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Chaitén update, 19 February 2009 20 February 2009

Posted by admin in activity reports, Chaitén, Chile, eruptions.
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SERNAGEOMIN have issued a special bulletin reporting on the events of today at Chaitén. Translation as follows.

19.02.2009 Eruption of Chaitén Volcano – Special Bulletin

The absence of significant changes in the seismic monitoring record indicates that the process of generating the pyroclastic flows occurred at the level of the dome. The trigger mechanism for the flows could correspond to collapses of Dome 2 or explosions occurring within it. Both processes have been identified as events with the potential to occur in previous bulletins.

In consideration of the current course of the volcano’s eruptive activity, the occurrence of large flows that may affect the town of Chaitén cannot be ruled out at this stage.

Visual monitoring

According to information provided by telephone from Chaitén, by Captain Alejandro Villablanca of the Carabineros, at approximately 11:00 there was an explosion with ash emission at Chaitén volcano. This was recorded by the DGAC camera from the airfield at Chaitén and by Mr Dagoberto Guzmán. The photographic record shows that the pyroclastic flows descended the river valley in the direction of Chaitén. Moreover, the administrator of Pumalín Park reported that an ash cloud descended via the río Blanco, approximately 5km, towards Chaitén.

Fig 1.
Photograph 1. View of pyroclastic flow from the DGAC camera at Chaitén.

Fig. 2.
Photograph 2. Photograph of pyroclastic flow along the río Chaitén, provided by Mr Dagoberto Guzmán and taken from the White Bridge at Chaitén.

Seismic activity

The record of seismic activity indicates that similar behaviour to that of recent weeks has been maintained. However, from 10:28, a change was observed with increasing amplitude (energy) of the background signal and generation of energetic tremor.

SERNAGEOMIN maintains continuous monitoring of seismic activity and Volcanic Red Alert.

Seismic records

Preceding hours, seismicity similar and comparable to that reported in previous bulletins.
09:20-10:02 – no seismic anomaly
10:02 – 1 earthquake comparable to those of preceding days
10:02-10:28 – no seismic anomaly
10:28 – increase in the amplitude (energy) of the background signal (tremor)
10:28-11:00 – energetic tremor
11:00-11:50 – energetic tremor and 8-9 earthquakes of magnitude comparable to those of preceding days
11:50-12:40 – tremor less energetic than previously, and 2-3 earthquakes similar to those of preceding days

Fig. 3.
Fig. 3. Seismogram in GMT, for local time subtract 3 hours. At around 10:28 there was an increase in tremor and the numbers of earthquakes.

[End of SERNAGEOMIN bulletin.]

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

Information
Global Volcanism Program: Chaitén – summary information for Chaitén (1508-41)
SERNAGEOMIN – Servicio Nacional de Geología y Minería (Spanish)
Erupción del Volcán Chaitén – extensive coverage of the Chaitén eruption

The Volcanism Blog

Comments

1. Callan Bentley - 20 February 2009

Cool images.


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