Category: Dyke intrusions

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Small eruption took place in Katla volcano in July 2011

According to the news on Rúv this evening it is now a opinion at Icelandic Met Office that a small eruption did take place in Katla volcano during the days 8 and 9 July 2011. This eruption was however larger then the eruption in Fimmvörðuháls in Eyjafjallajökull volcano last year (2010). But this is based on tremor data from around Katla volcano during this summer. But this is what Einar Kjartansson geologist at Iceland Met Office says in the news at Rúv this evening. Even if this small eruption did take place in Katla volcano it does not seems to have eased the pressure inside Katla volcano, so a large eruption in Katla volcano is still a possibility in the close future. Note: GVP has updated Katla volcano eruption status to the year 2011!

This conclusion was reached by checking out the cauldron that formed during this event. But they show a sign that they had a sudden melt taking place. But that melt can only happen of lava got into contact with the ice and fast melted it. This is also the reason why there was a 5 meters flood in Múlakvísl glacier river that did destroy the bride over it. But it is also a fact that the harmonic tremor in Katla volcano during this period was the same as that did happen during the eruption in Eyjafjallajökull volcano. The only difference was that it it was stronger from Katla volcano then in Eyjafjallajökull volcano it seems (at least from what I can see from the data). Even if it lasted for a shorter time then in Eyjafjallajökull volcano.


The tremor on Slysaalda SIL station on 9 July 2011 at 00:36 UTC. Copyright of this picture belongs to Iceland Met Office.


Alftagrof SIL station on 9 July 2011 at 00:36 UTC. Copyright of this picture belongs to Iceland Met Office.


The area that was active and had a eruption on 8 and 9 July 2011. Copyright of this picture belongs to Iceland Met Office.

Even with this small eruption it is clear that Katla volcano is not done with its eruptions. Since the large one is not yet over. When that happens is a good question and nobody has a answer too at the moment.

Note: This is also what did happen in Hamarinn volcano the week after. But I also think that volcano did have a minor eruption in July 2011. As the signatures are the same from what I can gather. So that makes three eruptions in Iceland for the year 2011 if confirmed later on.

Icelandic News with this. Use Google translate with care on it. Since it does not understand.

Allt bendir til Kötlugoss (Rúv.is, Icelandic, Picture)
Segir Kötlu hafa gosið í sumar (DV.is, Icelandic, Picture)
Lítið eldgos í Kötlu í sumar (mbl.is, Icelandic)

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Earthquakes in Katla volcano, strong sulphur smell in Múlakvísl river before the earthquake happened

This morning there has been some earthquake activity in Katla volcano. But it has also been reported in the news this morning that a really strong sulphur smell was found around 06:00 UTC on nearby farm to Múlakvísl river this morning. But this was before the earthquake did happen. I am not sure if this sulphur smell continues to be felt in the area close to Katla volcano. No changes in water hight has been detected in Múlakvísl glacier river.

The ML2.6 earthquake in Katla volcano was on 2.3 km depth. This was mostly a dike intrusion into the bedrock of the Katla volcano caldera.


The earthquake swarm this morning in Katla volcano. Copyright of this picture belongs to Iceland Met Office.


High resolution of the Katla volcano earthquake this morning. Along with correct depth and size. This picture is released under Creative Commons licence. See Licence page for more details.

As before. This is just a wait and see what is going to happen in Katla volcano as before.

Icelandic News of the sulphur smell in Múlakvísl glacier river.

Brennisteinslykt fannst við Múlakvísl í morgun (Vísir.is, Icelandic)
Brennisteinslykt við Múlakvísl (mbl.is, Icelandic)

Update 1: According the news on Rúv this activity suggests that hydrothermal activity is continuing to increase in Katla volcano caldera. But the news also says that this activity is something like that did happen from the year 2002 to the year 2004, when hydrothermal activity did increase before it started to get lower again. It is also pointed out my Matthew Roberts that Múlakvísl glacier river is sensitive to changes in Mýrdalsjökull glacier and small floods can happen without any warning in it due to increased hydrothermal activity.

Rúv news in Icelandic about this.

Bendir til aukinnar jarðhitavirkni (Rúv.is, Icelandic)

Blog post updated at 13:07 UTC, 23 September 2011.

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New earthquake swarm in Katla volcano

After few quiet days in Katla volcano. It seems that new earthquake swarm is about to start in it. But this earthquake swarm did start with a ML2.8 earthquake (automatic size) at 10:55 UTC. This earthquake have been followed by smaller earthquakes. So far there have not been many earthquakes in this earthquake swarm. But the largest earthquake took place on what I think is the fissure where the eruption in the year 1918 took place.


The earthquake swarm can be seen here. Copyright of this picture belongs to Iceland Met Office.

The largest earthquake clearly has magma signature in my opinion. As it can be seen on my geophone recording of this earthquake.


The ML2.8 earthquake. This picture is released under Creative Commons Licence. Please see licence web page for more details.


High resolution of the Katla volcano ML2.8 earthquake. The bump later on this earthquake trace is the second earthquake that only had the size ML0.9 according to the automatic size estimate. This picture is released under Creative Commons Licence. Please see licence web page for more details.

There seems to have been some type of tremor event on Goðabunga SIL station just before the earthquake. I am not sure what event this was. But it does not appear on other SIL stations around Katla volcano.


Goðabunga SIL station. Copyright of this picture belongs to Iceland Met Office.

For the moment the only thing that can be done is to wait and see what happens in Katla volcano.

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New earthquake swarm in Katla volcano during the day

Today there was a new earthquake swarm in Katla volcano. This earthquake swarm was in the caldera of Katla volcano, same as the earthquake swarms that have happened inside Katla volcano since July, when this pattern of activity did start.


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

It has been few hours since the earthquake activity did stop in Katla volcano. If the pattern that has been ongoing for the past week and longer there should be a harmonic tremor spike in few hours time. But that it currently hard to know if this pattern is going to hold up or not. But I have every reason to believe that it is going to do so. For the moment, all that can be done is to wait and see what happens next in Katla volcano. At the moment, I have not seen any harmonic tremor spike during the day or at current time when this blog post is written.

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More harmonic tremors in Katla volcano

It seems that Katla volcano is not as quiet it seems to be. For the moment the harmonic tremor seems to be small and only properly observable on one SIL station due to how weak it is at current time. So far two harmonic spikes have happened. This is most likely a hydrothermal system going crazy under the glacier close to Lágu Hvolar SIL station, rather then magma on the move (or at least that is what I think).


Harmonic tremor at Lágu Hvolar SIL station. The harmonic tremor can be seen at the end of this tremor plot. Copyright of this picture belongs to Iceland Met Office.

There has not been a lot of earthquake activity in Katla volcano during the last 24 hours or so. But that might not mean anything, as eruption can and have started without any warning at all (example: Grímsvötn volcano May 2011). So for now, it is more wait and see and more waiting it seems.

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Magma on the move in Katla volcano

While the source of the harmonic tremor yesterday in Katla volcano is not immanently clear. It is has been concluded that magma is on the move inside Katla volcano. It has been suggested that the harmonic tremor yesterday in Katla volcano is a mixture of both hydrothermal activity and water flows under the glacier. But hydrothermal activity has increased in Katla volcano since July and seems to be continuing on that path for now.

The earthquake activity in Katla volcano has been growing since July, when a sharp harmonic tremor spike did take place and was followed by a glacier flood that did destroy the Múlakvísl river bridge. But that flood did peak at ~5 meter high.

Currently the activity is quiet in Katla volcano. But that might be because the earthquakes are not being detected by the bad weather that is currently in this area (and all over Iceland for the fact).

Here is a overview of the change in activity since Week 34.


The earthquake activity in Katla volcano during Week 34. The number is the cauldron in Katla volcano. Notice the interesting earthquake activity in SE part of Katla volcano, well outside of the caldera area. Copyright of this picture belongs to Iceland Met Office.


The earthquake activity in Katla volcano during week 35. The earthquake activity in SE part of Katla volcano continues at the same place. Copyright of this picture belongs to Iceland Met Office.


The earthquake activity in KAtla volcano during week 36 (current week, last updated today 7. September 2011). Earthquake activity in SE part of Katla volcano continues as before.Copyright of this picture belongs to Iceland Met Office.

Current activity in Katla volcano is quiet (less detection due the storm is also a factor in this). But that can change without any warning at all and at any time. But there is no reason to scaremonger what is going on in Katla volcano. It is a fact of life and cannot be changed. So the best way is to prepare if people live close to Katla volcano, or if you live far from Katla volcano the best thing is to monitor and learn from what is now happening in Katla volcano. Scare tactics do not any good and serve no purposive at all and never done so.

Icelandic news about the activity in Katla volcano. Use Google translate to understand. But be aware it is not approved by Santa.


Ekki ótvíræð merki um yfirvofandi gos (mbl.is, Icelandic)
Engin augljós skýring á óróa (mbl.is, Icelandic, 6. Sept, 2011)
Flogið yfir Kötlu (mbl.is, Icelandic, 6. Sept, 2011)
Kvika safnast saman undir Kötlu (Rúv.is, Icelandic)
Fylgjast með aukinni virkni í Kötlu (Vísir.is, Icelandic, Video in Icelandic, 6. Sept, 2011)
Jarðhiti aukist mjög mikið undir Kötlu (Vísir.is, Icelandic, 6. Sept, 2011)

Update 1: According to news the local emergency units and police have started to review the evacuation plans and emergency plans in the case of a eruption in Katla volcano.

News about that can be read here, if you risk Google Translate.

Fara yfir áætlanir um viðbrögð (mbl.is, Icelandic, 7. Sept, 2011)

Blog post updated at 00:43 UTC on 8. Sept, 2011.

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Most likely water creating harmonic tremors in Katla volcano (for the moment)

In the news from Rúv at 22:00 UTC it was sad that water is the most likely source of the harmonic tremors in Katla volcano. But it seems that hydrothermal activity in Katla volcano is increasing and melting the glacier. But for the past few hours there have been signs of hydrothermal melt water getting into Múlakvísl glacier river, making the river have more water then normal and increasing conductivity in it. This is not glacier flood as such. The cauldrons that formed in July have not changed according to this news, but it was not reported if they had actually gotten deeper or larger.

Due to cloud cover it was not possible to explore the north part of Mýrdalsjökull glacier. Just the south part. According to the news on Rúv at 22:00 new small cauldron have formed in the south part of Mýrdalsjökull glacier. They are shallow at present time and may have taken few weeks for form to present size (not sure how big they are), but among this cauldrons is a cauldron that has not been seen for past seven to eight years, cracks have formed around the cauldron and he has gotten deeper and water has collected in the cauldron. But with more earthquake activity and increased hydrothermal activity under the glacier. So more monitoring is needed on Katla volcano according to Magnús Tumi Guðmundsson volcanologist at University of Iceland.

Note: When I wrote this blog post. It seems that new earthquake swarm is about to start in Katla volcano. At least I think so.

News about this events in Icelandic. Use Google translate if you want to insult the Easter-bunny.

Telja að vatn valdi óróa (Rúv.is)
Engin augljós skýring á óróa (mbl.is)
Jarðhiti aukist mjög mikið undir Kötlu – dæmigerð einkenni að menn eigi að búa sig undir gos (Vísir.is)

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Strong harmonic tremor pulse starting in Katla volcano

There seems to be a strong harmonic tremor pulse starting in Katla volcano. I do not think that this is anything else for the moment. I do not have any more details at the moment. But I am going to post updates when I know more.

Start of the harmonic tremor pulse on the SIL stations that he appears best on.


Slysaalda, north of Katla volcano. Copyright of this picture belongs to Iceland Met Office.


Rjúpnafell, South-west of Katla volcano. Copyright of this picture belongs to Iceland Met Office.


Lágu Hvolar SIL station. Copyright of this picture belongs to Iceland Met Office.


Álftagröf SIL station. South of Katla volcano. Copyright of this picture belongs to Iceland Met Office.

The start of the harmonic tremor event can be seen on the end of harmonic tremor chart. It stands out as it above the background noise on the SIL station. Next update on the SIL stations (10 or 20 min until it happens) is going to show more how big event this is going to be.

More updates when I know more on what is taking place in Katla volcano.

Update 1: The Public Civil Emergency Authority (Almannavarnir) in Iceland has increased monitoring with Katla volcano. But they have not declared any emergency level yet. Announcement about that in Icelandic can be found here. But scientists where flown over Mýrdalsjökull glacier at 18:00 UTC today (6. September 2011).

According to the news there has been increase in conductivity in Múlakvísl river. But for the moment the water level has not increased. There has been speculation that the tremor was created by water on the move. But that is unclear at the moment, however it is quite possible that more water is on the move under Mýrdalsjökull glacier.

Currently the harmonic tremor in Katla volcano has dropped back to normal levels. For the moment everything is quiet in Katla volcano. But that can change at any time without any warning.

News about this in Icelandic.

Órói undir Mýrdalsjökli (Rúv.is)
Fylgjast með aukinni virkni í Kötlu (Vísir.is)
Eftirlit aukið með Kötlu (mbl.is)
Flogið yfir Kötlu (mbl.is)

Update 2: It seems that a new harmonic tremor episode is about to start in Katla volcano. So far it has remained small. But it is impossible to know if that is going to change suddenly or not. Update 2b: There is also some wind noise on the seismometers around Katla volcano. This wind is increasing background noise. It often look like a tremor increase, while in reality it is not.

Blog post updated at 18:37 UTC.
Blog post updated at 18:46 UTC.
Blog post updated at 20:03 UTC.
Blog post updated at 20:29 UTC.

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Growing harmonic tremor spike in Katla volcano

It seems that Katla volcano is going to keep me busy for coming days and weeks.

At this moment it seems that there is a growing harmonic tremor in Katla volcano. This harmonic tremor started today after the earthquake swarm that took place earlier today. After it stopped a spikes of small harmonic tremor spikes did start to appear. During the past few hours they have been growing in size. But it seems that the harmonic tremor drops for few moments between spikes.


Earthquake swarm that took place yesterday in Katla volcano. Copyright of this picture belongs to Iceland Met Office.

This earthquake swarm was mostly small one. With largest earthquakes going up to around ML2.1.


Slysaalda SIL station. Harmonic tremor appears poorly on this SIL station. Copyright of this picture belongs to Iceland Met Office.


Rjúplafell SIL station. The harmonic tremor signal can be seen here clearly, even if it a small one. Copyright of this picture belongs to Iceland Met Office.


Lágu Hvolar SIL station. The harmonic tremor signal can be seen poorly on this SIL station. But it signalled with minor change in the background noise on this SIL station. Copyright of this picture belongs to Iceland Met Office.


Álftagröf SIL station. The harmonic tremor spike can be seen most clearly here, as it goes clearly above background noise. Copyright of this picture belongs to Iceland Met Office.

From what I can tell this harmonic tremor signal is growing every few hours or so. It is possible that this is a repeat of what did happen in July. But for the moment it is too early to know that for sure at the moment. But for the moment there is no eruption about to start in Katla volcano.

When I was writing this blog post, it seems that a new earthquake swarm is about to start in Katla volcano. But the earthquake swarms in Katla volcano often start slowly with few earthquakes, but they seems to grow with time.

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Earthquake swarm in Katla volcano

Today (3. September 2011) at 16:45 UTC a earthquake swarm did start in Katla volcano. So far this earthquake swarm has been small, with the largest earthquake just with the size ML2.7 at the depth of 1.1 km (automatic data). But the quality of this earthquake was good, so location is accurate from what I can tell.

I am not sure at this moment if there is a harmonic tremor spike following this earthquake swarm or not. As the earthquakes are long period due the fact that they are created by magma movement in Katla volcano. This might be dike intrusion. But for the moment it is hard to know that for sure.


The area of earthquake activity today in Katla volcano. Copyright of this picture belongs to Iceland Met Office.


The ML2.7 earthquake (automatic size) in Katla volcano caldera. This picture is released under Creative Commons Licence, see Licence web page for more details.


Harmonic tremor plot of the current activity. Latest activity is at the end of the tremor plot. Copyright of this picture belongs to Iceland Met Office.


Harmonic tremor plot of the current activity. Latest activity is at the end of the tremor plot. Copyright of this picture belongs to Iceland Met Office.


Harmonic tremor plot of the current activity. Latest activity is at the end of the tremor plot. Copyright of this picture belongs to Iceland Met Office.

I cannot tell at the moment what is going on in Katla volcano. But the earthquakes tell me that the reason why they are happening is because of magma is moving inside Katla volcano. But latest data (not shown here) do however show that no harmonic tremor is currently ongoing, if it ever started during this earthquake swarm. I am expecting the earthquake swarm to continue and last for the next few hours. But I must point out that that is what might happen, as sometimes earthquake swarms just stop when you think that they might be about to start for real.