Video of El Hierro Volcano

Posted on November 9, 2011 by marcia

El Hierro Volcano (Canary Islands) : Red alert – video recorded from an helicopter on November 8

Last update: November 9, 2011 at 3:28 pm by By Armand Vervaeck and James Daniell

Update 09/11 – 15:09 UTC :
Helicopter video footage from yesterday November 8 as published by Diario El Hierro (video recorded by the Cabildo El Hierro)

(video on website below or @http://www.youtube.com/watch?v=HFaZK6rE2vM&feature=player_embedded)

YouTube Direkt

Update 09/11 – 14:01 UTC :
– Joke has just reported that she had spoken to the technicians and the Cabildo (authorities). The technicianstold her that the installation of the webcam was almost finished and that only the software had to be configured. The least that we can say is that this news is hopeful !
– Pevolca did meet at noon and as could be expected nothing new has been decided

Update 09/11 – 13:04 UTC :
The Rámon Margalef has been throwing a buoy near the eruption vent yesterday. The ship is now circling the area. What the ship is doing know can be called a calculated risk. We have to admit that the ship is doing great work in continuous sampling of the emitted gases and the water (he has been observed many times at the edge of the stain the last couple of days). As Patrick Allard was telling in this article before, the composition of the gases is predominant in calculating the risk for the population.
– El Pinar webcam is live again, but it is hard to see any detail in the sea due to the back-light

Update 09/11 – 12:41 UTC :
Picked up from the comments made below (Name and address known @ ER)
Cabildo de El Hierro and Telefonica are installing 2 webcams in La Restinga to enable people to follow LIVE the eruption events.
Cabildo de El Hierro y Telefónica ya están instalando 2 webcam en La Restinga para el seguimiento en directo del fenómeno eruptivo Twitter
If this message is confirmed, this is really good news, as Telefonica is the main telecommunications company in Spain and is maybe the only instance who is able to guarantee huge amounts of traffic.

Very Important Update 09/11 – 12:22 UTC :
– Scientists in La Restinga and Guardia Civil who is currently flying over the earlier jacuzzi location have reported that the vent has probably closed completely. The activity has completely stopped at the moment. The Rámon Margalef Oceanographic ship is now close to the eruption vent is is probably taking gas samples and water samples.
We expect to publish images soon.
The closure of erupting vents is a normal phase in this kind of activity. This does not mean that the volcano activity is completely over. If the volcano continues in the same pattern, the seismic activity may getting stronger again as the magma trying to find his way to the surface has been blocked.

for more and updates, go to: http://earthquake-report.com/2011/09/25/el-hierro-canary-islands-spain-volcanic-risk-alert-increased-to-yellow/

Undersea Volcano off Canary Islands

Posted on November 8, 2011 by marcia

Canary Islands Eruption

Undersea Volcano Now Just 70 Meters from Surface

Photo Gallery: The Growing Undersea Mountain off El Hierro

DPA/ IGN

In the Atlantic Ocean, off the Canary Island of El Hierro, 20-meter high jets of water are being spat into the air as the sea boils amid the stench of sulfur. The undersea volcano, which is set to create new land, is growing ever-nearer to the surface — but is the existing island at risk from the explosive eruptions?

The monster rises out of the water”, screamed the Spanish newspaper La Provincia. Scientists, meanwhile, are being a bit more level-headed about the undersea volcano south of El Hierro in the Canary Islands; they now believe it is in the third phase of its eruption — fountains of water have been shooting out of the Atlantic up to 20 meters in the air over the last few days. On Tuesday, some local residents even saw stones being catapulted out of the sea.

A seething maelstrom, dozens of meters across, is bubbling away in the ocean. Measurements show that the vortices are significantly warmer than the surrounding water.

So far, the volcano has only shown its explosive power beneath the water. But now the outbursts to the south of El Hierro are frothing up the surface, as if the ocean had hiccups. The lava is piling up on an underwater mountain. That the eruption is capable of firing jets of water into the air shows that this mountain is growing — the center of the eruption is approaching the surface. Geologists believe that new land could soon emerge from the sea, and islanders are alreadylooking for a name for the new territory. There are only 70 meters to go until the mountain reaches the surface, experts from Spain’s National Geographic Institute (IGN) have reported.

But how big is the risk to nearby residents? Last weekend, hundreds of people had to leave their homes in the southern part of El Hierro as streets were closed. And locals can quite literally smell the danger — stinking sulfur fumes are drifting across the ocean. The Volcanology Institute of the Canaries, Involcan, has reported a three-fold increase in carbon dioxide levels — a warning signal that further volcanic activity can be expected.

Clear Sign of Impending Eruptions

Seismic disturbances on the seabed have also been spreading. Since July, more than 10,000 minor earthquakes have shaken El Hierro, but since Oct. 22, the tremors have become increasingly stronger with some even surpassing four on the Richter scale. The quakes are showing a pattern typical of flowing magma, the so-called harmonic volcanic tremor — a clear sign of impending eruptions.

And scientists have been warning since September that if and when those eruptions do occur, they could well happen on land. In recent days, the tremors have shifted from the south to the north of El Hierro. Because most of the quakes there had occurred at a depth of ten kilometers or greater, there was probably no immediate risk of an eruption in the area, the local authorities had said. The magma had been confined to the deep.

But it has now started moving upwards — the most recent earthquakes have been shallower.

There could soon be eruptions in or near the El Golfo valley on the northern coast, the IGN has warned. And an outpouring of lava could prove dangerous not only if it happens on land, but also in shallow water, where it could result in large steam explosions, says Ramon Ortiz, scientific adviser to the local government.

Hot Spot Volcanoes

Off the southern coast, meanwhile, pumice stones and a massive sea of ash are drifting across the water. An initial analysis of the material produced by the volcano so far has surprised experts: It provided “clear evidence of the explosive potential” of the volcano, geochemist Domingo Gimeno Torrent of the University of Barcelona told the El Hierro Diaro newspaper.

Most so-called hot spot volcanoes, like those in the Canaries, produce basaltic magma with a relatively small proportion of silicon dioxide (SiO2). SiO2 acts like a glue, producing very viscous magma, leading to a buildup of gases which results in an explosive mixture. The Geochemist Torrent said the El Hierro volcano, however, is feeding off two supplies of lava; a less volatile basalt magma and a much more explosive, SiO2-rich magma.

The risk of large, explosive eruptions in the Canary Islands “should not be neglected,” warned geoscientist Rosa Sobradelo from the Spanish National Research Council (CSIC) in Barcelona in a report in the “Natural Hazards and Earth System Sciences” journal. How often such events happen is unknown. But even the most momentous explosions of the past few centuries remained localized.

And there are no fears of large eruptions on land, according to the IGN. The only risk is in the immediate vicinity of the eruption site, where there may be lava flows and rocks flung into the air.

from: http://www.spiegel.de/international/europe/0,1518,796612,00.html

El Hierro Update

Posted on November 5, 2011 by marcia

El Hierro Volcano (Canary Islands) : Red alert – an impressive new stain forms in front of the coast

Last update: November 5, 2011 at 1:58 pm by By Armand Vervaeck and James Daniell

Data update 05/11 – 13:04 UTC :
Harmonic tremor remains very strong, while there were some slightly weaker periods during the night (see graph below).
– we have no data update from the Las Calmas sea at the moment. Only the picture below, which reveals a growing grey stain. The grey stain is believed to contain a lot of eruptive material.
– The webcam soap goes on, it takes 25 siestas before somebody @ El Pinar decides to do something (Joke is running the marathon to get something done).
Focal depths are still at a safe 17 to 21 km. But … what is safe, if a fissure eruption is going on only at a depth of 150 meter or less (as Raymond says) in front of the southern coast.

The eruptive grey and greenish stain during Saturday morning (right bottom corner, one of the oceanographic ships) – image copyright and courtesy Delmi Alvarez and Carias7.es

Update 05/11 – 12:13 UTC :
Our friends at IGN have a hard time too, as their servers are almost strangled by the many people visiting their lists and graphs. We have to thank IGN for their outstanding open source information. Specialist followers always want more, but we never had the feeling that information was kept away or hided from us.
The same goes to the government of the Canary Islands, the local administration and the UME, IGN, CSIC and other people guarding the safety of the islanders. They have an extremely hard time in communicating a very complicated information without a 100% guarantee (please bear in mind we talk about a volcano)

Update 05/11 – 12:13 UTC :
The coastal village / town of La Restinga is almost strangled by the current events. The village, mainly dependent on small fisherman and diving companies, is going through his hardest time since his existence. As all trade did came to a standstill since the early evacuation days, people have hardly something to eat! Aid has been promised, but the political and administrative hassle takes too long.

Update 05/11 – 11:28 UTC :
Pevolca will meet this morning at 12:00 UTC to discuss the present situation. We expect that Pevolca is re-considering the (partly) closure of the Los Roquillas tunnel due to the frequent and strong earthquakes. The landslides and rockfall yesterday evening at Las Puntas (greater Frontera area) and the mandatory evacuation of 11 houses are indications in that direction.

Update 05/11 – 11:15 UTC :
3 rather strong earthquake respectively 3.0, 3.5 and 3.9 have struck the El Golfo area to the North West of Frontera. The focal depths were in between 20 and 21 km (as most of the others before).
The big difference with prior periods is that we now are having AND continuing strong earthquakes AND also INCREASED STRONG harmonic tremor. The rescaled IGN graph (yesterday evening) is almost saturated again.All this means very strong volcanic action below El Hierro.

Harmonic tremor from midnight UTC (05/11) until 11:00 UTC – image courtesy IGN

Update 05/11 – 08:44 UTC :
After last nights powerful 4.4 earthquake and even more after the shallower 3.6 earthquake with epicenter in the Puerto Naos area (south of the Island and almost below the Jacuzzis), the population of El Hierro is struggling in between the “Remain Calm” message of Pevolca and what they feel and see and smell themselves.

Los Roquillos tunnel closed until the early morning hours
The Director of the Civil Protection Plan for Volcanic Risk (PEVOLCA) has decided this evening to close thetunnel access road until 7.30 am as a preventive measure due to the 4.4 earthquake which took place at 20:36 hours. The possibility that a larger quake could occur according to the National Geographic Institute (IGN) required the notification to the public. The opening of the tunnel in the morning will be done with surveillance and security measures in place.
– The families living in 11 houses in Las Puntas have been evacuated out of fear of damaging landslides

Update 05/11 – 00:37 UTC :
New 3.6 magnitude earthquake occurred at 00:16 UTC in the Puerto Naos area. The depth : 11 km. The quake was felt by islanders.

Data Update 04/11 – 18:53 UTC :

– Very strong harmonic tremor continues to feed the current eruptive vents
– The harmonic graph below is saturated from 13:00 UTC on = strong eruptive period
– 1 strong 3.8 magnitude earthquake at 13:41 UTC – location : El Golfo bay (approx. 4 km out of the coast – depth : 21 km
– 26 earthquakes since midnight UTC (less because of the eruptive period) – 2 earthquakes in between 1.5 and 2, 8 in between 2 and 2.5
– 2 earthquakes were felt by the islanders

harmonic tremor graph saturated since 13:00 UTC – image courtesy IGN Spain

Interesting photos:

Image courtesy Presidencia del Gobierno de Canarias – Click on the picture to see all the other pictures taken today

Strong November 4 turbulent waters – image courtesy government Canary Islands and IGN

to read more, get updates, see the videos, go to: http://earthquake-report.com/2011/09/25/el-hierro-canary-islands-spain-volcanic-risk-alert-increased-to-yellow/

Continued Seismic Activity at El Hierro

Posted on October 20, 2011 by marcia

El Hierro Volcano (Canary Islands) : Red alert – seismic activity not over yet

Last update: October 20, 2011 at 3:55 pm by By Armand Vervaeck and James Daniell

Update 20/10 – 15:53 UTC:
– 10 earthquakes have been recorded by IGN (max. magnitude : 2.0) since midnight UTC.
– The diving companies, one of the important sub-economies on the island, are living through a very bad period. Cancellations have been coming in until december 2012. Alpidio Armas hopes that the present crisis situation will end soon and that business will gradually be back to normal.

El Mundo Radiography animation of the El Hierro volcano eruption

Update 20/10 – 7:46 UTC: Spanish newspaper El Mundo did something what you can expect from a quality newspaper, they invested money in afantastic animated overview of what happened . The animation is divided into the following parts :
– Geography of El Hierro
– Divergent fault line
– location and size of the craters/cinder cones
– Ocean sea floor surrounding El Hierro
– Eruption specifics.
We advise our readers to take a look at this great animation. Click here to watch the El Mundo animation

Update 20/10 – 7:37 UTC: slight changing harmonic tremors during the last 8 hours. Since midnight IGN reported 2 earthquakes (this number can change when IGN updates her records).
The number of earthquakes yesterday was the highest in number since October 10 when the active period started

Port of La Restinga on October 19 – many fish died by the acidic water – image courtesy and copyright Desiree Martin

Update 19/10 – 23:58 UTC: Killing nature. Due to the lower Ph, the water is very acid and a lot of fish did not survive it. The picture at right has been shot in the port of La Restinga.

Update 19/10 – 23:55 UTC: A total of 16 volcanic earthquakes have been recorded on Wednesday. Max. magnitude: 2.6

Update 19/10 – 17:44 UTC: La Restinga fishermen demand that the Ramon Margalef will not only have geologists on board, but also the “best possible biologists”. They want to know from the biologists when their fishing grounds will get back to normal.

Red Alert—El Hierro Volcano

Posted on October 16, 2011 by marcia

El Hierro Volcano (Canary Islands) : Red alert – eruption bubbles visible from the island

Last update: October 16, 2011 at 2:12 pm by By Armand Vervaeck and James Daniell

This is Part 3 of the El Hierro Volcano eruption report

Update 16/10 – 12:39 UTC : The giant gas bubbles occur at a frequency of approx. every 15 minutes

Update 16/10 – 11:19 UTC : Giant bubbles visible from the coast! (see also update from 10:44 UTC)

Eruption bubbles at El Hierro – picture courtesy and copyright laprovincia.es

Update 16/10 – 10:44 UTC : Villagers are mentioning “bubbles” coming up in the spotted area in the sea. We expect to receive fastly images from the bubbles as the many camera teams with their superior equipment will certainly be able to shoot detailed video from an event which can be seen by the naked eye.
Ramon Ortiz, a technician from the CSIC (Centro Superior de Investigaciones Científicas) is predicting that a new island is being formed at this moment and that the chance that it will happen now is evaluated as very probable, at least of the eruption process will continue a little longer.

Update 16/10 – 09:50 UTC : The volcano’s activity can in part be evaluated in looking at the “live” seismogram published by the official Spanish geographic agency IGN. We hope that scientist will be commenting later today on what has happened around midnight (see seismogram below). We also hope that we will get more detailed video and pictures from the supposed new fissure area later today.

Update 16/10 – 09:40 UTC : PEVOLCA, the team of scientists and local authorities is meeting at El Pinar at 13:00 (1:00 PM) local time this afternoon.

A few words of merit : At earthquake-report.com we have the feeling that we are residing at El Hierro. Joke Volta’s multiple emails and SMS’s are like a webcam for us. Joke talks not only with a lot of people in the village, but also with people from the press, with the mayor and even the president of the Canary Islands. In the name of our thousand’s of readers we thank Joke for her relentless energy to feed us with news.
– As earthquake and volcano followers in almost every corner of the world, we know from many experiences that local people are often kept away from the news and that politicians, mayors etc can only be seen on TV.
El Hierro is a TOTALLY DIFFERENT story. Even when they get loads of irritating comments from villagers of La Frontera for not opening the tunnel, local and province politicians and authorities are still AMID the islanders and are open to a talk with everyone. At earthquake-report.com we are experiencing this as a unique and much to be respected service to the people who elected them. The information bulletins from the local authorities to the islanders are very detailed and has even more information than can be read in the press. Also this service is of great value to the population.

Update 16/10 – 08:39 UTC : Joke Volta reports from El Hierro
– everything is calm this morning and even the journalists seems to have stayed ion bed longer today
– everybody is still “excited” about yesterday’s experience. The images of hot pumice arriving at the surface waters is the 100% proof that the earlier coloring is really an eruption. Also the non-believers became believers at the end.
– have just had a conversation with Jesus Perez, Chief security as they call him locally. He told me informally that nobody knows the next phase of the eruption, but that everybody from the safety team is prepared that the eruption will gradually come close to sea level and that steam explosions cannot be excluded.
– Yesterday afternoon, “the green spot”or so called ”mancha verde”, was seen fom the village of el pinar.
– At 5 pm yesterday (17:00), the complete council of El Pinar was gathered in a special meeting, to proclame to the population of this small mountain-village the start of the red tape proceeding in askingeconomical help to european, and national organizations, for supporting this crisis situation.

Undersea Volcano Near Canary Islands-Eruption Effects

Posted on October 11, 2011 by marcia

El Hierro. Google Maps

Spain’s Instituto Geográfico Nacional (IGN) confirmed on Tuesday that an underwater eruption has occurred five kilomtres off the southern coastline of El Hierro, the smallest of the Canary Island. The eruption is Spain’s first since the eruption in 1971 of the Teneguía volcano on the island of La Palma (Canary Islands).

Scientists Monitor Underwater Volcano Eruption Near El Hierro

By MARK DUNPHY – Tue Oct 11, 2:53 p

The IGN says all three of its seismic stations on El Hierro in the Canary Islands have registered a volcanic tremor of low frequency in the south of the island at La Restinga (population 547), the southern-most village in the Canaries. Residents of the town were summonsed to a local football field on Tuesday afternoon to be briefed on provisional evacuation procedures in the event of another eruption closer to the shore.

Scientists from IGN and CSIC (Consejo Superior de Investigaciones Científicas), meanwhile, have conducted a reconnaissance flight over the sea to the area south of the island, where they have located dead fish floating on the surface five kilometres from the coast. The dead fish were identified in an area where lower seismic magnitude occurred on October 9, at a depth of approximately 2 km.

The present volcanic activity is understood to be occurring at a depth of 600 metres (just under one kilometre) below sea level, in the Las Calmas sea.

Scientists from IGN, CSIC and the University of Cadiz have established their monitoring base at La Restinga. Efforts are underway to determine if the subsea volcanic vent is widening and if so, in which direction (away or toward El Hierro).

Initial reports of the eruption were received from crews on board four separate ships. Local media agency Canarias7 reported on Monday that Government authorities have suspended ferry activities to and from the 285 square-kilometre island.

English language newspaper islandconnections.eu reported: “The martime chief for the province of Santa Cruz de Tenerife Antonio Padrón has issued a recomendation that boats should not sail closer than four miles off El Hierro. Divers have also been told to suspend all activities.

El Hierro (highlighted) on Google Earth

The eruption takes place amidst an unprecedented earthquake swarm in El Hierro. The number of earthquakes recorded since July 17, 2011 on El Hierro has now exceeded 10,000.

Hierro, a shield volcano, has had a single historic eruption from the Volcan de Lomo Negro vent in 1793. The eruption lasted approximately one month and produced lava flows.

The recent surge in the number and intensity of earthquakes prompted officials from the IGN and The Canary Islands Government to raise the alert level for the Hierro volcano to ‘Yellow’ late last month. The alert remained in place on Monday, but the estimated 11,000 residents of El Hierro were being reassured not to be alarmed.

The majority of the earthquake activity shifted from El Golfo in the island’s northwest to beneath the Las Calmas Sea in the south earlier this month. Surface deformations exceeding 35mm have also been recorded on the island in recent weeks.

Evacuations

A dramatic rise in recorded earthquakes on El Hierro prompted officials to evacuate some local residents, shut El Hierro’s main tunnel, and close local schools on 27 September.

The Spanish Civil Guard (Guardia Civil) advised almost 50 residents of the municipality of La Frontera to leave their homes because of landslide fears. Two units of the Spanish military’s emergency intervention unit (EMU) were also placed on standby to depart the nearby island of Tenerife to assist in the possible evacuation of hundreds of other El Hierro residents.

Meanwhile, the island’s main tunnel (Tunel del Golfo), which links Frontera to Valverde, was shut forcing motorists to travel across the 280-sq-km island via a mountain road. The Cabildo de El Hierro also ordered the closure of schools.

Canary Islands Volcano Yellow Alert

Posted on October 10, 2011 by marcia

El Hierro Volcano (Canary Islands) : October 10 : PEVOLCA latest report

Last update: October 10, 2011 at 9:49 pm by By Armand Vervaeck and James Daniell

Parador de El Hierro, gives a good idea on the coastline – Click on the picture to watch a video

Update 10/10 – 21:31 UTC : Fishing vessels have been ordered not to throw their nets in the expected eruption area. As far as now, no gases or bubbles have been detected in the area which is supposed to be the eruption area. This does not necessarily mean that there is no eruption, but that the depth of the magma vent is at least several hundred meters below sea level.
In the meantime, the harmonic tremors are unchanged (see link below).
Emergencia El Hierro has not published a new report tonight.

Update 10/10 – 17:01 UTC : Ramon Ortiz, a vulcanologist specialized in Canary Island volcanoes and currently advising the authorities, says in ElMundo that today’s eruption will be probably at a depth greater than 600 meter below sea level and about 5 km to the southeast of El Hierro.
Ortiz also said that the the Harmonic Tremors which started this morning showed that the eruption had started. They were reported in this site only hours after they started (see link and description below).
The latest eruption on the Canary Islands took place on La Palma Island in 1971 (see the video below from this eruption).

IMPORTANT UPDATE 14:31 UTC : PEVOLCA has just published a Press Statement that it is still unsure that an eruption is going on in the Las Calmas Sea. Scientists of IGN which make part of the PEVOLCA committee have stated that IGN has recorded the emission of volcanic gases at the south side of the island. The committee stresses that the gases are NOT dangerous for the population.
Additionally IGN reported that the emission might also be an eruptive phase but at the present time there is no 100% proof for it. A certainty however, IGN reported, is that “purely volcanic harmonic tremors” have started.

Historic Evidence of Collapse of Canary Islands Volcano

Posted on October 6, 2011 by marcia

Scientific paper reveals massive historic Tenerife volcano flank collapse

Last update: October 6, 2011 at 10:57 am by By Armand Vervaeck

Written by Dave Petley
Dave Petley is the Wilson Professor of Hazard and Risk in the Department of Geography at Durham University in the United Kingdom. His blog provides a commentary on landslide events occurring worldwide, including the landslides themselves, latest research, and conferences and meetings.

This post provides a brief review of a new paper that describes a newly discovered catastrophic landslide deposit in Tenerife.
One of the most intriguing but poorly understood landslide types is that of thevolcanic flank collapse. In a volcanic flank collapse, the side of a volcano fails, usually catastrophically, generating a landslide. These slides can be really big – tens or even hundreds of cubic kilometers – and they can travel huge distances along the sea floor. Such failures grabbed attention a few years ago due to the potential (overstated, in my opinion) for generating a catastrophic tsunami.

However, we understand such phenomena really poorly. There are a number of reasons for this, principally that:
a. They occur rarely (globally about one in every 25 years on average), so actually recording one is a challenge
b. the remains tend to lie in a very dispersed state on the floor of the deep ocean. Fieldwork at 4 km water depth remains difficult, even if you are really good at holding your breath.

However, it is one particular aspect of these landslides that remains elusive, but is crucially important. This is the trigger of the collapse event (i.e. of the landslide itself). Numerous mechanisms have been proposed, including sea level change, climate change, hydrothermal pressure, intrusion of volcanic material, and various others. It has proven very difficult to ascertain the importance of each of these. This is an important question if we are to reliably estimate the hazard associated with future potential collapses.

In a paper published in Geology this month, Harris et al. 2011 report a very interesting find on the island of Tenerife, one of the Canary Islands. This is the remains of an ancient collapse event on the south-eastern part of Cañadas volcano. The landslide deposit, which is up to 50 metres thick, has been mapped across a large area – 90 square kilometres – and this is just the onshore component of the mass, which may extend another 50 km offshore. The deposit consists of a classic debris avalanche material, with large (typically up to 12 m long axis), shattered blocks in a highly disrupted, unsorted matrix. This is typical of a highly energetic, very large collapse event. Intriguingly, in the upper part of the deposit some fluviolacustrine (water/lake) sediments are found in the remains of hollows, indicating that in the aftermath of the landslide shallow lakes formed on the surface, presumably as a result of blockages created by the landslide. Associated with the landslide deposit are the remains of pyroclastic flows.

Volcanic Activity on Canary Islands prompts Evacuations

Posted on September 28, 2011 by marcia

Rising Volcanic Activity Prompts Evacuations On El Hierro, The Canary Islands

By MARK DUNPHY – Wed Sep 28, 4:45 pm

MODIS satellite image of The Canary Islands on Tuesday 27 September 2011

Fears are growing that the El Hierro volcano in The Canary Islands could soon erupt after seismic activity beneath the island increased dramatically during Tuesday and Wednesday.

Over 150 earthquakes were recorded on the smallest of the Canary Islands during Tuesday prompting officials to evacuate some local residents, shut El Hierro’s main tunnel, and close local schools.

At least 20 earthquakes, exceeding magnitude 3.0 on the Richter Scale, have been felt by local residents during the last 24 hours. The most recent earthquake, which measured 3.4 magnitude, was recorded just off the southern tip of the island at 07:04 am Wednesday.

The rise in seismic activity last night prompted the Spanish Civil Guard (Guardia Civil) to advise almost 50 residents of the municipality of La Frontera to leave their homes because of landslide fears.

Plans are also underway to evacuate more of the island’s 10,000 residents, according to Canarias7.es. The newspaper reported that two units of the Spanish military’s emergency intervention unit (EMU) will depart nearby island Tenerife this afternoon to assist in the possible evacuation of hundreds of El Hierro residents.

Meanwhile, the island’s main tunnel (Tunel del Golfo), which links Frontera to Valverde, has been shut forcing motorists to travel across the 280-sq-km island via a mountain road. The Cabildo de El Hierro also has ordered the closure of schools on Wednesday.

Hierro, a shield volcano, has had a single historic eruption from the Volcan de Lomo Negro vent in 1793. The eruption lasted approximately one month and produced lava flows.

The Canary Islands Government commenced an in-depth geological survey of El Hierro earlier this month in an effort to determine the source of an earthquake swarm. The Government raised the volcanic risk level to ‘Yellow’ on Sunday, the highest alert status since an unprecedented earthquake swarm commenced in mid-July.

The unprecedented seismic activity commenced on 19 July (the activity was first reported by iWeather Online on 26 July). In excess of 8,200 earthquakes have been recorded up to Wednesday, 28 September 2011.

Up to last weekend, the majority of earth tremors ranged between 1 and 3 magnitude. However, the majority of quakes are now registering between 2 and 4 magnitude and are occuring at depth of 14-17 kilometres, according to the National Geographic Institute (IGN).

Speaking to the El Pais newspaper, volcanologist Juan Carlos Carracedo suggested that an eruption on El Hierro would “not be a major surprise”. He explained: “It is the youngest of the Canary Islands. There is a ball of magma which is rising to the surface and it is stationed at the limit of the earth’s crust. At the moment we do not know if that ball of magna will break the crust and cause an eruption.”

IGN Director, María José Blanco said that any eruption on El Hierro would most likely have a “low explosion value”. He added that an imminent eruption is unlikely.

In the meantime, the frequent and increasingly intense earthquakes being felt throughout El Hierro are unlikely to appease the residents of and visitors to the tiny island.

for more, go to: http://www.irishweatheronline.com/news/earth-science/geology/rising-volcanic-activity-prompts-evacuations-on-el-hierro-the-canary-islands/39807.html/comment-page-1

El Hierro Volcanic Risk

Posted on September 24, 2011 by marcia

El Hierro (Canary Islands, Spain) : volcanic risk alert increased to “yellow”

Last update: September 25, 2011 at 12:59 am by By Armand Vervaeck and James Daniell

The Canary Islands government has set the ‘yellow alert’ for the population of El Hierro as a lot of volcanic tremors are continuing to occur below the island since last July.
The ‘yellow alert’ decision bas been after consulting the PEVOLCA, and is based on the conclusions of the meeting of the Scientific Committee. The committee met on Saturday morning in El Hierro. Main reason for the alert increase where the increasing number of volcanic earthquakes as well as deformations (up to 30 mm change from the beginning).
The current ‘yellow alert’ phase does not mean that an eruption is eminent, but that the population will be informed on the risks and will be informed how to take certain protective action.
At this stage the ‘Cabildo de El Hierro’ will be responsible for informing the public of the practical aspects of the action plan including meeting points, shelters and evacuation plans.
The website is www.emergenciaselhierro.org.
The Canary Islands government will report weekly on the evolution.

Image courtesy ign.es

Interesting links
Map of El Hierro with the seismic activity projected on it
Graphic of the number of earthquakes and their depth since July 18
Deformation graphics (look at the stations HI01 to HI04)

GPS Deformation Image courtesy ign.es

http://earthquake-report.com/2011/09/25/el-hierro-canary-islands-spain-volcanic-risk-alert-increased-to-yellow/

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