The ongoing eruption at Chaitén has tended to exercise a near-monopoly over the attention of volcano-watchers lately, but there has been much of volcanological interest going on elsewhere. Mount Etna, for a start, has been having an active time of it over the last few weeks.

After a quiet period of some seven months, Etna resumed activity with increased seismic activity and intermittent explosive activity of strombolian character between 21 and 28 April from a fissure on the eastern flank of the South East Crater at the summit.

From 21:00 local time on 1 May swarms of earthquakes were recorded along the north-eastern rift zone, and significant degassing took place at the South East Crater and North East Crater.

On 10 May between 13:00 and 14:00 UTC an increase in the intensity of tremors at the volcano indicated resumption of eruptive activity, although poor visibility prevented direct observation. The eruption involved strong strombolian activity at the South East Crater and lava emission (lava flows advanced about 6.4km along the western side of the Valle de Bove), and lasted to the early evening when seismic activity returned to normal background levels and the eruption ceased. Ashfall was reported from multiple locations during 10-11 May.

13 May saw powerful seismic signals and explosive activity in the early morning. Several powerful earthquakes were recorded and a significant thermal anomaly was recorded at the summit. A plume of ash was emitted around 11:30 which was blown towards the north-east of Sicily and Calabria: ashfall was reported in several villages in north-eastern Sicily. A significant eruptive fissure opened north-east of the South East Crater, between 2700 and 2900 metres above sea level. Sustained strombolian activity and the emission of a plume of ash was observed during the afternoon, although visibility remained poor. Repeated earthquakes on the north-eastern flank of the volcano indicated the migration of magma to this area.

Fumarolic activity continued into 14 May, with evidence of some effusive lava eruption from the new fissure. Visual observations on 14 May confirmed the appearance of not one but two new eruptive fissures, one just east of the summit craters and the other to the north-east of the South East Crater. From this latter opening lava flows were emerging, eventually extending for approximately 5 km.

The latest reports (17 May 2008) indicate that Etna is currently at low levels of seismicity and is producing strombolian activity and effusive lava flows from the two new fissures. Small ash-laden eruption plumes are reaching several hundred metres in altitude.

The current eruptive activity has posed no danger to life or property.

Sources for the above summary: Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Catania, current activity bulletins; Global Volcanism Program, weekly volcanic activity reports for Etna; Activolcans, volcanic activity reports; news sources as listed below.

Information
Global Volcanism Program: Etna - summary information for Etna (0101-06=)
Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Catania - INGV-CT is the volcanological authority responsible for Etna; current activity reports are here
Toulouse Volcanic Ash Advisory Centre - volcanic ash advisories for the area that includes Etna

News
Eruptions subside at Sicily’s Mount Etna - AFP, 11 May 2008
Etna volcano rumbles back to life in Sicily - AFP, 13 May 2008
Etna: INGV, vulcano ‘buono’ ma attenti a meccanismi inediti - AGI News, 13 May 2008 (Italian)
Mount Etna flows back to life - BBC News (video), 14 May 2008
Eruzione Etna: continua l’attività eruttiva, le colate sono ancora alimentate - Tempo Stretto, 15 May 2008 (Italian)

• Eruption of Chaitén continues without interruption: eruption column 4-5km in altitude
• Town of Chaitén seriously affected by flooding and lahars: more of the same to come
• Ashfall has taken place to the west of the volcano, volcanic material deposited in the sea is being carried northward by the coastal current
• Changes in seismic activity indicate fragmentation and instability around the volcano’s central conduit and beneath the lava dome
• An explosive destruction of the lava dome and collapse of the eruption column, producing pyroclastic flows, remains a possibility
• USGS scientists are arriving shortly to collaborate with SERNAGEOMIN in monitoring the volcano: SERNAGEOMIN is enhancing its seismic network

The Servicio Nacional de Geología y Minería (SERNAGEOMIN) of Chile issued a new bulletin on the situation at Chaitén on 16 May 2008. There’s a lot of information in this latest bulletin so I have summarized the key points as I understand them above, and provided a complete translation of the text below, as follows:

The plinian eruptive activity of the volcano Chaitén is continuing, and over the last two days the column of gases and ashes has been maintained at an altitude not exceeding five kilometres above sea level.

At 07:30 yesterday, 15 May, the upper section of the volcano’s eruption column was observed, reaching an altitude of four kilometres above sea level. The plume was directed towards the north-east due to strong south-westerly winds of up to 140 km/h.

During the day a Bolkow 44 helicopter of the Chilean Navy was able to make a reconnaissance flight over the town of Chaitén and the surrounding area to observe the situation of the Amarillo and Michinmahuida rivers.

Mudflows or lahars were observed which have affected the town of Chaitén, still covering the areas around the channel of the Chaitén river and the southern area of the town, without so far affecting the central plaza, the administrative centre and the areas surrounding the harbour and maritime offices. The airfield, for its part, is covered by water and ash, so entry by both land and air to the town is impeded.

The same helicopter was used to collect data from the seismological stations at Chumildén, Auchemó and Chaitén Norte. In addition, the overflight permitted various observations to be made as follows:

a) Ash has fallen throughout the valley and delta of the rivers Blanco and Rayas and the forests are covered by a mantle of white ash.

b) The marine litoral current, which moves in a northerly direction along the coast of Chile, is carrying a great deal of ash and islands of pumice northwards along the coast. The volcanic material (water coloured light green - milky) is principally from the bay of Chaitén and the Blanco-Rayas river delta. The progress of this ash-bearing body of water was clearly visible as far as Pumalín bay, and it continues to advance northward.

c) Between 12:00 and 13:00 a very cold ‘viento puelche’ [i.e. a cold and dry easterly wind] dispersed fine ash to the west, which even fell on the ship Aquiles and on the island of Talcán. On some parts of the ship the covering of ash reached between 0.5-1.0mm in thickness. During this period ashfall affected the area from the Blanco-Rayas river mouth as far as the mouth of Chaitén fjord.

Mudflows (lahars) and the runoff of large quantities of sediment have continued to fill the channels of the Chaitén and Blanco-Rayas rivers, which can no longer accommodate the normal flow of water. Consequently, the Chaitén river will continue to flood, affecting new areas of the town of Chaitén.

Areas most susceptible to the occurrence of flows of mud and rocks (lahars) and landslips have been identified along the road connecting Chaitén and Futaleufú, in the vicinity of the latter-named town and the other populated areas south-east of the volcano these may be caused by heavy rainfall and occur over a prolonged period.

Seismic activity

Over the past two days marked changes have been witnessed in the seismic activity [of the volcano]. A swarm of earthquakes, mainly of the HB [hybrid] type, has occurred, which is interpreted as related to a fracturing of the main conduit with subsequent ascent of magmatic fluids by the conduit and also through the dome. The later predominance of LP type earthquakes confirms the seismic instability of the system, the origin of which is related to the evident movement of magmatic fluids. In consequence there remains a certain possibility of future major explosions causing the destruction, in whole or in part, of the dome and the generation of pyroclastic flows through the collapse of the column. Nor can the possibility of new lateral explosions be disregarded.

SERNAGEOMIN has reinforced its team on the ground with three additional scientists and technicians and has begun preparations to move its centre of operations to the city of Queilen. In addition, all necessary preparations have been made for the arrival next Saturday of specialists from the Volcano Disaster Assistance Program of the United States Geological Survey, who will collaborate on volcano monitoring with SERNAGEOMIN and will bring additional monitoring equipment.

From next Monday the installation of four new stations with telemetric data transmission and helicopter support will bring about, as soon as possible, the reception of real-time seismic data in Queilen.

In this situation, SERNAGEOMIN maintains Volcanic Red Alert for the area of Chaitén.

End of SERNAGEOMIN bulletin, 16 May 2008.

A press release regarding the Volcano Disaster Assistance Program (VDAP) assistance to Chile was issued by USAID on 16 May 2008. The VDAP is a joint program of the United States Geological Survey and the US Agency for International Development - there’s a recent Volcanism Blog post about it here.

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 - volcanology information from the Servicio Nacional de Geología y Minería (Spanish)

An interesting post at the NOVA Geoblog today: ‘Volcano monitoring: last night’s PGS meeting’. Does the USGS have monitoring equipment on every US volcano? Does it have monitoring equipment on every dangerous US volcano? If it did, how expensive would it all be? And what does this picture…

…tell us about the contemporary volcano monitoring situation in the United States? Visit NOVA Geoblog to find the answers to all these questions.

[N.B. The above is a public domain NASA image. As it happens this picture is on my wall at the moment, as it's the picture for May on the 2008 IAVCEI Volcanoes Calendar.]

Chaitén volcano is maintaining its eruptive activity, reports Chile’s Oficina Nacional de Emergencia today, and a change in wind direction has brought ashfall to areas west of the volcano that have hitherto been spared:

The eruptive process continues at Chaitén volcano. The volcano itself could not be observed today because of the cloud cover in the area.

Since late yesterday a light ashfall has been occurring in some sectors of Chiloé Island, principally affecting the islands of Butacheque, Metaluf, Quenac and Tac and the communes of Quemchi, Achao, Castro, Chonchi and Queilen. Municipal teams are distributing masks in the sectors concerned.

According to information from the Meteorological Directorate of Chile this situation will continue until the early hours of tomorrow morning, Friday 16 May. The orientation of the wind to the north-east and later to the east has been partly responsible for the carrying of ash into these areas. During the morning the Chaitén area will experience cloud cover and rain.

The areas of Chiloé being affected by the ashfall are all towns, villages and small islands on Chiloé’s east coast. The Dirección Meteorológica de Chile, to judge from their forecast for the Los Lagos region (PDF) expects predominantly northerly winds to continue today, along with yet more rain, which does not bode well for the already lahar-engulfed town of Chaitén.

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 - volcanology information from the Servicio Nacional de Geología y Minería (Spanish)

Chaitén volcano showed increased activity today, Thursday 15 May 2008, with heavy ashfall, loud noises and many earthquakes.

The Oficina Nacional de Emergencia (ONEMI) reports today that military personnel in Chaitén ‘perceived loud noises coming from the volcano, abundant ashfalls and electrical discharges around the top of the mountain’. Heavy cloud cover and rainfall prevented observation of the eruption cloud. The ONEMI bulletin also confirms earlier reports that 90% of the town of Chaitén is flooded.

‘This further activitation of the volcano is a situation that is really worrying us’, Sergio Galilea, Intendente of the Los Lagos Region, told Reuters today. The Reuters article describes the volcano as having ‘increased its activity, with frequent small earthquakes’, and quotes Miguel Munoz of ONEMI: ‘pyroclastic flows are continuing, and there is a more pronounced emission of ash’. A report from Canal 13 observes that ‘There’s nothing encouraging in the picture from Chaitén’, with ‘heavy rains and floods nearly destroying the place, on top of increased activity from the erupting volcano’.

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 - volcanology information from the Servicio Nacional de Geología y Minería, Chile (Spanish)

News
Aumenta actividad volcán chileno, pueblo cercano bajo lodo - Reuters América Latina, 15 May 2008 (Spanish)
Aumenta actividad de volcán Chaitén - Canal 13, 15 May 2008 (Spanish)

According to the Chilean Oficina Nacional de Emergencia (bulletin, 14 May 2008) the town of Chaitén is currently severely flooded because of a combination of the overflowing of the Chaitén river and the recent rains: ‘According to reports from an overflight of the Chaitén area conducted by the Air Force, the town is 90% flooded due to increased flows of the Río Blanco or Río Chaitén and the occurrence of precipitation’. The river was reported on 13 May to be choked with volcanic ash and pumice, causing flooding.

Terra España today has a full report on the situation at Chaitén:

The suffering city, stricken by the tragedy of the violent eruption of the volcano which forced the evacuation of its more than 4,000 people on 2 May, now faces relentless rain. According to reports from the area, the accumulation of water ranges from 50 centimeters to one meter, and in some cases is mixed with mud of the sediments which the volcano has deposited in the Río Blanco and Río Rayas.

The Chilean Government has ordered that the 50-kilometre exclusion zone around the town of Chaitén will remain in place for the next three months because of the dangerous conditions in and around the town: ‘Many of the evacuated families asked the government for permission to return home to collect their belongings, but this was not permitted because of the deteriorating situation’.

Meanwhile fumarolic activity at the volcano Peteroa, situated on the Chile-Argentina border some 800 kilometres north of Chaitén, has provoked concern among the authorities, who are clearly determined not to be taken by surprise again. ONEMI notes today that the reports of increased activity may be due to changed atmospheric conditions making the fumaroles more visible, rather than any actual alteration in the volcano’s behaviour. The regional ONEMI director will be visiting the area to assess the situation tomorrow.

For all our Chaitén coverage: Chaitén << The Volcanism Blog

Information
Global Volcanism Program: Chaitén - summary information for Chaitén (1508-41)
Global Volcanism Program: Planchón-Peteroa - summary information for Planchón-Peteroa (1507-04=)
ONEMI, Oficina Nacional de Emergencia - Chilean government emergencies office (Spanish)
SERNAGEOMIN - volcanology information from the Servicio Nacional de Geología y Minería, Chile (Spanish)

News
Nuevo aluvión deja a casi todo Chaitén bajo el agua - 123 Chile, 15 May 2008 (Spanish)
Un 90% de Chaitén está bajo el agua por las fuertes lluvias y el desborde de ríos - Terra España, 15 May 2008 (Spanish)
Ponen candado pueblo chileno por volcán e inundación - Reuters América Latina, 15 May 2008 (Spanish)

In a bulletin issued yesterday, 13 May 2008, New Zealand’s geohazards monitoring organization GeoNet warns that ‘Elevated gas output, high lake temperatures and volcanic tremor continue to indicate elevated unrest at Ruapehu’.

CO² and SO² levels in Ruapehu’s gas plume are both significantly above normal background levels, and a slight increase in the levels of volcanic tremor has continued, with some periods of stronger tremor. The temperature of Crater Lake remains elevated, fluctuating between 34°C and 36.8°C:

Sustained heat from depth is required to keep the temperature this high for this length of time. It is believed that the source of this heat is magma within the volcano conduit. This magma is also producing the higher than normal gas flow and chemical changes. … These observations are consistent with the volcano-hydrothermal system responding to recent eruptions and ongoing interaction with magma in the volcano conduit. The volcano remains in a status of unrest and the possibility of further activity remains at the volcano. If further eruptions occur, they may occur without warning.

The New Zealand Herald quotes GNS Science volcanologist Dr Tony Hurst as saying that on the basis of these signs Ruapehu ’was not likely to erupt this year, but the signs did point to an increased risk of volcanic activity. That could mean steam plumes, gas bubbles and fountains from Crater Lake, he said’. The Herald’s report on Ruapehu is cheerfully categorized as a ’natural disasters story’.

The alert level for Ruapehu remains at level 1 (departure from typical background activity, signs of unrest).

For all our New Zealand coverage: New Zealand << The Volcanism Blog

Information
Global Volcanism Program: Ruapehu - summary information for Ruapehu (0401-10=)
GeoNet volcanoes - volcano information from GeoNet, the organization responsible for volcano monitoring in New Zealand
GeoNet Volcano Alert bulletins - volcanic activity bulletins from GeoNet

News
Restless Ruapehu emits danger signs - NZ Herald, 14 May 2008
Molten rock on the move in NZ volcano - Radio Australia, 13 May 2008
Scientists warn Ruapehu emitting more gas - Stuff.co.nz, 13 May 2008

A new satellite image of Chaitén volcano in eruption has been published at the NASA Earth Observatory Natural Hazards web site. The image was captured by Moderate Resolution Imaging Spectroradiometer (MODIS) equipment aboard NASA’s Terra satellite on 12 May 2008.

Above: the plume from Chaitén can be seen in the bottom left, extending eastwards across Argentina. Heavy ashfall can be seen north of the plume as a grey stain on the brown landscape of Patagonia. The original image with NASA commentary can be found here.

NASA images courtesy Jeff Schmaltz, MODIS Rapid Response Team at NASA GSFC.

For all our Chaitén coverage: Chaitén << The Volcanism Blog

There is a superb collection of Chaitén satellite imagery at the MiGeo geology blog, which provides excellent coverage of all aspects of geology with a particular emphasis on natural hazards. The blog comes out of Peru, and is in Spanish.

The article gives access to more than thirty satellite images, which come from a wide range of sources (and are fully referenced and linked back to those original sources) and cover the whole period of the eruption from 2 May 2008 onwards.

The article is an invaluable resource for understanding the Chaitén eruption: Erupción del Volcán Chaitén, Chile.

For all our Chaitén coverage: Chaitén << The Volcanism Blog

The Chilean Servicio Nacional de Geología y Minería (SERNAGEOMIN) has issued a new bulletin today, 13 May 2008, regarding the ongoing eruption at Chaitén volcano.

Yesterday, 12 May, SERNAGEOMIN carried out overflights and assessed the height of the eruption column as 8 kilometres above sea level. During the overflight ‘at least four explosions were observed that generated columns of a similar height, which were carried to the north-east by the prevailing strong (80-100 km/hr) south-west winds’. The overflight also revealed several acres of burned forest on the northern flank of the caldera ‘due to minor pyroclastic flows generated by the collapse of the base of the eruptive column and/or lateral explosions around the crater’, while areas to the north-east ‘have also been severely affected by small pyroclastic flows and the forests entirely levelled and burned’. The overflight also provided more information on the condition of the Chaitén lava dome:

The central dome presented a thick vertical column of gas and ashes from a crater of about 1 km diameter, located on the northern flank of the dome and extending towards the top. Western and north-western areas show the traces of many minor pyroclastic flows on their flanks, which have burned all vegetation inside the caldera, and even beyond its northern edges.

The overflight investigated the flooding of the Río Chaitén (also known as the Río Blanco) in Chaitén town yesterday and confirmed that the cause was ‘the large volumes of ash and pumice’ being carried by the river … the channel has been filled in by volcanic sediment’:

This process resulted from the accumulation of large amounts of ash and pumice in the headwaters of the Río Chaitén, which rises in the caldera of the volcano of the same name. The deposition of this material into the river will have caused the mud flow (lahar), a process that will recur, especially if there are heavy rains during the next few days.

The bulletin reports an increase in the number of VT seismic events around the volcano over the last 36 hours, and swarms of minor earthquakes have been recorded at intervals not exceeding 5 minutes.

The continuing concern for SERNAGEOMIN is ’possible future explosions causing the total destruction of the dome and the generation of large pyroclastic flows by the collapse of the eruption column, which would descend radially from the volcano through the adjacent valleys’. This highly destructive outcome is the worst-case scenario about which SERNAGEOMIN volcanologists and others have been warning for the last ten days: it remains a very real possibility.

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 - volcanology information from the Servicio Nacional de Geología y Minería, Chile (Spanish)