… but it’s turning out to be a busy weekend. I’ll catch up with things as soon as I can.

Click on the map for a larger version (1280 x 898 pixels).

The Smithsonian Institution/United States Geological Survey Weekly Volcanic Activity Report for 28 October – 3 November 2009 is available on the Global Volcanism Program website. The following is a summary and not a substitute for the full report.

• The current report: Weekly Volcanic Activity Report.
• Previous reports: Weekly Reports Archive.
• The SI/USGS map of volcanoes discussed this week.

New activity/unrest: Ebeko (Russia), Galeras (Colombia), Karangetang [Api Siau] (Indonesia), Manam (Papua New Guinea), Nevado del Huila (Colombia), Soufrière Hills (Montserrat).

Ongoing activity: Barren Island (India), Chaitén (Chile), Dukono (Indonesia), Karymsky (Russia), Kilauea (Hawaii, USA), Kliuchevskoi (Russia), Krakatau (Indonesia), Popocatépetl (Mexico), Rabaul (Papua New Guinea), Sakura-jima (Japan), Shiveluch (Russia), Suwanose-jima (Japan).

Note: a.s.l. = ‘above sea level’.

NEW ACTIVITY/ UNREST

Ebeko (Russia). A gas-and-steam plume rising 300 m above the crater and drifting 1-2 km NNE was seen on 26 October. No evidence of ash deposits was seen on the snow cover. Gas-and-steam plumes rose 250 m above the crater and drifted 2 km E on 28 October and NNE on 29 October. The Level of Concern Color Code remained at Green.

Galeras (Colombia). INGEOMINAS raised the Alert Level to the second-highest level of Orange (‘eruption probable within days or weeks’) on 30 October. Degassing decreased and seismicity increased from 27 October, reflecting conditions seen prior to previous eruptions. Gas emissions were reported to have been low during the days preceding 3 November, and seismicity had decreased on that day.

Karangetang [Api Siau] (Indonesia). Based on a pilot observation and analyses of satellite imagery, Darwin VAAC reported an ash plume to 3 km a.s.l. and drifted 90-185 km W on 3 November.

Manam (Papua New Guinea). Based on analyses of satellite imagery, Darwin VAAC reported ash plumes to 2.1 km a.s.l. that drifted 35-55 km NW during 1-2 November.

Nevado del Huila (Colombia). INGEOMINAS reported that on 28 October a pulse of tremor was followed by an ash plume that rose to 8.3 km a.s.l. Overflights on 30 October and 2 November revealed a high rate of lava dome growth compared to the previous observation on 23 October. An ash layer covered the W part of Pico Central. Continuous and intense degassing originated from areas where thermal anomalies were detected, and resulting gas plumes drifted NW. The volume estimate for the new lava dome was nearly 9 million
cubic metres. On 31 October an ash plume, observed through satellite imagery, pilot observations, and web camera views, was reported drifting 65 km S. During 31 October-2 November, thermal anomalies were detected on satellite imagery. On 2 November, a small plume seen on the web camera drifted SE. Gas plumes, occasionally accompanied by ash plumes, drifted 35 km SE. On 3 November INGEOMINAS reported that a pulse of tremor was followed by an ash plume that rose to 11.3 km a.s.l. and drifted SW, and ashfall was reported in communities downwind. Another ash plume rose to below 6.7 km a.s.l. and drifted E. Collapses from the W side of the dome generating small pyroclastic flows and incandescence were observed from Mosoco (20 km SSW).

Soufrière Hills (Montserrat). During 23-30 October seismic activity was at a slightly lower level that the previous week. Numerous pyroclastic flows occurred in most of the major drainage valleys and rockfalls were concentrated in the S. Heavy rainfall caused lahars in the Belham Valley to the W. On 28 October two pyroclastic flows traveled 2 km W down Gages Valley. On 29
October a 40-m-high spine was seen protruding from the summit. Changes in lava-dome morphology seen on 30 October, and occurrences of pyroclastic flows traveling NE, indicated that growth was concentrated in the central part of the lava dome. The Hazard Level remained at 3.

ONGOING ACTIVITY

Barren Island (India). Darwin VAAC reported an ash plume rose to 1.8 km a.s.l. and drifted about 55-75 km W on 1 November.

Chaitén (Chile). Buenos Aires VAAC reported a diffuse ash plume possibly mixed with steam and gas rose from the lava dome complex and drifted SSE on 30 October. On 1 November a plume drifted 20 km W.

Dukono (Indonesia). Darwin VAAC reported that an ash plume rose to 1.5 km a.s.l. and drifted 35-110 km NE and N on 31 October.

Karymsky (Russia). Seismic activity was above background levels during 23-27 and 30 October, a possible indication that ash plumes rose to an altitude of 3.7 km a.s.l. No seismic data was available on 22 and 28 October. Analyses of satellite imagery revealed an ash plume that drifted 120 km E on 23 October, and a thermal anomaly during 23-26 and 29 October. The Level of Concern Color Code remained at Orange.

Kilauea (Hawaii, USA). During 21-27 October lava flowed SE from underneath the Thanksgiving Eve Breakout (TEB) and rootless shield complex through a lava tube system to reach the Waikupanaha ocean entry. Lava began entering the ocean at a second location 700 m to the W on 31 October. Thermal anomalies detected in satellite images and visual observations revealed active surface lava flows. Breakout lava flows were located inland of the Waikpuanaha entry and also
immediately W of the County Public Viewing trail. Intermittent incandescence was seen from the Pu’u ‘O’o crater floor and an East wall vent. The Halema’uma’u crater vent continued to produce a diffuse white plume that drifted SW. Incandescence originated from occasionally spattering holes from a surface inside the vent cavity. On 3 November a collapse of the surface revealed a circulating and spattering lava pond below. Preliminary measurements indicated that the sulphur dioxide emission rate at the summit remained elevated: 800 tonnes/day was measured on 30 October (2003-2007 average rate = 140 tonnes/day).

Kliuchevskoi (Russia). During 23-30 October seismic activity was above background levels. Tremor increased on 26 October. Strombolian activity ejected tephra 200 m above the crater and fumarolic activity was occasionally noted. Satellite imagery revealed a daily thermal anomaly. The Level of Concern
Color Code remained at Orange.

Krakatau (Indonesia). Between August and 29 October seismicity and the occurrence of eruption plumes decreased. The Alert Level was lowered to 2 (on a scale of 1-4).

Popocatépetl (Mexico). A small explosive event on 29 October produced an ash plume that rose to 6.4 km a.s.l.

Rabaul (Papua New Guinea). During 28-29 October Darwin VAAC reported that ash plumes from Tavurvur cone rose to 2.4 km a.s.l. and drifted 35-45 km N, E, and SE.

Sakura-jima (Japan). Tokyo VAAC reported that during 28 October-3 November explosions produced plumes to 1.2-2.7 km a.s.l. Some plumes drifted W, SW, S, SE, and NE.

Shiveluch (Russia). During 23-30 October seismic activity was above background levels, possibly indicating ash plumes to 3.7 km a.s.l. On 29 October ash plumes possibly rose to 6.9 km a.s.l. Fumarolic activity was occasionally seen. Analyses of satellite imagery revealed a large thermal anomaly over the lava dome during 22-27 October and an ash plume that drifted 24 km NE on 26 October. Tokyo VAAC reported an eruption on 30 October that produced a plume to 7 km a.s.l. Later that day a possible eruption plume rose to 6.1 km a.s.l. An eruption on 1 November produced a plume to 4.9 km a.s.l.

Suwanose-jima (Japan). Tokyo VAAC reported explosions on 30 October and 2 November, without details of possible resulting emissions.

ACKNOWLEDGEMENTS AND DISCLAIMER

The foregoing is a summary of the Smithsonian Institution/United States Geological Survey Weekly Volcanic Activity Report covering 28 October to 3 November 2009. It is provided for information only, and is based on but not a substitute for the full report, which comes with its own criteria and disclaimers. The map base is derived from the Smithsonian Institution/USGS/US Naval Research Laboratory This Dynamic Planet website.

For all our coverage of the SI/USGS Weekly Volcanic Activity Reports: Weekly Volcanic Activity Reports « The Volcanism Blog.

Nevado del Huila: picture from 2 November 2009 overflight (copyright INGEOMINAS). [source]

Colombian volcano Nevado del Huila remains at the second-highest level of Orange, ‘eruption likely within the next few days or weeks’.

Colombia’s state geological service INGEOMINAS has issued two bulletins about Nevado del Huila within the last 24 hours. The most recent bulletin, a brief ‘reporte extraordinario’ published at 20:30 local time on 3 November, reports a partial collapse of the new lava dome, with effects limited to the summit area of the volcano:

… during the evening, localized collapses of the dome towards its western sector [were observed], which generated small pyroclastic flows and incandescence, both limited to the upper part of the volcano, without compromising, for the moment, the Páez river.

The previous bulletin, released at 17:00 local time on 3 November, includes information from the most recent overflight which took place on 2 November. This bulletin notes that ‘in the current week 1177 seismic events were recorded’, of which 82 were rock-fracturing events, 1014 related to fluid dynamics with the volcanic system, 10 were hybrid events, and there were 71 pulses of tremor related to gas and ash emissions. Two tremor pulses are described as particularly notable:

The first occurred on 28 October at 02:00 (07:00 UTC); according to a VAAC report a column of 4 km altitude was observed from the summit of the volcano. The second pulse was recorded in the early morning today, at 02:54 (07:54 UTC). This event was associated with an acoustic signal reported by local inhabitants, and ash fall in Inzá, Mosoco, Jambaló and Belalcázar, to the south-west of the volcano. The VAAC report for this event shows a column which reached an altitude of 7 km above the summit of the volcano and that dispersed mainly towards the south-west.

Through the Nevado del Huila webcam ‘intense degasification of the system with pulsing escape of ash at the surface’ has been observed. The overflights of 30 October and 2 November monitored the growth of the new lava dome which has developed on top of the dome constructed in November 2008: ‘the volume of the new dome extruded at the surface is estimated to be about nine million cubic metres’.

A short video of the 2 November overflight (.mpg, 10.1 MB) is available from this page at the Popayán observatory website. The photograph at the top of this post was taken during this overflight and shows Nevado del Huila from the north-west. Intense degassing can be seen around the new dome, located on the western flank, and fresh ash deposits blanket the slopes of the volcano (image copyright INGEOMINAS, reproduced here for non-commercial purposes in accordance with the terms of use).

For all our Nevado del Huila coverage: Nevado del Huila « The Volcanism Blog.

Information
Global Volcanism Program: Nevado del Huila – summary information for Nevado del Huila (1501-05=)
INGEOMINAS Popayán – main page for the Observatorio Popayán, which monitors Nevado del Huila

The alert level for the Colombian volcano Galeras remains at the second-highest level of Orange, ‘eruption likely within the next few days or weeks’. The latest INGEOMINAS bulletin, issued on 3 November at 18:00 local time, reports:

Seismic activity has increased both in number and in energy level; the events associated with the fracturing of crustal material are largely located in the vicinity of the main crater, at depths of less than 2 km and magnitudes of under 2. However in the last fifteen hours the seismicity has markedly declined.

Volcanic gas emissions have been low; particularly, in the last few days, no emissions of sulphur dioxide (SO2) have been detected.

The process of development at Galeras shows a similar behaviour to that recorded in the days leading up to the eruptive event of 30 September 2009.

The simultaneous threat of activity at Galeras and Nevado del Huila is exercising the minds of governmental and NGO officials in Colombia. Emergency authorities have estimated the number of people at ‘imminent risk’ from the two volcanoes at 9000, reports Caracol Radio, but there is the usual reluctance among those living in at-risk areas to evacuate: ‘The communities in the area of high risk are still unaware [of their danger], they have not evacuated to safe points’, complains Carlos Iván Márquez of the Colombian Red Cross.

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

News
Nueve mil personas en riesgo por amenaza de erupción en volcán Galeras y Huila – Caracol Radio, 3 November 2009
Habitantes no atienden orden de evacuación – El Liberal, 4 November 2009

Information
Global Volcanism Program – Galeras – summary information for Galeras (1501-08=)
Portal Corporativo de INGEOMINAS – Instituto Colombiano de Geología y Minería
Observatorio Vulcanológico y Sismológico de Pasto – Pasto volcanological observatory main page

The Peruvian volcano El Misti is very close to the country’s second city of Arequipa: just 17 km separates the city with its ~1 million inhabitants from the volcano’s crater. The image above, a mosaic of two ISS astronaut photographs that is today’s Image of the Day at the NASA Earth Observatory, shows the potentially dangerous relationship clearly. Larger versions of the image, and a full commentary, are available over at the Earth Observatory. There is, however, no scale bar on the Earth Observatory images, so I have added one to the small version above.

El Misti Volcano and Arequipa, Peru – NASA Earth Observatory (2 November 2009)

[Astronaut photographs ISS021-E-8370 and ISS021-E-8371 were acquired on 16 October 2009 by the Expedition 21 crew. Additional images taken by astronauts and cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth.]

Information
Global Volcanism Program: El Misti – summary information for El Misti (1504-01=)
Instituto Geológico Minero y Metalúrgico – Geological, Mineral and Metallurgical Institute of Peru (Ingemmet)

Boris Behncke has posted a tip-off in the comments here that some significant earthquake activity has been recorded along the Reykjanes Ridge south-west of Iceland yesterday and today. The majority of the activity, including a large number of magnitude 3+ quakes and some exceeding magnitude 4, occurred yesterday, Sunday 1 November. Today things have been quieter.

The Reykjanes Ridge, part of the Mid-Atlantic Ridge system, is a volcanically active area, and these earthquakes may be related to submarine volcanic activity.

The Tatun (or Datun) volcano group (TVG) is in the north of Taiwan, 15 km to the north of the capital, Taipei. New research in the area by a Taiwanese/Russian scientific team involving the dating of eruption products at is now provoking alarm, it says here:

Datun Mountain, a dormant volcano located on the north of Taipei City, is an active volcano with a possible magnitude that can devastate the entire wider Taipei area with approximately six million residents if eruption occurs, a new study by the Academia Sinica says. The recent report used volcanic ash and mudflow in the analysis and claimed that Datun Mountain was an active volcano. A previous study had showed that the last eruption occurred 200,000 years ago and classified it as a dormant volcano.

The new study appears to suggest that the most recent eruption was a mere 5000 years ago: hence headlines claiming Taipei risks volcanic devastation, alarming comparisons between a putative eruption and the earthquakes of 1999, and even that old favourite, warnings of a new Pompeii. However, the most recent eruptive activity before the latest study had been dated at 20,000 years ago, not 200,000 years ago, so it was already understood that the volcano had been active in relatively recent times. The Global Volcanism Program notes: ‘The latest dated eruptions in the group took place over a roughly 3000-year period beginning about 20,000 years ago’.

Overall, it is not news that there is risk of potential activity at Tatun. An article in the Journal of Volcanology and Geothermal Research in 2007 described the Tatun Volcano Group as ‘a potentially active Quaternary volcano’ and noted that ‘Because of lack of any activity in historical times it has been classified as an extinct volcano, even though more recent studies suggest that TVG might have been active during the last 20 ka’ (in any case, when assessing whether a volcano is extinct or dormant, ‘activity in historical times’ is no guide). The article went on to observe that seismic studies ‘indicate that a magma chamber may still exist beneath TVG and that a future eruption or period of unrest should not be considered unlikely’.

There’s nothing wrong in waking up the people of northern Taiwan to the risks posed by their local volcano, but (as ever) sensationalized press reports are perhaps not the best way to do it.

UPDATE. Taiwan News Online quotes Chaing Chung-jung of the Taiwan Central Geological Survey: ‘Chiang said that the possibility of the mountain erupting again is “extremely low”. “Besides, volcanic eruptions can be predicted”, he said, urging that there is no need for people to panic over the matter’. This story still claims, erroneously, that the ‘last eruption of Datun Mountain occurred 200,000 years ago’, however.

Information
Global Volcanism Program: Tatun Group – information on the Tatun Volcano Group (0801032A)
Yangmingshan National Park: Datun Mountain – information from the Yangmingshan National Park website

News
Datun Mountain is active, can devastate Taipei: study – The China Post, 2 November 2009
Volcano near Taiwan’s capital is still active, scientists warn – My Sinchew, 2 November 2009

The Tigua people of Ecuador live in a rural area south-west of the capital, Quito, high in the valleys of the Andes. Their colourful and distinctive paintings depict scenes of communal life: festivals, markets, farming, daily activities. The volcano Cotopaxi presides over many of these pictures, symbolizing the spirit of the Ecuadorian landscape.

These paintings occupy that shifting and ambigous territory of cultural production in which indigenous artistic creativity depends for its sustenance upon tourist patronage, but they do represent a genuine pictorial tradition, not merely a commodified fabrication. Every part of the picture is filled with colour and life, and naive-seeming but complex tricks of perspective and distortion are used to draw the viewer into the landscape and bring order to the tumult of incident depicted. Tigua art conveys joy, lushness and life: it brims with vibrancy and colour, and conveys the spirit of the volcanic landscapes of the high Andes, and of those who live among them, beautifully.

For all ‘Saturday volcano art’ articles: Saturday volcano art « The Volcanism Blog.

SERNAGEOMIN bulletin no. 108 on the Chaitén eruption, covering the period 1-15 October 2009, has been published and can be accessed (PDF) via the SEGEMAR website. A shortened version can be found on the SERNAGEOMIN website. Translation of the complete document as follows:

CHAITÉN VOLCANO
TECHNICAL BULLETIN NO. 108
1-15 OCTOBER 2009
OVDAS-SERNAGEOMIN

1. Visual monitoring

During most of the period covered by this bulletin, the volcano has remained covered by cloud. Occasonally images captured by the DGAC camera have allowed observation of columns of gases and ash emerging from the dome complex (Fig. 1, A).

SERNAGEOMIN-OVDAS personnel in the field confirm the growth of the domes and continual degasification with two important concentrations: one in the centre of the volcano, enriched with water vapour and ash) and the other towards the east of the volcano (predominantly water vapour); equally, numerous minor emissions are visible located on the volcanic edifice.

On the other hand, on 14 October at midday a vigorous explosion of the ‘piston type’ was generated: that is to say, a dense vertical projection of ash accompanied by a dispersion of particulate material forming a large cloud towards the west (Fig. 1; B to E).

Fig. 1. (A) Images from the DGAC camera, showing emissions of gases and ash. (B-E) Sequence of the ‘piston’ type explosion, occurring at midday on 14 October.

2. Seismic activity

In the process of increasing the monitoring network, currently in progress, a seismological station has been installed 1.5 km from the principal crater, located on the edge of the caldera, and there is a choice of seven sites for future stations which will complement with a high level of detail the monitoring of the activity of Chaitén volcano.

The seismicity recorded by the Chaitén volcano network has remained stable, showing a predominance of hybrid (HB) type earthquakes, with an average that has not exceeded 12 earthquakes per hour and with local magnitudes calculated as situated within the range 1.0 to 4.1. It is notable that there were fewer than 1-2 earthquakes per hour with magnitudes of more than 3.5.

3. Conclusions and interpretation

The preceding information indicates a ‘usual’ behaviour within the eruptive cycle of the volcano, indicating that the eruptive activity continues with the growth of the dome complex and the occurrence of possible ‘piston’ type explosions.

On the other hand, the quantity of pyroclastic material both from rock falls and emitted by the block-and-ash flows and lateral explosions has created large accumulations in the adjacent valleys and particularly the valley of the Chaitén river, so that the occurrence of lahars towards Chaitén during periods of intense rain cannot be ruled out.

In consequence, given that the seismicity remains at elevated levels – an effect of the growth of the dome complex – and that the eruptive activity continues with the possibility of the generation of block-and-ash flows in random directions, which may affect surrounding valleys with the generation of new lahars, SERNAGEOMIN suggests maintaining Volcanic Red Alert.

OVDAS-SERNAGEOMIN
16 October 2009

[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

News that a U.S./French team of chemists claim to have found ‘compelling evidence’ of a previously unknown volcanic eruption that occurred 1809 and that may have been responsible for the global cooling noted during the period 1810-19. The evidence comes from ice samples from Greenland and the Antarctic:

‘We’ve never seen any evidence of this eruption in Greenland that corresponds to a simultaneous explosion recorded in Antarctica before in the glacial record’, said Mark Thiemens, Dean of the Division of Physical Sciences at UC San Diego and one of the co-authors of the study. ‘But if you look at the size of the signal we found in the ice cores, it had to be huge. It was bigger than the 1991 eruption of Mount Pinatubo in the Philippines, which killed hundreds of people and affected climate around the world’.

Read on: ‘Previously unknown volcanic eruption helped trigger cold decade’ (UC San Diego news release, 27 October 2009).

[H/T: commenter Perry.]

UPDATE. The 1809 eruption may be unidentified but it’s certainly not ‘unknown’: see comments below.