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Chaitén update, 11 August 2009 (bulletins 101 and 102) 11 August 2009

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Two new SERNAGEOMIN bulletins on the ongoing eruption at Chaitén to catch up with: no. 101 (PDF), covering 8-15 July 2009, and no. 102 (PDF), covering 16-22 July 2009. Nothing has been made available since, and neither of these bulletins is yet available on the informes page of the Observatorio Volcanológico de los Andes del Sur (OVDAS) website; this inability to provide even the most basic information in a timely manner is all too typical of the way SERNAGEOMIN does things. The PDF links above are to SEGEMAR (Servicio Geológico Minero Argentino), via Werner Luis’s Erupción del volcán Chaiten site.

These two bulletins are, like their immediate predecessors, sketchy and formulaic, and there is no point in providing full translations. Bulletin 101 (8-15 July 2009) reports the eruption column reaching up to 1.2 km above the dome complex, persistent block-and-ash flows indicating continuing growth of the dome particularly in the western part, and stable seismicity with daily averages of 22 hybrid (HB) earthquakes with magnitudes up to 4.2, and 11 with magnitudes of below 3.0. RSAM levels have not exceeded 150,000 units. The conclusion warns of the continuing danger of block-and-ash flows and lahars, and announces the maintenance of Volcanic Red Alert. Bulletin 102 is exactly the same, except that the plumes are reported to be reaching up to 1.5 km above the dome complex, and the daily average of hybrid earthquakes of greater than magnitude 4.0 is given as 20.

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Chaitén update, 27 March 2009 27 March 2009

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Chaiten Volcano 17 March 2009 (photo Nicolas La Penna Chaitur.com)
Chaitén volcano at sunset on 17 March 2009: close-up of the pinnacle and lava dome (photograph by Nicolas La Penna, Chaitur.com).

SERNAGEOMIN have a summary of a new Chaitén bulletin on their website, dated 25 March 2009 and covering the period 17-23 March, but the full document has apparently not yet been made available. As soon as I have a copy, I will post a full translation. The main points from the summary bulletin are:

  • Constant degassing and steam emission, with varying ash content, continues at the dome complex.
  • Gravitational collapses of unstable areas of the dome continue, possibly slightly increased in number, causing block-and-ash flows.
  • Dome growth appears to be restricted to the central-southern area, where the tall central spine and a significant portion of dome 1 are located.
  • The central spine is very tall, unstable, and shows very high temperatures.
  • Block-and-ash flows continue to generate ash plumes which disperse mainly to the north and east-south-east.
  • There has been a significant decrease in seismicity, with fewer hybrid (‘HB’) earthquakes and lower magnitudes, suggesting a slowing in the rate of dome growth.
  • The dangers of further dome/pinnacle collapses generating debris flows and lahars along the Chaitén river valley remain.
  • SERNAGEOMIN is maintaining Volcanic Red Alert.

In other Chaitén news, the Chilean Government has announced that planning for the ‘new Chaitén’ at Santa Barbara will be completed this year, with full-scale development of the new town beginning in 2010. Basic services at the site are to be installed over the next two months.

Chaiten Volcano 17 March 2009 (photo Nicolas La Penna Chaitur.com)
Chaitén volcano at sunset on 17 March 2009: view from  Chaitén town (photograph by Nicolas La Penna, Chaitur.com).

Many thanks to Nicolas La Penna of Chaitur.com for contributing the photographs that accompany this article. These images clearly show the height and instability of the central pinnacle: note, too, the smaller pinnacle and rough surface of the southern part of dome 1 in the foreground – signs of active lava extrusion – and the constant degassing and steam emission from throughout this section of the dome complex.

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

Chaitén update, 27 February 2009 27 February 2009

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Bulletin no. 78 on the eruption of Chaitén volcano, covering the period 20-24 February 2009, has been released by the Chilean geological service SERNAGEOMIN. It is available from the OVDAS website (PDF) and has also been published on the SERNAGEOMIN website. Beware of the latter link: because huge images have been squeezed into small spaces on the page (forcing 3264 pixels width into 350 pixels) rather than properly resized the whole thing is very slow and unresponsive. Anyway, translation as follows (click on ‘more’ for the whole document).

ERUPTION OF CHAITÉN VOLCANO
TECHNICAL BULLETIN NO. 78
20-24 FEBRUARY 2009
OVDAS-SERNAGEOMIN

Visual monitoring

An overflight carried out today, 24 February, in a UH-1H helicopter of the Chilean Air Force, in conjunction with the Presidential Delegate and representatives of the DOH [Dirección de Obras Hidráulicas – Hydraulic Works Directorate] and Vialidad [Dirección de Vialidad – Roads Directorate] allowed the verification of the current state of eruptive activity, the morphology of the domes and the dimensions and precise location of the area affected by the collapse that occurred last Thursday (19.02.09).

Also observed was the distribution of the pyroclastic flows and the block-and-ash deposits, originating with the collapse of the domes, across the headwaters of the río Chaitén and in the depression (basal ring) which surrounds the domes (Fig. 1).

The escarpment or scar of the collapse is oriented in an approximately south-western direction, with a greatest length of approximately 500m (in the south-western direction) and a maximum height of the of the escarpment slopes of 200m. The area of collapse is located in the south-western quadrant of the dome complex and affects, approximately, some 10% of the total volume. The collapse escarpment surrounds the south and west of the spine or pinnacle which has grown in the central sector of the dome complex. The majority of the material removed is from Dome 1, the development of which began in May 2008 (Figs. 2 and 3).

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Chaitén update, 24 February 2009 24 February 2009

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Bulletin no. 76 on the eruption of Chaitén volcano, covering the period 19-20 February 2009 and thus covering the dome collapse of 19 February, has been released by the Chilean geological service SERNAGEOMIN. It is available from the OVDAS website (PDF) and from Werner Luis’s Chaitén site (PDF), and has also been published in slightly edited form on the SERNAGEOMIN website. Translation as follows (click on ‘more’ for the whole document).

ERUPTION OF CHAITÉN VOLCANO
TECHNICAL BULLETIN NO. 76
19 TO 20 FEBRUARY 2009
OVDAS-SERNAGEOMIN

Visual observation

Today, Friday 20 February, in coordination with the Intendente Regional, the Presidential Delegate and the National Director and Regional Director of ONEMI, among others, an overflight of the area of Chaitén volcano was carried out [by SERNAGEOMIN] in a Twin Otter aircraft of the Chilean Air Force. Because of the conditions of low cloud it was not possible to observe the eruptive activity, the dispersal of the plume, nor the development of the collapsed sector of the dome.

The overlight revealed that there are continuing emissions of water vapour along the course and banks of the upper sector of the río Chaitén (Blanco), which are interepreted, on a preliminary basis, as a result of the contact between water in the river with hot volcanic deposits produced by the pyroclastic flows and the rocks and ashes originating from the collapse and lateral explosion from the south of the dome which occurred on the morning of Thursday 19 [February].

Using photographs obtained in the overflights of yesterday, Thursday, and observations made during the overflight of today, Friday, it was estimated that the pyroclastic flows and rock-and-ash flows associated with the collapse and lateral explosion of the dome involved a quantity of approximately 30 million tonnes of material being removed its southern slope (10 million cubic metres). This material is dispersed in the form of sediments and volcanic deposits on the floor of the upper part of the valley and on the lower slopes of the sides of the upper course of the río Chaitén (Blanco). The preceding increased, considerably, the quantity of volcanic material available in the headwaters of the river and, again, increased the danger of the generation of continuous or sporadic lahars, encouraged by the intense and prolonged rains, which continue to affect the town of Chaitén long-term, especially in the winter.

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Chaitén update, 20 February 2009 20 February 2009

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SERNAGEOMIN have a new and very lengthy Chaitén update available on their website: 20.02.2009 Sernageomin Informa sobre el Volcán Chaitén. Translation as follows (first part only below – click on ‘more’ to read the whole thing).

[N.B. BBC News have a short video from the overflight referred to in this report, available here.]

20.02.2009 SERNAGEOMIN report on Chaitén Volcano

Until approximately 10:28 yesterday the seismic activity had remained essentially similar to that registered on preceding days. From 10:28 a small swarm of earthquakes began of HB type, associated with a slightly energetic background tremor, which was related to the collapse of a significant sector of the southern slopes of the domes, lateral explosions and block-and-ash flows and pyroclastic flows, all directed towards the south, which reached the upper part of the valley of the Chaitén river up to 5km north of the city of the same name. In addition, it generated eruption columns which, around 14:00, reached approximately 8km in altitude, with a dispersal plume directed to the south-east, precipitating ash towards the town of Futaleufú.

In several previous reports the certain possibility of an occurrence of such collapses of the domes towards the south, with lateral explosions and the generation of block-and-ash flows and pyroclastic flows, has been highlighted. In accordance with the preceding, we reiterate what was stated in the special report issued yesterday, in the sense that it is not possible to rule out the occurrence of new collapses, lateral explosions and the generation of large pyroclastic flows that could affect the town of Chaitén and also towards other sectors of the volcano, in addition to the dispersal of ash which will affect areas situated, principally, in the south-east and north and south.

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Chaitén update, 19 February 2009 20 February 2009

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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

Chaitén update, 18 February 2009 18 February 2009

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The Chilean state geological service SERNAGEOMIN have published a bulletin dated 11 February 2009 on their website. It is apparently available nowhere else at the moment. Translation as follows.

11.02.2009 SERNAGEOMIN Bulletin on Chaitén volcano

The seismic activity of Chaitén volcano between 2 and 9 February has remained unchanged in the number and the magnitude of events, indicating that the growth of Dome 2 continues, although the earthquakes have occurred more to the east or at greater depth beneath the volcano.

However, the speed of extrusion of viscous lava is somewhat higher than in previous periods, judging from the prominent pinnacle which forms the summit. The continuing growth of Dome 2 and the presence of this large pinnacle forming its summit is continuing to generate new gravitational collapses, creating block-and-ash flows which, eventually, could affect the heads of the principal valleys, depending on their volumes.

Visual monitoring

Observations carried out during a field trip to maintain the seismic stations installed in the area, between 2 and 9 February, showed that Dome 2 remains in constant eruption and continues to increase its volume.

Indeed, on 7 February between 12:00 and 14:30 two photographs were captured from the Chaitén locality which showed a bulky Dome 2 atop Dome 1.

Figure 1.
[Figure 1 caption reads: Photographs of 7 February where the complex of domes can be seen and it is possible to see a prominent pinnacle on the summit of Dome 2 which forms its summit, with very sharp sides.]

Moreover, it is possible clearly to see a prominent and impressive pinnacle that forms the summit of Dome 2, with very unstable sharp and steep slopes, which could collapse at any moment and produce block-and-ash flows.

On 9 February at 12:00 another photograph showed the voluminous complex of zones with the enormous pinnacle that forms the summit of Dome 2. The eventual massive collapse of this pinnacle of the dome could generate voluminous block-and-ash flows, descending through the neighbouring valleys.

Figure 2.
[Figure 2 caption reads: Photograph of 9 February showing the voluminous complex of domes, with a prominent pinnacle that forms the summit of Dome 2, the instability of which tends towards a gravitational collapse, generating block-and-ash flows possibly affecting the neighbouring valleys depending on their volume.]

Seismic activity

During the latter period, the seismic monitoring network of Chaitén volcano has continued to show HB-type earthquakes, with an average of 2 earthquakes per hour and with magnitudes varying between 1.8 and 3.8.

Between 5 and 7 February a large number of earthquakes with magnitudes ranging between 3.3 and 3.8 were registered. On 8 February the number of earthquakes registered declined, however the magnitude of of these events has been maintained, with earthquakes up to [magnitude] 3.8.

According to preliminary calculations of the epicentral distances from Santa Bárbara station the earthquakes have been located more to the east or beneath Chaitén volcano at greater depths.

Moreover, on 6 February at 09:08 (local time) a VT-type earthquake located 22km from the Santa Bárbara station was registered, at a magnitude of 2.5.

Consequently, in view of the continuance of the seismic activity associated with the growth of the erupting dome and the formation of large pinnacle at its summmit, with the certain possibility of the generation of block-and-ash flows, SERNAGEOMIN maintains Volcanic Red Alert.

[End of SERNAGEOMIN bulletin.]

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Chaitén update, 5 February 2009 5 February 2009

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SERNAGEOMIN have published bulletin no. 72 on the Chaitén eruption. The original document in Spanish can be found at the OVDAS website (PDF). Translation as follows.

ERUPTION OF CHAITÉN VOLCANO
TECHNICAL BULLETIN NO. 72
28 JANUARY TO 2 FEBRUARY 2009
OVDAS-SERNAGEOMIN

1. Visual monitoring

Observations made through the DGAC camera during this period reveal that Dome 2 is maintaining constant eruption and is increasing in volume, as judged from the recurrent collapses of its unstable walls. On 28 January between 10:39 and 10:44 a marked vertical projection of ash was noted, forming a dense column of some 500m in height, possibly caused by a small explosion. However, there was an immediate collapse of the dome and a block-and-ash flow was produced to the west, and it is not possible to rule out the occurrence of a lateral explosion in the same direction (Fig. 1). On that day and also on 30 January block-and-ash flows continued to form.

Figure 1.
Figure 1. View from the DGAC camera in which a dense vertical column of ash some 500m in height can be seen (left, red arrow) and the generation of a block-and-ash flow to the west because of a collapse of Dome 2 and/or a lateral blast.

Figure 2.
Figure 2. Collapses and formation of block-and-ash flows towards the west on 28 January (left and centre) and 30 January (right).

2. Seismic activity

The seismicity recorded by the Chaitén volcano monitoring network has remained relatively similar to the preceding period. It showed an average of one HB-type earthquake per hour, with magnitudes varying between 1.5 and 3.9. On 29, 30 and 31 January earthquakes of greater magnitudes of between 3.8 and 3.9 were registered. Subsequently, the magnitude of these events decreased to a maximum value of 3.2. Preliminary calculations locate these HB-type earthquakes in the area to the south of, and in some cases beneath, the caldera of Chaitén volcano. In addition occasional VT-type earthquakes appeared with magnitudes of less than 1.0.

3. Conclusions and interpretation

The seismic activity of Chaitén volcano has remained unchanged in number and magnitude of envents, which indicates that the growth of Dome 2 continues, although the rate of extrusion of viscous lava could be somewhat lower than at previous stages. Continuing dome growth, with the continued generation of new collapses forming block-and-ash flows, could eventually affect the heads of the main valleys.

In consequence, bearing in mind the persistence of seismic activity associated with the growth of the erupting dome, with the consequent generation of block-and-ash flows, SERNAGEOMIN maintains Volcanic Red Alert.

[End of 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

Chaitén update, 28 January 2009 28 January 2009

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SERNAGEOMIN bulletin no. 71 on the eruption of Chaitén volcano, dated 27 January 2009 and covering the period 19-27 January 2009, has just been published. The complete document (PDF) can be found at Werner Luis’s Chaitén site, and a shortened version is available on the SERNAGEOMIN website. Translation as follows.

ERUPTION OF CHAITÉN VOLCANO
TECHNICAL BULLETIN NO. 71
19-27 JANUARY 2009
OVDAS-SERNAGEOMIN

1. Visual monitoring

Following the major collapse of most of the pinnacles of the summit of Dome 2 between 10:59 and 12:00 on 19 January towards the south-eastern and eastern flanks, with the consequent generation of block and ash flows, the instability of the steep slopes of the erupting dome continued to produce smaller collapses with the formation of small block and ash flows for some days. During the overflight carried out on 21 January it was possible to see that the summit of Dome 2 did not display the prominent pinnacles observed on 15 January, therefore, 19 January brought about the gravitational collapse of the majority of these (Fig. 1). Also, on the eastern flank of the erupting dome constructed on Dome 1, several ridges and scars could be seen where various block and ash flows have occurred and continue to occur (Fig. 2).

Moreover, there has been a predominance of water vapour and volcanic gases of the H2S type (Fig. 2). The reddish brown ash rising above the active dome 2 is due to the generation of particulate material associated with the block and ash flows, that is to say, fine material from powdering of the viscous lava that forms the new domes.

Figure 1.
Fig. 1. View of the erupting Dome 2 (grey colour) constructed atop Dome 1 (reddish brown colour). The pronounced pinnacles clearly observed on the summit before the collapse of 19 January can no longer be seen.

Figure 2.
Fig. 2. Eastern flank of the upper part of the erupting dome constructed atop Dome 1, where several ridges and scars show where block and ash flows have occurred and continue to occur. In the gaseous emissions there is a predominance of water vapour and H2S [hydrogen sulphide] type volcanic gases.

During the overflight a thermal camera from the University of Buffalo (USA) was also used, which revealed that the area of highest temperature corresponded to the summit of Dome 2 (main point of eruption, the site of the pinnacles), and also showed that many hotspots remain on Dome 1 and that several deposits of the block and ash flows still show elevated temperatures.

2. Seismic activity

The records provided by the Chaitén volcano monitoring network show a decrease in seismic activity compared with the previous week (Fig. 3). The number of HB-type earthquakes had an average of 1 earthquake per hour, with magnitudes varying between 1.5 and 3.8. The earthquakes which reached the greater magnitudes in some cases were only 2 or 3 events per day. Moreover, during this period, there were only about 8 VT-type earthquakes recorded, with magnitudes of less than 0.8.

In preliminary form, the HB-type earthquakes have continued to be localized in the vicinity and south and, in some cases, beneath the caldera of Chaitén volcano.

Figure 3.
Fig. 3. Seismograms from the STAB station for 19 January (left) and 24 January (right), showing a decline in the number of HB earthquakes during the last few days.

3. Conclusions and interpretation

The seismicity associated with the eruptive cycle of Chaitén volcano has decreased in the number of events, which suggests a continuation of the extrusion of viscous lava, but with a lower emission rate, in comparison to the past week. However, while the growth of the dome continues, it may generate new collapses which will, possibly, affect the heads of the principal valleys.

In consequence, bearing in mind the persistence of seismic activity associated with the growth of the erupting dome, with the consequent generation of block and ash flows, SERNAGEOMIN maintains Volcanic Red Alert.

[End of 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

Chaitén update at the Eruptions blog 25 January 2009

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The Chaitén eruption has volcanologists and geologists everywhere excited, and was evidently the subject of much discussion at the American Geophysical Union Fall 2008 meeting in San Francisco.

Dr Erik Klemetti was there, and has posted a valuable update on his Eruptions blog summarizing what was said about Chaitén at the meeting and giving copious links to the relevant abstracts and other sources. Among the interesting points to note are that we seem to be looking at a very deep source for Chaitén’s magma and that earthquakes may have played a role in instigating the eruption. Check out Dr Klemetti’s post for the background.

There’s no doubt that Chaitén is going to be keeping the scientists busy for a long time to come.

Chaitén coverage here at The Volcanism Blog: Chaitén « The Volcanism Blog.
Chaitén coverage at Eruptions: Chaiten « Eruptions.

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