Category: Harmonic tremors

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Continued harmonic tremor in Katla volcano

The harmonic tremor that started yesterday in Katla volcano continues. It is however at less strength then yesterday. Often there are small earthquakes following it. They can be poorly observed on my Heklubyggð geophone. Few earthquakes have happened during this unrest. GPS data is unreliable, as it has not been updates since mid December 2011 (why that is I do not know). At current time it seems that this harmonic tremor is dropping down at the moment. It is impossible to know for sure if this is the end of this tremor in Katla volcano for the moment or not.


The tremor noise as seen on Slysaalda SIL station. Copyright of this picture belongs to IMO.


The harmonic tremor noise as seen on Skrokkalda SIL station. Copyright of this picture belongs to IMO.

There are now two possible reasons why this is happening. This might be an increase in hydro-thermal activity in north part of Katla volcano. Second reason might be that this is magma moving around inside Katla volcano at depth, then out visible effects on the surface. That is earthquakes have not happened following this event to any extent. There have only been two registered earthquakes so far. There location is both poor and depth poorly located. It has been my experience that following smaller event of this type there is generally an earthquake swarm in Katla volcano caldera. The time is is from from this type of event to take place until the earthquake swarm takes place differs a lot.

Last minor eruption that took place in Katla volcano was on 6. September 2011. My blog posts about it can be found here. It was believed at the time this was water. But today I now think this was an small eruption rather then water flooding under Mýrdalsjökull glacier.

Strong harmonic tremor pulse starting in Katla volcano
Most likely water creating harmonic tremors in Katla volcano (for the moment)

Both blog posts are from 6. September 2011.

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Harmonic tremor pulse in Katla volcano

Today there was an harmonic tremor pulse in Katla volcano. I am not sure when this harmonic tremor pulse did start. But I am guessing around 15:22 UTC or maybe around 16:00 UTC. It seems that this harmonic tremor pulse was small, considering the activity in July 2011 in Katla volcano (an minor eruption). This harmonic tremor pulse seems to have happened in the north part of Katla volcano, outside the caldera from my best estimates but might well be inside it in the north part of it. But it hard to be sure on that detail. From what I can tell, this harmonic tremor pulse does not appear on my geophones clearly. But it might have appeared on Hekla geophone poorly. But it is hard to be sure on that due to wind noise. When this is written the harmonic tremor pulse appears to be dying down. But there is still an possibly that it might pick up again or an new one might start without warning. It is impossible to know for sure how long this is going to stop after this harmonic tremor pulse. This harmonic tremor pulse is due to dike intrusion in Katla volcano at depth, so earthquakes might not happen until it reaches shallower surface in the crust. If the dike intrusion gets that far to start with.


The possible location of the harmonic tremor marked by the poorly located earthquake in Katla volcano. Copyright of this image belongs to IMO (Iceland Met Office).


The harmonic tremor on the Slysaalda SIL station where it is the strongest. But that means it is closest to this SIL station. Copyright of this image belongs to IMO (Iceland Met Office).


The harmonic tremor pulse on Goðabunga SIL station. The harmonic tremor pulse is weaker here then on Slysaalda SIL station. Copyright of this image belongs to IMO (Iceland Met Office).


The harmonic tremor pulse on Skrokkalda SIL station. One of the SIL station that have the most distance from Katla volcano area where the tremor pulse is taking place. Copyright of this image belongs to IMO (Iceland Met Office).


The harmonic tremor pulse can clearly be seen on Lágu Hvolar SIL station. Copyright of this image belongs to IMO (Iceland Met Office).


The harmonic tremor on Smjörgil SIL station, it is located in the flanks of Eyjafjallajökull volcano. This SIL station is close to Goðabunga SIL station. Copyright of this image belongs to IMO (Iceland Met Office).

What happens next in Katla volcano is hard to know. It all comes down to wait and see what happens next in Katla volcano. Eruptions in Katla volcano in January – February time period are not common, but due happen at times. So this harmonic tremor pulse might be an advance warning of what is to come. But that is just speculation on my part. It is impossible to know for sure what happens in Katla volcano until it happens.

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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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El Hierro volcano eruptions ends (again)

Based on the harmonic tremor data in the past few hours it seems that the eruption in El Hierro volcano has ended again. How long or if the eruption has really ended now is impossible to know at the moment. However it is clear based on the tremor activity that all eruption activity has ended and it did so suddenly and after sharp increase in activity several hours before that.


The activity in El Hierro volcano today. Notice the spikes when the eruption suddenly gains energy and how fast it dies out based on the tremor data. Copyright of this image belongs to IGN (Instituto Geográfico Nacional).

Even if the eruption has ended. For the moment anyway. The area where the eruption took place is going to have hydro thermal activity for several months to comes, and up to many years if there are any shallow dike intrusions in the base of El Hierro volcano (and Island). I do not yet know if the eruption has ended, or if this is just an brake in the current eruption cycle. But next few hours to days are going to make it clear if this is an break or not. But I would not be surprised if the eruption started again at the same location, or an new one. As this is shield volcano and there eruption pattern often have breaks in them for shorter and longer periods of time.

Update 1: It has been sad that the graph has once again been re-scaled. To what size I do not know for sure. But in an comment on Facebook it was sad to be around -36dB. If that is the case. I am wrongly interpreting the data. Because of that. I have no idea what is going on in El Hierro volcano at the moment.

Update 2: It seems that activity has renewed again in El Hierro volcano. It started around 04:06 UTC and lasted until around 10:00 UTC. Then it started again at 16:00 UTC and is currently ongoing. This is now an eruption that happens in episodes. That means there are going to be longer and shorter breaks between eruptions in El Hierro volcano.


Activity in El Hierro volcano today. The increase in harmonic tremor marks the start of new eruption in El Hierro volcano. Copyright of this image belongs to IGN (Instituto Geográfico Nacional).

Blog post updated at 00:50 UTC on 20.01.2012.
Blog post updated at 19:31 UTC on 20.01.2012.

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New video of the eruption in El Hierro volcano

The eruption in El Hierro volcano continues with on and off rhythmic at the moment. So fluxuations in the harmonic tremor plots can be rather huge. That is from considerable amount of tremors down to no harmonic tremors at all.


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

Here is also an video of the eruption in El Hierro volcano. I do believe that this pictures are rather new. But I am not sure. The audio is Spanish.

It is impossible to know for how long El Hierro volcano is going to keep up the current eruption pattern. But this pattern might stop at any time, without any warning at all.

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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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Hydrothermal activity in El Hierro volcano

For the moment the eruption in El Hierro volcano has ended. The current harmonic tremor that is being detected might well be from hydrothermal activity that is currently in the area that erupted. But even if the eruption has ended, the area that erupted is going to be warm for many weeks to come. This is going to create hot springs below the sea level, among other ocean phenomena connected to this type of hydrothermal activity.


Harmonic tremor levels remain close to background levels at El Hierro volcano. Taken today at 16:05 UTC. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).

As for future activity in El Hierro volcano. It is important to remember that eruption activity might start again on a new fissure. But that would be pre-seeded by earthquake activity. After the eruption activity stopped there has been some earthquake activity. But it is not at that level I would expect before a new eruption where about to start in El Hierro volcano. For the moment however things remain quiet in El Hierro volcano. A relieve to the local people in the area I would think.

Other

I want to remind people of the volcano and earthquake forum. It allows for more discussions on volcanoes, earthquakes and other stuff that might not belong to this blog.

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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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Harmonic tremor pulse in Grímsfjall volcano

There have only been seven months since (May 2011) the last eruption in Grímsfjall volcano. But it seems that Grímsfjall volcano is getting ready for its next eruption. Even if the last eruption was the largest one for at least 140 years in Grímsfjall volcano. So far earthquake activity remains low in Grímfjall volcano. But I am not sure if that means anything for the moment. But there has been in earlier lead up to a eruption a build up of earthquake activity in Grímsfjall volcano.

Today at least two harmonic tremors spikes have been detected by IMO. But this type of harmonic tremor pulse have been detected before in Grímsfjall volcano. Older blog posts on that subject can be found here and here. But this time around it seems that the harmonic tremor is stronger then before. Currently it remains uncertain of there is a glacier flood starting from Grímsvötn lake, as was the case last time this type of harmonic tremor pulse was detected in Grímsfjall volcano.


Harmonic tremor in Grímsfjall volcano at 00:21 UTC on 5 December, 2011. Copyright to this picture belongs to Iceland Met Office.


The harmonic tremor in Grímsfjall volcano at 01:39 UTC on 5 December, 2011. Copyright to this picture belongs to Iceland Met Office.

There is a clear change in the harmonic tremor, as can be seen here. But why and what this actually means for Grímsfjall volcano I am not sure. But I am rather sure that this means a new eruption might only be several months away. But it is hard to know that for sure. But I am just base my estimate on earlier experience with Grímsfjall volcano. But it might not mean anything after last eruption.


The GPS data from top of Grímsfjall volcano. The data is missing for the last few days. Must be because of snow and ice. But given the last data set, the change so far it not that great since the eruption last spring. Copyright to this picture belongs to Iceland Met Office.

What happens next in Grímsfjall volcano is a big question. But it seems that Grímsfjall volcano is going to go for a new eruption. When that might happen I have no idea.

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Activity remains low in Iceland. Eruption continues in El Hierro volcano

At the present time the earthquake activity remains low in Iceland. This goes for both Katla volcano and other areas of Iceland. This is the regular quiet time in Iceland, as it happens sometimes. For the next days, there is a risk of frost-quakes as the ground freezes over in a cold snap.

El Hierro volcano, Canary Islands

The eruption in El Hierro volcano continues as before. New eruption vents have been opening up at random in the south part of El Hierro volcano. Earthquake activity to the north has dropped. While at the same time, the earthquake activity seems to have increased slightly to the west part of El Hierro volcano. I am not sure why that is yet.

In the tremor data. I have been seeing several explosions taking place. But they create a spikes in the tremor plot, that is different then what happens when a earthquake takes place.


The current harmonic tremor from El Hierro volcano. Explosions are the spike activity (30 November, 2011). Some of this however might be sudden increase in eruption activity. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).

Other then that. The eruption in El Hierro volcano seems to be about the same for the moment as it has been for the past almost two months now. So far it is impossible to know when this eruptions ends. But eruption in La Palma volcano lasted about one month on average. Eruptions in Lanzarote volcano have lasted about three months (last eruption was in the year 1824). Based on this. This might be a eruption that lasts for about 3 to 5 months at the longest in my opinion. But what actually happens is just something that is a wait and see matter.