possible glacier floods due to this increased hydrothermal activity in Katla volcano. But floods are expected to take place without any warning now in this area.

Icelandic News with pictures of the cauldrons.

Þrýstingur fellur í sigkötlunum (Rúv.is, Picture)
Ferðamenn koma ekki nálægt sigkötlum (Vísir.is, Icelandic, Picture)
Ferðamenn aka ofan í ketil sem er að springa (Vísir.is, Icelandic, Picture)
Ástæða til að vakta svæðið (mbl.is, Icelandic, Picture)
Sigkatlasvæðið er varasamt (mbl.is, Icelandic)
Sigkatlasvæðið stækkað (mbl.is, Icelandic, Picture)

Blog post updated at 00:51 UTC 20. July 2011.

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Small harmonic tremor spike from Hamarinn volcano

There seems to be a small harmonic tremor spike taking place in Hamarinn volcano (Bárðarbunga volcano) at the moment. This tremor spike is not strong at the moment. This tremor spike appears to have been pre-seeded by few long period earthquakes (not all of the earthquakes seen on Skrokkalda are from Hamarinn volcano, few are from Katla volcano), but that suggests that magma is on the move in Hamarinn volcano. But this would the second harmonic tremor in a time period of 48 hours it seems.


The harmonic tremor spikes can be seen at the end of this tremor plot. Copyright of this picture belongs to Icelandic Met Office.

Currently it is impossible to know what happens in Hamarinn volcano. As it’s pre-eruption behaviour is rather unknown. But if there is a eruption in this area I am expecting a lot of earthquakes, with size well over ML3.0.

Blog post updated at 16:20 UTC.