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’.

(more…)

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’.

(more…)

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

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

After a quiet couple of years, Mayon volcano in the Philippines has been showing signs of increased activity in recent weeks, with heightened seismicity, inflation, and an intensified glow from the crater. Today a phreatic explosion took place and ash was erupted 200 metres (650 feet) above the crater. The Philippine Institute of Volcanology and Seismology (Phivolcs) is keeping Mayon under close observation: it is one of the archipelago’s more active volcanoes. A major eruption is not imminent, according to Phivolcs, but steam and ash explosions may occur over the coming days.

Mayon, a 2463-metre stratovolcano, is famous for the near-perfect symmetry of its cone, as well as its ability to unleash destructive eruptions, with hazards including pyroclastic flows, lahars and heavy ashfall. Particularly violent eruptions causing many deaths occurred in 1814 and 1897; more recently an eruption in September 1984 caused no fatalities after warnings from Philvolcs brought about the evacuation of more than 70,000 people from at-risk areas near the volcano.

News
Mayon spews ash after two-year silence - ABS-CBN News Online, 10 August 2008
Mayon spews ash; Phivolcs reminds residents of danger zone - GMANews.TV, 10 August 2008
Mayon volcano under tight watch after mild explosion - Philippine Daily Inquirer, 10 August 2008

Information
Global Volcanism Program: Mayon - summary information for Mayon (0703-03=)
Philippine Institute of Volcanology and Seismology - Phivolcs homepage

No dramatic developments at Okmok, but the eruption continues. The latest weekly report from the Alaska Volcano Observatory comments that over the last week an ash and steam plume reaching altitudes of between 3000 and 10600 metres (10000-35000 feet) have been continuously erupted and light ash fall has taken place on Umnak and Unimak islands. From 28 to 30 July Okmok went to aviation colour code red because of a particularly vigorous eruptive episode: it is currently at colour code orange. Seismic activity is elevated but steady. During this eruption there have been periods of continuous and pulsating tremor strong enough to register on the seismic networks of neighbouring Alaskan volcanoes.

Image: Photo of Okmok’s eruption plume on July 30, 2008, as seen from the NOAA ship Oscar Dyson, located about 80 nautical miles to the north of Okmok. Photograph taken by Lt William Mowitt, National Oceanic and Atmospheric Administration. [source]

Information
Global Volcanism Program: Okmok - summary information for Okmok (1101-29-)
Alaska Volcano Observatory Okmok eruption page - Okmok information and updates from the AVO

An explosive eruption appears to have taken place at Chaitén this morning. This was the webcam image at 08:59 (local time): a sizeable eruption under way at the caldera.

By 09:29 heavy ashfall was taking place, mainly to the west of the volcano.

The view at 11:00 shows a wide eruption plume passing directly over the town. This image is reminiscent of the early days of the eruption at the beginning of May.

More recent images indicate that the eruption has subsided, with a lighter, thinner plume (but still larger than anything we saw yesterday) and less evidence of heavy ash content.

The latest bulletin from Javier De Leonardis in Esquel (issued at 11:20 local time, Spanish text available here) notes that an overflight yesterday ‘detected partial collapses in the central part of the new dome’ and the removal (through collapse) of some of the material of the dome. With regard to the seismicity of the volcano the bulletin reports that:

new equipment is being installed to detect the depth of the earthquakes, which have decreased in quantity but have maintained high intensity (about 4.0M). The epicentres are in the area of the volcano but if the focuses are deep (10-20km or more) there is no risk of a reactivation, on the other hand if they are originating at 5-6km in depth (below the chamber) this would be evidence of the ascent of new magma which, added to the collapse of the dome, could result in a large explosive eruption.

More coverage at Alan Sullivan’s Fresh Bilge blog.

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

An e-mail brings the latest SERNAGEOMIN report (dated 30 July 2008), available here at Werner Luis’s site, on the Chaitén eruption. Seismic activity remains significant and intriguing, despite a recent slight decrease, and the high proportion of more powerful quakes is notable. Some information on the depths of these earthquakes over the last few days would be of great interest.

Special Report on Chaitén volcano, 30 July 2008

Between 1600 yesterday and 0800 today, 30.07.08, Pumalín, Santa Bárbara and Llifén stations detected 6 earthquakes per hour (96 earthquakes in 16 hours), within which one earthquake per hour was of a magnitude between 3.6M and 4.0M (16 earthquakes in 16 hours). The other earthquakes remained around 2.5M. So, with regard to the previous 24 hours, it seems that in the last 16 hours there has been a slight lowering both in the total number of earthquakes and in the number of greater magnitude.

Between 0100 and 0400 today 30.07.08, four significant earthquakes were recorded, which reached magnitudes of approximately 4.0M and were perceptible to police in the area of Chaitén. According to data from ONEMI in the region, none of the major earthquakes was perceived in Hornopirén. These major earthquakes are located, provisionally, 7.0km north-east of the volcano.

The weather at Chaitén has been clear today for the first time in some days, producing some nice images on the airfield webcam. The image below, showing a low eruption plume, was taken at 13:28 local time.

As Alan Sullivan points out there is evidence of a new vent in the west or south-west portion of the caldera.* It’s clearer in the image below, which is a detail of the view captured at 12:23 today: a small plume, just to the left of the main emission column.

* As also suggested by JC’s comment on this post of 29 July. Well spotted.

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