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Chaitén bulletin no. 96 (8 June 2009) 10 June 2009

Posted by admin in activity reports, Chaitén, Chile, eruptions.
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Bulletin no. 96 on the eruption of Chaitén volcano, covering the period 2-8 June 2009, is now available as a PDF via the informes page of the Observatorio Volcanológico de los Andes del Sur (OVDAS) website. There is also a summary version (combined with a report on Llaima) on the SERNAGEOMIN website. Translation as follows.

ERUPTION OF CHAITÉN VOLCANO
TECHNICAL BULLETIN NO. 96
2-8 JUNE 2009
OVDAS-SERNAGEOMIN

1. Visual monitoring

Personnel of the Observatorio Volcanológico de Los Andes del Sur (OVDAS-SERNAGEOMIN) in the area have been able to observe that the volcanic activity continues, shown by the column of gas, water vapour and ash, which on occasion reaches a height of 1.5 km above the dome complex (Fig. 1a). From the northern sector, near a portable seismological station, continuing block-and-ash flows have been seen, indicating that the dome complex continues to grow, mainly towards the western sector of the caldera, although the major fumarolic and ash emission activity is currently exclusively in its central portion (Fig. 1b). Ashfall has been detected particularly towards the Santa Bárbara area, and occasionally on the town of Chaitén.

Figure 1a
Figure 1a. View of the column of gas and ash from Chaitén.

Figure 1b
Figure 1b. Detail of the domes and block-and-ash flows, principally in the western sector.

2. Seismic activity

The seismicity registered by the Chaitén volcano monitoring network has shown a slight tendency towards greater seismic activity, with an average of 15 events per day and maximum magnitudes of 4.4. Additionally, there has been a growth in seismicity of under [magnitude] 2.5, which has climbed to an average of 8-12,with a slight reduction during the last few days. The greater part of the seismicity consists of very similar wave forms, suggesting that it originates from the same source, particularly for the smaller earthquakes. When the seismicity of greater magnitude is evaluated, the events are shown to have increased slightly in number and amplitude, indicating a higher level of energy than in previous days. With regard to the seismic energy released RSAM, this has not exceeded 150,000 units.

3. Conclusions and interpretation

The eruptive activity continues with the sustained growth of the dome complex, which is rising and expanding, with the generation of block-and-ash flows (in different areas), sometimes perceptible from Chaitén. In general, the seismic activity during this period has increased. There is a continuing latent danger of collapse because of the growth of the domes, with possible explosions and generation of block-and-ash flows, which may affect the valleys adjacent to Chaitén volcano. In consequence, given that the seismic activity remains elevated as an effect of the growth of the dome complex, with the possibility of the generation of block-and-ash flows in random directions that may affect surrounding valleys, SERNAGEOMIN maintains Volcanic Red Alert.

OVDAS-SERNAGEOMIN
08.06.09

[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