Lava and ash spew from Mt Etna flights redirected

 

Lava and ash spewing out of a crater of the giant Etna volcano in southern Italy forced the closure of nearby Catania airport, ANSA news agency said late Sunday. With a high risk of volcanic ash being blown onto the runways, the airport was closed for safety reasons and flights redirected to nearby Palermo. It is the volcano’s 17th eruptive activity since the start of the year.

http://hisz.rsoe.hu/alertmap/site/?pageid=event_desc&edis_id=VE-20111024-32802-ITA

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Characteristics and possible evolution of the eruption in El Hierro

On this island, a volcanic eruption occurs fissure and surtseyana type. The volcanic materials could be found taquilitas.

Underwater volcanic eruption continues off the coast of South El Hierro. Eruptive focus closer to the surface of the sea it was located about 150 meters deep. The result of the shallowness on Saturday October 15 began to see the first magmatic material at the sea surface, but stopped a few days after coming to the surface, presumably because the eruptive mouth closed.

The eruption of El Hierro launched at sea pyroclastic

These pyroclastic materials collected by the ships that have come to the point eruption and even coastal areas south of the island rocks are composed of two distinct visually.

Characteristics of the materials recovered from the eruption magmatic

These pyroclasts were formed out of lava 150 meters deep and 2.4 kilometers from the coast El Hierro. On the outside are black and round or oval shaped, but inside is a white, porous material, full of gas bubbles formed by the magma dragged from deeper zones.
The dark material is, according to a preliminary study of non-tip, a taquilita. This type of rock is a volcanic glass formed after rapid cooling of basaltic magma. As for the white material needed more comprehensive analysis.

What kind of volcanic eruption is El Hierro

In addition, the volcanic eruption of El Hierro is fissural type, which means that the lava does go outside along a fracture that can break the surface along a fissure or opening several more or less aligned mouths .

And that is the underwater eruption that takes place on the island of El Hierro appears to have several sources. According to official information would be at least three places that have gone lava and gases.

The lava eruptions of this type of flow with relative ease, ie that are not highly viscous lavas and are not in their composition a high percentage of silica. Basic lavas would.

Surtseyana eruption in El Hierro, the four phases

Also described the surtseyana like rash, by the eruption of Surtsey Island in Iceland. However, in this case the name refers to a volcanic eruption under water near the sea surface and this name affect the eruptive mouths found in shallower waters. The deeper pockets of the underwater eruption does not fall under this denomination.

These eruptions are characterized by four distinct phases. In the first volcanic materials are sea surface as bubbles of lava. Then appear a white column of steam to be followed by explosions caused by the underwater volcano and acquire darker shades. In the fourth stage would form a small island where there would be a fountain of lava that would expand until it ceased to exit.

In the current situation shallower focus of eruptive fissure eruption of El Hierro , which was located about 150 meters deep according to the information given by the PEVOLCA, seems to have closed, although the eruption may continue in deeper areas Building island of El Hierro. However, the volcanic tremor continued on CHIE seismic station that could precisely target the lava is coming out somewhere.

Possible evolution of the volcanic eruption in El Hierro

Thus, the published data on this volcanic phenomenon, although difficult to predict the possible evolution glimpse. The volcanic eruption of El Hierro could be stopped at any time, although in view of the deformation on the island is not expected to be the case in the short term.

It could also continue the rash known foci and in the case of the shallowest, and after passing through the phases of the eruption surtseyana, become an island, but for this last step came to an end would require a large input of magma from below.

If the contribution of magma is higher than the amount of lava that comes out of the different foci or if one of these will be closed for any reason, then it can happen that will open new eruptive mouths, either at sea or on land. If this happened in the sea in shallow areas may be mentioned earlier phases of the eruption surtseyana .

How could last eruption of El Hierro

In any case, the data of deformation and earthquakes in El Hierro which records the IGN, they have not stopped, at least reflect the geological process continues its course, and even may point to the arrival of more magma beneath the island. As for the duration of the volcanic phenomenon , David Calvo, non-tip, aimed at RTVE that could be extended in time but the important thing is the observation and monitoring of underwater eruption near the island to be opened from other sources if any.

Translated by Google. Written by Daniel Martin

http://www.suite101.net/news/caracteristicas-y-posible-evolucion-de-la-erupcion-en-el-hierro-a69990

Deepest and most explosive underwater eruption ever seen happening near Samoa hotspot

Posted on October 20, 2011 by The Extinction Protocol

SAMOA – An underwater volcano bursting with glowing lava bubbles — the deepest active submarine eruption seen to date — is shedding light on how volcanism can impact deep-sea life and reshape the face of the planet. Submarine eruptions account for about three-quarters of all of Earth’s volcanism, but the overlying ocean and the sheer vastness of the seafloor makes detecting and observing them difficult. The only active submarine eruptions that scientists had seen and analyzed until now were at the volcano NW Rota-1, near the island of Guam in the western Pacific. Now researchers have witnessed the deepest active submarine eruption yet. The volcano in question, West Mata, lies near the islands of Fiji in the southwestern Pacific in the Lau Basin. Here, the rate of subduction — the process in which one massive tectonic plate dives under another, typically forming chains of volcanoes — is the highest on Earth, and the region hosts ample signs of recent submarine volcanism. “It was absolutely stunning and exciting, something we’d never seen on the seafloor before,” researcher Joseph Resing, an oceanographer at the University of Washington in Seattle, told OurAmazingPlanet. This submarine eruption is the deepest seen yet, about 2,200 feet (700 m) deeper than NW Rota-1. This was deeper than scientists had expected to see explosive eruptions. Water pressure goes up the further down you go, “so as pressure goes up, the ability of gas as it comes out of magma to cause explosions is diminished, and the thought was that you wouldn’t get explosive eruptions below about 1,000 meters (3,300 feet),” Resing said. Eruptions at centers of ocean floor spreading — where the majority of eruptions on Earth happen — generally seem to occur in relatively short episodes lasting hours to months, but West Mata appears to have erupted near continuously since it was first observed in 2008. This might be because magma is focused there, instead of being spread across many volcanoes at once. “However, this is a question that we don’t currently know the answer to,” Resing said. –OAP

Read more: http://theextinctionprotocol.wordpress.com/2011/10/20/deepest-and-most-explosive-underwater-eruption-ever-seen-happening-near-samoa-hotspot/

Shiveluch in violent eruption

Shiveluch volcano. © Photo: ru.wikipedia.org/NASA/JSC

Reports speak of a violent volcanic eruption of Mount Shiveluch on Russia’s Far Eastern Kamchatka Peninsula.

Smoke and ash from the volcano have climbed to 10 kilometres, sparking no-fly warnings for the surrounding area. Snow around the crater is rapidly melting, creating mudslides.

Shiveluch supports a caldera of 1.5 kilometres in diameter. Its current activity period started in 1980.

http://english.ruvr.ru/2011/10/16/58828158.html

Red Alert Issued In El Hierro Town As Underwater Volcano Erupts

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).

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, the southern-most village in the Canaries.  The estimated 537 residents of the town were summonsed to a local football field on Tuesday afternoon to be briefed on evacuation procedures.

A Red Alert has since been issued by local authorities for the town. A notice posted on the Emergencia El Hierro website on Tuesday evening stated: “Phase pre-eruptive. It involves the initiation of a preventive evacuation. Make yourself available to the authorities.”

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.”

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.

Read more: http://www.irishweatheronline.com/news/earth-science/geology/red-alert-issued-in-el-hierro-town-as-underwater-volcano-erupts/41346.html

 

 

Sixteenth paroxysmal eruptive episode from Etna’s New Southeast Crater

20111008_028_730

Ash and steam plume emitted during the paroxysmal phase of the eruptive episode of 8 October 2011 at the New Southeast Crater, seen from Trecastagni (about 15 km southeast of the summit of Etna), at 14:50 GMT (= local time -2). Photo taken by Boris Behncke, INGV-Osservatorio Etneo (Catania)

After little less than 10 days of relative calm, the 16th paroxysmal eruptive episode of this year at the New Southeast Crater (New SEC) of Etna has taken place on the afternoon of 8 October 2011. The culmination of this event, whose observation was very difficult due to bad weather, was rather brief but violently explosive, generating an ash cloud that was blown east-northeast by the wind. Once more, eruptive vents opened both on the southeastern and northern flanks of the New SEC cone.

20111008_Ferrera_400Strombolian activity and emission of lava flows from the eruptive fissure on the southeastern flank of the New Southeast Crater cone, seen from Belvedere, about 900 m southeast of the crater, at 14:14 GMT. Photo taken by Elisabetta Ferrera, University of Catania

20111008_Andronico01_400

The New Southeast Crater after the end of the 8 October 2011 paroxysm, seen from the western rim of the Valle del Bove about 2 km to the south, at 15:35 GMT. Lava is continuing to issue from the fissure on the southeast flank of the cone (at right), whereas a dilute ash plume is being emitted from the crater itself. Photo taken by Daniele Andronico, INGV-Osservatorio Etneo (Catania)

The first clear signs of a reactivation of the New SEC were recorded by the instrumental monitoring network of the INGV-Osservatorio Etneo (Catania) on the morning of 8 October, when there was a rapid augmentation in the volcanic tremor amplitude. This was accompanied by a shift of the tremor source toward the surface, and from its “normal” location beneath the Northeast Crater toward the New SEC. At about 11:00 GMT (= local time -2) the start of eruptive activity was distinctly evident in images recorded by the surveillance cameras as weak and discontinuous Strombolian explosions. Two hours later (13:30 GMT), lava started to overflow from the crater, as usual through the deep notch in its southeastern rim.

At around 13:45 GMT, vigorous Strombolian activity was observed from numerous vents along a short eruptive fissure on the southeast flank of the cone, which had first been active during the  29 August  paroxysm. After 14:15 GMT, weather conditions deteriorated, and the passage from Strombolian activity to sustained lava fountaining and ash emission was not directly observed. However, this passage, around 14:30 GMT, was well audible, and a dense ash and vapor plume rapidly rose above the weather clouds, and then drifted east. At the same time, a lava flow descended the western slope of the Valle del Bove, following the same path as the previous lava flows.

It was probably during this phase that eruptive vents opened on the northeastern flank of the cone, approximately along the fracture that had first opened during the 8 September paroxysm, and two small lava flows were emitted. The more voluminous of these, which issued from the lower end of the fracture, extended downslope for a few hundred meters to invade the central portion of the May 2008 eruptive fissure.

20111008_Zimbone_730

A panoramic view of the Valle del Bove and the New Southeast Crater during the 8 October 2011 paroxysm, seen from the Schiena dell’Asino on the southeast flank of Etna. Photo taken by Antonio Zimbone and published with kind permission of the author

The paroxysmal phase lasted little longer than 20 minutes and ended around 14:50 GMT; ash emission continued until about 17:45, when the volcanic tremor amplitude returned to levels similar to those preceding the paroxysmal episode, and the lava flow fronts appeared to stagnate. The ash cloud was blown east-northeastward by the wind, leading to ash and lapilli falls in a narrow sector that passed from the Ripe della Naca area and the village of Puntalazzo to the town of Mascali.

This paroxysm came little less than 10 days after the previous episode, and it was of shorter duration than any of its predecessors in the series initiated in January 2011 – the culminating phase of sustained lava fountaining and ash emission lasted only about 20 minutes. Another notable feature of this event is the minor eruptive activity on the northeastern flank of the New SEC cone, which occurred along the fracture of 8 September, oriented SSW-NNE in its upslope portion and bending SW-NE in its lower portion. In contrast, the fracture that opened in this area during the 28 September paroxysm lies further to the west, cutting the flank of the “Levantino”, a secondary cone formed in 2000-2001 on the north flank of the old SEC cone. The morphology of the New SEC did not undergo significant changes during this latest paroxysm, though it is likely that the accumulation of new pyroclastic material has led to some further growth in height of the cone.

http://www.ct.ingv.it/index.php?option=com_content&view=article&id=462

Earthquakes at El Hierro almost at 10,000 and Magma moving upwards

Friday, 07 October, 2011 at 17:12 UTC

The number of earthquakes recorded since July 17 , 2011 on El Hierro, the smallest of The Canary Islands, has almost reached 10,000, the Instituto Geografico Nacional (IGN) reported on Friday. The IGN also confirmed surface deformations exceeding 35mm on the 280-sqkm island, where residents have been put on alert for a possible volcanic eruption. The agency confirmed on Friday that 858 earthquakes, most of them located in the sea to the SW of the island, have been recorded in the 7 days since 30 September, 2011. During this period, 60 earthquakes were felt by the island’s estimated 10,000 residents. The strongest of the tremors measured 3.8 magnitude on the Richter Scale. Since 17 July, 9639 earthquakes with epicentres both North and South of the NW Ridge and depths between 10 and 15 km have been recorded. 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 Friday. 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 9 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 week 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.

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. According to ElHierro.com: “Although over 200 years have elapsed since the last eruption, El Hierro has the largest number of volcanoes in the Canaries with over 500 open sky cones, another 300 covered by the most recent outflows, and some 70 caves and volcanic galleries, notably the Don Justo cave whose collection of channels surpasses 6km in length.” El Hierro is located south of Isla de la Palma (population 86,000), currently the most volcanically active of the Canary Islands. About a half a million years ago, the volcano, Taburiente, collapsed with a giant landslide, forming the Caldera de Taburiente. Since the Spanish occupation, there have been seven eruptions.

http://hisz.rsoe.hu/alertmap/site/?pageid=event_update_read&edis_id=EQ-20110824-32077-SPI&uid=11509

Exclusion Zone Set Up Around Indonesia’s Anak Krakatau (Child of Krakatoa)

By MARK DUNPHY – Fri Oct 07, 2011

On July 31, 2011, a wispy ash plume rose above the volcano and drifted west (up in the below image). The natural-colour satellite image was acquired by the Advanced Land Imager (ALI) aboard Earth Observing-1 (EO-1). Dark gray areas of Anak Krakatau are composed principally of lava flows deposited in the 1970s, ’80s, and ’90s. These flows are topped by a young cinder cone near the center of the island. Green vegetation covers older lavas along the eastern coastline.  Image NASA. Instrument:  EO-1 – ALI

On July 31, 2011, a wispy ash plume rose above the volcano and drifted west (up in the below image). The natural-colour satellite image was acquired by the Advanced Land Imager (ALI) aboard Earth Observing-1 (EO-1). Dark gray areas of Anak Krakatau are composed principally of lava flows deposited in the 1970s, ’80s, and ’90s. These flows are topped by a young cinder cone near the center of the island. Green vegetation covers older lavas along the eastern coastline. Image NASA. Instrument: EO-1 – ALI

Anak Krakatau’s alert level has been raised to the second-highest level after the number of volcanic tremors soared from 200 a day to 7,200.  A 2-kilometre exclusion zone has also been established around the Indonesian volcano prohibiting tourists and fishermen from getting close to the volcanic island, located in the Sunda Strait between the islands of Java and Sumatra in Indonesia.

Indonesia’s Volcanology and Geology Disaster Mitigation Centre has expressed concern that an eruption could send incandescent rocks down its slopes and a considerable distance into surrounding waters.  The Center indicated, however, that a major eruption like that experienced in 1883 is unlikely.

Anak Krakatau, which is Indonesian for ‘Child of Krakatoa’, erupted briefly on Tuesday sending columns of ash and rock hurtling high into the air. The eruption was the biggest since January 2011 when ash was emitted more than 600 m into the air, forcing the evacuation of tens of thousands of residents. The volcano also erupted on 29th October 2010 leading Indonesian authorities to issue a level 2 alert.

The island exploded in 1883, killing approximately 40,000 people, although some estimates put the death toll much higher. The explosion is considered to be the loudest sound ever heard in modern history, with reports of it being heard nearly 3,000 miles (4,800 km) from its point of origin. The shock wave from the explosion was recorded on barographs around the globe.

http://www.irishweatheronline.com/news/earth-science/geology/exclusion-zone-set-up-around-indonesias-anak-krakatau-child-of-krakatoa/41012.html

Reykjanes Ridge Earthquakes Coincide With Rise In Seismic Activity At Katla Volcano

By MARK DUNPHY – Fri Oct 07, 12:05 pm

Reykjanes Ridge and Katla marked on Google Earth

Reykjanes Ridge and Katla marked on Google Earth

The Reykjanes Ridge, the part of the Mid-Atlantic Ridge that rises up to the ocean surface to the southwest of Iceland, has been hit by a series of earthquakes during the past 48 hours. The quakes have coincided with a surge in seismic activity in the vicinity of the Katla volcano in the south of Iceland.

The European Mediterranean Seismological Center (EMSC) has recorded at least eight subsea earthquakes about 850 kilometres southwest of the Icelandic capital of SW Reykjavík (pop 113,906).

The strongest of the quakes, a magnitude 5.7, was located 892 km southwest of the Icelandic capital Reykjavík. It hit at 00:39 GMT and was measured at a depth of just 10km, according to the EMSC.

Meanwhile, the Icelandic Meteorological Office noted that an earthquake swarm occurred underneath theMýrdalsjökull glacier in south Iceland on Wednesday and Thursday.

Approximately 30-40  earthquakes were recorded on Wednesday and Thursday. The strongest earthquake measured ML3.55 and was measured to have hit at a depth of 1 kilometre.  Seismic activity has since subsided. Only six earthquakes have been recorded at Mýrdalsjökull between 0000hrs and 1200hrs on Friday.

Geophysicist Benedikt Ófeigsson told visir.is said that while the situation is being constantly monitored, it has not been considered necessary to alert Iceland’s Civil Defense Department.

In recent weeks residents of Vik (population 300 approx.), located at the foot of Katla, have participated in emergency evacuation drills in the event of a volcanic eruption and subsequent glacial floods  affecting the small coastal town.

Read more: http://www.irishweatheronline.com/news/earth-science/geology/reykjanes-ridge-earthquakes-coincide-with-rise-in-seismic-activity-at-katla-volcano/40983.html