El Hierro Reawakened? [Updated 10/15/2012]

It seems as of this hour that the El Hierro volcano might have sprung a new vent underwater off of the Las Calmas area of the island. Earthquake-report.com has an interesting picture of what appears to be a vent on their El Hierro running forum. They quote blogger Jon Frimann as saying that this could be related to dike intrusion, and that eruptions can and do take place without harmonic tremor. Jon is correct to state this, as many eruptions can and do happen with little warning.

Image from Earthquake-report.com of supposed El Hierro coastal activity.

The current photographs from El Hierro, the continuing seismicity, and the apparently new activity in regards to the above photo point to a renewed activity phase for the island, which had not erupted since the late 18th century. While it is still far too early to tell, it appears that the island is once again erupting.

The fact that the activity has been mostly constrained now to the outer flanks, and submarine depths, suggests that the age of the volcano, and the coolness of the solidified lava above it may be protecting the mainland from any activity so far. Indeed this would seem to correlate with the fact that the island has had much uplift, but little subsidence despite the previous eruption releasing lava underneath the sea on the Southern tip of the island. Think of it like a solid chunk floating on a block of jell-o. The island is uplifting because it is currently too dense to fracture and create above-water vents, but uplifts because the ground beneath is lubricated by water, and is from thinner crust.

As the lava bubble forms to the SW of the island, the island would be uplifted to the NE which is consistent with the current measurements.

It could very well be at this time that continued activity on El Hierro might be exclusively submarine. Hotspot volcanoes, much like Hawaii's Loihi mount, tend to follow the path of least resistance to the surface. It could be that, much like the big island of Hawaii, the activity has moved south, and a new Canary Island may be in the works. We will likely not see the result of this migration of lava columns in our life time, as Loihi will take some 10,000 years to break the surface of the ocean in any significant way. But it is still a very fascinating process to watch, which is why El Hierro gets such a good amount of press among bloggers.

El Hierro's webcams were turned off some time ago, so coverage on the eruption will almost exclusively come from Earthquake-report.com, INVOLCAN, and IGN. I will post more updates as they become available.

*****UPDATE*****

INVOLCAN has released a statement regarding the pictures taken from a helicopter flight over the quake area:

"“El PEVOLCA confirma que no se observan parámetros anómalos en la zona sobrevolada por el helicóptero del GES. Científicos del INVOLCAN, que portaban una cámara térmica, y del Instituto Geográfico Nacional no han observado parámetros anómalos en el vuelo de reconocimiento que han realizado esta mañana en el helicóptero del GES, en la zona en la que ayer se atisbó una mancha blanca en el mar y burbujeo. Con este vuelo queda definitivamente confirmado que no se han producido cambios significativos en el proceso magmático activo en la isla de El Hierro, aunque se mantiene el análisis de datos de forma continua.”"

Translation:

"PEVOLCA confirmed that no abnormal parameters observed in the area flown by helicopter from the GES. INVOLCAN scientists, carrying a thermal camera, and the National Geographic Institute have not observed abnormal parameters in the flight of recognition they have done this morning at the GES helicopter in the area in which peered yesterday a white spot on the sea and bubbling. With this flight has been finally confirmed that there were no significant changes in the active magmatic process in the island of El Hierro, while maintaining the data analysis continuously."

Seismic activity today has produced several quakes since early yesterday, but has since subsided with no new significant swarms. If anything further develops, an update will be posted. For now things have not changed much in the last couple of weeks.



*****UPDATE*****

It seems the hype this time over El Hierro might be a bit premature. While there has been a lot of earthquakes lately, all have been at or below a depth of 19km, which is far, far below the earth's surface. El Hierro may have some turbulence at a great depth, but is by no means near an imminent eruptive phase at this time. Seismicity will most likely continue for some time, but may or may not result in further activity.

The main concern is really, at this point, for the people of El Hierro, and as of now, the are in no danger. The quakes, while numerous, do not amount to much more than a stirring of magma currents deep below El Hierro, which is expected given the displacement of materials caused by the last eruption. This could be merely crustal adjustments, or something foreboding... at this time, nobody really has an answer.

It is clear now, that this is an active island volcano. What cant not possibly be clear is whether or not the recent activity is a precursor to more. My gut instinct says that El Hierro will experience more activity in the near future, but m gut instinct is not beholden to scientific scrutiny, and therefore cannot be relied upon. Only time will tell at this point, and for now, it appears that El Hierro might just be having some indigestion from its last bout of activity.

As of now, I am pretty m uch going to stop posting about El Hierro unless it becomes particularly active. It is useless to speculate on El Hierro, as it has consistently made fools of bloggers and scientists alike with its random behavior.

If anything new develops (of interest), I will cover it. If you happen to want to monitor the volcano yourself, please go to Earthqauke-report.com's continuing coverage page. This page will keep you up to date with the latest on the volcano, as they have a reporter (Joke Volta) on the premise, as well as a great information sharing agreement with INVOLCAN and PEVOLCA.

****UPDATE 7/5/2012****

It seems that PEVOLCA has been chastised by a member of the El Hierro Government, stating that they jumped the gun or made false statements harmful to tourism on the island. The issue was that PEVOLCA issued the above picture prematurely claiming that this was a new vent, when this had not been confirmed by scientists or bathymetry readings whatsoever. It becomes a cautionary tale for scientists not to get too excited when they think they see something that has not yet confirmed, and to instead follow due diligence in proving what you are claiming.

Today, nothing much has changed at El Hierro. The situation is about the same as it has been. There has been no new inflation, and the continuing earthquake swarm is in the same location and same depths as it was in the last few swarms. It is anyone's guess as to how this plays out. If the quakes become much shallower, there is a potential for the magma to reach the lava tube system of the 2011 eruption and possibly re-pressurize the shallower system. For now, the quakes are at a steady 20-18km in depth, on the NE part of El Hierro, and they have been at about the same magnitudes for the greater part of the day. No large quakes were felt today, but seismographs continue to record minimal harmonic tremor, and small, frequent quakes no bigger than 2.0.

*****UPDATE 7/7/2012*****

After a day or so of calm, with very little amounts of earthquake swarms in comparison to last few days, the quake swarms and uplift of El Hierro have resumed.   The below seismograph image details the currently (as of this writing) swarm, which has reached a little over half an hour in duration at this time now been sustained all throughout the end of the day. Many had thought the island would be calming down after some light subsidence of the islands deformation, but this new swarm may change that.

*****UPDATE 7/16/2012*****

The deformation and quake swarms at El Hierro seem to be subsiding. This can be chalked up to probable gas release as a result of decompression from the rising magma reservoir, and should continue gradually as the quake swarms and magma injection subside. This in no way means that the island will not have further swarms or injection in the future, although for now it appears the events are over.

The events of the past few weeks are similar to the events that preceded the eruption of "Bob" the underwater volcanic cone off the coast of La Restinga. Over 2,500 quakes have been recorded since the start of the swarm.

There was a lull in quake activity prior to the initial eruption, however seismic instruments and GPS measurements were not in place at the time, so the volcanologists that now know this is an active volcano are in data collection mode. Currently, here is a synopsis of what has occurred within the last month:

Quake swarms and vertical/NE deformation were observed. There has been no significant fluctuation in C02/S02 emissions from the erupting cone or on the island. Deformation reached a peak of approximately 10cm, and as of three days ago, began to subside with 1-2cm of negative inflation occurring. Injections of magma into the magma chamber are confirmed, however since the last avenue for magma to reach the surface has been blocked by cooling and water, this event has ended.

The end of the event likely indicates that the magma injected has reached a critical point and is rejecting new magma. This is probably because the current reservoir has no outlet, and thus is changing magma currents from the mantle by producing resistance and/or feedback due to the fact that the pressure in the chamber is too weak to breach the surface (crust) and generate an eruption at this time.

What this means is that El Hierro is again primed for eruption, however it may not end up in an eruption, rather it could simply cool into a 'crystal mush' over time and generate heightened microseismicity on the island for a long time, given that no crustal adjustments that allow magma to escape to the surface occur.

The future of El Hierro at this time is uncertain. I will be keeping a close eye on it, however until anything new develops, I will probably stop updating this post. Stay tuned for more volcano news!!

*****UPDATE 7/25/2012*****

After a relatively calm week, El Hierro Island is shaking again, and deformation is resuming (there have been several D/I [Deflation/Inflation] events within the last few days). There have been sketchy reports from residents about discoloration in the sea in the El Golfo bay area, however no scientific evidence yet suggests this is related to seismicity or quakes (algae blooms can have the same effect on water color).

The seismicity is remaining at the West tip of the island, mostly underneath a lighthouse at a depths of about 20km, however the new swarms include some stronger quakes, at depths of 3km or less (very shallow respectively) int he same region which leads to the question "Are these shallow quakes magma dike intrusion, or are they simply structural adjustments to the inflating magma chamber and other quakes?". Only time will tell in this case, as more data becomes available.

In any case, this has been a busy day on the island.

*****UPDATE 8/10/2012*****

Inflation is being confirmed by INVOLCAN and IGN, quoted as 'rapid'. This is normal behavior for an active volcano and does not mean that an eruption is imminent, although it does make it more likely. Currently quakes are ranging from 10km-8km below the surface of the island. Shallower quakes are suspected to be crustal adjustments to stress from below and are not considered to be directly volcanic in nature. However the magma chamber IS re-inflating, so it could be a matter of months or years for the volcano to resume its activity. It could also be that the chamber inflates, but does not erupt. Updates will be posted as they happen!


*****UPDATE 8/23/2012*****

The seismic swarm at El Hierro has calmed down, and numbers are looking more similar to the numbers of quakes that were occurring before the most recent swarm. It is confirmed that the last swarm was magma intrusion, with what consequence, nobody is certain. For now, vertical deformations are stable, with slight subsidence, but the amount of deformation that has occurred has left the island about 10cm taller than it started out as, so the injection was significant.

*****UPDATE 9/10/2012*****

Seismicity has increased according to IGN/INVOLCAN and Volcano-report.com. Quakes are occurring with more frequency and intensity, and the depth of the quakes has risen to approximately 10km. While this could be simple crust adjustments, it definitely looks more like magma is trying to rise again. D/I events continue to occur.

*****UPDATE 10/15/2012*****

Seismicity remains constant at El Hierro, and deformations are going up and down. What this means at this time is uncertain, but around 10-20 events a day are still being recorded at various centers within the volcano, at a depth of around 10-13km, which is a bit shallower than it was about two months ago when the depths were 15-20km. This could indicate that magma is slowly pushing its way to the surface, but as a lot of the government funded instruments and science teams have been shut down due to the Spanish budget crisis, I am relying solely on earthquake data and the folks who are still covering the story at Earthquake-report.com.

Seismicity Picks Up At El Hierro

El Hierro Island in the Canaires made headlines last year when a submarine eruption occurred less than a mile off the coast of the fishing village of La Restinga, creating an underwater cinder cone, and providing a demonstration of a Serretyan eruption (An eruption consisting on gas filled lava 'balloons' that burst at the ocean surface in a puff of flame, only to sink to the ocean floor and pile up) that thrilled scientists and other volcano enthusiasts. The eruption technically ended some time after the government said it did, but lately seismicity has been picking up and the epicenters of the quakes appear to be getting shallower.

As far as the folks over there at Earthquake-report.com are concerned, they have been on top of things from the get-go with a 'reporter', Joke Volta, on the ground, taking daily pictures and reporting on any earthquakes or changes.

The last few days have seen on average 5-10 smallish quakes, with some larger (mag 4.0 and up) earthquakes. When the seismic swarms resumed, the depths and locations of the quakes were fairly consistent, with most being at the Western tip of the island, 20km below a lighthouse. These quake swarms have now migrated to the center of the island in the area known as El Golfo (the area that resembles a crater, but is actually the result of an avalanche thousands of years ago), and are now occurring at shallower depths (the latest swarm is taking place at a depth of around 12km).

INVOLCAN and PEVOLCA, in conjunction with ER seem to believe this is indeed related to magma dike intrusion at this time, and preparations are underway to possibly raise the alert level of the volcano again from "Green" back to "Yellow", but this is only preparation and precaution, and as of now there is no cause to actually raise the alert level, although I suspect if the quake swarms continue for a lot longer, we will probably see the alert level raised, and maybe even another eruption from the island.

Deformation on the island lately has been stable, although since the end of the last eruption, the island has been uplifted some 10cm! This clearly indicates magma rising in the chamber. Some subsidence has occurred, but for the most part the island right now is stable. Time will tell what the results will be.

*****UPDATE 8/17/2012*****

Earthquake-report.com is reporting over 58 quakes have occurred in the last day in the El Golfo region of El Hierro.

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. 

Video from El Hierro's Underwater Volcano Released

Video of the actual volcano underwater off the coast of La Restinga, El Hierro in the Canary Islands (Spain) shows a degassing and slowly erupting cone. The video, published by IGN (Institutio Geografico National) shows in very clear water, the surface of the vent degassing. It is the first video published by scientists that clearly shows what is actually happening under water, giving us our fist actual observation of the cone itself.

The eruption at El Hierro was declared over by the government, much to the chagrin of scientists and volcanologists who insist the eruption is not over, merely slow. The government is apparently quite eager to declare the eruption over as tourism has actually suffered, not prospered, during this eruption. Sensationalist news media, and negative press caused the usually booming tourist industry to slow to a crawl, and residents and businesses were forced out of the small fishing town of La Restinga, putting a large dent in their economy.

However this is a dangerous presumption for the government to make. First of all, the eruption is NOT over, and second, giving residents and tourists a false sense of security in regards to the volcano is ill advised. It is still quite possible that other vents can open up, or that activity at the main vent can resume. It is impossible to say, but in most scientists views, the eruption at El Hierro would be over as soon as there are little to no earthquakes and NO harmonic tremor.

The interesting thing about the volcano and the government is the clear attempt to cover up what is actually going on. The webcams have been shut off completely. The webcams were shut off due to "cost concerns" as the provider claimed that they were too expensive. I highly doubt that they are. This apparent "blackout" of information coincides completely with the Spanish government's declaration that El Hierro is now a "green" zone, ie: safe for tourists, boats etc. There is still a very small exclusion zone for commercial boats around the vent, but the port and town are now open.

And even as government officials claim the eruption is at an end, there was a 2.7 magnitude earthquake directly under the erupting vent, and more earthquakes in the El Golfo region (the El Golfo basin is an area that has been highly seismically active, with some scientists wondering whether or not there is another open vent at the bottom, out of reach of our instruments). So with an active and hot cone, earthquakes every day in and around the erupting vent, and now visual confirmation of the vent itself with an underwater camera... one has to ask themselves, who is the Spanish government kidding? 

Government Officials Declare El Hierro Eruption Over... When It's Not

Apparently under public pressure to declare the resort island of El Hierro "open for business", Government officials in Spain/Canary Islands have declared the alert level at El Hierro be lowered to "green" (the level before the eruption). This occurs as INVOLCAN conducted an R.O.V. mission to the crater, and discovered that yes, in fact, the volcano is still very much erupting, although the characteristics of the eruption has changed. While there is no vigorous "jacuzzi" on the surface, below the water a lot is still going on.

The eruption is very much like the submarine eruptions produced by Loihi on the southern end of the Big Island of Hawaii. Pillow lavas are being extruded onto the sea floor, and continue to do so.

So was this declaration of "green" a politically motivated, and non scientific maneuver? You betcha. I don't think there would be one actual scientist studying this volcano that would say the eruption has ended. If that were true... well obviously lava would not be flowing, now would it?

So the eruption actually continues at this time. The type of eruption this has ended up as is not a Surtseyan eruption, as many people thought might occur, rather the eruption type is called an "Serretyan" type eruption. Earthquake-report.com has a lot more info on this, but I thought I'd share their great image they published on what characterizes a Serretyan eruption.

Descriptive image of a Serretyan eruption, from Earthquake-report.com

El Hierro is a difficult volcano to analyze and monitor as it has turned out to be very unique in its eruption characteristics. Many thought a pyroclastic cone would develop on the island, or that an eruption would ensue in the El Golfo bay (probably because it is shaped like a caldera, even though its just a massive collapse scarp), which actually still has the potential to happen, but it ended up being a very benign submarine eruption that never reached the water's surface. While not an exciting eruption to watch, the concept of this volcano is pretty intriguing, and of great scientific interest, as this volcano is displaying some mechanics that we don't often get to witness.

In any case, if anything interesting happens at El Hierro, I'll be sure to post about it! I simply wanted to share this with the readers to notify that the eruption is still going on, despite what governments may say!

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.

El Hierro Eruption Officially Over?

Reports from earthquake-report.com are saying that INVOLCAN will officially declare the eruption at El Hierro to be over today, possibly lowering the overall alert level to "green" and allowing the village of La Restinga to slowly return to normalcy. Tremor for the past few weeks has been at a minimum, with little to no changes, save the very slight increases and decreases in amplitude, and occasional small earthquakes. For now it seems, the eruption of "Bob", the submarine volcano that ALMOST made it to the surface of the water, is over.

This however does not mean that activity on the island as a whole is finished. Indeed, deformation is still occurring, and earthquakes are getting shallower at other locations around the island. So, while the village of La Restinga may be able to breathe a sigh of relief that "Bob" has gone to sleep, the rest of the island as a whole is still on pins and needles. The last eruption of El Hierro occurred in the 18th century, and lasted two years.

While many volcano enthusiasts and scientists alike were watching El Hierro with anticipation of being able to see a well-documented Surtseyan type eruption (which ended up not happening), the island chain of Jebel Zubair in Yemen pulled a fast one on us and had an island-producing eruption behind everyone's back. Quite frustrating if you were hoping to witness the actual birth of an island from start to finish. It's really too bad that the Zubair group of volcanoes isn't really monitored that well, or we might have gotten our wish.

All things said and done, the ending of the El Hierro eruption, and the lowering of the alert level for La Restinga will likely come as a relief to islanders, as they have been hurt economically by the closure of the fishing port, and the hotels/cafe's which were evacuated during the heightened alert. While the local and Spanish governments might have used the eruption as a tourist draw, like they do on Hawaii or Iceland, the local media hyped the story and scared lots of people and tourists from the island. Only bloggers, and locals were actually reporting on this eruption objectively (or close to objectively), which has given me much more respect for bloggers and freelance journalism.

In any case, my best wishes to the residents of El Hierro, and hopes that if activity does resume, or start in another area, it will be as mellow as the eruption of "Bob", and merely be an interesting, not violent, occurrence. Time will tell if the island has gone back to sleep, but as far as the local government and the scientists at INVOLCAN are concerned, it's time to consider the eruption over... but a word of caution, I'm pretty sure volcanoes don't have to follow government law or statements... we're living on their schedule, not the other way around.

Even though the eruption has "officially" ceased, there will be some remnant activity at the volcano, such as degassing, and occasional structural adjustment quakes.

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.

Eruption at El Hierro Slows, But Quakes Increase

The harmonic tremor at El Hierro has been extremely low for the last couple of days, but the volcano is still weakly erupting magma, and mostly degassing. However there were a record of over 20 earthquakes yesterday and into today, with the quakes becoming shallower and shallower, possibly a precursor for another vent in the SW part of the island off the coast. The magma chamber is not done yet with El Hierro.

The harmonic tremor is at a low point due to probable vent collapse, and re pressurization of the chamber (think of it like putting your thumb, or a cork, in a running garden hose, but on a much more massive scale). The pressure will build up and the eruption of the current vent will either resume, or the magma will find another route to the surface. It is anyone's guess where and when, but it seems likely that the new vent if it does pop up will be to the West of the current cone (Bob).

The current tremor and analysis from El Hierro volcanologists confirm this, and now the island waits to see the next phase of this historic event. More than likely, this will result in another submarine cone building event. If another cone/fissure does erupt in another location, you can be pretty sure that the first cone (Bob) will stop erupting as magma diverts to an easier route. This may be already taking place, with harmonic tremor so low, and quakes so numerous and shallow, it could very well be that "Bob" is dead.

This would actually end up being a good thing for the village of La Restinga as their main port and tourist spots have remained closed out of an abundance of caution, and all sea faring routes have been cut off. This has hit the economy hard. An eruption to the West of "Bob" would be of minimal consequence to business, especially if "Bob" is confirmed to be done erupting and the government re-opens boat traffic to La Restinga (not to mention the hotels and cafe's).

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.

                           

Powerful Tremor This Morning At El Hierro, Then Significant Decline

Early morning at El Hierro displayed lots of activity at the volcano, as seismic tremor more than tripled the average of the past few days. After this long (3-4 hour) period of heightened activity, the tremor has ground to a near halt for the last 12+ hours. This has become quite the pattern at El Hierro, where there will be periods of heightened explosiveness underwater, followed by a day or so of quiescence, with violent resumption of activity for a few hours after the pause. I would assume that given this pattern, there will most likely be more activity tomorrow morning.

The current tremor graph below:


                               
El Hierro has been a confusing volcano to watch as it has stopped and started its eruptive phase several times. It is unclear at this point whether or not this will be the main event at the volcano, or if there is more in store for this island. There have been rumors of thermal anomalies on the actual island as of late (as per a video on Earthquake-report.com) that are UNCONFIRMED, and probably bogus, as well as rumors of a 2nd vent in the El Golfo region of the island (the North shore). Due to depths off the North shore, this has never been confirmed.

The magma chamber under El Hierro has seismic implications of being quite large, not by any means a monogenetic cinder cone eruption. It is likely that this eruption, and activity at El Hierro as a whole, may continue for some time.

After the activity this morning, El Hierro has been pretty quiet. Late afternoon observations showed a weak stain, and high surf, which has washed a lot of the discolored water away from the vent area. When the ocean calms down, activity will likely be more apparent.

*****UPDATE*****

As I suspected, given the pattern of eruption so far for El Hierro, tremor has indeed again picked up some 24 hours after the last spurt of activity started. The eruption is currently producing elevated tremor, and the occasional flaming lava balloon can be seen on the water surface. Below is today's tremor reading, where you can see the nearly perfect 24 hour relation that has been the case for the last week or so.

The volcano will probably have 2-4 hours of high tremor, collapse the vent again, and re-pressurize about 20-25 hours later resulting in the resumption of tremor... let's see if this pattern holds!

El Hierro Eruption Back to Full Force

The eruption at El Hierro has gained much strength since yesterday. There is consistent harmonic tremor, lots of lava stones floating to the surface of the water, and increased gas emissions. The eruption is now back to the same strength more or less than when it began some months ago. The eruption has had short periods of quiescence as the magma chamber re-pressurizes and explodes after multiple collapses of the underwater vent system.

Below is a live JPG of the current harmonic tremor for today.

                                            
The past few days have seen a dramatic rise in both tremor and surface activity. For the past two days, smoking lava stones could be seen on the live webcam at La Restinga, and CO2 emissions have been steadily rising once again. By all indications, this will be a long eruption with many pauses, but ultimately resulting in either the birth of a new Canary Island. Keep your eyes peeled for its first appearance soon!

El Hierro Activity Strong Today, Volcanic Tremor Vigorous

The El Hierro Volcano has picked up activity this morning and into the afternoon with strong harmonic tremor, multiple recorded underwater explosions, and lots of steaming lava rocks floating to the surface. The tremor began to pick up before dawn at El Hierro, and continued throughout the day with one of the most vigorous displays of activity yet. This volcano is far from done erupting.

Below is today's tremor graph from IGN.

The obvious increase in volcanic tremor this time did coincide with surface activity. Even though the tremor is currently a bit lower than earlier, smoking lava stones and a very strong and colorful stain on the ocean surface can easily be seen on the live webcam.

If El Hierro can sustain this eruption for a couple more months, it is highly likely it will breach the surface and enter into a Surtsetyan, or island building phase. This would be characterized by a large increase in emissions and explosive activity, eventually (probably) resulting in a more Strombolian type eruption from the cone (at least this is what I gather will happen when the cone can get free of the water, given the type of ejecta making its way to the surface). With gassy lava like this, it will probably end up being quite a show.

It is time for those of you who gaze at the volcano to remain vigilant. I for one would be overjoyed to see the birth of this new island live on camera (of course I'd rather be there, but that costs lots of money!). Keep your eyes peeled!

After Two Day Break, El Hierro Roars Back To Life

The last two days at El Hierro saw a calm stain on the water with few if any smoking lava stones, low harmonic tremor, and very little else. That ended this morning, when tremor again picked up, more smoking stones could be seen on the surface and emissions bounced back. El Hierro is not done yet.

                                                                                    

Images from El Hierro Telefonica/Movistar cam.

Today's current tremor. note the large increase over the last couple of hours.

El Hierro has been doing this off and on again eruptive cycle for weeks now, if not months. This is probably related to vent collapse and re-pressurization, leading to sporadic bursts in activity. Likely this will keep going on for quite some time. Tremor is QUITE strong today, so if you have the opportunity, you should check out the cam and keep your eyes peeled for some cool activity.

Morning Activity At El Hierro Reveals Vigorous 2nd Vent

The activity at El Hierro Volcano has taken an interesting turn. The 2nd large vent to open up has created a strong jacuzzi area and emitted many smoking lava stones (SLS).Views on this morning's webcam revealed two very distinct 'jacuzzi' areas, with the Eastern vent emitting far more floating steamy lava rocks. These were numerous and frequent this morning.

The harmonic tremor (below) seemed to correspond with the activity.

The lava stones are shown below.
                                     

 The activity, for now, continues as it has now for months.

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. 

The Mechanics of the El Hierro Eruption (and current update)

The El Hierro volcano is a vexing one to watch and attempt to predict. While predicting any volcanic activity is not a science, more of an art, there are some typical signs for volcanic eruption that most scientists use to gauge the intensity, duration, and potential eruption time window. For El Hierro it seems, a lot of these rules are out the window and useless.

Harmonic Tremor (HT) is a seismic signal that is typically generated after preceding earthquakes, which indicates moving magma underground. This is usually indicative of an ongoing or soon to be starting eruption. This is not always so however, as El Hierro has proven time and again during this eruption. Some days, there are many smoking lava balloons and an intense jacuzzi, despite an absence of HT or earthquake activity. Slow effusion of underwater lava it seems can be independent of any HT signal. This has been the case now for weeks.

To scientists and remote bloggers, using HT monitors could give the false impression that the eruption has ended (Jon Frimann of the Iceland Volcano Blog uses this reasoning a lot). Without visual confirmation of the cone underwater, some bloggers leap to the conclusion that with an absence of strong HT, that the eruption MUST be over. If you were looking at an erupting cone, but your seismographs weren't showing any tremor, would you believe your eyes, or your instruments?

There are of course many other indications of an ongoing eruption. Gases, CO2 and SO2, can tell scientists what is going on inside the magma chamber. SO2 is usually indicative of a stable, and mild eruption, while large spikes in CO2 usually precede larger explosive activity. Monitoring these gases in real-time is the best way to really gauge the 'attitude' of the volcano at any given moment. CO2 and SO2 emissions at El Hierro remain stable, which suggests a stable eruptive cycle for now. If there are any spikes or dips, this could merely mean the magma chamber is either gearing up for a large explosion, or simply recharging/reloading.

Despite the fluctuations in HT and SO2/CO2 emissions, the visual observations of El Hierro don't seem to match up with instrument data very often. This is a unique volcano, like all of the other volcanoes of the world, and each has its own mechanisms for erupting, so using old methods from more active volcanoes simply will not produce the same results. Its important for those that monitor this volcano to realize that the eruption will only be "over" when the volcano is out of juice. Given the long duration of this eruption, and the supposed size of the magma chamber, I don't see this eruption ending any time soon. It will likely go on for a few more months, if not a year.

We do not know the exact size of the magma chamber, but like the Hawaiian Islands, Iceland, and other "hotspot" type volcanoes, eruptions can last years, or simply have a tiny eruption. The eruption at El Hierro is very much like the eruptions of Hawaii, specifically those of the Loihi Seamount, where an underwater volcano (that last erupted in 1996) is expected to one day create a new Hawaiian Island (in about 10,000 years or so!). The eruption at El Hierro is much shallower than Loihi so the time table here is around a couple of months if it keeps going. There has been an ongoing eruption in Hawaii from Kilauea since 1983, proving that sustained eruptions can and do occur on hotspots. This could be the beginning of a long term eruption at El Hierro... I would not be surprised.

This morning El Hierro is displaying vigorous jacuzzi activity, with occasional bursts of smoking lava stones. HT is gradually picking up again (which only means that somewhere in the chamber, magma is moving), and a few quakes were recorded. The activity has consistently ramped up on the surface the closer the vent gets to the surface of the ocean, and I expect it will continue to do so.