Chaitén bulletin no. 97 (16 June 2009) 20 June 2009Posted by admin in activity reports, Chaitén, Chile, eruptions.
Tags: Chaitén, Chile, South America, volcanic activity reports, volcanic eruptions
Bulletin no. 97 on the eruption of Chaitén volcano, covering the period 9-16 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. 97
9-16 JUNE 2009
1. Visual monitoring
Personnel of the Observatorio Volcanológico de Los Andes del Sur (OVDAS) who have been carrying out the collection of data from the seismological stations in the area have observed that the eruptive activity continues without change, shown by the column of gas, water vapour and ash rising up to 1.5 km above the dome complex. From the northern sector (Los Gigios) the continuing growth of the domes, mainly towards the western area of the caldera, has been observed, although the major fumarolic and ash emission activity is currently exclusively in the central sector. Because of adverse meteorological conditions it has not been possible over the last few days to observe the volcano through the DGAC camera installed at Chaitén.
2. Seismic activity
The seismic monitoring network of Chaitén volcano has registered an average of 18 HB-type [hybrid] earthquakes per day, with maximum magnitudes of up to 4.4, values similar to those recorded in the preceding weeks. With regard to seismicity with magnitudes of less than 2.5, on 10 June an increase was noted, climbing to 20 earthquakes, then declining up to 16 June. Much of the seismicity presents very similar wave forms, which suggests an origin in the same source, particularly for the smaller earthquakes. Regarding the seismic energy released RSAM, this has remained under 150000 units.
3. Conclusions and interpretation
The eruptive activity continues with the sustained growth of the dome complex, visible at times, which continues to expand in height and extent, with generation of block-and-ash flows. Seismic activity for this period has been maintained, both in average number and in magnitude. The latent danger of collapse caused by the growth of the domes continues, with possible explosions and generation of block-and-ash flows, which may affect the valleys adjacent to Chaitén volcano. In consequence, bearing in mind that seismic activity has remained elevated as a result of the growth of the dome complex, with the possibility of the generation of block-and-ash flows in random directions that may affect the surrounding valleys, SERNAGEOMIN maintains Volcanic Red Alert.
[End of SERNAGEOMIN bulletin.]
The above document can perhaps best be described as ‘sketchy’. There is often a rather perfunctory air to these Chaitén bulletins from SERNAGEOMIN: an ‘informe’ as lacking in detail and information as that reproduced above really is not worthy of the name. Even after making every allowance for the pressures upon SERNAGEOMIN and its limited resources, one cannot help concluding that communicating with the public is just not something it particularly cares about. This attitude will have to change if the planned Chilean National Volcano Monitoring Network, in which SERNAGEOMIN will play a central role, is to do its job effectively.
For all our Chaitén coverage: Chaitén « The Volcanism Blog.
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