jump to navigation

Chaitén bulletins: no. 111 (1 December 2009) and no. 112 (15 December 2009) 14 January 2010

Posted by admin in activity reports, Chaitén, Chile, eruptions.
Tags: , , ,
trackback

The two most recent Chaitén bulletins from SERNAGEOMIN to be made publicly available (via the SEGEMAR website and at Werner Luis’s Chaitén site) are no. 111 covering 14 November to 1 December 2009 (PDF) and no. 112 covering 1-15 December 2009 (PDF). Translations as follows.

CHAITÉN VOLCANO
TECHNICAL BULLETIN NO. 111
14 NOVEMBER TO 1 DECEMBER 2009
OVDAS-SERNAGEOMIN

1. Visual monitoring

The area of Chaitén volcano has remained covered by cloud for most of this period, because of the poor weather conditions. Nevertheless, OVDAS personnel based in the area were able to observe an increase in fumarolic activity on 18 November characterized by a column of some 3,000 m altitude, principally composed of water vapour (Fig. 1). This activity was related to rumbling sounds and a slight increase in seismicity recorded on that day.

Moreover, on 22 November the DGAC camera recorded a vigorous emission of steam, gases and ash with an altitude not surpassing 1000 m above the dome complex (Fig. 2).

Figure 1.
Figure 1. Image acquired from Chaitén on 18 November (SERNAGEOMIN).

Figure 2.
Figure 2. Images from the DGAC camera in Chaitén recorded on 22 November. [Click image to enlarge.]

2. Seismic activity

As part of the implementation of the Chaitén volcano monitoring network, SERNAGEOMIN staff have installed four new seismological stations during November, named Bonito-2, Camahueto, Torre and Caverna. These stations are currently undergoing trials and are transmitting their signals in real time to OVDAS, and their data will shortly be incorporated into the routine analysis of the volcano’s activity.

It is important to note that the proximity of these stations to the centre of the Chaitén volcano dome complex, principally the stations Caldera (1.3 km), Bonito-2 (3 km) and Camahueto (5 km) allows for optimal registration of the seismicity associated with the eruptive activity.

Between 14 November and 1 December, STAB and PILL stations registered the following seismicity:

Type of earthquake: Hybrid HB
Average: 16 daily
Total: ~272
Magnitude: max. 4.3, min. 1.5

The activity shows slight fluctuations with a tendency towards decline, both in the number of earthquakes and in magnitude. Notable is the occurrence of 2-3 earthquakes daily with magnitudes greater than 3.5.

The greater part of the seismicity presents similar wave forms, which suggests that they have their origin in the same source and reflect the same mechanism of origin.

3. Conclusions and interpretation

The activity analysed continues to show relative stability, which indicates that the eruptive cycle continues with the growth of the dome complex.

Therefore, bearing in mind that the seismicity 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 which may affect the surrounding valleys and include the generation of new lahars, SERNAGEOMIN suggests maintaining Volcanic Red Alert.

OVDAS-SERNAGEOMIN
1 December 2009

[End of SERNAGEOMIN bulletin 111.]

CHAITÉN VOLCANO
TECHNICAL BULLETIN NO. 112
1-15 DECEMBER 2009
OVDAS-SERNAGEOMIN

1. Visual monitoring

The images from the DGAC camera located in Chaitén show that the eruption continues with its column of water vapour, ash and gases (Fig. 1A), which occasionally climbs to 2.0 km above the dome complex. On 7 December two centres of emission were observed located in the north and the south of the dome complex (Fig. 1B). Moreover, on 8 December, a block-and-ash flow was registered, indicating that the dome complex continues to grow (Fig. 1C).

Figure 1.
Figure 1. Images acquired by the DGAC camera from Chaitén on 7, 8 and 11 December. [Click on image to enlarge.]

2. Seismic activity

Between 1 and 15 December, STAB and PILL stations registered the following seismicity:

Type of earthquake: Hybrid HB
Average: 10 daily
Total: ~152
Magnitude: max. 4.5, min. 1.5
RSAM: 150,000 units max.

According to the information from these stations the seismic activity has declined both in number of earthquakes and magnitude. However, two earthquakes per hour stood out with magnitudes greater than 3.5. The information obtained from the stations closest to the volcano is characterized by a greater number of earthquakes of lower magnitude, that were not registered by STAB and PILL stations, which suggests that this activity is concentrated in the upper part of the volcano.

The greater part of the seismicity presents similar wave forms, which suggests that they have their origin in the same source and reflect the same mechanism of origin.

3. Conclusions and interpretation

Although the seismicity recorded during this period has declined it remains high. This fact, associated with the generation of block-and-ash flows referred to earlier, indicates that the eruptive activity continues with the growth of the dome complex, possibly at a lesser rate of growth compared with that of the preceding periods. Moreover, there is a continuing latent danger of collapses, possible explosions and generation of block-and-ash flows, which may affect the valleys adjacent to Chaitén volcano. In consequence, SERNAGEOMIN maintains Volcanic Red Alert.

OVDAS-SERNAGEOMIN
15 December 2009

[End of SERNAGEOMIN bulletin 112.]

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
Erupción del Volcán Chaitén – extensive coverage of the Chaitén eruption

The Volcanism Blog

Comments

1. Les Francis - 15 January 2010

Viewing was quite good Thursday – first time for weeks. Plume has a very large base.

2. Guillermo - 17 January 2010

Sorry comments are closed for this entry