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Explosive eruptions at Galeras 26 April 2009

Posted by admin in activity reports, Colombia, eruptions, Galeras.
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An explosive eruption took place at Galeras volcano in Colombia at 19:32 local time on Friday 24 April 2009, with a second, less powerful eruption at 20:09. Nobody was hurt and no damage was done, although some ashfall was reported. An evacuation of high-risk areas around the volcano was ordered and, as usual, widely ignored.

Over the preceding 48 hours there had been a reduction in the seismicity associated with fluid movements within the volcano, and a rise in the numbers of rock-fracturing earthquakes. This led to an increase in the alert level for Galeras to Orange (eruption probable within days or weeks) in the early morning of 24 April.

On 25 April the Observatorio Vulcanológico y Sismológico de Pasto issued a bulletin immediately the 19:32 eruption occurred, raising the alert status for Galeras to the highest level of Red (eruption imminent or under way). A detailed bulletin was issued at 21:10 which reported the following:

  • An ‘eruptive process’ began at 19:32, the most important eruptions taking place at 19:32 and 20:09. The first eruption was the most powerful, but the second was of longer duration.
  • The two events were visible from Pasto: incandescence and the projection of blocks towards the north were observed during the first eruption. Ashfall was reported in districts north-west of the volcano, up to 20 kilometers away. Washington VAAC reported the altitude of the ash column as 6 km above the summit.
  • Significant increases in seismicity occurred around 20:19 and 20:30, the first of which was associated with renewed eruption of incandescent material and the second with loud noises.

The most recent bulletin was issued at 12:10 yesterday, 25 April, which announced the lowering of the alert level to the second-highest state of Orange (eruption probable within days or weeks), and reported ‘seismic signals associated with dynamic fluid processes’. Some of these seismic upswings were associated with ash emissions reaching up to 1000 metres above the summit of the volcano. Since the eruption no ‘tornillo’ type or hybrid earthquakes have been registered; both types were evident before the eruption. An INGEOMINAS/Fuerza Aérea Colombiana overflight took place yesterday morning which reported erupted material including blocks on the north side of the summit area, three areas in which traces of forest fires were visible, and thermal anomalies with temperatures of up to 100°C on the western side, reflecting the presence of erupted volcanic materials. Emission of gases ‘with a strong smell of sulphur’ was taking place at the principal crater. Volcanic bombs thrown out during the eruption had travelled up to 2-3 kilometres from the crater.

The local authorities ordered an evacuation affecting 7000 people in response to the eruption. As on previous occasions, however, the order was almost entirely ignored. ‘People are not paying attention to the emergency announcements’, complained Nariño provincial governor Antonio Navarro Woolf: ‘The people living around the volcano believe more in la Virgen de las Mercedes [Our Lady of Mercy] than in the alerts’. It seems that only 300 people responded to the emergency announcements and moved to the shelters. ‘Es mejor prevenir que tener que lamentar‘, says Navarro Woolf: ‘it is better to prevent than to have to regret’.

There are photographs of the eruption and a video available on the Pasto Observatory website.

For all our Galeras coverage: Galeras « The Volcanism Blog.

News
Nueva erupción en el volcán Galeras, en Nariño – Caracol Radio, 24 April 2009
Entra en erupción un volcán en el sur de Colombia, en la frontera con Ecuador – AFP, 25 April 2009
‘La gente no atiende los llamados de emergencia’: Navarro WoolfEl País, 26 April 2009
A nivel naranja bajó alerta del volcán Galeras, reportó IngeominasEl Tiempo, 26 April 2009

Information
Global Volcanism Program – Galeras – summary information for Galeras (1501-08=)
Portal Corporativo de INGEOMINAS – Instituto Colombiano de Geología y Minería
Observatorio Vulcanológico y Sismológico de Pasto – Pasto volcanological observatory main page

The Volcanism Blog