Category: Tremor plots

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Eruption in El Hierro volcano ends

It seems that the eruption that has been taking place in El Hierro volcano is over. All yesterday there was an increase in harmonic tremors in El Hierro volcano, suggesting that the power of the eruption was increasing again. But around 10:30 UTC this morning the harmonic tremor dropped and around 11:00 UTC the harmonic tremor stopped completely. Signaling the end of the eruption that has been taking place for almost three months in El Hierro volcano.


The harmonic tremor in El Hierro volcano 27. December 2011. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).


The harmonic tremor today (28. December 2011) in El Hierro voclano at around 16:35 UTC (when the picture is saved). On this picture the drop in harmonic tremor can clearly be seen. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).

The current end of the eruption does however not mean that El Hierro volcano is over. It just mean that the current eruption that lasted for close to three months is over. It might well be that eruption activity is going to continue in El Hierro volcano in few months to years time. But only time is going to tell us if that is the case or not. But for the moment, the eruption in El Hierro volcano has ended.

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Overview of activity in Iceland, Spain and Canary Islands

This is a overview of activity in Iceland, Spain and Canary Islands. This is just an short overview. So not all events are included. But it has been quiet during the Christmas holidays.

Iceland

During the 24 to 26 of December there was not a lot of earthquake activity in Iceland. Three small earthquake swarm took place in Katla volcano. In Hengill volcano there was one small earthquake swarm in a location where earthquakes swarms have been taking place for past few weeks. In Katla volcano there was a earthquake swarms inside the caldera. This earthquake swarm are an reminding sign of the activity that is currently taking place in Katla volcano. But this activity took place in north-west part of the caldera. Since Sunday the activity in Katla volcano has again dropped for the time being. But that might change at any time. The largest earthquake that happened was an ML2.3 earthquake. It appeared clearly on my geophone at Heklubyggð.

Stormy weather in Iceland has made it difficult to monitor earthquakes during the past days. This is unlikely to change in next few days. As the path of the winter storms appears to be directly over Iceland at the moment.

Other then this. There was general quiet scene in Iceland during this weekend in Iceland.

Spain

During the weekend Spain had many minor earthquakes. With the largest one going up to ML3.5 in size, based on automatic size estimate. I do not know if anyone of this earthquakes where felt by humans. This earthquake activity is normal for Spain.

Canary Islands

The eruption in El Hierro volcano continued as it has been doing for the past three months. No earthquake appeared on the IGN automatic earthquake list. Harmonic tremor remained the same during the weekend. But yesterday and today there have been reports of new fissures opening. But this does not appears to have changed the harmonic tremor levels on the seismographs on El Hierro Island. This suggests that the currently the eruption remains the same. But I do not know what main eruption vents are open at the moment. They might be at great ocean depth and there eruption signs might not appear on the surface of the ocean.

Other then this it has been quiet in Canary Islands.

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Earthquake swarm in Bárðarbunga volcano

During the night there was an small earthquake swarm in Bárðarbunga volcano. The largest earthquake in this earthquake swarm was ML3.04 in magnitude. It had the depth of 8.5 km. This might have been a n dike intrusion. But it is hard to know that for sure at the moment. This earthquake swarm only lasted for an about 2 to 3 hours before it stopped.


The location of the earthquake swarm in Bárðarbunga volcano. Copyright of this picture belongs to Iceland Meteorological Office.


The earthquake swarm also did appear clearly on the tremor plots on the SIL stations that are close to Bárðarbunga volcano. The second set of spikes there are from Hamarinn volcano. Copyright of this picture belongs to Iceland Meteorological Office.


This earthquake swarm was also seen on Grímsfjall volcano SIL station. The rise in harmonic tremor is due to a storm that is passing over Iceland at the moment (going to go over Iceland today). Copyright of this picture belongs to Iceland Meteorological Office.

Hamarinn volcano

Following the earthquake swarm in Bárðarbunga volcano an earthquake swarm did start in Hamarinn volcano. This earthquake swarm is so far small and the largest earthquake so far is an ML1.9 in magnitude. But Hamarinn volcano had an minor eruption in July 2011. That minor eruption created an glacier flood that was larger then the flood that did come from Mýrdalsjökull glacier the week earlier. Activity after that has however been little and few earthquakes have taken place. It is impossible to know if there is going to be any more eruptions in Hamarinn volcano. But it cannot be ruled out given current activity in it.

Year in review on Rúv News

Rúv News has put up an page with major events in Iceland during the year 2011.

Grímsfjall volcano eruption in May 2011 can be viewed here.
The glacier flood from Mýrdalsjökull glacier due to the small eruption in Katla volcano can be found here. Sadly there is no mention of glacier flood from Hamarinn volcano yet.

This video should be available outside Iceland. If it is not. Please let me know I can send an complain email to Rúv News about it.

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Harmonic tremor continues to drop in El Hierro volcano

It seems that currently the eruption in El Hierro volcano is coming to an end. I do not know if this is an permanent end to the current eruption or just an short break in it. The reports that I have seen so far suggest that the main crater out of the coast of La Restinga has stopped erupting. The current harmonic tremor however suggests that an eruption is still taking place somewhere. But I have no idea where that might be at current time, and so far no clues where that might be. But the lack of earthquakes north of El Hierro Island suggests that an eruption might be taking place there. But that is just speculation.


The harmonic tremor in El Hierro volcano at 20:36 UTC. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).

Other then this. There is not that much to report from the eruption in El Hierro volcano, or what is left of it at current time. If there are any major changes. I am going to report them soon as I can. But at current time. It does not look like there is isn’t a lot needed to be reported on the eruption in El Hierro volcano.

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Update for the eruption in El Hierro volcano

As the eruption in El Hierro volcano moves closer to the second month. Information on what has been going on has gone bit hard to come by (for me anyway). As people settle with there new reality (erupting volcano). But that does not stop me from reporting on it.

The current status of the eruption is that nothing much has changed since last blog post. But yesterday there where reports of new vents opening up off the south coast of El Hierro volcano. But this is the area where current eruption has been taking place the past month and a half. It remains to be seen if that is going to change or not. But earthquake activity has continued in north part of El Hierro volcano. This earthquake activity seems to be a mixed one. But that means there are both earthquakes due to dike intrusions and local tectonic earthquakes. I now think that this earthquake activity is going to continue all the eruption. I am not sure why a eruption has not started in north part of El Hierro volcano yet. But for the moment it is just earthquakes. The strongest earthquakes in this area can go up to Mb5.0 in size. But I base that on what type of rock makes up the area, along with the thickness of the crust. But that is from 10 km thick.


The earthquake activity for the past 48 hours in El Hierro volcano (picture from 22 November, 2011). Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).


Earthquake activity in El Hierro volcano for the past 4 days. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).


The earthquake activity from July 2011. This earthquake activity maps out well where the magma lies in the El Hierro volcano. But as the magma expands in the crust, it creates earthquake activity. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).

The harmonic tremor tells me what is going on in the eruption, when I lack all other visual data on what exactly is going on. But the harmonic tremor increases or drops depending on the strength of the eruption. But that aspect of the eruption is based on how many and how large fissures are open at the time.


The harmonic tremor as it is today (22 November, 2011) at 21:11 UTC. The eruption as can be seen is around the same level as before. But this is not the strongest the harmonic tremor has been. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).


The harmonic tremor when the eruption was more active then today. This can clearly be seen by how the harmonic tremor is stronger then the scale of the harmonic tremor plot. This happens when a new fissure opens up and its eruption is at the strongest. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).

The IGN web site on El Hierro volcano eruption can be found here. But it is in Spanish.

I am continuing to monitor this eruption. Even if it is a long term eruption, but that are eruptions that are longer then 1 month. As the for the eruption as a whole, little change has taken place in terms of strenght and location of the eruption. But that might change without warning as before.

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Possibility of a new fissure has opened up in El Hierro volcano eruption

It seems by the harmonic tremor data that a new erupting fissure has opened up somewhere in El Hierro volcano. But given lack of visual observation I do believe that this fissure is at really great depth, and is not leaving any signs on the surface that a new eruption is taking place. Where this new fissure might be is unknown to me at present time. But based on the harmonic tremor data this new eruption seems to be powerful one. It should be expected that new fissures opens up a random while El Hierro volcano is erupting. So far the fissures that have been opening up have been short and out in the ocean. It should also be expect that erupting fissures stop erupting for no reason and with no warning at all. This seems to have happened as I am writing down this blog post.


The harmonic tremor from the eruption in El Hierro volcano yesterday. It can be seen on this harmonic tremor chart that the eruption was powerful all yesterday. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).


The harmonic tremor around 22:07 UTC. At that time the eruption was in full power as can be seen. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).


The harmonic tremor at 22:46 UTC. Notice how the drop is sudden when the new eruption fissure stops erupting. What happens is that the magma source that fed the erupting fissure did dry up. Why and how that happens in unknown to me. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).

This might mean that a new fissure might open up in the next few hours to days. Where that might happen is impossible to know. But as the fissures have been open up so far, it is going to be in a North – south line (about) in El Hierro volcano. What has however become a problem in my opinion is that the magma might have “boiled” the rock and made it soft. So it might not make a earthquakes before a eruption starts in it. This might be the case if the magma has been in the crust for the past 5 weeks. But the only example of that type of event that I know of was in Eyjafjallajökull volcano last year (2010), when a new fissure did open up suddenly and without any earthquakes or warning after 4 weeks of eruption. The reason for that was the same one on what I think might be happening in El Hierro volcano.

From what I can tell, based on data and earthquakes it does not seems that the eruptions in El Hierro volcano are over. As new magma continues to flow in from depth (the mantle). Until that flow stops, El Hierro volcano is going to continue to erupt. However there might be breaks from few hours and up to several weeks between eruptions, in that case no eruption would be taking place. This has its origin in the fact that this is a fissure rift events of shorts, a similar eruption took place in Krafla volcano in Iceland for over a 10 year period. Movement and flash inflation and deflation are also to be expected during this period in El Hierro volcano eruption. As it has many similarities of the eruption in Krafla volcano in Iceland. But it is not exactly the same, just similar. As Krafla volcano is on the inter-plate rift zone. While El Hierro volcano is on a hot spot rift zone, far inside the Africa Plate.

Update on the forum: There have been some technical difficulties with the whois registration. How that works out is not yet clear. I am going to short that issue out before I set-up the forum on the domain. In the case I have to register a new domain name. What happens in this case should be come clear next week I hope.

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Katla volcano newest earthquake swarm

During the night of the 16th of November, 2011 there was a new earthquake swarm in Katla volcano. This earthquake swarm is a part of ongoing pattern in Katla volcano. This pattern started after the small eruption that took place in Katla in July 2011. It was observed yesterday that there was a deep earthquake in Katla volcano, with the depth of 28 km. This earthquake did most likely did happen due to a dike intrusion deep inside Katla volcano, but it might well be that this was just a normal earthquake. It is hard to know that for sure. But deep dike intrusions are well known in Katla volcano. Sometimes they are followed by a harmonic tremor for few moments or minutes.


The earthquakes from Katla volcano can clearly be seen on this tremor plot from Iceland Met Office. But they make the spikes that are on it. Copyright of this picture belongs to Iceland Met Office.


The location of last earthquake swarm in Katla volcano. Most of the earthquakes are inside the caldera of Katla volcano. Copyright of this picture belongs to Iceland Met Office.


The largest earthquake in this earthquake swarm. Its size was ML2.35 and it had the depth of 4 km. This picture is released under Creative Commons Licence. Please see the top bar (there is a link there) for more information on this.

This was a long period earthquake. But this is the only clue at the moment that Katla volcano is going to erupt soon. But when is still a unknown question at present time.


The frequency analysis of the ML2.35 earthquake. As can be seen here this earthquake has really low frequency component. But most of the energy goes into about 2Hz frequency. This picture is released under Creative Commons Licence. Please see the top bar (there is a link there) for more information on this.

It is impossible to know how many earthquake swarm Katla volcano is going to have before it erupts. But this is a one way street that Katla volcano is now on. For us humans, we just have to wait and see what happens next. Nothing else can be done when it comes to forces of nature. When the time comes, get out of the way of Katla volcano.

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Analysis of the earthquake pattern in El Hierro volcan

Please note that this is not a professional analysis of the recent earthquakes in El Hierro volcano. So it might be wrong. It also might not hold any science value at all.

During the eruption of El Hierro volcano a earthquakes activity has been in the north part of El Hierro volcano. This earthquake activity is most likely created by dike intrusions into the bed rock. At this moment it is unclear if any of them are going to reach the surface. There also seems to be some minor connection between the earthquake swarms and how active the eruption is in the south part of El Hierro volcano is. But what and how that connection is and works is unknown to me at present time. The strongest earthquakes that have happened so far are up to Mb4.6 in size (I do not think that this earthquake size has been downgraded. But I might be wrong).

The current location of the earthquake swarm has not changed a lot during the past few weeks. So it is more or less in the same place. There are however reports that the earthquakes are getting shallower. But it is currently unknown if that is because of magma movements or because the crust is releasing stress because of the dike intrusions in El Hierro volcano. A full list of earthquakes larger then ML2.5 can be found here (EMSC).

The results of this dike intrusions are going to that in some areas of El Hierro Island a hot springs and other types of hydrothermal activity might show it self. Without warning. But that can result in this type of hot springs.


Picture is from Hveragerði, Iceland. Picture taken by me (Jón Frímann Jónsson). This picture is released under Creative Commons Licence. See Creative Commons Licence web page for more details (link in top bar).

This is also going to be the result for El Hierro volcano after the eruption end, if any magma remains shallow in the crust to cool down.


A 48 hour map of the earthquake activity in El Hierro volcano. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).

The earthquake are in almost N-S line, that is most likely the fault line that might erupt if it opens up. But as it stands now. Most of it would be out to the sea. But the exact length of a fissure is impossible to predict. What happens is only clear when it starts erupting.


The 4 day amount of earthquakes in El Hierro volcano. There are some earthquakes in south El Hierro volcano. But those earthquakes are fewer and smaller in size. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).


The total number of earthquakes in El Hierro volcano since the magma intrusion started in July 2011. As clearly can be seen on this picture, the new area with earthquakes makes a clear signal that it a magma injection into the rock. Rather then result of tectonic movements in the area due to the eruptions. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).

Update on the eruption it self: Explosions appears to be taking place in El Hierro volcano again. That suggests that the eruption is once again more powerful, after a few hours of lowered activity. It is not yet confirmed if any new vents have opened up closer to the shoreline. There are pictures that suggest it. But nothing is confirmed at this moment. But it cannot be ruled out that new fissure is going to open up closer to the coast. If that happens, it is going to be noticed if the depth is shallow enough.

As for the eruption in El Hierro volcano. I now classify it as long term eruption, as it has lasted for longer then 1 month. So rather then sharp blog posts about what is going on. I am going to post regular updates on what is happening in El Hierro volcano eruption. If there are any major changes. I am also going to cover that soon as possible. But I am not always in front of the computer, and El Hierro volcano is far away. But I am doing my best regarding this eruption.

Blog post updated at 12:25 UTC on 16 November, 2011

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Sharp increase in eruption activity from El Hierro volcano

This is a short update on El Hierro volcano.

There has been a increase in harmonic tremor activity from El Hierro volcano. This suggest that new vent or vents might be opening up in El Hierro volcano. But this type of eruption pattern is to be expected from a fissure eruption. Like the one that is currently taking place in El Hierro volcano.


The harmonic tremor jump in El Hierro volcano at 16:06 UTC. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).

There are also some explosions that can be seen on this tremor chart. But they form spikes that can be spotted if looked closely. Is is now also possible to monitor the eruption via web cam located on El Hierro Island. That web cam can be found here.

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Update on the eruption in El Hierro volcano on 9 November, 2011

Short note on comments: This is a short notice on comments. This blog has been getting a spam flood for the past few days. During the past 2 days or so there have been over 300+ spam comments that my spam filter has captured. This makes it ever so hard to find real comments that go into the spam box by accident. If your comment disappears for no reason after it has been posted. Then the spam filter has captured it. Please do not re-post it, as then following comments are just going to go into the spam box too. I have to manually un-check them as spam and approve them. So if you post three comments with the same link, I am going to clear the three comments with the same link. But given the amount of spam that this blog is getting there is always a risk that comment is going to get lost and permanently deleted.

It is also important that if you get “comment is held for moderation” that you do not re-post what you are commenting on. As the comment is going to wait in the moderation until I clear it. I am not always around to check for this, so it might take few hours or more until I approve the comment/s.
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The eruption in El Hierro volcano is ongoing and does not appear to show any signs of ending. However the strength of the eruption has dropped a bit during the past two days. But this was to be expected, since this is a fissure eruption and it has mostly been erupting from the same vents during the past four weeks.

It has become a bit difficult to get accurate information on what is going on El Hierro Island. So I am not going to speculate on that. But from what I can gather it seems that dangerous gas level has been detected on the ground. But the reports that I am reading are bit unclear on this. This has also been mentioned in comments on this blog.


The harmonic tremor from the eruption in El Hierro volcano at 15:23 UTC on 9 November, 2011. Copyright of this picture belongs to IGN.

As can be seen on this tremor plot the harmonic tremor in the eruption is dropping. Explosions that have taken place are also clear on this tremor plot. That might be because the eruption vent is getting smaller, therefor less magma is being push out the erupting vent. Or the currently erupting vent might be closing up. As so often happens with fissure type eruptions. If that happens does not mean that this eruption cycle is over. It just means that the current eruption vent has closed up. New fissures are most likely to open up in coming weeks as the eruption goes on. Where and when it impossible to know for sure.

Earthquake activity continues in north part of El Hierro volcano. This are most likely dike intrusions into the bed rock there. So earthquake activity should be expected to continue north west of the town Frontera. If a dike intrusion manages to find a path to the surface in this area there is going to be a eruption and earthquake activity should drop following that. But until and if that happens there are going to be earthquakes. There is also chance of hydrothermal activity to show up in this area if a dike intrusion gets shallow into the bed rock. But is not go up from the ground and start a eruption. This might also be the reason why some part of El Hierro Island are experiencing high levels of toxic gas for the moment.

I am going to post more on the eruption in El Hierro volcano as I know more what is going on.