El Hierro Activity Ramping Up Again

El Hierro, the volcano in the Canary Islands, may not be quite done yet (as was suspected by a great many following the behavior of this volcano). Although officially the government had lowered the volcanic threat alert level down to "Green", many volcanologists and volcano enthusiasts (including myself) were skeptical about the government's stance on the volcano. This week nearly 20+ earthquakes occurred at depth and some more shallow, as a science vessel captured images of a submarine ash and gas emission at "Bob", the submarine cone of El Hierro.

Other indications point to renewed or at least intermittent activity of the volcano, and much to the chagrin of the authors at Earthquake-report.com, the Spanish government seems to be covering it up, or at least attempting to obscure observations from the rest of the world and scientific community. For what reasons, nobody knows, but I suspect it is another wrong-headed attempt to get tourists to come back to the island.

While the El Hierro submarine vent has been relatively quiet these past couple of months, it has remained in a state of degassing, and the recent emission points to the possibility that the eruption could easily resume at any time. The amount of magma erupted is still far smaller than the volume of the actual magma chamber, and most likely much smaller than the amount of new magma that was injected into the chamber. Due to these facts, it is likely that the El Hierro island could see a longer period of eruptive activity in the future (this could be a precursor event to a more 'traditional' eruption above land, but so far there have been no records of serious GPS deformation, or increased CO2 emission on land).

The volcano caused quite a stir in the scientific community when the eruption was preceded by many thousands of small quakes. The island itself had not had an eruption since the 1700's, which was poorly documented internationally (locally, there is a wealth of knowledge and history), and most people had thought the Island to be dormant. That changed when a presumed eruption started taking place off the coast of the fishing village of La Restinga. The eruption was spotted when dead fish started washing ashore, and a large 'stain' on the oceans surface manifested. This was followed by what is known as a Serretyan eruption, which produced 'lava balloons' - bubbles of gas filled lava that would float to the oceans surface, and produce a fiery burst when the lava cracked and exposed superheated gas to oxygen. The lava rocks would then fall back to the ocean floor, building the underwater cinder cone further.

This continued for some months, and eventually dwindled down to a degassing phase. Many people had hoped/thought that the volcano would eventually create a brand new mini Canary Island, in what is called a Surtseyan eruption (where a submarine volcano breaks the water's surface to crate either an ephemeral island, much like what occurs regularly in the Marianas island/volcano chain, or a more permanent island like the recent eruption of Jebel Zubair in Yemen). It would have been a spectacular site for those on the island, and those that were watching the eruption webcam before the Spanish government shut it down (apparently running a webcam is really expensive! Yeah right...).

So I will again follow the goings on at La Restinga like I did before the eruption ended to bring you updates as they happen. This is a fun and suspenseful volcano for me to write about because it is such an unusual eruption, and it's occurring on an Island that didn't have much historical eruptive history. I always enjoy a good surprise. I'm not so sure the residents at La Restinga do however, as apparently they are beginning to loathe the attention that their volcano is getting, both from the reporters at El Hierro, and their own government.

El Hierro Activity Still Apparent, Government Pretending It's Not There

The Spanish government at El Hierro is quickly trying to sweep the eruption under the rug. Even while Earthquake-report.com's Joke Volta continues to photograph clear evidence of underwater activity, underwater video showing degassing and small amounts of erupting lava, and even while seismographs continually record weak volcanic tremor, the government has insisted that the eruption is over. And to prove just how serious they are, they are lowing ALL alert levels, including near the eruption zone itself to "green".

This has a lot of people, especially the folks over there at Earthquake-report.com, scratching their heads as to why a government could actually be so careless. This whole eruption at El Hierro has been incredibly mismanaged by their tourism industry, and the government. Indeed the government has even stood in the way of actual scientific data on the eruption even being made public! Their stance has been one of fear, and thus far has crippled the economy of the small town of La Restinga, rather than helped it. From over cautious evacuations to cover ups, to the downright irresponsible LIFTING of the alert level, it seems the only people who know the truth were those that watched the web cams and hovered over the seismic data. And now the webcam is gone.

This has been a very odd volcano to report on, not because of its submarine eruption near a bustling tourist town, but because of the politicization of a volcanic eruption. It is a story that belongs in a bad volcano movie (Sorry Tommy Lee Jones!), not the real world.

Volcanic eruptions, when benign, and non-threatening as El Hierro is, typically should be a boon for communities and countries. Hawaii volcanoes national park in the US regularly draws tens to hundreds of thousands of visitors a year, all who want to see molten lava hit the ocean in giant explosions and witness the birth of new land. Iceland had an incredible surge in tourism when Eyjafjallajökull erupted in 2010. Italy's Etna volcano is famous worldwide for its frequent and spectacular paroxysms. And there are multiple volcanoes in South America such as Arenal, Poas, Tungurahua, and more that are regular draws for tourists and scientists alike...

So why did the El Hierro situation go the exact opposite way? First, the government tried to sweep it under the rug. Then it admitted something was going on, and it overreacted and evacuated large portions of the island, and also TOLD tourists not to show up. After that, they regularly butted heads with scientists, telling them what they could and could not make public about a geological event, sewing distrust. And if you are a regular reader of Earthquake-report.com and Joke Volta's adventures there, you'd know that she is now under pressure to "shut up" by the locals who are starting to blame her and Earthquake-report.com for the lack of tourists (or scaring them away) because of her efforts to document every day of the eruption (which is what GOOD volcanologists DO!).

This is kind of spooky. Why on earth would the Spanish government want to cover up an eruption that is CLEARLY ongoing? Its quite strange and disturbing to think that a government can be so incompetent in regards to a natural geological event. It could have gone so differently for the island of El Hierro and the town of la Restinga. They could have had thousands of sight seers, and busy cafe's, but the government instead scared everyone, and tried to un-do their mistake. Now it's simply a mess, and nobody is very happy about it. 

It Is Official: El Hierro Eruption Has Ended

INVOLCAN has declared the eruption of El Hierro to be over, and the alert status of the island has been lowered from Red to Yellow. The village of La Restinga can finally open its doors to tourists again, however maritime activity is still restricted due to probable degassing, and swimming in the water is still off limits pending a chemical analysis of the water to determine its safety. Sea life has already begun to repopulate the area, a good sign for the fisherman of the village.

The eruption at El Hierro was preceded by a lengthy period of volcanic earthquakes, which were used to size up the magma chamber. The island was on Yellow alert for a long time, before a "jacuzzi" was spotted in the ocean, and harmonic tremor increased. The eruption of the underwater cone "Bob" started as an underwater fissure eruption, eventually resulting in a cone building event. Several collapses of the main vent stalled the eruption, which stopped and started several times. On occasion, floating "Lava Balloons", or gaseous bubbles encased in molten rock, would float to the surface and emit steam, and sometimes flames once the bubbles burst and allowed oxygen to interact with the heat. This however was as exciting as the eruption got.

For about a month now, the eruption has all but ceased entirely. Harmonic tremor has been at low to background levels, and there has been very little if any surface activity since February. This is what led the scientists to declare the eruption over, although their maintaining of alert level Yellow does indeed reflect what many of us know, that activity can resume at any time, and caution is still in order. Some volcanoes have a small cone building event as a precursor to a larger eruption, something that is certainly not out of the question.

Current uplift sensors show the island to be stable, which could mean that the magma reservoir has not deflated, and merely extruded the lava to form "Bob" because it was the easiest path to the surface. Quakes are still ongoing at El Hierro in an area not near "Bob", and it is still worth keeping an eye on the island. El Hierro and the Canaries have been compared to the Hawaiian islands in regards to the type of eruptions it produces. The theory goes that El Hierro, like Hawaii, is a hotspot type volcano. These are highly unpredictable as we have no way of imaging or monitoring the mantle plumes that are though to be responsible for hotspot volcanoes.

It is my guess that activity will pause now for probably months, and either slow subsidence will take place, or activity will resume in another location. It is now a game of wait and see. In any case, I doubt that the residents of El Hierro will ever forget now that they are living on an active volcano, and will be ever mindful of the power that lies beneath their feet.

Tremor Gradually Increasing Again At El Hierro

Harmonic tremor at El Hierro is very gradually increasing, at an almost imperceptible rate, but it is occurring. The tremor from yesterday to today is now about twice as strong as it was, but is still very low, and the eruptive vent is not displaying any surface activity at this time. This could mean that the magma is slowly (and I mean VERY slowly) building up again and is re-pressurizing the vent. At this time however, this is all uncertain, and we will need to wait and see if this is an anomaly, or a pattern.

Tremor readings at El Hierro, showing a very slowly increasing amplitude.

The eruption at El Hierro has been at a very low level the past couple of weeks, but is still apparently ongoing. The eruption is being compared to submarine eruptions in Hawaii such as Loihi, in that underwater flows are continuing slowly, but surely. Degassing is still taking place, although at a very low level compared to a couple of weeks ago. The "Jacuzzi" is spotted intermittently, but remains weak and doesn't stick around for long. It is possible that the activity could resume, or simply diminish.

El Hierro Eruption Continues At Low Level

While the harmonic tremor readings are nearly flat, and visuals on the surface of the ocean have been few and fr between, the El Hierro submarine eruption is continuing at a low rate. For the last few days, the "jacuzzi" and stain area have made faint appearances, and water temperatures over the vent are still high enough to generate a steamy haze over the vent area. Today the jacuzzi area is a bit stronger, even though harmonic tremor is about the same as it has been for the last week or so.

The earthquakes to the West of the eruption zone have been continuing, varying from up to 20 quakes per day, down to a low of about 7. They are getting shallower in this area, indicating the possibility of more magma movement possibly to a different area. This could explain why "Bob" (the unofficial name for the submarine volcano) has shown minimal activity, because magma may be finding another route through the crust. It could also be that "Bob" is simply re-pressurizing, and the renewed jacuzzi and heat activity could indicate that the cone itself is heating up again and getting ready for another round of eruptive activity. Only time will tell. This could simply be underwater cooling and degassing, but this would not account for the activity today (the ocean is a GREAT heat sink, especially for cone building events such as this).

There have been regular scientific expeditions to the eruption area, with several scientific vessels taking bathymetry readings, and sonar scans of the ocean floor. From what I've read on Earthquake-report.com (they are fortunate enough to have a local reporting for them and taking daily photos), an ROV missions is planned in the near future to take direct video of the vent area, however due to currents and sometimes bad weather, they haven't had much luck getting the remotely operated vehicle deployed yet (they are insanely expensive, so they will always err on the side of caution when it comes to this equipment).

So until we have direct observations from the sea floor, it is hard to tell what the state of the eruptive cone is in at this time. All we can infer from tremor, and surface observations is that this eruption is continuing at a low level as it has been for the past week or so. This could change at any time.

In a previous post about El Hierro, I pointed out the similarities between El Hierro and the Hawaii island chain. While Earthquake-report.com picked up on this idea as well, they erroneously compared this eruption to that of Kilauea, instead of its newer and less active neighbor, Loihi. The surface eruption on Hawaii's Kilauea volcano is unimpeded by ocean water, and is able to create stable channels for lava to flow onto the surface. Loihi (first detected in eruption in 1996) is a submarine volcano SW of the Kilauea summit, and has periods of activity followed by long periods of dormancy, and has a lot of the same characteristics of the El Hierro submarine eruption.

While it is my belief that El Hierro, like Hawaii, is a "hot spot" type volcanic system, the dynamics are different from Hawaii. The chemical makeup of the lava is different, the location is certainly different, and instead of an underwater shield volcano (like Loihi), this seems to be a mere cone building event not separate from the main volcanic system at El Hierro.

Hot spot volcanic systems like the Hawaiian and the Canary islands can have long period of eruption like Kilauea, or short periods of strong activity... really the range of activity these spots are capable of is huge. El Hierro might be entering a phase of long term activity given the quakes, their locations, and the duration of what people thought was probably going to be a very small event. This is a volcano still worth watching, and is of great scientific interest.

*****UPDATE 2/27/2012*****

Activity at El Hierro is unchanged. Low and almost nonexistent harmonic tremor, coupled with light degassing and small jacuzzi visible. Probably the actual eruption of "Bob" the underwater cinder cone is over. However GPS data indicates uplift of the island of El Hierro itself, and quakes are clustering at the northern end of the island. El Hierro appears to be inflating, and it is not unreasonable to think that another cone building event, possibly on the island itself, may occur in the future. When is impossible to say.

El Hierro Volcano Eruption Winding Down

After 3-4 days of continually weak harmonic tremor at El Hierro volcano, it appears that the eruption is starting to wind down on the underwater cone. This does not mean that the risk of further activity, or other eruptive vents opening is over. Over the last few days, around 20 or so earthquakes a day have been recorded to the West of "Bob" (the tentative name for the underwater cone), gradually rising from 20KM beneath the surface, to 7KM yesterday, indicating a rapid dike intrusion. The GPS data shows a stable (not deflating) surface, which indicates that the magma chamber is still quite loaded.

Currently, the harmonic tremor at El Hierro is at a very weak level, with very minute occasional spikes (most likely those spikes are related to the earthquake activity to the West, and not from the vent itself), with the trend going lower and lower. This of course could indicate that the vent has collapsed and is simply re-pressurizing, and is merely gearing up for more action, but as the tremor has been gradually decreasing to the point it is now, my guess is that the vent is sealing up to the point where it can no longer erupt without some massive pressure from the magma chamber.

If anything further happens at El Hierro, rest assured I will cover it. For now, it may be time to finally say, "Bob has gone to sleep"

*****UPDATE 2/17/2012*****

Last evening, there were some images captured of nighttime smoking lava stones seen on camera, a bit to the East of "Bob", even while harmonic tremor remains nearly flat, proving once again that HT readings often do not correspond to actual lava emissions. HT is flat again today, although there was a 2.5 mag quake in the area which residents probably felt a little bit. There is no visible stain on the oceans surface, however a research boat and her crew reported smelling sulphur directly over the vent. It's really anyone's guess at this point as to what the situation looks like. It could easily be a "pillow lava" flow going on at the ocean's floor with occasional rising lava balloons (gas filled lava blobs that combust on the the ocean surface). Pillow lavas typically do not emit underwater "smoke" nor do they release a large amount of gas (it's more like squeezing toothpaste out of a tube, and is fascinating to watch video's of). At least this is my theory. If anything else happens, I will post another update.

*****UPDATE 2/18/2012*****

Tremor still extremely low, but surviving. It is probable some activity is occurring underwater, however any activity is weak with no visible "jacuzzi" area, and there has been no visual observations of lava balloons, or a stain. Current webcam views show a calm blue sea, with no disturbances.

Earthquakes however continue to pick up, with approximately 20 quakes a day over the last few days, and a 3.3 magnitude tremblor this morning. This definitely says that there is still a large, and active magma chamber underneath the island that probably has more in store. With the final collapse of "Bob" and cessation of eruptive activity, it is entirely possible that the magma must find another way to the surface in another location. With the locations and depths of the current quake swarms, it looks a bit likely that this might end up being off of El Hierro's SW coastline, directly W of the main vent.

This could end up being the last post about El Hierro for a while, as other volcanoes demand attention.

El Hierro Tremor Increases, Activity Resumes

2/09/2012

After a two day break from anything major at El Hierro, the volcano is gradually picking up steam again. Tremor for today shows a very slowly increasing amplitude, and webcam images show a very prominent stain with jacuzzi area once more. Some smoking stones could be seen on the water's surface.

Seismograph from IGN for today which shows slowly increasing harmonic tremor.

The activity at El Hierro is hard to predict, and even harder to forecast. At this point, the eruption is clearly a much longer term eruption than scientists could have expected, and it appears to have no real end in sight. Earthquakes and tremor are persistent, and the cone shows no signs of stopping its growth any time soon. I am awaiting the results of the latest survey of the cone to see whether or not it is getting much closer to the surface. At last glance, it was approximately 35M below the sea surface, but the cone has suffered several collapses so this is probably no longer accurate (could be higher, or lower).

There have been a couple rumors (but they are ONLY rumors) of thermal areas being detected on the terrestrial island, but this has NEVER been confirmed. A good NASA snapshot could easily kill that rumor, and one will probably come along eventually. 

*****UPDATE 2/9/2012-2/10/2012*****

The tremor is still increasing, while surface activity remains unchanged. What this means at this time is unknown, but could indicate further magma injection into the El Hierro magma chamber. This has been steadily increasing since early yesterday until now, with tremor showing no signs yet of abating or decreasing. This probably means further underwater explosive activity will occur within the next day or so. The reinvigorated tremor readings from IGN can be seen below.

*****UPDATE 2/11/2012*****

The tremor at El Hierro is decreasing again, after three days of moderate and sustained tremor. A stain is still visible on the water surface, and a jacuzzi area comes and goes.

Decreasing tremor at El Hierro today.

*****UPDATE 2/13/2012*****
The harmonic tremor readings at El Hierro volcano in the Canary Islands have been erratic the last couple of days. Frequent fluctuations between medium-strong, to barely readable have been the pattern the last couple of days. This most likely indicates an unstable cone/fissure vent, and consistent magma pressure on the vent. Currently, tremor is low, but picking up, suggesting that the volcano is slowly clearing whatever obstruction may be in the vent.

Below is the current tremor readings for today.

                           

El Hierro Update

El Hierro tremor picked up this morning as a large stain and jacuzzi area reappeared after the lull in activity yesterday. This morning a ship could be seen cruising the stain area, presumably a scientific ship collecting data. Vent collapse yesterday built up pressure and caused nearly 10 small earthquakes, followed by a resumption of harmonic tremor and eruptive activity today. This is becoming a pattern.

Plenty of smoking lava stones could be seen live on the camera, with the ship swooping around to try and scoop them up before they burst and fall back to the ocean floor in a fiery pop. The presence of these smoking stones rules out a simple hydrothermal surface eruption, and confirms lava is still being emitted at the vent. It also appears that multiple smaller vents have opened aside from the main vent, as there are two smaller jacuzzis present in webcam images. there is a second large vent, and a much smaller one as of now. The larger new vent is to the East of the original one, and the smaller vent is N of the original vent. This totals nearly three vents active from what I can see on cam.

Smoking lava stone right of ship this afternoon at El Hierro.

El Hierro will likely continue to erupt for some time. You can see today's current tremor graph below.

Tremor this morning, Image copyright IGN.

As is the case with many "hotspot" volcanic systems, they are hard to predict, and often will have long term effusive eruptions like Kilauea in Hawaii. The eruption at Kilauea has entered its 25th straight year of activity with no end in sight. El Hierro could end up being this type of long term eruption, or simply cease at any time, however given the size of the magma chamber, and the characteristics of this eruption, I'll say that El Hierro has plenty still to give. 

Activity Strong Today At El Hierro

The Canary Islands volcano does not seem to want to quit. Despite reports around the web and other blogs that say "El Hierro Eruption Stops", it seems again that El Hierro is making fools out of those who try to predict this volcano. Today the activity is quite high, with more lava balloons (gas filled lava that floats on the surface of the water) visible day and night, and a very strong "jaccuzzi" area present during the afternoon at El Hierro (below).

Picture from Movistar/Telefonica webcam.

El Hierro has been in a sort of on-off-on-off-on pattern with its eruptions, probably due to structural adjustments and dome collapse underwater. Once magma pressure builds again, activity resumes. This is probably indicative of a large magma chamber beneath the island. My guess is that the volcano probably has plenty of life in it yet, and that we can't expect it to stop anytime soon.

Pictures posted on Earthquake-report.com from the local scientific expeditions show that there are now two vents active underneath the water. The main vent, lovingly referred to as "Bob", and a nameless vent closer to the shore, but much smaller. The dual jaccuzzis can be seen in the image above. 

The main vent is now a mere 30-50 meters below the sea surface, and if activity continues, we will most likely bare witness to a surtseyan eruption within a couple months. Just last month a similar eruption created a new island in the Jebel Zubair chain in Yemen. Since that area isn't closely watched, and is rather deserted, that eruption was a surprise only identified by local reports and satellites. Scientists did not witness the start of the eruption underwater, and thus only knew of the eruption once it breached the surface, so we have no way of knowing how long Jebel Zubair erupted for. 

We are fortunate with El Hierro to see the precursors to the eruption in the form of a vast amount of earthquakes, along with the underwater cone building phase, and hopefully the surtseyan island forming phase. This will have been a complete record of an eruption, and will no doubt be invaluable to science.