Category: Earthquakes

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What is happening in El Hierro volcano

This is a special blog post about the volcano El Hierro in the Canary Islands. The resons for this blog posts are those that this activity is interesting and there is not a lot happening at the moment in Iceland due to bad weather (nothing gets recorded in this bad weather).

Currently El Hierro volcano is a phase that I personally call a magma intrusion phase (I have no other word for it). But that means that magma is currently coming from a depth, that is more then 20 km below the volcano and up the crust directly below the volcano. It is impossible to know how long this phase is going to last. As a example this phase for Eyjafjallajökull volcano lasted for good part of 17 years (with some breaks). When the pressure is high enough in the sill that is now forming in El Hierro the magma is going to break up the surface.

This pattern can clearly be seen on this image here.


The magma is flowing up into the volcano at around 30 degree angle from the depth of more then 20 km. When a new magma injection starts, a new earthquake swarm starts in El Hierro. This magma injections are different in size and length. But as more magma collects into the bedrock in El Hierro the stronger earthquakes are going to take place. But this increases the pressure on the rock and inside the magma chamber that is now forming and can clearly been seen with the earthquake pattern. Copyright of this picture belongs to Instituto Geográfico Nacional.

I did see a picture that was made on Eruptions blog that did show his clearly, both the feeder channel of the magma and the magma chamber that is currently in the making. It seems that magma inflow into the new magma chamber or the sill in El Hierro is stable at the moment. But I base that view on the constant earthquakes that are currently taking place. But this magma inflow seems to have been stable since 16 July, 2011 when the magma started to push upwards into El Hierro.

Earthquakes that signal new inflow of magma do not need to be strong in size. But they are deep, with the most depth around 20 km. But the crust in this area is around 10 to 26 km thick. As this is a ocean crust in this area. But the Canary islands are the thickest crustal part in the area. But it is also important to notice that the magma chamber or the sill is expanding in all directions, not just upwards. That in it self is also going to create deep earthquakes. But those earthquakes should remain a bit outside the main area of the deep earthquakes that are currently taking place in the area.

I am expecting a lot more earthquake activity when or if El Hierro starts erupting. But when that might happen impossible to know for the moment. The only thing that can be done is too wait and see what happens.

Update 1: Here is the earthquake activity for today (30 September, 2011).


Earthquake activity of today (30 September, 2011). There is less earthquake activity today. This happens when magma flows into a volcano. This did also happen with Eyjafjallajökull volcano in the year 2010. If anyone has the direct link too this plot, please leave it in the comments. Thanks. Copyright of this picture belongs to Instituto Geográfico Nacional.

Update 2: Links too El Hierro information can be found here.

Update 3: The Spanish news channel Canal 24 can be found here and it is live.

Update 4: Here is a news in english about the evacuation of El Hierro. It is from 28 September, 2011. Evacuation of El Hierro begins as fears of volcanic eruption grow. Thanks to Dr. John v. Kampen that did send this to me with a email.

Note: There are new pictures of Eyjafjallajökull volcano, Fimmvörðuháls craters here. They show the difference from the year 2010 and in the year 2011. The text is in Icelandic.

Also. Please support my effort so I can buy two new geophones and add them to my monitoring network in Iceland. Thanks! 🙂

Blog post has been updated 30 September, 2011 at 22:12 UTC.
Blog post has been updated 30 September, 2011 at 22:25 UTC.
Blog post has been updated 30 September, 2011 at 23:08 UTC.
Blog post has been updated 1 October, 2011 at 14:48 UTC.

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Hengill volcano man made earthquake swarm

The man made earthquake swarm in Hengill volcano that happened today seems to have subsided, as it is most likely that Orkuveita Reykjavíkur has stopped pumping down water into the new drill hole that they where using today.

Over 400 earthquakes have been recorded in this man made swarm. I am not sure on the depth on most of the earthquakes. But it is in the range of 1 to 10 km from what I can tell. The largest earthquake in this earthquake swarm was ML3.4 in size, it had the depth of 3.9 km.


The man made earthquake swarm in Hengill volcano. Copyright of this image belongs to Icelandic Met Office.

I am going to post earthquake traces on Sunday or Monday. I am currently not at “home” (where my main computers are located), as I am taking this weekend off (if nothing large happens this weekend).


Two of the earthquakes from the man made earthquake swarm in Hengill volcano. This picture is released under Creative Common Licence. See licence web page for more details.

It is hard to know what happens as Orkuveita Reykjavíkur continues to pump down water into Hengill volcano. All that can be done is too wait and see what happens.

Blog post updated at 21:48 UTC on 26. September 2011.

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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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A ML2.7 earthquake in Skagafjörður rift zone (mostly extinct one)

This earthquake is a odd one. But it is rare that earthquakes happens in this are of Iceland. But it is not unheard of. As there have even been small earthquake swarm in this area few years ago (2 or 3 years ago I think). This area is part of Skagafjörður rift zone (pdf file) (also known as Skagafjörður Volcanic zone), but that is believed to be a failed rift zone that formed in about 1.7 million years ago. Just around when current eastern rift zone started to form in Iceland.


The ML2.7 earthquake is the left corner of this image, a bit far away from TFZ earthquake zone. Copyright of this image belongs to Icelandic Met Office.


The ML2.7 earthquake seen from Sauðárkrókur geophone that I am going to run until December 2011. Sadly, no live gif image of it due to network issues. Please note that this geophone is in a noisy location. This picture is released under Creative Commons Licence. See licence web page for more details.


The ML2.7 seen on Hvammstangi geophone. Sadly, no live gif image of it due to network issues. This picture is released under Creative Commons Licence. See licence web page for more details.

I do not know if there are going to be more earthquakes in this area. But it seems that this earthquake has happened in a area with known faults from post-glacial times (they are on my geological map of Iceland). So for now all that can be done is to wait and see what happens next this this area. But I am not expecting anything special in terms of more earthquake activity. There are no active volcanoes in this area.

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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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More new tremor spikes in Katla volcano

Yesterday and today there where two tremor spikes in Katla volcano. This follows a higher then normal background noise that I cannot directly trace only to wind as I did first think. What is going on is not clear, but it remains a bit of events just before the July 1999 minor eruption (suspected). But it has been speculated by scientist that event was related to inflation event deep inside Katla volcano systems. But the actual fact remains unclear. More information on the event in July 1999 can be read here (in Icelandic).

Pictures from the year 1999 of the harmonic tremor event in July that year.


The harmonic tremor spikes in July 1999 in Katla volcano. Copyright of this picture belongs to Iceland Met Office.

There was also special note on this tremor chart here from skh SIL station (now gone). But in the year 1999 this signal was most clear on Snæbýli SIL (snb). But today this signal appears to be most clear on Goðabunga SIL station and Eystri-Skógar SIL (esk) SIL station. I do not know what the difference is. But it clearly is something.


The harmonic tremor spikes in July 1999 in Katla volcano. Copyright of this picture belongs to Iceland Met Office.


The harmonic tremor spikes in July 1999 in Katla volcano. Copyright of this picture belongs to Iceland Met Office.

Please note that all earthquakes have been cleared from this old SIL tremor plots.

Current day activity in Katla volcano looks like this on the SIL stations where it is most clearly seen.


Odd spikes can be seen here on this tremor plot. I do not know what they are. Copyright of this picture belongs to Iceland Met Office.


Hard to see spikes can be seen on Goðabunga SIL station. They are the same as from Eystri-Skógar SIL station. Copyright of this picture belongs to Iceland Met Office.


Same as above. But stronger then on Goðabunga SIL station. Copyright of this picture belongs to Iceland Met Office.

It is hard to know for sure what this signals means. But I am sure that this signals are going to mean something someday. But when is hard to know.

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Earthquake swarm in Öræfajökull volcano sparks interest

The earthquake swarm in Öræfajökull volcano three weeks ago has sparked interest among volcanologist and geologists in Iceland. As the last earthquake swarm in Öræfajökull volcano was only the third earthquake swarm to take place in the last 20 years. But this was a subject of a news from Stöð 2 (Channel 2) this evening.

While a eruption is not expected any time soon from Öræfajökull volcano. It is clear that Öræfajökull volcano has started the long (?) path to a eruption (question mark, as we all know sometimes volcanoes just skip the long waiting part and go strait to the eruption phase as a surprise to everyone).

News about this from Stöð 2 (Channel 2).

Skjálftahrina í toppgíg Öræfajökuls (Vísir.is, Icelandic, Video in Icelandic, News drama)

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Two earthquake swarms during the night.

During the night there where two earthquake swarms in Iceland. One of this earthquake swarms was man made.

The larger earthquake swarm was in Hengill volcano and was man made. It happens and the hydrothermal plant pumps down cold water into the bedrock and changes the pressure and strain in the bedrock and nearby sediments that make up this area. The earthquakes only happens when cold water is being pumped down into the ground. When they are not pumping cold water into the ground, no earthquakes happens. Largest earthquakes in this man made earthquake swarm where ML2.5 and ML2.2 according to automatic measurements of Iceland Met Office. But most of the earthquakes where less then ML1.0 in size.


The man made earthquake swarm in Hengill volcano. Copyright of this picture belongs to Iceland Met Office.

The second earthquake swarm that did happen during the night was in Katla volcano. This earthquake swarm is no surprise to people how have been watching Katla volcano activity since July. This earthquake swarm in Katla volcano was however small during the night. But there did more earthquake activity in Katla volcano around 18:00 UTC yesterday. But overall it seems that Katla volcano has slowed down a bit compared to last few days.


Earthquakes in Katla volcano during the past 48 hours. Copyright of this picture belongs to Iceland Met Office.

For the moment it is rather quiet in Iceland, as there is currently not that much activity in Katla volcano. But that can change without any warning at all. As Iceland is highly active in both volcanoes and earthquakes.

Icelandic news about the earthquake activity in Hengill volcano.

Jarðskjálftar í boði Orkuveitunnar (Rúv.is, Icelandic)
Jarðskjálfti á Hellisheiði (Vísir.is, Icelandic)

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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.