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’.

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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 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’.

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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

The weather at Chaitén has been clear today, giving some excellent views of the volcano from the Chaitén airfield webcam. The following video (19 seconds long) is a compilation of webcam images from this morning, kindly contributed to The Volcanism Blog by Olaf Kossner.

Clicking on the image below will take you to a Photobucket page where you can view the video.

Many thanks to Olaf Kossner for providing this video.

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

Generally speaking, the English-speaking media lost interest in Chaitén some time ago. The New York Times, however, has remembered that the eruption is still going on and has an article by Alexei Barrionuevo in its 9 August issue: ‘Fear and uncertainty in volcano’s shadow’.

On May 2, the volcano that bears this town’s name burst into activity, spewing hot gases and ash some 12 miles into the sky. Most residents left, as some scientists warned that the volcano could be heading toward an eruption on the scale of Mount Vesuvius, the volcano that in A.D. 79 wiped out the Roman city of Pompeii in less than a day.

Journalists love that ‘could be another Pompeii’ stuff.

The emphasis of the article is on the devastation of Chaitén town and the consequences for its inhabitants. There is also coverage of Chile’s vulnerability to volcanic hazards and the new impetus given to Chilean volcano monitoring by the eruption.

‘Volcanoes are a part of nature, you can’t worry about them’ - quote from Johnny Delgado, cattle rancher from just outside Chaitén, now evacuated to Puerto Montt.

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)

A new powerpoint presentation on Chaitén has been made available by the USGS/USAID Volcano Disaster Assistance Program, who have been working with the Chileans at Chaitén. Back in June the VDAP gave a presentation to President Michelle Bachelet of Chile (TVB post about the presentation here), and the latest briefing, given on 6 August for the benefit of the Office of U.S. Foreign Disaster Assistance, is an updated version of the June presentation.

The 6 August briefing can be downloaded directly, all 27MB of it, from this link at the USGS ftp site; you’ll need a powerpoint viewer to see its cheesy graphics and horrible typography in all their glory.

The majority of the presentation is the same as the earlier June version, but there is some new information. There’s a preliminary hazard map of Chaitén volcano dated 11 May 2008 (no updates since?) showing clearly what a bad idea it is for Chaitén town to be where it is, details of recent flight disruptions, and cumulative probability charts plotting possible outcomes as they stood in June (again, nothing more recent has been made available).

There is also fresh information on the lava dome, giving the following estimates for the end of July:

• Average lava dome eruption rate ~60m³/s (the average given in June was ~37m³/s)
• Area ~1.4 million m² (area given in June ~540,000m²)
• Volume ~350 million m³ (volume given in June ~55 million m³)

There is also a ’science postscript’ which contains the following observations on and questions arising from the Chaitén eruption:

• rhyolite extrusion rates unusually high
• sulphur dioxide emissions unusually low
• ash deposits unusually fine grained
• magma hot (850°C) and ascended rapidly from depth (>6km?)
• tectonic connection to the Liquiñe-Ofqui Fault Zone (LOFZ) - is this a tectonically-pressured eruption?
• ongoing interpretation of current earthquakes

With regard to the last point, there is no interpretation of the recent seismic activity in this presentation.

Many thanks to commenter Hawkeye for locating this presentation and bringing it to my notice.

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)

Yesterday SERNAGEOMIN and ONEMI officials and scientists took advantage of the better weather to overfly Chaitén volcano in a Chilean Air Force aircraft. A couple of videos of the overflight have turned up on YouTube:

Autoridades sobrevolaron el volcán Chaitén - a report from Televisión Nacional de Chile’s 24 Horas news channel.

El Gong sobrevoló el Volcán Chaitén - video report on the overflight from southern Chilean news service El Gong.cl.

There is a great deal of video material on Chaitén available on YouTube: always worth a search.

For all our Chaitén coverage: Chaitén « The Volcanism Blog

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

The following video, created by Javier De Leonardis, compresses the images captured by the Chaitén airfield webcam yesterday, 31 July 2008, into a 34-second video. The weather yesterday was good, with clear skies for much of the day, resulting in a wonderfully clear view of the eruption plume.

The picture below is not the video itself but a link to the video, which is hosted at Photobucket. Just click on the image or on this link to view the video. (The video is also available at Werner Luis’s Chaitén site.)

The main plume is low, but vigorous, and a smaller plume from the new vent can be seen to the left of the main column. Chaitén is maintaining continuous emission, three months into this eruption.

Many thanks to Javier De Leonardis for providing this video.

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