Category: GPS Monitoring

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Increased eruption activity in El Hierro volcano

I was going to post this yesterday. But I fell a sleep at 17:00 UTC and I didn’t wake up until 03:00 UTC.
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The eruption in El Hierro volcano continues as it has been doing for past few weeks with little change. The first eruption vent that did open south of El Hierro Island has continued to erupt. But so far no Island has formed and it is unclear if it is going to form, as the depth is great in this area. Since yesterday around 06:00 UTC the harmonic tremor has been increasing. But this suggests that new vents have opened up in the south eruption area. I got some pictures of that yesterday in the email. But they did not show anything new in my view. Thanks to the readers how did send me those pictures.

The current fluctuation in the harmonic tremor from El Hierro suggests that magma is on the move in the north part of El Hierro Island. Both off the coast and maybe inland on the Island where earthquakes have been taking place. It is impossible to know how this is going to develop during the next few hours to days. As that depends on the rock structure of El Hierro Island and earlier eruptions.

Earthquake activity

During the past two weeks the earthquake activity have been growing in the North-west part of El Hierro Island. The reason why this is happening is that a new fissure is about to open in this area. As I have mentioned before in earlier blog posts. When and where is impossible to know for sure. The largest earthquake so far took place this morning, it size was ML4.0 with the depth of 20 km. But this is the automatic data from IGN. This pattern of earthquake activity is most likely going to continue during this eruption process in El Hierro volcano. Since the eruption type here is a fissure eruption.

It is worth noting that earthquakes in once place does not mean that the eruption is going to happen in that place. As the magma can travel in dikes all over the El Hierro Island and show it self anywhere on the Island it self. So the general risk is high in my opinion. The only action that can be taken is to be prepared for sudden eruption of new vents on El Hierro Island. Since there is a good amount of magma on the move inside El Hierro volcano.


The harmonic tremor in El Hierro at 08:54 UTC (when picture is saved). The spikes are earthquakes, and harmonic tremor spikes are the “waves” in the harmonic tremor pattern. Copyright of this picture belongs to Instituto Geográfico Nacional.

Update 1:

* When I wrote this blog post. This two earthquakes took place.

1109584 02/11/2011 08:37:11 27.9267 -18.1084 3 1.7 mbLg NW FRONTERA.IHI
1109582 02/11/2011 08:36:00 27.5986 -17.9594 1 1.9 mbLg S EL PINAR.IHI

This are the most shallow earthquakes that I have seen so far. From the depth it is possible a magma has found a clean path to surface in this two areas. Sadly there is no map. So I am not sure where this earthquakes took place in El Hierro volcano.

Update 1b: The earthquake have been revised. Now the depth is 9 km for the ML1.7 and 22km for the ML1.9.

The shallow earthquake.

1109584 02/11/2011 08:37:11 27.9304 -18.1107 9 1.7 mbLg NW FRONTERA.IHI [+]

I am going to post more information when I know more on what is taking place in El Hierro.

Blog post updated at 11:24 UTC on 2 November, 2011

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Special report: Rift zone eruption continues at El Hierro volcano

This is going to be a short blog post about what is going on in El Hierro. But I have a longer blog post planned for tomorrow.

The current eruption in El Hierro volcano is a fissure eruption. As such a new eruption vent can be expected for the time while magma continues to be injected into El Hierro volcano from depth (28+ km). When a new fissure starts to open it is pre-seeded by a swarm of earthquakes. Lack of this knowledge, or some type of ignorance about this fact has me worried that a eruption. As there is a real risk of eruption happening close to a populated area in El Hierro. It is also a fact that a new fissure can open up extremely fast and with no warning at all. Since when the magma reaches the surface there is no guarantee that the fissure is going to open up with a swarm of earthquakes. In most cases that I know about, the eruption fissure opens up with no earthquakes at all and with no earthquakes. The only earthquakes that take place is when the magma is breaking a path up to the surface.


Earthquakes during the last 10 days in El Hierro volcano. The new magma injection appears clearly with earthquakes ion this map. Copyright of this picture belongs to Instituto Geográfico Nacional.


All earthquakes in El Hierro volcano since July. The new magma injection appears clearly on this map. Copyright of this picture belongs to Instituto Geográfico Nacional.

At this moment it is unclear if the new magma injection has got into contact with the magma that started to inject under El Hierro volcano in July 2011. If that happens the two magma injections are going to merge. But what happens after that is unknown to me. As I have never seen that type of process happen before.

When the El Hierro island is viewed from above it is clear that there are eruption periods where the El Hierro Island is covered with eruption cones in fissure eruptions. It is close to impossible to know if that this the case now or not. But I fear that it might be the case, as it has been long time since El Hierro erupted last time and the Island grows in fissure eruption jumps that take some time to pass over. One such eruption period jump appears to have started on 10 October, 2011. How long it is going to last depends on how large it is going to be. But this is going to last more then few weeks. But there are going to be breaks in between eruption episodes in El Hierro.


The harmonic tremor in El Hierro just before midnight of 28 October, 2011. The spikes are earthquakes N to NW of El Hierro Island. Copyright of this picture belongs to Instituto Geográfico Nacional.

There has been some drop in harmonic tremors from the first (and only?) eruption vent just outside the coast of El Hierro. This means that it might be closing up. But that is normal for this type of eruption. When this eruption vent closes up or just before it closes up. A new eruption vent is going to open up at new location. As the magma inside El Hierro volcano supports that in my opinion. When and where is the unknown factor in this equation.

As for the question on how long this eruption period could last. I am hoping that it is going to be over when I move to Canary Islands (maybe El Hierro Island) in about 4 to 10 years time (at the latest). But this type of eruption take a long time to finish. So covering this eruption(s) is going to be ongoing for some time now.

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Special report: New magma intrusion into El Hierro volcano, Canary Islands, Spain

Few days ago a new magma intrusion did start in El Hierro volcano, Canary Islands, Spain. But this means that the pressure is increasing inside El Hierro current magma still. The new magma is going the same path as before, and is forming a new sill north-west part of El Hierro volcano. It seems that this magma has not yet encountered the magma that is already inside El Hierro volcano. What happens when the new magma encounters the slightly older magma is a open question. But I am sure what happens is going to be interesting and is going to create a new eruption vent in my opinion.


The new magma intrusion in El Hierro. It is not yet in contact with the existing magma in El Hierro. It is hard to know exactly what happens when the new magma gets into contact with the magma that is already in El Hierro. Copyright of this picture belongs to Instituto Geográfico Nacional.

What is really interesting about this new magma is that this seems to be a new intrusion from a new conduct below El Hierro. This conduct does not appear in the earthquakes that started in July 2011 to today. There is a great risk that more new conducts are going to open up under El Hierro in this same manner. But this means that new magma can start to flow into El Hierro at new point under El Hierro. But that is always marked by a increase in earthquake activity where a new magma intrusion starts in El Hierro. This new magma intrusion into El Hierro appears to be rather small at the moment. But it is most likely going to grow over the next few weeks.


Current harmonic tremor levels in El Hierro volcano. Given by the current harmonic tremor level this eruption remains small. But the harmonic tremor is poorly to not being detected on nearby Canary Islands. The spike in the tremor plot is a earthquake. Copyright of this picture belongs to Instituto Geográfico Nacional.

It seems that IGN did rescale the tremor plot in the early beginning of the eruption. Making me draw false conclusions on what was going on in El Hierro. But it seems that the eruption is stable and has been from the beginning. But so far this is a small eruption, based on the tremor data. I say it is small because the harmonic tremor is not detected about ~60 km away from El Hierro. As a example in the eruption of Grímsfjall volcano, the harmonic tremor was detected clearly up to ~200 km away from the eruption. But the harmonic tremor signals how much magma is moving inside a volcano up to the surface. But not how explosive the eruption is. But explosions can and are detected on seismometers when a eruption goes explosive.

If anything major happens in El Hierro. I am going to update this blog post.

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Special report: Update 6 on the eruption in El Hierro, Canary Islands, Spain

Special note: Please notice that my (personal) watching system is also going to include the mainland of Spain (mainland Spain has two volcanoes that I am aware of, along with some earthquake activity) when I change it next month, along with Canary Islands. Everything else is also going to be a subject to a special reports if the event is important enough. That is not always going to be case however. But I am going to post more details on this in the beginning of next month.
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Little seems to have changed in the eruption of El Hierro since my last update on it. That was on 19 October, 2011. Harmonic tremor is constant, but appears to have dropped a little in the past few days. But with the fluctuation that is often increases again before it drops down again. This means that the eruption is ongoing, but is loosing power to continue at current eruption vent. This was not unexpected. This has however not slowed down inflation in El Hierro from what I can gather on GPS data on El Hierro.

As the current eruption vents close down it seems that earthquakes have started again under El Hierro. But the earthquakes have the depth from 28 km and up to around 5 km. This strongly suggests that new magma is entering under El Hierro and is again increasing the pressure inside the El Hierro magma sill (or chamber, but note that El Hierro does not have a stable magma chamber it seems). This increases earthquakes while the magma does not have any good path up to the surface. When a new path for the magma starts to form again, a large earthquake swarm is going to take place in El Hierro. It is not going to be anything bigger then already has taken place in El Hierro already. With the largest earthquakes going up to Mb5.0 in size. That is at least my opinion.


All the earthquakes that have happened in El Hierro since magma intrusions started in July 2011. This pictures clearly shows in my view the amount of magma (in terms of size, not volume) that is under El Hierro at the moment. As it is marked on the outer layers by the earthquakes. Copyright of this picture belongs to Instituto Geográfico Nacional.


The harmonic tremor in El Hierro at midnight on 21 October, 2011. As can be seen, it fluctuates a little bit. Copyright of this picture belongs to Instituto Geográfico Nacional.

The major risk in the current eruption cycle of El Hierro is the risk that new eruption vent is going to open up nearby a human population without warning. But El Hierro has a lot of cinder cones from earlier eruption cycles. That creates the risk that a new eruption vent is going to open up on dry land without warning. But it is impossible to know when and where that might happen.

Claims that this eruption in El Hierro is going to create tsunami due to landslides are false and have no basic in fact or reality. As landslides are unlikely to happen in this eruption episode or if a eruption happens on dry land.

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Special report: Update 5 on El Hierro eruption, Canary Islands, Spain

This is a special report on the eruption in El Hierro, Canary Islands, Spain.
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From the harmonic tremor data during the current eruption in El Hierro. It seems that the eruption has dropped in strength during the past 48 hours or so. But that most likely means that the current eruption crater is closing up. But this does not mean that the eruption is over, as new fissures might open up without any warning close the El Hierro Island or on the island it self. It is impossible to know that for sure at this moment. As it currently stands it is unlikely that a new Island is going to form offshore of El Hierro island, as the current eruption crater does not seem to have the energy to break the surface of the ocean. Earthquake activity in El Hierro volcano remains about the same as it has since the eruption did start on 10 October, 2011.


Harmonic tremor in El Hierro volcano at 18 October, 2011 at 23:26 UTC. Copyright of this picture belongs to Instituto Geográfico Nacional.

For the moment, the only thing that can be done is to wait and see what happens next. But it is clear that the eruption in El Hierro is far from over from the data that I have seen so far. But this eruption might pause for days to weeks, as that is not uncommon thing for a volcano to do during a active eruption cycle.

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Special report: Update 4 on the eruption in El Hierro, Canary Islands, Spain

Short note on comments: During the eruption in El Hierro there has been a lot of comments on this blog. Over the past 4 days (or so) there have been about ~1500 comments. If your comments is held for moderation, the blog says so. Do not try to repost your comment if that is the case. As the second comment is just going to be held in moderation as the earlier one. It takes me a little while to approve the comment and to make it appear. If your comments disappears and cannot be seen, the spam filter has eaten it. It also takes me a while to check the spam filter and restore comments that have gone there. Please do not just post comment with nothing but links, that increases the risk that the comment is going to be eaten by the spam filter.
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Short note: Please note that I am not a expert in the field of volcanism, volcanoes and earthquakes. I never claim to be one. Regardless if I am asked or not. I am a man with interest in this field. I read a lot of books and studies on volcanoes and earthquakes. But that does not make me a expert in this field. If you want to speak with a expert, go and find one. Because I am not it.

Now. About the eruption in El Hierro volcano in Canary Islands. This is going to be a short blog post about the eruption.

From what I can tell and the information that I have seen. At least two more vents have opened up on the from what I can gather on the pictures and the reports from Canary Islands. So far all the new vents are under the ocean and at depth of no less then 150 meters. So seeing them directly is quite hard for the moment. There are continues deep earthquakes under El Hierro volcano, but that suggests that new magma is flowing into El Hierro volcano.

During the weekend floating magma bombs where (or some type of magma, I do not have the exact word for it in English at the moment) floating on the ocean. But this means that at least one of the vents that started erupting in the beginning is getting close to break the surface of the ocean. If the eruption continues in that vent for a little while longer. If it gets above the surface of the ocean, it is going to form a island and a lava eruption is going to start once the ocean cannot get any more into the crater.


The harmonic tremor of the eruption in El Hierro volcano today (16 October, 2011) at 22:35 UTC. Copyright of this picture belongs to Instituto Geográfico Nacional.

There is a risk of new fissures in El Hierro opening up without warning. From what I am estimating, the area that this can happen has expanded about ~5 km or so from my original estimate that I made in few blog posts ago. The risk of new fissure opening up on land is going to remain high while this eruption is taking place. But this might well be a period of eruption activity for El Hierro. It is impossible to know for how long it is going to last, it could be weeks or it could be months and up to years of activity.

I am going to post more information on El Hierro when I know more tomorrow. I am also going to write about the earthquake activity in Hengill volcano tomorrow if I have time to do so.

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Special report: Update 3 on El Hierro eruption in Canary Islands, Spain

I am going to fully integrate Canary Islands into my watch volcano monitoring system in the beginning of next month, but Canary Island won’t be part of my emergency system until I move to Canary Island (that is because of technical reasons mostly). When that happens, blog post regarding earthquake and volcano activity won’t be a special report. Just a normal blog post as with Icelandic volcanoes. I am doing this as I plan on moving to Canary Islands in about 10 years time (+- maybe few years depending on how my plans work out). A name change on this blog is planned in the beginning of the year 2012. But it takes a while for me to think up a new name for this blog.
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The eruption in El Hierro volcano continues at the same phase as before. With little change so far. Currently the eruption seems to be in two vents, as it did when it started on Monday. There have been unconfirmed reports of new vents opening up closer to the coastline. But given lack of direct evidence that should be there. I do not believe that a new vents have opened up closer to the coastline so far.

Deep earthquake continue in El Hierro volcano. But that means a new magma is coming in from the mantle and is flowing upwards into the volcano. For long as deep earthquakes are being recorded the eruption is going to continue. It is impossible to know for how long this inflow of magma from the mantle is going to continue. But this means that the eruption is going to continue for time being. With the risk that new vents might open up at any time on and around El Hierro volcano. This inflow of new magma has also been confirmed by GPS measurements on El Hierro volcano (the island). But since the eruption did start, no major change has been seen on the GPS real time data.


The harmonic tremor in El Hierro volcano yesterday. Copyright of this picture belongs to Instituto Geográfico Nacional.


The harmonic tremor in El Hierro volcano today (until 21:20 UTC about). As can be seen by comparing the pictures between today and yesterday. Not much has changed since yesterday in terms or harmonic tremor. Copyright of this picture belongs to Instituto Geográfico Nacional.

If a eruption vents open up on a land. The following eruption is going to be lava only. No volcano ash and no explosions as El Hierro is a shield volcano like the one on Hawaii and that means only lava eruptions. If a eruption vents opens up on the shallow coastline, there are going to be explosions for as long the ocean water can get into the crater. The moment it closes up the explosions stop and lava eruptions starts.

Please note that I am on slow internet connection (3G). So I am not going to post anything if the internet connection is really slow, as sometimes seems to happen. I am going to try and solve this issue by using my 3G phone and connect that way. At least I am going to try and see what happens.

Blog post updated at 03:20 UTC on the 15 October, 2011.

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Special Report: Update 2 on the eruption in El Hierro

This is a special report on the eruption in El Hierro. This is also a good time (as any) to announce that I plan to write about volcanoes in Canary Islands in the future. As I plan on moving to the Canary Islands in about 10 years time (no reason to start late on this). But I have already induced the Canary Islands volcanoes into my personal watch system. But I have my own personal system to watch volcanoes in Iceland and now Canary Islands. However, Canary Islands are not part of my personal emergency system until I move to Canary Islands.

Update to the name of this blog is going to happen soon, but I am not sure when. But I am going to move in a about 10 years time (going to live in Denmark until that happens). Until then, they are going to go into special report group and only major events are going to be blogged about. Please note that this might change if I move earlier to Canary Islands then I now plan.

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The eruption in El Hierro volcano continues today, as it did yesterday. But the strength of the eruption appears to have dropped today from what it was yesterday. But this does not mean that the eruption is over. It just means that the current fissure that is erupting is about to close up, mostly due to the material that it has been ejecting into the ocean floor. That means a new fissure or vents is about to open up somewhere. When and where is impossible to know. But this is the nature of volcanoes that erupt in this manner, but El Hierro is a shield volcano [second link here]. Good examples are Krafla volcano and Vestmannaeyjar Island volcano. Both of those volcanoes are in Iceland.

Today around 14:20 UTC there was a sharp tremor drop in El Hierro. This means that the magma flow dropped in the current eruption fissure. This also means that if the pressure is not enough that fissure is going to stop erupting. Because of this has happened a new fissure or a vent should be expect at any time as I have told before. When and where that might happen is impossible to know, as that outcome depends on where the magma finds its pathways inside the volcano. There might not be any earthquakes before this happens, as the rock is unlikey to be hard enough to make them. Some small earthquakes might happen if the rock layer is hard enough. Today few deep earthquakes have been recorded. This means that new magma is getting into El Hierro volcano from the mantle (where no earthquakes happen). This also means that this eruption might take place for some time now. But it is impossible to know for how long, as there might be a lot of magma flowing up from the mantle it self and up to El Hierro volcano.


The harmonic tremor and the drop in the harmonic tremor today. Copyright of this picture belongs to Instituto Geográfico Nacional.

Many people have been wondering why this eruption has not been seen. The fact is that depth drops quiet fast around El Hierro Island. Around 4 km out the depth is close to 1.5 to 2 km, it is only close to the island that the depth starts to get shallower. At the moment is is hard to say what happens next in this eruption on El Hierro. But more vents should be expect to open up then have already have.

I am going to update this blog post if anything changes in El Hierro volcano eruption.

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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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New harmonic tremors spikes in Katla volcano

This has become almost a daily occurrence. But today there was one harmonic tremor spike (at least) in Katla volcano. It is unclear why this harmonic tremor spikes happen in Katla volcano. But they often do happen just before a earthquake swarm starts, but often several hours before (sometimes). I am not sure why that is. But one idea is that this activity is connected to hydrothermal areas that are under the Mýrdalsjökull glacier.

Earthquake activity has been quiet in Katla volcano today. But it is hard to know for sure if that is going to last. As earthquake activity appears to be on the rise in Katla volcano during the whole of the year 2011 according to news in Iceland (see earlier blog post for details).


Harmonic tremor spike as seen on Lágu Hvolar SIL station. The spike is between 04/09 and 05/09. The spike is a small top in the tremor chart (hard to spot). Copyright of this picture belongs to Iceland Met Office.


Harmonic tremor spike as seen on Snæbýli SIL station. The spike is between 04/09 and 05/09. The spike is the broad band that suddenly appears in the tremor data. It is easier to see then on Lágu Hvolar. Please note that it seems that Snæbýli SIL station has gone offline again, as it has stopped updating. Copyright of this picture belongs to Iceland Met Office.

It is clear that Katla volcano is going for a eruption. But the question remains is just when that is going to be, but it is impossible to predict when a eruption is going to take place in Katla volcano. But the signs have come clear in my opinion in this matter. For the moment it is just waiting and watching. But this might be a long wait until something happens in Katla volcano.