On 18 August a Red Alert was imposed by the La Araucanía regional government on a number of localities around Llaima because of increased seismicity. ONEMI’s bulletin on this development notes that ‘The seismic activity recorded in recent days is comparable to that recorded in the days before the start of the eruption on 1 January and preceding the reactivation of February 2008′. SERNAGEOMIN’s alert for Llaima remains at Volcanic Alert Yellow.

The team at the Llaima visual observation project (POVI) have sent over the following two images, showing Llaima in eruption amid the clouds of 18 August. Both views are taken from the south and show the eruption plumes produced by the volcano’s sporadic ash emissions being blown eastwards (from left to right). The upper picture was taken at 16:20 local time and the lower at 17:17 local time.

Our thanks to the team at POVI for sharing these imags with The Volcanism Blog. The POVI Llaima website has further pictures of this eruption, and a spectacular time-lapse video of the eruptive activity on 18 August.

For all our Llaima coverage: Llaima « The Volcanism Blog

Information
Global Volcanism Program: Llaima - summary information for Llaima (1507-11=)
Volcán Llaima - information from the Observatorio Volcanológico de los Andes del Sur (Spanish)
Oficina Nacional de Emergencia - Chilean government emergencies office (Spanish)
SERNAGEOMIN - Servicio Nacional de Geología y Minería, Chile (Spanish)
Proyecto Observación Visual Volcán Llaima - Llaima Visual Observation Project

SERNAGEOMIN have issued their Bulletin No. 49 on the Chaitén eruption, dated 19 August, which can be found (as a PDF) at Werner Luis’s Chaitén site. The document runs to three pages and includes a number of illustrative figures. The overall picture is one of a steady-state low-level eruption with variable but basically low seismicity. The changes in seismic behaviour at Chaitén over recent days do not appear to correlate with any changes in the volcano’s eruptive behaviour: increases in seismicity did not relate to increases in eruptive activity, and recent decreases have not corresponded to declines in activity. SERNAGEOMIN are keeping a close watch on developments are are maintaining Volcanic Red Alert, as before.

To read the whole document in translation, complete with figures, click on ‘more’.

ERUPTION OF CHAITÉN VOLCANO
FORTY-NINTH TECHNICAL BULLETIN
16-19 AUGUST 2008
OVDAS-SERNAGEOMIN

1. Visual observations

During the morning of 16 August, the eruption column could not be clearly observed from Queilen. Only at noon was it possible to see, among the clouds, grey-coloured emissions, without being able to estimate the height of the column or the direction of dispersal of the plume. On 17 August continuation of adverse weather conditions prevented direct observation of the volcano. On 18 and 19 August several images of the volcano were obtained, through the cameras at Chaitén airfield and from Queilen (Figs. 1 and 2). In these images a column not exceeding 2km in height could be seen, with a plume reaching a slightly higher altitude and dispersing towards the east. According to estimates made from Queilen, the dispersion plume would have reached 3km in altitude, also being visible from Puerto Montt.

Fig. 1. Images captured on 18 August (left) and 19 August (right) by the northern camera located at Chaitén airfield.

Fig. 2. Photograph taken from the town of Queilen on 19 August at approximately 14:00, where a wide eruption column was observed, whitish and no more than 2.0km in height.

2. Seismic activity

Saturday 16 August was marked by an absence of significant earthquakes. Only five small earthquakes were recorded, three HB-type and two VT-type, both around magnitude 1.2M. Seismic activity on 17 August remained low, with four earthquakes, three HB-type and 1 VT-type of magnitude 1.2M, the latter recorded at 04:27 (Fig. 3). On 18 August the volcano continued with low seismicity, with five small HB-type events and three VT-type, with magnitudes below 1.5M.

Fig. 3. Sismogram recorded by PUMA station on 17 August indicating the four earthquakes detected on that day.

On 19 August a slight upsurge in seismicity was recorded, marked by a sudden increase in the number of HB-type earthquakes, with two to three low magnitude earthquakes per hour (Fig. 4).

Fig. 4. Seismogram from PUMA station for 19 August on which a significant number of HB-type earthquakes are recorded.

3. Conclusions and interpretation

During the last few days seismic activity has remained relatively low and eruptive activity has continued without major variations (column moderately vigorous, with emission of pyroclasts, gases and water vapour, about 2.0km in height). Thus, the low seismicity has not accompanied significant decreases in eruptive activity in the same way in which, during the month of July, the increase in seismicity was not associated with evident increases in the energy of the eruption.

Considering the changes in seismic behaviour, which do not correlate with significant variations in eruptive activity; the permanent presence of HB-type earthquakes combined with VT-type earthquakes, interpreted as indicative of the movement of magmatic fluids and the rupture of rocks in the interior of the volcanic system, SERNAGEOMIN maintains Volcanic Red Alert and monitoring of the evolution of eruptive and seismic activity.

[Report ends.]

For all our Chaitén coverage: Chaitén « The Volcanism Blog

Information
Global Volcanism Program: Chaitén - summary information for Chaitén (1508-41)
ONEMI, Oficina Nacional de Emergencia - Chilean government emergencies office (Spanish)
SERNAGEOMIN - Servicio Nacional de Geología y Minería (Spanish)
Erupción del Volcán Chaitén - extensive coverage of the Chaitén eruption

Chaitén may not be doing anything particularly dramatic at the moment, but it is still erupting, as it has been continuously for more than three months, and the effects of its activity on the region remain profound. Even if the volcano is no longer on the front pages (even in Chile itself), it is important not to forget about Chaitén. One English-language insight into the effects the eruption has had and is still having on local communities is provided by the Chile Forum at allchile.net, which has a lively thread on Chaitén which started at the same time the eruption and is still going strong. Click here to visit the discussion.

For all our Chaitén coverage: Chaitén « The Volcanism Blog

The most recent SERNAGEOMIN bulletin on Llaima (12 August 2008) noted that the volcano was showing activity similar to that of previous days. The pyroclastic cone within the main crater, which has been the seat of recent eruptions, was producing ‘an intense and continuous emission of steam, with small quantities of volcanic gases’; seismicity was reported to be at a low level. On 13 August weak ash emissions and nocturnal incandescence were reported by the POVI Llaima observation project.

Today from POVI comes news that Llaima is erupting once again with sporadic weak ash emissions that are being carried to the east by strong winds. The following picture comes from POVI and shows clearly the pulses of ash cloud produced by the activity within the main crater.

Many thanks to our friends at POVI for this information and the image, which is copyright POVI. Information about and pictures of all recent and current activity can be found of course at POVI’s Llaima site.

For all our Llaima coverage: Llaima « The Volcanism Blog

Information
Global Volcanism Program: Llaima - summary information for Llaima (1507-11=)
Volcán Llaima - information from the Observatorio Volcanológico de los Andes del Sur (Spanish)
Oficina Nacional de Emergencia - Chilean government emergencies office (Spanish)
SERNAGEOMIN - Servicio Nacional de Geología y Minería, Chile (Spanish)
Proyecto Observación Visual Volcán Llaima - Llaima Visual Observation Project

The latest SERNAGEOMIN technical report on the eruption of Chaitén, dated 13 August 2008, arrived by e-mail yesterday. The original document (PDF) can be found at Werner Luis’s comprehensive Chaitén site. The report came labelled ‘47th technical report’ but is headed ‘48th technical report’; frankly, I have lost count and don’t know which it should be, but that’s not terribly important. It is one of the longest and most detailed reports SERNAGEOMIN have issued and contains some interesting information about seismic activity at and around Chaitén between 2 and 13 August. It does not, however, offer any predictions as to the volcano’s future behaviour.

To access a full translation of this report (including all nine figures), click on ‘more’.

Eruption of Chaitén volcano
Forty-eighth technical report
5-13 August 2008
OVDAS-SERNAGEOMIN

1. Visual observations

On 5 August, at around 14:00, a police patrol in Punta Auchemó reported an increase in the height of the eruption column, reaching 2km altitude. At around 14:05, this new increase was confirmed from the town of Chaitén. On the next day it was not possible to make any observations of the volcano because of the bad weather conditions. On 7 August, it was possible to see a clear grey-coloured emission, which rose about 2.5km above the dome, and then turned towards the east. Significantly, on the southern flank of the dome deposits of snow could be made out, confirming that at least the southern surface of the dome was cold (Fig. 1). On the morning of 8 August it was possible to see a continuous emission of gases and ash which, however, was lower than that observed on the previous day (Fig. 2). On 9 August it rained through the whole day and from the town of Chaitén continuous noises associated with emissions of gas and ashes were heard. The poor weather conditions continued during 10, 11 and 12 August, preventing any viewing of the eruptive activity.

FIG. 1. Clear emission of gases and ash observed from Chaitén on 7 August 2008. Altitude was estimated as greater than 2.5km. In the photograph it is possible to see the southern flank of the dome covered by snow (red arrow).

FIG. 2. Photograph taken on the morning of 8 August 2008 (www.dgac.cl). Clearly visible is the column of ash and gas of approximately 1.5km height above the dome. Behind, at a higher altitude, it is possible to see the volcanic plume heading eastwards.

At around 08:30 on 13 August, after three days of bad weather, it was possible again to see the continuous emission of gas and ashes (Fig. 3). From about that time until noon, the column reached a height of around 2.0km (see scale in Fig. 3) and then turned eastwards, with a continual fall of ashes (green arrow). A new picture of the volcanic activity was taken on the same day at about 14:30 from the area north of the volcano (valley of the río Rayas), confirming the altitude and moderately vigorous activity of the column (Fig. 4). Some reports indicated even greater heights of the eruption column (6-7km), which seemed to correspond to specific increases in the eruptive activity. Moreover, from the north it was possible to see that there were two active emission centres with columns of different colours. The emission centre in the eastern sector of the dome had a white colouration and emitted, principally, water vapour, with a minor proportion of ash. The emission centre in the southern sector of the dome was very active, had a grey colouration and emitted, principally, pyroclastic material. From approximately 13:00 on 13 August the prevailing winds drove the plume towards Chaitén, covering the town and precipitating ash for several hours. It was confirmed that during the night the accumulated thicknesses were of the order of 1.5mm (Fig. 5).

FIG. 3. Photograph taken at 08:30 today, 13 August. Clearly visible is the column of ash that rises 2km above the caldera of Chaitén, and then blows away towards the east. The green arrow highlights a continuing fall of ash beneath the plume.

FIG. 4. Photograph taken from the northern flank of the caldera at 14:30 on 13 August 2008. In this image it is possible to see that the column does not exceed 2.0km in height, with a significant plume dispersing to the south. This photograph reveals, moreover, the two emission centres, originating columns with different coloration. On the left, white emissions in the eastern sector of the dome and, in the centre, a more vigorous emission, of grey colour, situated in the southern part of the dome

FIG. 5. Ash precipitated on the town of Chaitén in the afternoon and evening of 13 August.

2. Seismic activity

On 5 August, five new VT-type (volcano-tectonic) earthquakes were registered, two of them with magnitudes close to 2.0M, confirming a slight upturn with respect to the low activity reported during the previous three days. The epicentres of these earthquakes, like the majority of other earthquakes occurring during the previous days, were located in the area south-west of the volcano (Fig. 6). The hypocentres of these earthquakes were located, preliminarily, between 3km and 9km deep, with an error of 4-6km. In addition, on the same day, for one hour, an increase in the amplitude of background tremor and the appearance of some LP-type earthquakes was detected, which coincided with an increase in eruptive activity, which was also reported from Auchemó by the police.

On 6 August, seven VT-type earthquakes were recorded, two of which had considerable magnitudes of 2.5M and 2.3M (Fig. 8, blue ellipses), the depths of which were estimated at 6 and 7km, respectively. That same day, the Cantera station recorded 1-2 LP-type (long period) earthquakes per hour, all of very low magnitude, barely standing out from the background tremor.

FIG. 6. Epicentres recorded from 2 to 5 August 2008. The red ellipses (5 August 2008), green (3 August 2008) and yellow (2 August 2008) correspond to the approximate errors calculated with the Seisan program.

FIG. 7. Epicentres located on 6 August 2008, the blue ellipses represent the errors on the surface.

The seismic activity continued during 7 August without major changes. On that day 14 VT-type earthquakes were recorded, three of them of 1.3M, 1.5M and 1.7M. The other earthquakes did not reach 1.0M, only just being recorded by Cantera station.

On 8 August 15 VT-type earthquakes were recorded, the majority less than 1.0M. Additionally, at 19:30 two major earthquakes were detected, one HB-type (hybrid) followed by a VT of 2.5M, the highest recorded since Cantera station was installed (Fig. 8).

On 9 August the activity increased, with 25 earthquakes counted, five of those being HB-type (movement of fluids) and 20 VT-type (rupturing of rock), six of the latter being recorded with magnitudes close to 1.5M. Associated with this specific increase there was also an increase in the amplitude of the background tremor, marked by at least three identifiable LP-type earthquakes during the early morning of 9 August.

On 10 and 11 August seismic activity was again observed to drop, falling back to the average recorded in previous days. On 10 August, 12 VT-type earthquakes were recorded, six of them with magnitudes around 1.5M. Also, on 11 August 15 VT-type earthquakes were counted, three of those with magnitudes around 2.0M. It should be emphasized that on both days LP-type earthquakes were also recorded (one or two per hour), however their magnitudes hardly stood out from the background tremor. With regard to their locations, as with the earthquakes located in previous days, more than 90% were located in the area south of the volcano. However, the largest of these earthquakes, of magnitude 2.0M recorded on the night of 10 August, was located about 7km to the north-north-east of the Chaitén caldera, at a depth of 3km.

FIG. 8. Seismograms of 8 August at Cantera station. It is possible to distinguish two different types of earthquakes, the first classified as hybrid (HB), associated with the injection of magmatic fluids, and the second VT-type, attributed to the rupturing of rocks.

Finally on 12 and 13 August seismic activity continued to decline slightly, with four earthquakes on 12 August and seven on 13 August, all of the VT type and with magnitudes of less than 1.5M. Additionally, on both days HB-type earthquakes were recorded. The two most important HB-type earthquakes were recorded at 08:18 and 16:22 on 13 August (Fig. 10). Regardless of the striking volcanic activity seen on 13 August, seismicity remained low in comparison to the rest of the week.

FIG. 9. Seismograms recorded by Cantera station on 13 August from 04:00 to 14:00 GMT. It is possible to see two of the most significant HB-type earthquakes observed on 13 August, with magnitudes much lower than similar earthquakes detected in previous days

3. Conclusions and interpretation

In the past week, seismic activity has shown no significant or large variations, remaining at averages not exceeding 15 VT-type earthquakes per day. Nor were earthquakes of large magnitudes recorded, with no more than 9 earthquakes with magnitudes around 2.0M being registered. However, on 9 August it was possible to detect a small increase, which lasted for about 24 hours. While during that day the bad weather conditions prevented any viewing of the eruptive activity and measurement of the height of the column and dimensions of the plume, the noises associated with this activity were clearly perceptible from the town of Chaitén. In this period, VT-type earthquakes continued to be concentrated in the area south of the volcano.

In this new period of low seismic activity, the increases in seismicity and consequently of eruptive activity were not marked only by an increase in the number of VT-type earthquakes or by an increase in their magnitudes, but were rather evidenced by an increase in the number and amplitude of HB-type (hybrid) earthquakes, which are associated with fracture and movement of magma in the volcanic system. In accordance with this last phenomenon, there was an increase in background tremor and in the registering in the seismogram of LP-type earthquakes, the latter being associated with the movement of fluids.

Finally, the eruptive activity recorded today, 13 August, was not associated with an increase in seismicity. The occurrence of two HB-type earthquakes (Fig. 9) could relate to a subsequent smaller increase in eruptive activity, time-specific and of short duration, which occurred at noon today, then returned to ranges similar to those observed in previous days. Without doubt, the weather today allowed the plume to move southward, covering and precipitating ash over Chaitén.

Taking into account the increases that have been seen of eruptive and seismic activity, with the detection of the presence of combinations of earthquakes of VT, HB, LP type and background tremor, SERNAGEOMIN maintains Volcanic Red Alert and monitoring of the evolution of eruptive and seismic activity.

[Report ends.]

For all our Chaitén coverage: Chaitén « The Volcanism Blog

Information
Global Volcanism Program: Chaitén - summary information for Chaitén (1508-41)
ONEMI, Oficina Nacional de Emergencia - Chilean government emergencies office (Spanish)
SERNAGEOMIN - Servicio Nacional de Geología y Minería (Spanish)

The NASA Earth Observatory has published a rather striking image today showing the spread of the sulphur dioxide cloud released by Kasatochi since it began erupting on 8 August. The image, captured by the Ozone Monitoring Instrument on NASA’s Aura satellite on 12 August, shows the gas looping counter-clockwise across the Pacific Ocean and spreading across Canada and the United States.

The image as shown above has been cropped slightly to fit in here at The Volcanism Blog. To see the original image with an extended explanatory caption, click here. Take some time to explore the NASA Earth Observatory: it is a wonderful resource, for volcanoes and much more.

Information
Global Volcanism Program: Kasatochi - summary information for Kasatochi (1101-13-)
Alaska Volcano Observatory - AVO page on the Kasatochi eruption

The most recent SERNAGEOMIN bulletin on Chaitén was issued yesterday (dated 12 August 2008). It reports poor weather conditions preventing direct observation of the volcano, except on the morning of 8 August when ‘a continuous emission of gas and pyroclasts’ was observed ‘which generated an eruptive column of more than 1 kilometre in height that dispersed towards the east’. The picture above was taken from the town of Chaitén on 8 August and shows ‘the dome and the column of steam, gases and pyroclasts’.

An increase in the number and magnitude of volcanic-tectonic (VT) earthquakes was recorded over the preceding 24 hours, along with a ’sporadic appearance’ of hybrid (HB) and long period (LP) earthquakes and an increase in background tremor, ‘phenomena attributed principally to the ascent of magmatic fluids’. The bulletin ends by suggesting that the characteristics of this seismic behaviour can be interpreted as ‘indicators of internal activity within the system that, eventually, could manifest in increases in the eruptive activity of the volcano’.

The press in Chile and Argentina is reporting today that Chaitén volcano is showing signs of an increase in eruptive activity: the headlines suggest a possible ‘reactivation’ of the eruptive cycle. El Mercurio reports:

Although there were no explosions registered yesterday afternoon at Chaitén volcano, the massif showed an increase in its eruptive activity, which resulted in a greater expulsion of ash from its crater … In view of the erratic behaviour of the volcano, the volcanologists of Las Lagos Region are dealing with two possible scenarios: the end of the eruptive cycle or the beginning of an entirely new [eruptive cycle]. The latter case would be the more worrying as it cannot be ruled out that the massif - which began erupting on 2 May - will repeat the process with which it began and that the eruption will be prolonged for years in a cyclical manner.

A report in 123 Chile describes a column of ’smoke’ (humo) from Chaitén reaching six kilometres in altitude yesterday aftenoon: ‘during the night a rain of ashes was produced which fell on the abandoned city. The volcanic reactivation coincides with earthquakes of 2.2 on the Richter scale’. The Argentine newspaper Diario Los Andes also describes Chaitén volcano producing ‘a column of six kilometres in height, raining ash on the desolate town of the same name, and a series of earthquakes of medium intensity’.

UPDATE: The latest technical bulletin from SERNAGEOMIN has just arrived in my inbox (thanks, Javier). It’s a long and detailed document and I won’t be able to get around to translating and reporting on it until tomorrow, but it is worth noting that the ‘increased activity’ reported by the media (as instanced above) refers to 13 August and has not been continued. Today the activity has been at a lower level once again, similar to that of recent weeks.

For all our Chaitén coverage: Chaitén « The Volcanism Blog

News
Volcan Chaitén: Registran aumento de sismos y del temblor de fondo - infochubut.com, 13 August 2008 (Spanish)
Volcán Chaitén presentó reactivación de su proceso eruptivo - El Mercurio, 14 August 2008 (Spanish)
Se reactivo el Chaitén: columna de humo es de seis kilómetros - 123 Chile, 14 August 2008 (Spanish)
El Chaitén, nuevamente en erupción - Diario Los Andes, 14 August 2008 (Spanish)
Volcán Chaitén presentó reactivación proceso eruptivo - Ansalatina, 14 August 2008 (Spanish)
Increased activity at Chile’s Chaiten volcano - PR-Inside.com, 14 August 2008
Spike in activity at Chile’s Chaiten volcano - USA Today, 14 August 2008

Information
Global Volcanism Program: Chaitén - summary information for Chaitén (1508-41)
ONEMI, Oficina Nacional de Emergencia - Chilean government emergencies office (Spanish)
SERNAGEOMIN - Servicio Nacional de Geología y Minería (Spanish)
Erupción del Volcán Chaitén - extensive coverage of the Chaitén eruption

Three volcanoes are currently active in the Aleutian Islands: Okmok, Cleveland and Kasatochi. Chris Rowan at Highly Allocthonous ponders on this near-simultaneous eruption of three volcanoes in the same neighbourhood in an interesting post and asks. ‘Could the eruption of one have triggered the others?’ Answer: ‘no’. Disappointing news for volcanic chain-reaction catastrophists everywhere.

Kasatochi volcano in the Aleutian Islands erupted on 7 August: full information about this dramatic and powerful eruption can be found at the Alaska Volcano Observatory and via the coverage at Eruptions.

The images above come from the NASA Earth Observatory site (click on each image to go to the original Earth Observatory page for that image). The upper image, from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite, shows Kasatochi’s brown eruption plume swirling counterclockwise from the volcano on 8 August 2008. The lower image comes from the Ozone Monitoring Instrument on NASA’s Aura satellite and indicates the levels of sulphur dioxide released by the Kasatochi eruption. The image was captured on 10 August 2008. The NASA caption for this image notes that the Kastachi eruption cloud contained about 1.5 million tons (1.36 million tonnes) of sulphur dioxide, and is one of the largest volcanic SO² clouds scientists have tracked since Chile’s Hudson volcano erupted in 1991.

Information
Global Volcanism Program: Kasatochi - summary information for Kasatochi (1101-13-)
Alaska Volcano Observatory - AVO page on the Kasatochi eruption

This natural-colour image of Kilauea releasing an eruption plume was captured on 7 August 2008 by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite and is available on the NASA Earth Observatory site in both low-resolution and high-resolution versions. The grey eruption plume from the volcano can be seen blowing away to the south-west.

For all our Kilauea coverage: Kilauea « The Volcanism Blog.

Information
Global Volcanism Program: Kilauea - summary information for Kilauea (1302-01-)
USGS Hawaiian Volcano Observatory - main page for the HVO
HVO Kilauea Status Page - the latest activity reports for Kilauea