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.
After the eruption ended in El Hierro volcano it seems that minor magma dike intrusions have been taking place. This magma intrusions so far appears to be deep and not big. Given the depth and the size of the earthquakes that are currently taking place. This also suggests that new magma continues to flow into El Hierro volcano. But that flow might be at slower rate then it was early in the year 2011 before the eruption started. The largest earthquake in this swarm had the size ML2.8 with the depth of 12 km. Based on automatic data.
The current earthquake activity in El Hierro volcano. The earthquake swarm in question was small in size. Copyright of this picture belongs to IGN.
The earthquake activity appears clearly on this picture. The highest peak is the ML2.8 earthquake. Copyright of this picture belongs to IGN.
It is hard to know for sure what this means for future eruption events. Before the earthquake swarm today there was an small eruption somewhere in El Hierro volcano. It can be seen by the harmonic tremor levels. But this event was small, a lot smaller then earlier events. All that can be done is to wait and see what happens next 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.
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.
Based on the earthquake activity in El Hierro volcano it seems that new magma injection has taken place, or is taking place at current time in El Hierro volcano.
This new magma injection into El Hierro volcano has already been followed by stronger harmonic tremors and more activity on the surface. As should have been expected when this happens. It is impossible to know at the moment how large and how long this new magma injection is going to last. But while it is ongoing, more eruption activity should be expected from El Hierro volcano. So far nothing suggests that new vents are about to open up in El Hierro volcano at the moment.
Other then this renewed activity. Nothing else has been happening in El Hierro volcano. There have been some news reports (in Spanish, use Google Translate to read) about new thermal anomalies in El Hierro volcano. This might just be hydro-thermal activity following dike intrusions at shallow depth.
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.
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.
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.
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.
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.
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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