The current tremor data now suggests that a new vent or vents have opened or are about to open up just outside north-west coast of El Hierro volcano. The depth where the main earthquakes have been taking place is about 100 to 300 meters (but might be more). So far the largest earthquakes to take place in this area was a ML3.9 with the depth of 22 km. What is important in this is not the fact that the earthquakes are at great depth. But also the fact that a more shallow might not take place. As that was not the case when the eruption started in El Hierro on 10 October, 2011. It is unlikely that there is going to be any shallow earthquake activity before a new eruption vents opens up. As that was not the case on the 10 October, 2011 from what I can remember.
Current harmonic tremor in El Hierro. So far there has not been much change in harmonic tremor as can be seen here. But that can change without warning. Copyright of this picture belongs to Instituto Geográfico Nacional.
I am not sure how strong earthquake this area can make. But I am guessing that it might well be in the upper Mb5.5+ range. The earthquakes that are now taking place are due to magma injection. Not a tectonic one. There is a difference between the two. But this rifting in El Hierro might trigger a earthquake close to El Hierro Island in near future, that earthquake would be a tectonic one. Not a earthquake created by magma movements.
So far the new vents are still unconfirmed. But there are signs in the harmonic tremor data that new eruption vents might be opening up or have already opened up. But at this moment I am waiting for a confirmation on this actually taking place. That is going to take a few hours, given the experience so far.
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.
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)
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.
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.
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.
A large landslide did fall last Friday in a valley called Eyjafjarðarsveit. This is the largest landslide in this area for 17 years, when a smaller landslide did fall from a different mountain in this area. This landslide was large enough to block a small river that is in this area. Next farm to this landslide is about 7 km away from it. They do not tell what direction (north or south) the farm that is closest to this landslide is. The mountain that this landslide did come from is called Torfufell.
New from Rúv about this landslide.
Stór skriða féll í Eyjafjarðarsveit (Rúv.is, Icelandic, Pictures)
Update 1: Here is a new news about this landslide. It says that the area is going to be up to 30 years to recover in terms of flora and plants in the area that is just mud at the moment. The main rock in this area is Rhyolite. It is now also believed that two landslides took place in this area. But when it came down. It did travel 1.5 km down the valley. It also did create a lake (I have no idea if it is permanent new lake or not) where the landslide did block the river.
Landslagið gjörbreytt eftir skriðuföll (Rúv.is, Icelandic, Picture)
Fréttir: Gerbreytt landslag eftir skriðuföll (Rúv.is, Icelandic, Video, Flash)
Note: Next blog post about the eruption in El Hierro is going to be tomorrow. It seems that not a lot has been happening in the eruption of El Hierro today and yesterday.
Blog post updated on 20 October, 2011 at 22:16 UTC.
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)
This is a special report on the eruption in El Hierro, Canary Islands, Spain.
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.
Today (18 October, 2011) at 08:53 UTC a earthquake swarm started in TFZ. So far this earthquake swarm is small in nature, only about dozen earthquakes so far. But the largest earthquakes have been with the size of ML3.6 according to IMO automatic earthquake detection system (called SIL). There is a good chance that this earthquake swarm is going to continue for the next few hours. But it is hard to know that for sure at the moment.
The area with the earthquake activity in Tjörnes Fracture Zone (TFZ). Copyright of this picture belongs to Iceland Met Office.
There are no volcanoes in the area where this earthquake swarm is taking place.
Blog post was updated at 11:58 UTC on 18 October, 2011
This is a short note on the Hengill volcano man-made earthquake swarm.
The earthquake swarms that have been taking place in Hengill volcano are man made due to Orkuveita Reykjavíkur pumping down water at the depth of 2500 meters or more (down to 4000 meters from what I have read). It is clear that Orkuveita Reykjavíkur (short name OR) does not have any option but to continue this water pumping, as it is mandated that they do so in there operation permit. They have been doing this for some time now. But when they started using new drilling holes to pump down water the earthquake swarms started to happen. The people at OR claim that it is unlike that this earthquake swarms are going to grow in size and magnitude. I do not agree with that assessment.
It is my view that increased water pumping into the bedrock is going to increase earthquake activity. This has been agreed on by geologist that are not connected to OR or the government. But the largest earthquake that this area can make is Mw 6.0 in size according to a estimate on this area. So far, the largest earthquakes have been up to ML 4.0 in size so far. A jump in magnitude from ML3.5 size that was in earlier pumping was done.
There is also risk of pollution of the groundwater from heavy metals in the hot water (lead, zinc, copper and others). But this risk also seems to have been underestimated. As they claim that pumping down the water below the 800 meters groundwater line does not affect the groundwater. But it seems that no studies (that I know) have been done to confirm this.
News on Rúv about this.
Aukin dæling mun auka skjálftavirkni (Rúv.is, Icelandic)