Category: Magma

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New earthquake swarm in Katla volcano

When I just think that Katla volcano had gone quiet. It starts a earthquake swarm to proof that I had it wrong.

This earthquake swarm in Katla volcano is not big. But the largest earthquakes where up to ML2.6 in size according to Iceland Met Office web page. This earthquake swarm is located in Katla volcano caldera, in the area that have been most active since July 2011. No harmonic tremor has followed this earthquake swarm.


The earthquakes in Katla volcano today. Copyright of this picture belongs to Iceland Met Office.


The tremor plot of the earthquake from Slysaalda SIL station. Copyright of this picture belongs to Iceland Met Office.


The earthquake swarm on Alftagröf SIL station. Copyright of this picture belongs to Iceland Met Office.


The earthquakes as they did appear on my geophone at Heklubyggð (Hekla volcano). This picture is released under Creative Common Licence. See the Licence page for more details.

This was most likely a small dike intrusion in Katla volcano caldera. But that seems to be the major driving force behind this earthquakes that are currently taking place in Katla volcano caldera. It is hard to know for sure if this earthquake swarm is going to continue or not. But this high earthquake activity in Katla volcano suggests that it is not far away from erupting. But it is impossible to know when a eruption might take place at current time.

Icelandic News about this earthquake swarm.

Smáskjálftar í Mýrdalsjökli (mbl.is, Icelandic)

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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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Possible harmonic tremor spike in Katla volcano (it might just be the weather)

With all the bad weather in Iceland during the past few days it is hard to be sure on this. But it seems that a harmonic tremor spike is about to start in Katla volcano. So far this spike is rather small from what I can tell at the moment. At the moment it is impossible to know how this develops, if this is a harmonic tremor spike to begin with in Katla volcano.


Current earthquake activity in Katla volcano. Copyright of this picture belongs to Iceland Met Office.


Current tremor levels in Katla volcano. The harmonic tremor spike can be seen at the end of this plot. Copyright of this picture belongs to Iceland Met Office.


The possible harmonic tremor spike in Katla volcano. Copyright of this picture belongs to Iceland Met Office.


The possible harmonic tremor spike in Katla volcano. Copyright of this picture belongs to Iceland Met Office.

This might just be bad weather. It is hard to know at the moment. But currently the weather is decent. But there is a new storm coming over Iceland in the next 12 hours or so, at least that is the weather forecast now from what I can gather.

In September over 480 earthquakes where recorded in Katla volcano caldera. But this is the most earthquake activity since at least the year 1999. The largest earthquake in September in Katla volcano was a ML3.4 with the depth of 5.2 km.

More the earthquake activity in Iceland during the month of September.

Jarðskjálftayfirlit í september 2011 (Vedur.is, Icelandic, Picture)

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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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Earthquake swarm in Askja volcano and Katla volcano

During the night there was a earthquake swarm in Askja volcano and in Katla volcano. The earthquake swarm in Katla volcano might be ongoing, but it is hard to know that for sure at the moment.

The earthquake swarm in Askja volcano are signs that volcano is preparing for a eruption period. But it seems like that magma has been starting to collecting in Askja volcano last year (in March of 2010). This progress also seems to be moving along faster then I did expect last year. But the earthquake swarm that took place during night was because if a possible dike intrusion from Askja volcano that got into the crust inside Askja volcano fissure swarm. So far the pressure of the magma is not high enough to start a eruption and I am unsure how long this progress needs to continue before Askja volcano is ready for a eruption. The largest earthquake that happened during the night was ML3.4 and on around 1 km depth according to the news on Rúv.


The earthquake area in Askja volcano. It is outside the main Askja volcano, but inside Askja volcano fissure swarm, the star marks the location of the ML3.2 earthquake (automatic size). Copyright of this picture belongs to Iceland Met Office.

Earthquake activity continues in Katla volcano as before. Most of the earthquakes are as before just small ones. Currently the earthquakes do not appear to be from dike intrusion as happened last week (5 October, 2011) with the earthquakes that where up to ML3.9 in size (checked data). After this large earthquake swarm activity dropped considerably. But it has been picking up again slowly during the week. But earthquake observation has been difficult due to frequent storms during the past two weeks that have been passing over Iceland. This storms have had wind up to 30m/s and wind gusts up to 56m/s (recorded).


The earthquake swarm in Katla volcano caldera. This area was active this summer when there was a minor eruption in Katla volcano. Copyright of this picture belongs to Iceland Met Office.

For the moment it is hard to know what happens next in Katla volcano or in Askja volcano. But it is clear that Askja volcano is preparing for a eruption (along with Kverkfjöll volcano). It is clear that Katla volcano is continuing to prepare for a eruption. But it is impossible to know when and how big that eruption might be. Until a eruption takes place, more dike intrusions with following earthquake swarms should be expected in Katla volcano.

Note: I am going to write more on El Hierro volcano (Canary Islands, Spain) later today. When I know more on what is going on in that volcano. But information gathering takes a little time when it is in a language that I do not properly understand yet.

News on this from Rúv.is.

Jarðskjálfti við Lokatind (Rúv.is, Icelandic)

Blog post updated at 14:23 UTC on 11 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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Special report: Update on El Hierro volcano eruption

While everything is quiet in Iceland. I am going to continue my coverage of the eruption in El Hierro volcano. Information in English also seems to be lacking for some reason. Please note that I have little understanding of Spanish, so I am just using the data that is available to me on the internet to figure out what is going on.

First I want to say that I am not a expert. I never claim to be one. My knowledge of volcanoes and earthquakes are the result of hard work and studying them on my own (reading research papers and other sources).

It is bit unclear what is going on in El Hierro. But from what I can tell least two things have happened during the past 24 hours. The first thing is that a eruption started at ocean floor around 04:18 UTC yesterday (10 October, 2011). This eruption appears to have been small and was not noticed on the surface of the ocean. Around 06:10 UTC this morning (11 October, 2011) a large movement of magma started to take place inside El Hierro volcano. Where exact break up of this magma is going to take place is unclear at the moment. But it is clear that a eruption is taking place and it is more chance then less that magma is going to find it self a new pathway up to the surface soon. As I do not think that the current eruption vent is keeping up with the current magma that is under El Hierro. But it is worth to notice that El Hierro does not seem to have a magma chamber, like Eyjafjallajökull volcano in Iceland so the eruption size is terminated by the current inflow of magma.

Here is a comparison of harmonic tremor charts from yesterday and today (10 and 11 October, 2011).


The harmonic tremor as it was on 10 October, 2011 at 21:08 UTC. Copyright of this picture belongs to Instituto Geográfico Nacional.


The harmonic tremor as it was on 11 October, 2011 at 20:29 UTC. As clearly can be seen it has grown by a margin or more (I can’t tell for sure) in the last few hours. Copyright of this picture belongs to Instituto Geográfico Nacional.

What is however really interesting is how this eruption is changing fast and without any warning at all. But this is however something that might be expected from a volcano like El Hierro. I see in the news that they are expecting earthquake activity before new vents or fissures open up. That is wrong assessment in my opinion. As new eruption vents and fissures can open without any or much earthquakes activity at all. Earthquake activity before a fissure vents open up depends only on the rock that the magma has to break trough. In many cases it does not have to create any earthquakes before a eruption starts. Good example of this is the eruption in Heimaey Island in the year 1973. Only a small earthquake swarm was detected before a eruption started. All I personally except before a eruption in a new place on El Hierro volcano is a minor earthquake activity. It is also hard to know if that earthquake activity can be detected based on the amount of harmonic tremor taking place at the moment.

Here is my personal assessment on where eruption might take place in El Hierro. Please note that it might be completely wrong. But I base my assessment on the data out there, that assessment might be wrong.


The most chance of the eruption in El Hierro in my personal opinion marked by the two red circles. Copyright of this picture belongs (original) to Instituto Geográfico Nacional.

There have been some deep earthquakes in El Hierro volcano over the past few hours. This deep earthquakes mean that new magma is flowing under El Hierro volcano. This means that the flow is steady (pressure pulse in the magma creates the earthquakes). So this eruption is far from being over it seems. How long it is going to last is a good question that currently nobody has a answer to at the moment.

I am going to update this blog post if I have to or if something new happens in El Hierro.