Category: Iceland

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Continued harmonic tremor in Katla volcano

The harmonic tremor that started yesterday in Katla volcano continues. It is however at less strength then yesterday. Often there are small earthquakes following it. They can be poorly observed on my Heklubyggð geophone. Few earthquakes have happened during this unrest. GPS data is unreliable, as it has not been updates since mid December 2011 (why that is I do not know). At current time it seems that this harmonic tremor is dropping down at the moment. It is impossible to know for sure if this is the end of this tremor in Katla volcano for the moment or not.


The tremor noise as seen on Slysaalda SIL station. Copyright of this picture belongs to IMO.


The harmonic tremor noise as seen on Skrokkalda SIL station. Copyright of this picture belongs to IMO.

There are now two possible reasons why this is happening. This might be an increase in hydro-thermal activity in north part of Katla volcano. Second reason might be that this is magma moving around inside Katla volcano at depth, then out visible effects on the surface. That is earthquakes have not happened following this event to any extent. There have only been two registered earthquakes so far. There location is both poor and depth poorly located. It has been my experience that following smaller event of this type there is generally an earthquake swarm in Katla volcano caldera. The time is is from from this type of event to take place until the earthquake swarm takes place differs a lot.

Last minor eruption that took place in Katla volcano was on 6. September 2011. My blog posts about it can be found here. It was believed at the time this was water. But today I now think this was an small eruption rather then water flooding under Mýrdalsjökull glacier.

Strong harmonic tremor pulse starting in Katla volcano
Most likely water creating harmonic tremors in Katla volcano (for the moment)

Both blog posts are from 6. September 2011.

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Harmonic tremor pulse in Katla volcano

Today there was an harmonic tremor pulse in Katla volcano. I am not sure when this harmonic tremor pulse did start. But I am guessing around 15:22 UTC or maybe around 16:00 UTC. It seems that this harmonic tremor pulse was small, considering the activity in July 2011 in Katla volcano (an minor eruption). This harmonic tremor pulse seems to have happened in the north part of Katla volcano, outside the caldera from my best estimates but might well be inside it in the north part of it. But it hard to be sure on that detail. From what I can tell, this harmonic tremor pulse does not appear on my geophones clearly. But it might have appeared on Hekla geophone poorly. But it is hard to be sure on that due to wind noise. When this is written the harmonic tremor pulse appears to be dying down. But there is still an possibly that it might pick up again or an new one might start without warning. It is impossible to know for sure how long this is going to stop after this harmonic tremor pulse. This harmonic tremor pulse is due to dike intrusion in Katla volcano at depth, so earthquakes might not happen until it reaches shallower surface in the crust. If the dike intrusion gets that far to start with.


The possible location of the harmonic tremor marked by the poorly located earthquake in Katla volcano. Copyright of this image belongs to IMO (Iceland Met Office).


The harmonic tremor on the Slysaalda SIL station where it is the strongest. But that means it is closest to this SIL station. Copyright of this image belongs to IMO (Iceland Met Office).


The harmonic tremor pulse on Goðabunga SIL station. The harmonic tremor pulse is weaker here then on Slysaalda SIL station. Copyright of this image belongs to IMO (Iceland Met Office).


The harmonic tremor pulse on Skrokkalda SIL station. One of the SIL station that have the most distance from Katla volcano area where the tremor pulse is taking place. Copyright of this image belongs to IMO (Iceland Met Office).


The harmonic tremor pulse can clearly be seen on Lágu Hvolar SIL station. Copyright of this image belongs to IMO (Iceland Met Office).


The harmonic tremor on Smjörgil SIL station, it is located in the flanks of Eyjafjallajökull volcano. This SIL station is close to Goðabunga SIL station. Copyright of this image belongs to IMO (Iceland Met Office).

What happens next in Katla volcano is hard to know. It all comes down to wait and see what happens next in Katla volcano. Eruptions in Katla volcano in January – February time period are not common, but due happen at times. So this harmonic tremor pulse might be an advance warning of what is to come. But that is just speculation on my part. It is impossible to know for sure what happens in Katla volcano until it happens.

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All quiet in Iceland volcanoes and earthquakes

Currently everything is quiet in Iceland. Most of this quietness is mostly due the winter storms that are passing over Iceland at the moment. When this changes I have no idea. But there are always several weeks during the year that are quiet in Iceland, both in activity in volcanoes and earthquakes.

This is the reason why I have not had so much to write about during the past few days and weeks. But it can’t be helped. Activity in the world also seems to be rather quiet, there are always earthquakes but most of them are small.

I also advice any tourist going to Iceland this time of year NOT to go up on volcanoes during the winter without experienced mountain travel guide. If you do that without an guide you are risking your own life, as the weather in Iceland is unforgiving and has killed people in matters of hours. The people in the news on Rúv got really, really lucky. The where just cold and where saved by rescue teams.

Icelandic News about people how got stuck on cliffs on Eyjafjallajökull volcano. Use Google Translate to understand.

Í sjálfheldu á Eyjafjallajökli (Rúv.is)

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Earthquake swarm in Katla volcano, earthquake in Hekla volcano

Tonight at 21:13 UTC there was an earthquake with the size of ML1.2, it had the depth of 0.1 km. But that is about 100 meters. This is the second earthquake in Hekla volcano during that past three weeks (almost an month since last earthquake did happen in Hekla volcano). So far nothing more has happened. But that might change without warning.


The earthquake in Hekla volcano. It is the red dot in Hekla volcano. Copyright of this picture belongs to IMO.

Katla volcano

Today at 16:04 to 16:27 UTC there was an minor earthquake swarm in Katla volcano. The largest earthquake had the size of ML2.6, with the depth of 1.4 km. Like before this earthquake swarm was because of an dike intrusion into Katla volcano caldera. But this suggests that the unrest that started in Katla volcano in July 2011 is not over. But for the moment it continues at lower rate then before. But that might also change without warning at any time.


The earthquake swarm in Katla volcano. The earthquake in Hekla volcano can also be clearly seen on it. Copyright of this picture belongs to IMO.

It is impossible to know for sure what is going to happen next in both of this volcano. But it is clearly worth watching what is going on. The earthquake in Hekla volcano can clearly be seen on my Heklubyggð geophone, as it forms an clear spike on it, the web site can be found here. Same does the largest earthquake from Katla volcano earlier today.

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Earthquake swarm on Reykjanes Ridge this morning

This morning at 05:48 UTC an earthquake swarm started on the Reykjanes Ridge. The earthquake swarm is believed to have been created by an dike intrusion in the area. Around 40 earthquakes have been recorded so far, the largest ones have had the size over ML3.0 in magnitude. But at the moment the earthquake swarm has stopped or is doing some idle time. As this earthquake swarm was created by an dike intrusion. It is not impossible that is going to resume in few hours to days time. But it is hard to know for sure what happens next in this area.


The area of activity. Please note that some earthquakes have wrong location due the distance from the SIL network. Copyright of this picture belongs to IMO.

This activity of dike intrusions suggests that this area of Reykjanes Ridge is getting more active then it has been since the year 1926, when the last confirmed eruption took place. But there might have been unconfirmed eruptions on the Reykjanes Ridge in the years 1966 and in 1970. It is also most likely that dike intrusion activity is going to continue for some time now. But as I sad above, it is impossible to know how long the breaks are going to be between activity episodes. Last large earthquake swarm in this area took place in early 2010 (Erik blog post about it can be found here). That activity was about one month before the eruption in Eyjafjallajökull volcano.

Largest earthquakes of this earthquake swarm appeared clearly on my geophones where the noise level was not too high. They can be viewed here on the 24 hour plot.

Icelandic news about this activity. Use Google translate and hope make sense of it.

Skjálftahrinan í rénun (Rúv.is)
Skjálftar við Eldey (Rúv.is)
Jarðskjálfti upp á 3,8 stig (mbl.is)
Á fjórða tug skjálfta við Eldeyjarboða (DV.is)

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More earthquake activity in Katla volcano

Yesterday (05.02.2012) there was an new earthquake swarm in Katla volcano. This activity suggests that it was due to dike intrusion as before in the Katla volcano caldera. The largest earthquake was ML2.1 with the depth of 0.1 (~100 meters) km. So this where really shallow earthquakes this time around.


The location of the earthquake swarm in Katla volcano yesterday. Copyright of this picture belongs to IMO.

This pattern of activity has been ongoing since July 2011, when a minor eruption took place in Katla volcano caldera. I am expecting this pattern of activity to continue for some time now. For how long I do not have any idea. It depends if this going to end in a larger eruption then took place in Katla volcano in July 2011 or if this is going to quiet down one day for several more years.

Activity in Katla volcano can be observed on Iceland Met Office pages. It also can be observed on a geophone that I run in Skeiðflöt (website here), a farm located few km south of Katla volcano.

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Earthquake swarm in Hengill volcano

There was an earthquake swarm starting in Hengill volcano. This earthquake swarm is at the usual location, close to the hydro-thermal power plant. But this earthquakes happen as the hydro-thermal power plant pumps down cold water into the ground.

This earthquake swarm started at 18:08 UTC on 04.02.2012. The largest earthquake so far in this earthquake swarm is an ML2.5 in magnitude according to automatic results from Iceland Met Office.


The earthquake swarm in Hengill volcano. Copyright of this picture belongs to IMO.

It is hard to know for sure if this is just the start of the earthquake swarm or not. But earthquake swarm have been common in this area over the past few months due to water being pumped down into the ground.

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First earthquake detected on Skeiðflöt geophone

This here is the first earthquake that I properly detect on my new geophone at Skeiðflöt farm. This is an ML2.0 earthquake in Katla volcano caldera according to IMO automatic SIL network. Even if there is high noise level I was still able to record it clearly. I might have recorded smaller earthquakes already. But they do not appear clearly so it is hard for me to be sure at the moment if I actually recorded them due to high levels of background noise.


The ML2.0 earthquake in Katla volcano caldera. This is based on automatic data and might not be 100% correct. This picture is released under CC licence. See Licence web page for more details.

This is promising for many reasons. It means that I can see earthquakes clearly even if there is high background noise level taking place at Skeiðflöt geophone. This also means that I am clearly going to see harmonic tremors and other events in Katla volcano, even in the glacier also. But this also depends on the noise level at the time. I do hope that the noise level is lower in summer then it is during the winter.

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Minor dike intrusion into Bárðarbunga volcano and earthquakes deep south of Iceland

Yesterday (03.02.2012) at 10:42 to 10:47 UTC there was an minor dike intrusion into Bárðarbunga volcano. Based on the earthquake activity and the depth that they where on. It seems that they did not go close to the surface. Based on the earthquake pattern, the dike intrusion did only go up to the depth of 12 km. But this dike intrusion did rise up from the depth of 22 km.


The dike intrusion into Bárðarbunga volcano. It can be seen by the dense earthquake swarm in Bárðarbunga volcano. Copyright of this picture belongs to IMO.

It is hard to know what this means. But it is for sure an clear sign of more activity in Bárðarbunga volcano. But this is no clear sign that an eruption might be about to take place in the nearby future.

Reykjanes Ridge

Yesterday (03.02.2012) there was an earthquake swarm deep south of Iceland. This earthquake swarm was located on the Reykjanes Ridge. It is impossible to know for sure what was going on at this location due to distance from land. But the average distance of this earthquake swarm is about 450 km south of Eldeyjarboða on the Reykjanes Ridge. The recorded size of this earthquake swarm was from ML3.1 to ML3.3. But that is most likely an underestimate of the earthquake size due to distance from the SIL network.


The star mark the earthquakes. Copyright of this picture belongs to IMO.

Other then this it has been quiet in Iceland. But that has more to due with storms and bad weather. But it has also been quiet in Iceland during the past few weeks. It might continue like that for some time now. When this ends is impossible to know for sure.

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Earthquake swarm in Katla volcano caldera

This morning there was an earthquake swarm in Katla volcano. This is the first earthquake swarm of the year 2012. This earthquake swarm is most likely created by an dike intrusion. Based on how dense the earthquake swarm appears to be. But that is often an sign of an dike intrusion in an volcano. How this earthquake swarm is going to evolve over the next few hours impossible to know for sure. That depends on what the magma is going to do that is creating this earthquake swarm.


The earthquake swarm in Katla volcano. It is dense as can be on this picture from Iceland Meteorological Office. Copyright of this picture belongs to Iceland Meteorological Office.

The earthquakes can be seen on my geophone web page here (English). The geophone at Skeiðflöt is going to go up this week. So all activity in Katla volcano is going to appear more clearly following that. Sadly. No high resolution of the earthquakes that take place is not going to be available until I move back to Denmark. As my main earthquake computer is offline and is going to be so until that time.

I am going to post updates to this if anything more happens. But it might take a while as I am travelling today to Reykjavík area and tomorrow I am going to Skeiðflöt tomorrow.