Category: Magma

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Overview of current events in Katla volcano and current status

Here is an overview of the current events in Katla volcano. This is the short version, as I have not had the time to go over all the data collected so far.

12 June: On this day I did notice the first harmonic tremor spikes. This tremor spike was small and only noticed on few SIL stations around Mýrdalsjökull volcano. No earthquake activity was detected following this event. At least no earthquake activity that was unusual in my opinion.

17 to 18 June: The first earthquake swarm took place on this day that I connect to the current events. This earthquake swarm was special and different from the normal earthquakes that I see in Mýrdalsjökull volcano caldera. It was how dense this earthquake swarm was. There was no or little harmonic tremor following this earthquake swarm.

21 June: New harmonic tremor spike took place in Katla volcano on this day. It was a bit stronger then the first one. But lot smaller then what did happen this weekend.

28 June: What appears as an glacier earthquakes did appear on this day. Along with normal earthquake activity inside the Katla volcano caldera.

After this the events of July 8 start, it did end on the 9 July after what is most likely an minor eruption inside the Katla volcano caldera. This event is over it seems and Katla volcano has once again paused. But that has happened repeatedly over the past few weeks. The time between stops is different and it is impossible to know when the current pause ends. It is also impossible to know what happens next time activity picks up in Katla volcano caldera. Currently the earthquake activity continues in the Katla volcano caldera, but there are few earthquakes happening now then earlier this weekend.

For now all that can be done is to wait and see what happens.

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All quiet at Katla volcano

Currently everything is quiet in Katla volcano. At the moment the harmonic tremor level have gone back to normal levels. But there appears to be some earthquake activity taking place inside Katla volcano caldera. But most of this earthquakes do not appear on the automatic earthquake list that IMO has. But it might be impossible to actually locate this earthquakes as they might just appear on single or two SIL stations.

The glacier flood is over and the flood water have continued to lower during the day.

It is hard to know for sure what happens next. But the current events started around 17. June when earthquake swarms started to appear on the Katla volcano caldera. This has been developing rather fast since then. I do not expect that to change any time soon. But what I think was harmonic tremor pulses started around 12. June.

For now however all that can be done is to wait and see what happens in Katla volcano. As I do not think that this is over. But we might be in for an few hours or days of an break until something new happens in Katla volcano.

Icelandic News about this.

Einungis brúin eftir (Rúv.is, Icelandic, Picture)
Highway no. 1 disrupted for weeks. (Rúv.is, English, German)

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Harmonic tremor drop down. New earthquake happen in Katla volcano caldera

It seems that on many SIL station around Katla volcano that the harmonic tremor has gone mostly down to background levels, on other stations it continues to drop. This are mostly SIL stations that are at the most distance to the source of the area that this minor eruption took place during the night. But at the moment this seems to be over. The main source of the activity appears to be where the eruption took place in the year 1918, or so scientists think at the moment.

According to the news there was an flood wave around 04:00 UTC during the night. When the water meters did show an rise of 5 meters suddenly. Soon after that the bridge over Múlakvísl river was lost in the glacier flood. This did close the main road 1 in this area, that area of the main road is going to remain closed for the next few weeks while they fix the damage done in the flood (build an new bridge).

Even if the harmonic tremor seems to be dropping. This does not seem to be over, as an earthquake activity did resume from around 13:00 UTC in the Katla. Since then the earthquake activity seems to have been building at slow rate.


Tremor plot at 18:23 UTC. The tremor is dropping. It also shows that earthquakes are taking place (spikes the tremor chart). Copyright of this picture belongs to the Icelandic Met Office.


Tremor chart from Goðabunga at 18:24 UTC. Copyright of this picture belongs to the Icelandic Met Office.


Dropping harmonic tremor on Lágu Hvolar. Earthquakes appear as spikes here. Copyright of this picture belongs to Icelandic Met Office.


Dropping tremor and earthquakes as before. Copyright of this picture belongs to Icelandic Met Office.


Earthquakes as they are tonight. The southern part of the caldera is having earthquake swarm, even if it is just an small one. Copyright of this picture belongs to Icelandic Met Office.

I am waiting too see how this develops. Something larger might happen. But nothing else might happen for an while in Katla volcano. The only thing that can be done is too wait and see what happens in Katla volcano.

Icelandic News about the road damage.

Meiri skemmdir en talið var (Rúv.is, Picture, Icelandic)

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Harmonic tremor still high in Katla volcano

Currently harmonic tremor remains high in Katla volcano. But at the moment the harmonic tremor is dropping. Earthquakes have also stopped for the moment. But currently the harmonic tremor is well above the background level for this area. It is still not clear if this was an eruption or just hydrothermal areas clearing it self of extra water. But in the news at Rúv noon they did report that the ice cauldrons that are normally there had deepened over the past few weeks in Mýrdalsjökull glacier.

Update 1: Earthquake activity has stopped for the moment. But I am expecting it to resume soon. As I do not think that this event is over, even if it has just paused for the moment.

Three cauldron have formed in Mýrdalsjökull glacier and large cracks have formed around them. All traffic has been banned on Mýrdalsjökull glacier and the glacier that comes from it.

Here are the current tremor charts from Icelandic Met Office web page.


Harmonic tremor is dropping as can clearly be seen on this picture. Copyright of this picture belongs to Icelandic Met Office.


Harmonic tremor is dropping as can clearly be seen on this picture. Copyright of this picture belongs to Icelandic Met Office.


Harmonic tremor is dropping as can clearly be seen on this picture. Copyright of this picture belongs to Icelandic Met Office.

I am going to post update on Katla volcano later today and earlier if anything major happens.

News with picture of the Mýrdalsjökull glacier. It is covered with dark ash from Eyjafjallajökull volcano eruption last year and volcano ash from the eruption in Grímsfjall volcano 2011.

Miklar sprungur í sigkötlunum (mbl.is, Picture, Icelandic)
Svona lítur jökullinn út (Rúv.is, Icelandic, Picture)
Þrír greinilegir sigkatlar (Vísir.is, Icelandic, Picture)
Brúin rofnaði af í heilu lagi (Vísir.is, Icelandic, Picture)
Óvissa um hlaup eða lítið eldgos (Rúv.is, Icelandic, Pictures)

Blog post updated at 13:13 UTC 9. July 2011.

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Glacier flood from Múlakvísl has been confirmed

According to the Icelandic news an glacier flood started around midnight in Múlakvísl (link should work, let me know if it doesn’t) glacier river that runs from Mýrdalsjökull glacier. Last time this type of event did happen was in the year 1955, when an minor eruption is believed to have taken place under the Mýrdalsjökull glacier. I do not know if that is the case now. As this might just be hydrothermal water being released due to increased activity in hydrothermal areas that are in Mýrdalsjökull glacier.

Following the flood there is an strong smell of sulphur and there might be dangerous gases in it. At current time the flood appears to be growing and according to the news (written at 01:54 UTC) the bridge was still safe. But there was just 1 meter from the river and up to the floor of the bridge.

Some minor earthquakes have been taking place in the past few hours, they do not appear on the automatic earthquake list on Icelandic Met Office web page. Some of them appear on my Hekla webicorder.

Currently the harmonic tremor is dropping. But that might not mean anything in the long run. So far everything suggests that an eruption has not yet started in Katla volcano. But given the current status that might not last long as it is. The best thing that can be done is to wait and see what happens. But no fear scaremongering please!

Added: When I just finished writing this blog post an new earthquake just started to appear on my geophone at Hekla volcano. IT is from Katla volcano for sure. It was in the ML1.5 to ML2.5 size range it seems. It was an long period earthquake as they have been so far. I think it is from the main caldera, not Goðabunga area.

Icelandic News about the glacier flood.

Hlaup hafið í Múlakvísl (mbl.is, Icelandic)

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Harmonic tremor continue to increase in Katla volcano

When this is written around 00:36 UTC on 9. July 2011 the harmonic tremor levels on SIL stations around Katla volcano have continued to increase. The latest spike in harmonic tremor levels happened after an ML1.5 (automatic size) earthquake that took place at 22:13 UTC. There has been an small earthquake swarm in Katla volcano caldera yesterday. But the largest earthquake in that earthquake swarm had the size ML2.4.

The harmonic levels are getting so strong that they have started to appear on stations around Hekla and on my own geophone, even if it is located almost 60 km away from the source of the harmonic tremor. Currently there is little to suggests that this is slowing down at the moment. But that might yet happen. But it is impossible to know for sure at the moment.

The lack of earthquakes tells me that the magma has not yet reached the surface. When or if that might happen is an good question that I do not have the answer to. But this might take several more hours until something happens in terms of earthquakes or other activity in Katla volcano.


Harmonic tremor can clearly be seen on this SIL station at the end of the tremor chart. This is saved around 00:36 UTC 9. July 2011. Copyright of this picture belongs to Icelandic Met Office.


Harmonic tremor can clearly be seen on this SIL station at the end of the tremor chart. This is saved around 00:36 UTC 9. July 2011. Copyright of this picture belongs to Icelandic Met Office.

As sad before the harmonic tremor can now be seen on SIL stations far away from Katla volcano. But the maximum range so far is around 65 km or so at the moment.

This is the last update for tonight. I am going post an update tomorrow on what has happened during the night. Even just to say people that things have slowed down or gone back to normal. Whatever happens. I am going to post information about it tomorrow when I awake up.

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Harmonic tremor in Katla volcano

At the moment there is an ongoing harmonic tremor going on in Katla volcano. It is just an small one, just above the background level noise floor. This is most likely an small dike intrusion. But nothing in the data from Icelandic Met Office suggests that an eruption has started in Katla volcano at this stage. But that might change without an warning, since this is an volcano after all. This change in harmonic tremor does not seems to be created by an glacier flood of some type. What is interesting is that this harmonic tremor pulse looks like an harmonic tremor pulse detected in the year 1999, just before an small eruption took place in Katla volcano southern caldera rim.

This harmonic tremor is in the high frequency range at the moment. But no change has been seen in the low frequency range at the moment. This is the same thing that did happen in the year 1999. At the moment however it is too early to know what is going to happen in Katla volcano for sure. All that can be done is to watch and wait. This might quiet down, or it might not. Only time is going to tell us what happens next. At the moment the harmonic is falling at fast rate, so this might be over.

Before the harmonic tremor pulse there was an earthquake swarm in Katla volcano caldera. The largest earthquake was ML2.1 and that was an long period event, but that tells me that magma was the source of this earthquakes in Katla volcano caldera. There where two earthquake swarms in the caldera today, but that makes total of three earthquake swarms in the Katla volcano caldera since the beginning of June.


The two earthquake swarms that took place in Katla volcano caldera today. Copyright of this picture belongs to Icelandic Met Office.


The only earthquake that I did record out of this earthquake swarm. This earthquake was ML2.40 with the depth of ~400 meters. This plot is filtered at 1Hz . This picture is released under Creative Common licence. See Licence web page for more detail.


Spectrogram of the ML2.4 earthquake in Katla volcano from this morning. This is filtered from 1Hz. This picture is released under Creative Common licence. See Licence web page for more detail.


Harmonic tremor can clearly be seen at the end of this tremor chart from the Icelandic Met Office. Copyright of this picture belongs to Icelandic Met Office.


Harmonic tremor can be seen at the end of this tremor chart from the Icelandic Met Office, but it is not clear at this SIL station. Copyright of this picture belongs to Icelandic Met Office.


Harmonic tremor can clearly be seen at the end of this tremor chart from the Icelandic Met Office. Copyright of this picture belongs to Icelandic Met Office.


Harmonic tremor can clearly be seen at the end of this tremor chart from the Icelandic Met Office. Copyright of this picture belongs to Icelandic Met Office.


Harmonic tremor can be seen (not clearly) at the end of this tremor chart from the Icelandic Met Office. Copyright of this picture belongs to Icelandic Met Office.


Harmonic tremor can clearly be seen at the end of this tremor chart from the Icelandic Met Office. Copyright of this picture belongs to Icelandic Met Office.

The harmonic tremor is strong enough on many SIL station to go above the background noise level on the SIL stations (wind, ocean waves etc..). But this is not an strong harmonic tremor. They can be stronger.

This does NOT mean an eruption is imminent in Katla volcano. What this does mean that is an magma is on the move inside the Katla volcano. What happens at later time is something that nobody can guess at current time. But it is now time to watch Katla volcano even closer.

It is also important to notice that nobody really knows how Katla volcano behaves before an eruption. We only get those answers after an eruption in Katla volcano. For the moment we can only wait and see what happens in Katla volcano.

I am going to post more updates if anything interesting happens. Also, there seems to have been an Long period earthquake at 22:14 UTC, most likely in Katla volcano. It appeared on my geophone close to Hekla volcano. I am guessing the size of this earthquake is ML2.0+.

Blog post updated at 22:39 UTC. Spectrogram picture added.

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Update on Hekla volcano status

Here is an update on Hekla volcano. First of, for the moment the inflation in Hekla volcano is deflating at the moment. This is following the same pattern as before last time this did happen. But that does not mean this might not happen again soon. For the moment, nobody knows what exactly is going on inside Hekla volcano as there are no earthquakes following this inflation period. The magma that is on the move down there is most likely moving deep down in the crust also, as Hekla volcano does not have shallow magma system that I know of (or is known of anyway).

What did happen inside Hekla volcano was most likely an dike intrusion somewhere in the volcano system. This dike intrusion did not create any earthquakes, that suggests to me that it was travelling trough an old dike system already in place inside Hekla volcano system. This is most likely to happen again in Hekla volcano, if that starts an eruption is hard to know for sure.

In regards to possible ash cloud from eruption in Hekla volcano is impossible of know for sure now what happens in next eruption. There might be an ash cloud, but then again there might not be. All that can be done is to wait and see what happens in the next days, weeks or years.


The GPS movement of Hekla volcano. The inflation and the deflation can clearly be marked here. There is an inflation spike around 2011.45 on this plot. But this did also happen in April/May I think (but it might be wrong). Daily updated chart can be found here. Copyright of this picture belongs to Icelandic Met Office.

It is also important to notice that Civil Emergency Authority (Almannavarnir) in Iceland advice against it travelling up to Hekla volcano at current time. Since an eruption can start in Hekla volcano without any warning at all and the maximum time that people have evacuate the mountain is from 1 hour and up to 1 hour and 30 min. No more then that. Being on top of Hekla volcano when an eruption starts is deadly to everyone. If you want to go up to Hekla volcano. Please let somebody know about and have an fully charged mobile phone with you at all times. As the Civil Emergency Authority send out an SMS message to all mobile phones in the area around Hekla volcano if an eruption is starting (I think they do that).

Icelandic News.

Almannavarnir: Hekla tilbúin í gos (Rúv.is, Icelandic)
Almannavarnir vara fólk við Heklu (Vísir.is, Icelandic)

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Magma movements under Hekla volcano have been confirmed

According to the news on Rúv the GPS movements that many have been seeing around Hekla volcano in the past few days are real. At the moment the civil disaster authorities have been notified and also local emergency authorities. Nobody seems to know what is going on with this magma moments for the moment. But they can be tracked with the GPS network to some extent. What is more interesting is that this does not seems to have started until few days ago. But first signals of this happening did take place in April and May, but at lot smaller scale. What is interesting is that fact that no earthquakes appear during this magma movements, there is also no harmonic tremor when the magma is moving around in the crust close to Hekla volcano. But if there is any earthquakes, noise or whatever coming from Hekla volcano it is going to appear on my geophone that is located about 16 km away from peak of Hekla volcano. The distance is even less from the actual edge of the Hekla volcano system it self.

Normally, there are no changes in the GPS network before an eruption in Hekla volcano. So this is highly unusual event in Hekla volcano since instrumental monitoring started few decades ago.

It is an question if this means an fissure style of eruption is going to take place in Hekla volcano. But that does sometimes happen, as with any volcano in Iceland. For the moment however the only thing that can be done is wait and speculate (within reason).

No eruption has started in Hekla volcano. But it can be assured that it might start without any warning and I might not be around the computer when that start, since I am working during the day and feeling tiered during the evening. But I am getting slightly better on that front, thankfully.

I am going to post more on this when I do know more, or if anything happens in Hekla volcano related to this.

Icelandic News about this.

Hræringar í Heklu (Rúv.is, Icelandic)

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New harmonic tremor spike in Katla volcano

Today around 16:00 UTC there was an new harmonic tremor in Katla volcano. This harmonic tremor has two sources. Hyrdothermal activity under the glacier, or magma moving deep inside Katla volcano (without creating many earthquakes in Katla volcano). It is unclear what is the case at the moment.

This spikes are so far not related to glacier floods from Katla volcano. But that sometimes also happen without an eruption being involved.


The harmonic spike can be seen here. Close the end of the chart. It is different then the background noise as it is more powerful then the background noise. Copyright of this picture belongs to Icelandic Met Office.

It is impossible to know what happens next. But it is also important to be aware of the fact that earthquake season is starting in Katla volcano. But that is normally from end of June to beginning of October (or when it starts to snow again in Iceland). So more earthquakes are going to be seen this summer also because of more SIL seismometers around Katla volcano.

So there is no reason to panic about Katla volcano at current time. But it is worth to keep watch on it anyway.

Notice: Updates might be an little few due the fact that I am now working all day during the week and I am tired in the end of the day with no energy to write new blog posts. But I am going to do my best anyway.