[breaking] Vulkaanuitbarsting bij Canarische Eilanden

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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:

[..]

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:

[..]

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:

[..]

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

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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.