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Cerro Azul update, 6 June 2008 6 June 2008

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The eruptive episode of the last few days may be over, but the latest (5 June 2008) Instituto Geofísico bulletin (PDF) on Cerro Azul paints a picture of significant ongoing activity. As predicted in the preceding (3 June 2008) IG bulletin (PDF) eruptive activity has developed at a new location.

The first part of the report provides some information about the eruption of 29 May to 1 June, which ‘took place in three different locations on the outer south-eastern flank of the volcano’. There were three distinct vents involved, the first ‘near the south-east rim of the caldera … generated six different lava flows (aa type) with thicknesses of up to 5m, that descended the south-east flank of the volcano very quickly’. The other two vents, both consisting of fissures 1km in length, were situated in the central part and at the foot of the south-eastern flank. The upper of these two produced lava flows ‘of up to 15m thickness’, the lower ‘also emitted several lava flows and formed eruptive cones of a greater height than in previous cases’.

‘While this eruptive episode in this part of the volcano was of brief duration’, notes the bulletin, ‘it was however of great intensity, since the lava flows extended to about 10 km long and covered an area of about 2-3km in breadth, giving an idea of the vast amount of lava which was erupted’.

In the evening of 3 June satellite thermal imaging revealed the presence of hot spots in the extreme south-east of Cerro Azul, which subsequently increased in intensity and migrated eastwards, ‘suggesting that new volcanic activity could have been initiated at this fresh location, as envisaged in our Special Bulletin No. 2 and as occurred during the eruption of 1998’. An overflight revealed a new 400-500m fissure on the eastern flank of Cerro Azul, where the volcano borders the neighbouring Sierra Negra volcano. Lava from this fissure was flowing towards the southern coast of the island of Isabela, and scoria blocks were being ejected to heights of up to 60m above the fissure. A northward-trending eruption column 50km in length was observed during the overflight and confirmed by satellite imagery. The continuing presence of hot spots at this new location has been detected by satellite, ‘so it is presumed that this [eruptive] activity is continuing’.

Information
Global Volcanism Program: Cerro Azul – summary information for Cerro Azul (1503-06=)
Instituto Geofísico (Escuela Politecnica Nacional) – Geophysical Institute of Ecuador

The Volcanism Blog

Cerro Azul: decline in activity 4 June 2008

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‘Giant tortoises safe as Galapagos volcano ends activity’ announces AFP in a news report today, and Ecuadorian newspaper El Universo agrees: ‘Volcán Cerro Azul dejó de erupcionar en Galápagos’. Talk of Cerro Azul’s activity ‘ending’ may be premature, however. The volcanologists of Ecuador’s Instituto Geofísico (IG) are rather more circumspect in their second special bulletin (PDF) on the eruption. They report that the lava flows from a fissure on the south-east flank of the volcano, which had reached a maximum extent of about 10km between Thursday 29 May and Sunday 1 June, ceased at around 15:00 local time on Sunday. The flow of lava gave way to emissions of water vapour and gas from the numerous vents along the fissure. At the same time satellite imagery revealed a decline in the intensity of the hot spot which had been detected near the fissure. However, the IG warns that there may well be further activity to come, with the focus of activity moving from the flank of the volcano to within the caldera:

While activity has decreased significantly for the moment and the emission of lava flows has ceased, a resumption in the coming days cannot be ruled out; it must be recalled that in the 1998 eruption, the activity was initially localized in the south-east flank, but a few days later the activity was located within the caldera, and lava flows were registered in the interior of the caldera. In the event that the latter situation is produced, since a gap exists in the interior of the caldera, there is a high likelihood that phreatomagmatic explosions will be generated, that occur when magma comes into contact with water, as attested by the deposits of volcanic material left on the edge of the caldera during past eruptions of the volcano.

A report from Terra España, quoting Galapagos National Park (PNG) officials, describes the seat of the eruption as ‘a radial fissure forming a crack about one kilometre in length, with a chain of small cones from which lava was expelled’. According to the PNG, only non-endangered species of flora were damaged during the eruption, there is no danger of forest fire because of the high rainfall at this time of year, and that no further damage from the lava is anticipated.

Information
Global Volcanism Program: Cerro Azul – summary information for Cerro Azul (1503-06=)
Instituto Geofísico (Escuela Politecnica Nacional) – Geophysical Institute of Ecuador

News
Giant tortoises safe as Galapagos volcano ends activity – AFP, 4 June 2008
Volcán Cerro Azul dejó de erupcionar en GalápagosEl Universo, 4 June 2008 (Spanish)
El volcán del archipiélago Galápagos deja de emanar lava y su actividad desciende – Terra España, 4 June 2008 (Spanish)

The Volcanism Blog

Cerro Azul: ‘new eruptive period’ under way 30 May 2008

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Cerro Azul in the Galapagos Islands is a 1640m-high shield volcano that last erupted (VEI=1) in 1998. According to the Ecuadorian Instituto Geofísico (IG) a ‘new eruptive period’ began yesterday evening (29 May 2008) with the detection of seismic signals in the vicinity of the volcano from 21:43 local time. Satellite images from the same time period revealed a hotspot on the southern side of Cerro Azul, and ‘a reddish glow’ was observed ‘in the direction of the volcano’. This morning, according to the IG’s Special Bulletin No. 1 (PDF) on Cerrro Azul, the activity was still in progress:

The satellite image (VAAC) of 07:15 (Galapagos time) this morning showed the presence of an eruption column, probably with low ash content, extending some 75 nautical miles to the north-west of the volcano. At the time this report went to press the presence of a hotspot in the vicinity of Cerro Azul could still be observed, so the production of lava flows is certainly continuing. Galapagos National Park personnel are currently conducting an overflight at the volcano, to ascertain more precisely the location of the eruptive centre and carry out an initial assessment of the spread of lava flows and their likely impact on the fauna and flora of the area.

Initial information from the overflight indicated that the eruption originates on the south-eastern flank of the volcano.

‘The eruption is a natural process of regulation, as the Galapagos Islands are of volcanic origin’, El Universo quotes a relaxed Galapagos National Park official as saying today.

The Eruptions blog has an informative report on this eruption.

Information
Global Volcanism Program: Cerro Azul – summary information for Cerro Azul (1503-06=)
Instituto Geofísico (Escuela Politecnica Nacional) – Geophysical Institute of Ecuador

News
Volcano erupts in Galapagos Islands – Associated Press, 30 May 2008
Galapagos volcano eruption threatens giant turtles – Reuters, 30 May 2008
Volcán Cerro Azul erupciona en islas GalápagosEl Universo, 30 May 2008 (Spanish)

The Volcanism Blog

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