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Chaitén bulletin no. 80 (26 February 2009) 2 March 2009

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SERNAGEOMIN bulletin no. 80 on the eruption of Chaitén volcano was issued on 26 February 2009. The original text can be found at the OVDAS website (PDF) and a slightly edited version is also available on the SERNAGEOMIN site. Translation as follows.

ERUPTION OF CHAITÉN VOLCANO
TECHNICAL BULLETIN NO. 80
26 FEBRUARY 2009
OVDAS-SERNAGEOMIN

Visual monitoring

Reports from SERNAGEOMIN personnel in the Chaitén area indicate that the eruptive activity is remaining relatively stable, with an altitude of the column of less than 2km. During the day some small collapses have occurred on the slopes of the pinnacle. On each occasion, there have been temporary changes in the eruption column, which has become wider and irregular and has turned clear brown in colour, because of the greater ash content. Small collapses were observed, for example, at 17:39, 18:44, 18:59 and 19:35, this last of greater magnitude (Fig. 1). Also, continuing eruptive activity with emission of ash and gases, with the growth of the dome, has been observed in the southern sector of dome 1. The columns are irregular and spasmodic, with a predominance of gas and ash over water vapour, along with numerous small fumaroles formed principally of water vapour.

Figure 1.
Figure 1. Partial collapse, of relatively small dimensions, of part of the pinnacle towards the upper part of the scar left by the collapse of 19.02.09, generating an irregular cloud of ash and gases which turns a clear brown colour (photograph by C. Gallegos, taken at 19:40 from Chaitén).

Seismic activity

The seismic activity presents no significant changes compared to that reported in yesterday’s bulletin, with 1-2 HB-type earthquakes with magnitudes within 2.5 and 3.6. The Seismological Service of the University of Chile reports, in addition, 2 earthquakes with depths of 15.1km and 14.4km, respectively.

Conclusions and interpretation

Growth and partial collapses continue at the pinnacle and the south sector of dome 1. The seismic activity continues without significant changes in comparison to the previous bulletin.

Taking into account the seismicity of the area of the volcano, the continuing probability of the occurrence of new major collapses of important parts of dome 1 and the pinnacle, generating explosions and associated pyroclastic and ash flows, along with the probability of the occurrence of new lahars during periods of prolonged and intense rainfall, SERNAGEOMIN maintains Volcanic Red Alert.

[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