Category: Fissures

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Analysis of the Helgafell mountain earthquake on Reykjanes

Icelandic Met Office has posted an interesting analysis of the last weeks earthquake on the Reykjanes. But this earthquakes where connected to Krýsuvík volcano activity. By relocating the earthquakes, it is possible for Iceland Met Office to see better how long and how deep the fault that created this earthquakes is. In this case, it was around 2 km long and the movement was east-west, like the one found on SISZ.


The re-located earthquakes. The green ones are normal locations, the orange ones are re-located earthquakes. Copyright of this image belongs to Iceland Met Office.

The orange ones are re-located using relative locations. I am not sure how this technique works. But it often gives better image on what is going on with the earthquakes. Both in terms of the fissure making the earthquakes and the depth where they are taking place.

The fissure in question was on N-S axes and is inclined about 70° in west direction. According to IMO, the aftershocks suggest that movement of this fissure was right slip, along with minor drop in it. That means this according to IMO. The west part of the fissure moved to north and down, while the west part of the fissure moved to the south and little bit upwards. According to IMO. This movements happens in SISZ on large fissures there (when they break).

I am currently waiting for more earthquakes in this area. This activity is not over in my opinion any time soon.

Source of data: Week 9 – Iceland Met Office (Icelandic).

Other: I am sorry for lack of updates. There has not been anything special going on and I have been working on confirming getting an apartment in May 2012.

Blog post updated at 09.03.2012 at 17:37 CET. Fixed spelling error.

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New earthquake swarm in El Hierro volcano

During the past few days there has been an earthquake swarm in El Hierro volcano in Canary Islands. Following this earthquake swarm there has been some increase in eruption activity. Resulting in some material reaching the surface of the ocean. The reason for this activity is that new magma is being injected into El Hierro volcano from depth. This magma is pushing the magma that is already there closer to the surface, creating dikes and sills in the rock along the way. This also increases the eruption in already open vents.


The harmonic tremor activity in El Hierro today. Copyright of this picture belongs to IGN.

The largest earthquakes in this swarm have had the size ML2.7 and ML3.4. They have been taking place at the depth of 12 to 15 km, based on early data from IGN.


The ML3.4 earthquake in El Hierro volcano that did happen during the night. Copyright of this picture belongs to IGN.

I am expecting this activity to continue for some time now. As it seems that more magma is coming up from depth. How long that progress is going to last is impossible to know. When it stops, it does so and only then the activity in El Hierro volcano is going to stop.

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Random minor eruptions in El Hierro volcano

It seems that the main eruption is over in El Hierro volcano, for now anyway. For the moment there are minor eruptions taking place in El Hierro volcano. This minor eruptions happen at random times and between them nothing is happening. This is clear by the harmonic tremor data from the sensors that are on the El Hierro Island it self.

This type of behavior is not a big surprise. I fully expected this to happen when this eruption started. The main risk now is that new vents might open up in new places without any warning at all. This seems to have already have happened to some extend. As I have been getting unconfirmed reports that new vents have opened up in this new eruption episodes that have only lasted for few hours. So far this new vents have not opened up on land. But this pattern of eruption increases the risk of that significantly. As magma appears to looking for a way out. But does not find the way out that last, or does not have the pressure to maintain an new vent open for long period of time. The vent that erupted the longest is estimated to be around 125 meter below the surface. So it has been guessed that its above 750 meters high (this is unconfirmed).


Harmonic tremor and lows in El Hierro volcano today. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).


The harmonic tremor activity yesterday (23.01.2012). As can be seen the activity starts, then stops again. This means that new vents are opening up again. Or that the older vents are opening up and starting to erupt again before stopping. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).


The activity on 22.01.2012. This as same in the past two days. Activity start before stopping again. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).

As for what happens in El Hierro volcano in the next weeks to months. It is close to impossible to know for sure what happens. As what happens next depends on the magma flowing into El Hierro volcano. It seems that this eruption is not over. Even if it continues with short breaks between eruption events.


Picture of the activity today (24.01.2012). I got this picture by email. Click on the picture for full size. Copyright holder of this picture wish to remain anonymous. Used with permission.

This picture clearly shows the active area today. There is also an highly active hydro-thermal area where the eruption took place, or have been taking place. There is also some chance of dike intrusions in this area creating new hydro-thermal areas. But dike intrusions can take place without any earthquake activity. If there is an earthquake activity, it does not need to have high amount of earthquake activity. Harmonic tremor can and often increases if an dike intrusion is taking place.

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Renewed eruption activity in El Hierro volcano

Since yesterday there has been an renewed eruption activity in El Hierro volcano. Harmonic tremor has not seen big increase however. This suggest that this new eruption so far is small and mot procuring a lot of lava to the surface. Some floating pyroclastic has been spotted on web cameras and by local people when they come up to the surface. This eruption activity appears be intermittent at the moment. Going on and off every few hours to days.


The harmonic tremor from the eruption in El Hierro volcano. Harmonic tremor remains low however, so there is not a lot of energy in this eruption at the moment. Spikes in the tremor chart are most likely explosions taking place in the eruption area. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).

The eruption appears to have started again following an new dike intrusion from great depth into El Hierro volcano. This was followed by few earthquakes. All of them where small. If more new magma flows into El Hierro volcano this new eruption episode is going to increase in strength and in power. But it is hard to be sure if that is going to happen or not.


Eruption area in El Hierro volcano. This new eruption seems to be closer to the coast line then before. Copyright of this picture belongs to INVOLCAN. Picture is via Eruption blog (Erik Klemetti)

It is impossible to know what happens next in El Hierro volcano. So watching is important thing to do.

Other blogs about this new eruption.

Renewed Activity at El Hierro in the Canary Islands (Wired Science)

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Eruption starts again then stops again in El Hierro volcano

Few weeks ago the eruption in El Hierro volcano stopped for few hours. Before it did restart at lower levels for few days. Then it stopped again. This type of behavior is not so unexpected as it seems that El Hierro volcano did get some minor magma injection in past few days and around the time the eruption did restart. But this injection of new magma was followed by minor earthquake swarm in El Hierro volcano, with one of the earthquake having the depth of 34 km (automatic depth estimate I think). But this new injections of magma seems to be small compared to the amount of magma that has already been injected into and erupted already in El Hierro volcano.


Harmonic tremor yesterday (03-01-2012) in El Hierro volcano. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).


Harmonic tremor today (04-01-2012) in El Hierro volcano. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).

Current level of harmonic tremor in El Hierro volcano suggests an small eruption in the area. But there is now an highly active hydro-thermal area where the eruption started and has been taking place for the past three months. But it is going to take several weeks and up to years for this area to cool down. Then there is also the chance of hydro-thermal activity in the area if there is an dike intrusion into the rock of the El Hierro volcano that has not erupted. If that is the case as might well be. It is going to decades and up to hundreds of years to cool down.

For the moment however the main eruption event in El Hierro volcano is over and it is going to remain like that until new magma is injected into volcano. But that might not happen for hundreds to thousands of years if the current sequence of events that led to current eruption is over. But only time is going to tell us what happens next is El Hierro volcano. As volcanoes are unpredictable in there nature.

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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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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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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.