[breaking] Vulkaanuitbarsting bij Canarische Eilanden

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Recordaantal aardbevingen op Canarisch eiland

Nog nooit eerder werden er zoveel aardbevingen achter elkaar geregistreerd op het kleine vulkanische eilandje El Hierro, het kleinste van de Canarische Eilanden. De reeks van maar liefst 720 bevinkjes heeft de overheid van deze eilandengroep voor de kust van West Afrika ertoe doen besluiten om voor het eerst in de geschiedenis een vergadering bijeen te roepen van het Stuurcomité van Vulkanische Monitoring. Dit comité werd opgericht om specifieke plannen te realiseren, die de burgerbevolking dienen te beschermen en noodplannen voor vulkanische risico’s moeten ontwikkelen. Inmiddels wordt gesproken over een ‘significante dreiging van seismische activiteit’.

Het Nationaal Geografisch Instituut (IGN) en het Volcanologische Instituut van de Canarische eilanden blijft nauwlettend de aardbevingen in de gaten houden, waarvan de kracht van de bevingen (elke dag!) ligt tussen de 1 en 3 op de Richterschaal. De meerderheid van de bevingen vindt plaats tussen 5 en 15 km diepte.

Volgens de autoriteiten betekent deze seismische activiteit nog niet direct dat een grotere, significante aardbeving zal plaatsvinden. Het merendeel van de bevingen die zijn geregistreerd, vonden plaats in het Noord Westen van het 280 vierkante kilometer kleine eilandje, bij het plaatsje El Golfo (zie foto hieronder). Een aardbeving op deze plaats zorgde er zo’n 50.000 jaar geleden voor, dat er een enorme landverschuiving plaatsvond, waarbij de helft van de vulkaan in zee gleed. Hierdoor ontstond een ca. 100 meter hoge tsunami die naar de overzijde van de Atlantische oceaan zou zijn gegleden. Schuin tegenover dit eilandje, in het verlengde van de resterende halve kratermond, ligt het Noord Amerikaanse continent..

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El Hierro Earthquake Swarm Enters Third Week
The intensity of earthquakes recorded on the smallest of the Canary Islands, El Hierro, has increased slightly during the last 24 hours. However, the total number of earthquakes recorded daily has lessened since the earthquake swarm initially began on 17 July.

The total number of tremors recorded during the past two weeks has now exceeded 1,050, according to the Instituto Geografico Nacional (IGN).

The majority of the earth tremors ranged between 1-2 magnitude, but during the past 24 hours there have been least five tremors measuring in excess of 2.0 magnitude on the Richter Scale. A 2.4 magnitude earthquake was recorded at 4:56 p.m. local time on Sunday (31 July 2011).

Approximately 50 earth tremors were recorded on Sunday, according to local earthquake monitoring agency Actualidad Volcánica de Canarias (AVCAN). The number is slightly down on the number of tremors recorded on Saturday and significantly less than the 195 earthquakes recorded on 22 July.

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The vast majority of the tremors have been recorded in the northwest of the 278.5-square-kilometre island at El Golfo, the location of a massive landslide that created a 100-metre high tsunami almost 50,000 years ago.

The earthquake swarm, prompted the Canary Islands Government to convene the first ever meeting on 22 July of the Steering Committee and Volcanic Monitoring, reflected in the Specific Plan Protection Civil and Emergency for Volcanic Risk, given what it described “the significant increase in seismic activity”. The Committee met again on Friday 29 July to discuss the low magnitude seismic activity. It reported that it had stepped up its seismic monitoring operations to identify the source of the earthquakes.

Following an evaluation of seismic and volcanological information gathered by the IGN and volcanological Institute of the Canary Islands, the Committee agreed to activate “monitoring and surveillance mechanisms necessary to coordinate the actions of civilian self-protection and information to people listed in the Plan” (translated from Spanish press release). It remains unclear, however, if the unprecedented seismic activitiy on El Hierro is a precursor to a possible future increase in earthquake or volcanic activity.

Earthquake swarms are events where a local area experiences sequences of many earthquakes striking in a relatively short period of time. The length of time used to define the swarm itself varies, but the United States Geological Survey (USGS) points out that an event may last for days, weeks, or months.

El Hierro’s Volcanic/Seismic Past

El Hierro is situated in the most southwestern extreme of the Canaries. The island was formed after three successive eruptions, and consequent accumulations, the island emerged from the ocean as an imposing triangular pyramid crowned by a volcano more than 2,000 metres high.

The volcanic activity, principally at the convergence of the three ridges, resulted in the continual expansion of the island. A mere 50,000 years ago, as a result of seismic tremors which produced massive landslides, a giant piece of the island cracked off, crashed down into the ocean and scattered along the seabed. This landslide of more than 300km3 gave rise to the impressive amphitheatre of the El Golfo valley and at the same time caused a tsunami that most likely rose over 100 metres high and probably reached as far as the American coast.

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The Swarm of earthquakes which started during July of 2011 have continued into August with 3277 earthquakes being recorded since August 1st 2011 until 23rd August 2011, this is a significant rise of earthquakes and has Experts keeping a close eye on the island.

The news may have lost interest when the swarm started in early July with over 1300 earthquakes being recorded for the month which was a huge increase in activity compared to the average 300 micro-quakes the area experiences a month.

But burying these facts wont make it go away, as figures and records show it is getting much worse with already 3277 Earthquakes being recorded in just the past 23 days. These are the figures that should cover the whole YEAR not 23 DAYS.

2010 the area registered 3661 earthquakes for the year.
2009 the area registered 4536 earthquakes for the year.
2008 the area registered 5158 earthquakes for the year.
2007 the area registered 5384 earthquakes for the year.
2006 the area registered 3689 earthquakes for the year.
2005 the area registered 4229 earthquakes for the year.

For 2011 the total stands at 6614, of which 4617 have happened in just the past 7 weeks.

2010 eruptions of Eyjafjallajökull saw thousands of Micro-quakes prior to the Eruption of this volcano.

(A microearthquake (or microquake) is a very low intensity earthquake which is usually three or less on the Richter scale. Microquakes occur often near volcanoes as they approach an eruption, and frequently in certain regions exploited for geothermal energy)

El Hierro Volcano: Is one of the Smallest of the Canary Islands, the origins of the Island date back some 100 million years when the Ocean floor shifted with the movement of the Earth's mantle. The crust cracked into a three pointed star releasing flows of Magma.

After 3 Eruptions, the island emerged from the ocean as an imposing volcano more than 2,000 Meters high.

It has now been over 200 years since the last Eruption but El Hierro although being the smallest Island has the Largest number of Volcanoes with over 500 open Sky Cones and another 300 covered by the most recent outflows.

There has been uncertainty surrounding reports of a historical eruption taking place in 1793.

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Op woensdag 24 augustus 2011 12:51 schreef zenkelly het volgende:

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Zowel het eilandje El Hierro, maar sinds maandag ook Gran Canaria zelf, dus. Ik heb het idee, dat het hier om 2 verschillende epi-centra gaat?

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Magma under El Hierro building up?
Well, we've been wondering when we might see more signs of magma rising underneath El Hierro in the Canary Island and now we seem to have got some. Over the last month, the island/volcano has experienced thousands of earthquakes that have waxed and waned in number, but seem to be increasing over time. A GPS survey of the area effected by the earthquakes has now found deformation - namely inflation - over part of the volcano. This inflation is on the order of ~1 cm over the last 20-25 days according to the Instituto Volcanologico de Canarias. There are also slightly increased carbon dioxide and temperature (above background) at the volcano as well. All of these signs add to up new magma rising in the volcano -

So the big question becomes "does this mean an eruption is around the corner?" Well, my answer to that is a resounding "maybe". Sure, these are all signs of magma emplacement, but there is likely as much chance of it all "stalling" in the crust as an eruption occurring. It will be how these factors - earthquakes, deformation, gas emissions, temperature - change over the next weeks to months that will give us a better idea of whether we will see the first documented eruption at El Hierro since 550 B.C. (or 1793 A.D., depends on if you trust the historical reports from the late 18th century).

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El Hierro: 6200 seismic events until 7 September
The Spanish Geographic Institute (IGN) reported that since 16 July, seismicity at Hierro was high above the background levels. Until 7 September more than 6,200 events had been located, most of them in the El Golfo area with hypocenters that were 10 km deep, all magnitudes were below 3. The seismic activity alternated between relatively calm periods and high-energy periods. GPS local network stations showed deformations of about 2 cm. High rates of carbon dioxide flux were measured in the anomalous area.

Geologic Summary.

The triangular island of Hierro is the SW-most and least studied of the Canary Islands. The massive Hierro shield volcano is truncated by a large NW-facing escarpment formed as a result of gravitational collapse of El Golfo volcano about 130,000 years ago. The steep-sided 1500-m-high scarp towers above a low lava platform bordering 12-km-wide El Golfo Bay, and three other large submarine landslide deposits occur to the SW and SE. Three prominent rifts oriented NW, NE, and south at 120 degree angles form prominent topographic ridges. The subaerial portion of the volcano consists of flat-lying Quaternary basaltic and trachybasaltic lava flows and tuffs capped by numerous young cinder cones and lava flows. Holocene cones and flows are found both on the outer flanks and in the El Golfo depression. Hierro contains the greatest concentration of young vents in the Canary Islands. Uncertainty surrounds the report of an historical eruption in 1793.

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Canary Islands: The local authorities at El Hierro have raised the alert status to yellow based on increased seismicity - both in terms of number of earthquakes and intensity, some earthquakes as large as M3. This new level of alert (spanish) means that the government of the island will release regular updates on the activity and make sure that appropriate emergency measures are in place.

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Op maandag 26 september 2011 09:10 schreef Ivo1986 het volgende:

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Denk je dat half Europa weg geblazen wordt?

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Island of El Hierro Prepares for possible Volcanic Eruption
The island of El Hierro in the Spanish Canary Islands is bracing itself for a possible volcanic eruption.

Situated in the Atlantic Ocean off the west coast of Africa, the Canary Islands are all volcanic, but there has been no volcanic activity on El Hierro since 1793.

However, a series of small earthquakes have been registered by sensors in the past two months and a quake of grade 3 on the Richter Scale registered last Thursday have caused the threat of volcanic activity to be raised from green to yellow for the first time in recent history.

Saturday produced another stronger tremor of 3.4 on the Richter scale which was felt all over the island.

Speaking to the El Pais newspaper, volcanologist, Juan Carlos Carracedo admitted an eruption on El Hierro would not be a major surprise.

"It is the youngest of the Canary Islands," he explained. "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."

Rather than having one large crater, the volcano on el Hierro consists of around 250 small craters.

"Any eruption would form cones on the high zones of the island and lava flows which would flow to the sea, although they would do so at a speed that would be slow enough for the population to be evacuated. It is something that could happen in days, weeks or months," said Carracedo.

El Hierro currently has a population of around 10,000 and regional government officials have begun informing them of evacuation protocols in case the worst should happen.

The last volcanic eruption in the Canary Islands took place on the island of La Palma in 1971, while the mainland town of Lorca was devastated by an earthquake of 5.2 on the Richter scale in May this year.

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Situation worsens at El Hierro. 3,5 event widely felt, 5 events over 2,5 in the last 2 hours. #Volcano

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Op dinsdag 27 september 2011 18:50 schreef spijkerbroek het volgende:
Op 1 oktober ga ik naar Gran Canaria.. ik zal m'n survivalkit maar meenemen

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2011-09-27 17:02:59.2 34min ago 27.68 N 18.06 W 14 3.4 CANARY ISLANDS, SPAIN REGION
2011-09-27 16:04:22.31hr 32min ago 27.63 N 18.06 W 11 2.6 CANARY ISLANDS, SPAIN REGION
2011-09-27 15:44:14.11hr 53min ago 27.68 N 18.08 W 17 3.8 CANARY ISLANDS, SPAIN REGION
2011-09-27 14:59:19.02hr 37min ago 27.68 N 18.07 W 16 2.5 CANARY ISLANDS, SPAIN REGION
2011-09-27 14:38:45.02hr 58min ago 27.59 N 17.99 W 11 3.6 CANARY ISLANDS, SPAIN REGION
2011-09-27 14:27:55.03hr 09min ago 27.68 N 18.08 W 17 2.6 CANARY ISLANDS, SPAIN REGION
2011-09-27 14:18:48.93hr 18min ago 27.63 N 18.02 W 13 2.7 CANARY ISLANDS, SPAIN REGION

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53 evacuated as seismic activity continues in Spanish island

MADRID (Xinhua) -- A total of 53 people were evacuated from their homes on the Spanish island of El Hierro on Tuesday night due to seismic activity in the area.

The evacuees were sheltered in school buildings or other relatives' homes in safe areas.

In recent days, there has been increased seismic activity, raising fears of the first volcanic eruption on the island since 1793.


There have been over 8,000 tremors registered since July. Although the vast majority of them have gone unnoticed by inhabitants, they have recently increased in intensity, tremors last week measuring 3.0 and 3.4 on the Richter scale.


The threat of volcanic activity on the island was raised from green to yellow for the first time in recent history and 32 more tremors were registered on Monday, the strongest of them being 2.0 on the Richter scale.


El Hierro, part of the Canary Islands in the Atlantic Ocean, is situated off the west coast of Africa and has a population of around 10,000. The recent seismic activity is thought to be caused by a ball of magma -- or molten rock -- pushing upwards beneath the earth's crust.

Instead of having one large crater, the volcano on El Hierro consists of 250 smaller craters. If an eruption did occur, lava would escape from these vents and flow towards the sea. A single explosive event, such as that experienced in Mount St Helens in 1980, is not expected by geologists.

This May, the Spanish mainland was hit by an 5.1 earthquake that took 10 lives and devastated buildings in Lorca in the south-west of the country.

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Scale of earthquakes seems to calm down
The Canary Islands Government and the Cabildo de El Hierro have decided Wednesday night that the schools of the island on Thursday resume normal activity, in view of recent scientific reports indicate that the scale of earthquakes seems to have slowed and has entered a stationary phase.

However, it will be closed to traffic, risk of landslides, the tunnel that connects the island's capital, Valverde, to the valley of the Gulf (north), the most affected by earthquakes, as reported by the director general Security and Emergency of the Canarian Government, Juan Manuel Santana.

This required to change school bus routes, so that children in the municipality of Frontera Valverde studying in his school reach across the top of the island.

The half a hundred people on Tuesday were evicted from their homes in the town of Frontera spend another night outside their homes (most are staying with family and only a dozen remain in the dorm Valverde), but tomorrow review your situation and decide whether they can return.

This was noted by the President of the Cabildo, Alpidio Armas, who has stressed that the islanders will have to learn to live with the situation presented in El Hierro from mid-July, a period in which the island has been rocked by more than 8,000 low-intensity earthquakes of volcanic origin, most imperceptible.

"This is a topic that we will have to learn to live, if not stopped. We're going to have to integrate into our lives, peace and responsibility," added Armas.

The chairman of the council has insisted the message of tranquility that all authorities have been saying for days and stressed that the scientific reports indicate that the situation appears to have entered a stationary phase.

In the same vein, Santana pointed out that such events are cyclical seismic events caused by the pressure of magma in the subsurface, so that "fall within the normal." In fact, the volcanic risk in light of El Hierro is still located in yellow, in a situation of "pre-alert."

The Director General of Security of the Canarian Government has also explained that the latest information available indicates that the focus of the earthquake is shifting to the south of the island.

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The Canary Islands government radio alert to all operators of the impending El Hierro volcanic eruption

The Canary Islands government radio alert to all operators of the impending El Hierro volcanic eruption on the island 12 kilometers

Scientists believe that in the next few hours can produce a 99% chance of eruption

Measurements and forecasts made by scientists on the island of El Hierro and the whole structure of IGN have pointed to the competent authorities within the Pevolca activated by the Canarian Government to the volcanic eruption is expected for several days can occur in next few hours at a point in the sea to twelve miles off the coast southwest of the island, which correspond to the town of Frontera.

The odds set by these scientists have risen to 99%, giving the reason Carracedo, which set the deadline for its experience and professional expertise long before any of that until now have come to the public.

In order not to alarm the population is deciding when to make public a statement giving an account of this incident, but was ordered by radio high alert all operators to be prepared, especially in the EMU and its device that includes a shelter for 2,000 people, if it is considered that the entire population evacuated.

At this time the technicians of the Canary Islands from the Cecoi El Hierro are already coordinating emergency resources and security and all air and sea operating when the eruption occurs.

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Vulkaan op Canarisch eiland staat op uitbarsten

Het Spaanse Canarische eiland El Hierro kreeg sinds 19 juli al duizenden aardbevingen te verwerken, waardoor magma naar het aardoppervlak geduwd wordt. Er wordt dan ook gevreesd dat het tot een vulkaanuitbarsting komt. Lokale functionarissen deelden woensdag nog mee dat meer dan vijftig personen uit het noordelijke dorp Frontera werden geëvacueerd uit angst voor aardverschuivingen.
Het leeuwendeel van de aardbevingen waren te zwak om door de eilandbewoners opgemerkt te worden, maar ze namen wel steeds toe in frequentie en intensiteit. Gisteren werden meer dan 100 trillingen opgetekend, waarvan de sterkste 3,8 op de magnitudeschaal haalde. Vandaag volgden opnieuw tientallen bevingen, waardoor de belangrijkste wegentunnel van het eiland werd afgesloten en honderden schoolkinderen thuis moesten blijven.

Op het eiland bevindt zich ook één grote vulkaan en ongeveer 250 kraters. De autoriteiten zien echter geen dreigende vulkaanuitbarsting, dat gebeurde op El Hierro voor het laatst in 1793. Indien het toch zover zou komen, is het niet nodig om alle tienduizend inwoners te evacueren, zei veiligheidschef Juan Manuel Santana aan de krant El Pais.

Veiligheidsverantwoordelijken zouden aan verschillende evacuatiescenario's aan het werken zijn. Ook worden overal op het eiland vergaderingen gehouden om de inwoners te informeren wat er moet gebeuren in geval van een uitbarsting.

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Op vrijdag 30 september 2011 10:21 schreef Scrummie het volgende:
Is er nou wel of geen risico tot uitbarsting? Ik lees zoveel tegenstrijdige dingen :S. Dan worden mensen geevacueerd, en even later worden ze weer terug gestuurd en is er geen beving meer waargenomen :S.

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Op vrijdag 30 september 2011 10:51 schreef stan12 het volgende:
http://www.avcan.org/

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Op vrijdag 30 september 2011 11:08 schreef stan12 het volgende:

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Nee, helaas niet! Lees hier al jaren mee maar heb me net maar eens aangemeld. Vind vulkanen ook zeer vet en vooral na mijn vakantie in IJsland.

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Op vrijdag 30 september 2011 11:57 schreef Takkembah het volgende:

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Huh, je kunt toch ook Engels klikken op de site?

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Hierro Volcano - John Seach

El Hierro, Canary Islands, Spain
27.73 N, 18.03 W
summit elevation 1500 m
shield volcano

El Hierro volcano is the westernmost, youngest and smallest of the Canary Islands. In the 2nd century A.D., Ptolemy considered it the western-most position of the world.

El Hierro Island covers an area of 278 sq km, and contains three well-defined ridges, arranged at approximately 120 degrees. According to the hotspot model of volcano formation, the current location of the Canary islands hotspot is under Hierro Island.

El Hierro volcano is still in its juvenile stage of shield growth, and has been modified by gravitational spreading which caused gigantic landslides. There are three volcanic structures on El Hierro Island - elongated topographic ridge (the Southern Ridge) and two semi-circular volcanic cones (Tinor volcano, El Golfo volcano).

Tinor Landslide was the earliest and directed to the northwest of Hierro Island.

El Julan produced a 15 km wide embayment in the southwest of the island. The landslide was approximately 60–120 cubic km in volume, and covered 1600 sq km of ocean floor.

Las Playas Landslide directed SE and had a volume of 25-35 cubic km.

El Golfo, Debris Avalanche
El Golfo is a major debris avalanche on the northern flank of Hierro Island, dated about 13,000 years ago. It has a width of 15 km and a scarp height of 1000 m. The landslide deposited 150-180 cubic km of debris on the seafloor down to a depth of 3000 m.

2011 Unrest
An earthquake swarm occurred at El Hierro volcano in July 2011 with 720 earthquakes measured in a week. The earthquakes were measured between magnitude 1-3, and most were at a depth of 5-15 km. The swarm occurred at El Golfo in the northwest of the island at the location of a landslide that created a 100 metre high tsunami about 50,000 years ago. The earthquakes were continuing at the end of September and some evacuations were ordered for people living near the volcano.

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Op maandag 3 oktober 2011 11:19 schreef Jumparound het volgende:

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En waarop baseren ze dat dan?

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2011-10-03 10:54:15.31hr 32min ago 27.64 N 18.07 W 17 2.8 CANARY ISLANDS, SPAIN REGION

2011-10-03 10:27:49.61hr 58min ago 27.63 N 18.07 W 14 2.7 CANARY ISLANDS, SPAIN REGION

2011-10-03 10:14:43.42hr 12min ago 27.63 N 18.08 W 15 3.4 CANARY ISLANDS, SPAIN REGION

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Magma on the move in El Hierro, Canary Islands

This is happening faster then I expected. But it seems that magma is now on the move upwards in El Hierro volcano in Canary Islands. This is evident by the earthquake patterns that are emerging from the volcano. Given the earthquake locations, most likely place for a eruption to take place is out on the ocean based on that. But sometimes magma can find different pathways up the surface without a lot of warning.



Latest earthquake map from Instituto Geográfico Nacional that shows clearly the earthquake pattern since the dike intrusion did start in El Hierro. Copyright of this picture belongs to Instituto Geográfico Nacional.

At the moment it is impossible to know when and where a eruption might start. It depends on many factors. But it is now clear that magma is on the move upwards. So far the magma seems to be around 10 km up in the earth crust under El Hierro. So it is clear that the magma is on the way up and most likely preparing for a eruption.

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35mm deformation at El Hierro
The Instituto Geografico Nacional (IGN) has reported surface deformations exceeding 35mm on the Spanish island of El Hierro, where residents have been alert for a possible volcanic eruption. The number of earthquakes recorded since July 17 on the smallest of The Canary Islands exceeded 9250 on Tuesday morning. IGN confirmed on Monday that 1172 earthquakes were recorded last week, the majority of which were located in the sea to the SW of the 280-sqkm island. 52 of the earthquakes were felt by the local population, estimated to be approximately 10,000. A further 10 earthquakes, exceeding 3.0 magnitude on the Richter Scale, were felt during Monday and early on Tuesday. 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.

Seismologists say the majority of the earthquake activity has shifted from El Golfo in the island’s northwest to beneath the Las Calmas Sea in the south. However, magma is now on the move upwards while the depth of earthquakes has become increasingly shallow in recent days with most being recorded at a depth of 10 to 14 kilometres. Movement of magma towards the surface signifies that a volcanic eruption is likely to happen, but the timing of such remains unclear. Volcanologist Juan Carlos Carracedo last week 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”.

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

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El Hierro scientist:'More worried about earthquakes'
The Scientist in charge of the team studying the seismic activity on the Canary Island of El Hierro, Nemesio Pérez, has told the press how is is more concerned about earthquakes on the tiny island than he is of any Volcano eruption "Usually in the Canaries, they have not been that explosive, just trickles of lava. There are victims when there are earthquakes, which is why I am more concerned about the earthquakes rather than the eventual eruption."

Perez, who is the scientific coordinator of the Canaries Institute of Volcanology (Involcan) continued : "Spain has a seismic alert system comparable to that of a third-world country," he says. "Predicting volcanic activity has three components: tremors, gas emissions and deformations. But in Spain, attention is only paid to the first stage."

He told reporters how any volcanic eruption would not be rare, but the uncertainty stems from the fact that in El Hierro there isn't just one major volcano but around 500 vents on the island. As such, no one can be sure where the lava will flow if there does end up being an eruption.

The problem that this causes is that it is impossible to monitor and cordon off each and evert vent, but each one could still produce potentially fatal toxic fumes.

The Island residents have actually felt around 60 of the 9'000 recorded earthquakes over the past two months, however the frequency and strength has increased over the past two weeks.

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Vulkaanuitbarsting Tenerife helpt aardverschuivingen te begrijpen

AMSTERDAM - De ontdekking van een grote vulkaanuitbarsting op Tenerife van 733.000 jaar geleden werpt nieuw licht op aardverschuivingen. Zo is men in de toekomst mogelijk beter voorbereid op de gevolgen van dit soort grote catastrofes.

Vulkanologen van de Universiteit van Leicester ontdekten op het Canarische eiland Tenerife een aardverschuiving ten gevolge van een grote vulkaanuitbarsting waarbij een deel van de zijkant van de vulkaan de zee in verdween.

Ze publiceerden hun bevindingen in de oktober-editie van het tijdschrift Geology.

Bijzonder

Het is bijzonder dat niet vrijwel de hele aardverschuiving door de uitbarsting de zee in verdwenen is. "Het is een van de best bewaarde en toegankelijke voorbeelden van zo’n ontzagwekkend fenomeen, omdat het puin van zulke aardverschuivingen zich meestal over de oceaanbodem verspreid en daardoor ontoegankelijk voor verdere studie", verklaart Dr. Branney, een van de onderzoekers.

Het achtergebleven puin en gruis op Tenerife bevat onder andere blokken van snel afgekoeld stollingsgesteente. Radioactieve mineralen in de gestolde lava maakten het voor de onderzoekers makkelijk om zeer precies de datum van de uitbarsting te bepalen.

Klimaatverandering

Klimaatverandering wordt vaak aangewezen als reden voor aardverschuivingen op eilanden in de oceaan. Dat was nu niet het geval. Een groeiende koepel van hete lava duwde van binnenuit de zijkant van de vulkaan naar buiten toe.

Zulke gebeurtenissen zijn niet ongewoon, maar komen zeer onregelmatig voor. Ze begrijpen is daarom van belang omdat de effecten duizenden kilometers verderop grote problemen kunnen veroorzaken.

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2011-10-06 12:27:35.131min ago 27.67 N 18.04 W 13 3.1 CANARY ISLANDS, SPAIN REGION
2011-10-06 10:47:31.92hr 11min ago 27.69 N 18.04 W 14 2.8 CANARY ISLANDS, SPAIN REGION
2011-10-06 10:38:24.52hr 21min ago 27.67 N 18.04 W 12 2.5 CANARY ISLANDS, SPAIN REGION
2011-10-06 10:35:53.02hr 23min ago 27.66 N 18.02 W 14 2.7 CANARY ISLANDS, SPAIN REGION
2011-10-06 10:30:10.72hr 29min ago 27.68 N 18.03 W 16 2.5 CANARY ISLANDS, SPAIN REGION
2011-10-06 10:28:05.02hr 31min ago 27.67 N 18.03 W 12 2.6 CANARY ISLANDS, SPAIN REGION
2011-10-06 10:24:34.72hr 34min ago 27.69 N 18.03 W 16 2.5 CANARY ISLANDS, SPAIN REGION
2011-10-06 10:21:02.02hr 38min ago 27.69 N 18.02 W 16 2.5 CANARY ISLANDS, SPAIN REGION
2011-10-06 10:16:11.02hr 43min ago 27.68 N 18.03 W 16 2.6 CANARY ISLANDS, SPAIN REGION
2011-10-06 06:34:04.36hr 25min ago 27.69 N 18.05 W 13 2.6 CANARY ISLANDS, SPAIN REGION
2011-10-06 05:43:12.37hr 16min ago 27.69 N 18.04 W 12 2.8 CANARY ISLANDS, SPAIN REGION
2011-10-06 05:03:17.07hr 56min ago 27.67 N 18.04 W 12 3.2 CANARY ISLANDS, SPAIN REGION

quote:

Op donderdag 6 oktober 2011 15:45 schreef bwt het volgende:
is ook erg goed te zien op de seismogr. data van mijn vorige post.