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Reventador update, 24 October 2009 24 October 2009

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Ecuador’s Instituto Geofísico has issued a new special bulletin for Reventador volcano, no. 7 of 23 October 2009 (PDF), which includes reports from an overflight that took place on 22 October.

The bulletin reports an increase in the number of long period seismic events and of explosions from 17:30 on 20 October. This was followed, from the afternoon of 22 October, by ‘a slight decline’ in the volcano’s activity, which nevertheless continued at ‘levels considered to be high’. Some of the explosions have been clearly audible in towns around the volcano and have generated ‘columns of steam and gas with little or no ash content which have reached a maximum altitude of 4 km’.

Instituto Geofísico staff carried out fieldwork at the volcano on 21 October and reported sounds of ‘cannonades’ of varying intensities, and the expulsion of incandescent material in the form of blocks and lava flows. An overflight on the morning of 22 October revealed that lava flows on the north and south flanks of the volcano are still active, and that the lava dome in the crater shows no signs of instability. The southern lava flow ‘has divided into four branches, and the greater part of it is situated above 2500 m above sea level (Figure 1)’, while ‘the northern flow is small and is situated above 3000 m above sea level (Figure 2)’. Temperatures of about 400°C within the crater and 250°C on the fronts of the lava flows have been shown in thermal images. SO2 emissions have averaged 500 tonnes/day.

Distribution of lava flows in the area south of the caldera of Reventador volcano, 22 October 2009 (S. Vallejo)
Figure 1. Distribution of lava flows in the area south of the caldera of Reventador volcano, 22 October 2009 (S. Vallejo).

Distribution of lava flows around the caldera of Reventador volcano, 22 October 2009 (S. Vallejo)
Figure 2. Distribution of lava flows on the north flank of Reventador volcano, 22 October 2009 (S. Vallejo).

The Instituto Geofísico daily bulletin for 24 October (PDF) reports continuing seismic signals of explosive events but no reports of ‘surface manifestations related to this type of activity’. Over the preceding 24 hours, 28 long period events were recorded, along with 17 explosive signals, ’16 bands of harmonic tremor and 9 of spasmodic tremor’. Loud rumbling sounds have been heard from the volcano.

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

Information
Global Volcanism Program: Reventador – summary information for Reventador (1502-01=)
Instituto Geofísico – Geophysical Institute of Ecuador

The Volcanism Blog

Continuing high level of activity at Reventador 20 October 2009

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Reventador volcano, 19 October 2009 (Instituto Geofisico, Ecuador)
Reventador, looking towards the eastern flank. Picture taken during the overflight of 19 October 2009 (Instituto Geofísico).

Activity at Reventador volcano ‘remains at a level considered to be high’, reports Ecuador’s Instituto Geofísico in the latest special bulletin, no. 6 of 19 October 2009 (PDF).

Swarms of long-period earthquakes interspersed by explosions have been recorded, with ‘the most energetic period beginning on 17 October at 23:26 (local time) and having a duration of approximately 10 hours’. The constant harmonic tremor signal during this period saturated Reventador’s seismic stations and was also recorded on the monitoring networks at Antisana volcano, which is approximately 50 km to the SSW, and Cayambe volcano, approximately 35 km to the NW.

Incandescence has been observed in the crater area and on the southern flank of the volcano, and local inhabitants have heard constant noises of roaring and explosions. A small grey-coloured eruption column (little ash content) was reported on the morning of 18 October. Thermal anomalies associated with the presence of lava and magmatic gases were registered on 19 October. Satellite ozone monitoring instruments registered a large quantity of sulphur dioxide emitted from the volcano during the end of last week.

On the morning of 19 October, Instituto Geofísico personnel undertook an overflight and were able to confirm that a lava dome is continuing to grow within the summit crater, and observed the presence of lava flows moving on both the south and the north flanks. The southern flow occupies the greater area and apparently divides into two branches. Small emissions columns were observed, without ash content but containing SO2 and of a blue colouring.

The Instituto Geofísico notes that the current activity ‘does not reach the high levels of energy released by the eruption of November 2002’.

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

News
El volcán ecuatoriano Reventador mantiene una alta actividad y se redobla la vigilancia – EFE, 19 October 2009
La actividad del Reventador aumentaEl Comercio, 19 October 2009

Information
Global Volcanism Program: Reventador – summary information for Reventador (1502-01=)
Instituto Geofísico – Geophysical Institute of Ecuador

The Volcanism Blog

Restless Reventador: increased activity reported 17 October 2009

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Ecuador’s Instituto Geofísico reports that Reventador volcano is showing signs of increased activity. In a special bulletin (PDF) issued on 15 October (PDF) intensified seismic activity was reported, with harmonic tremor signals saturating the seismic network; signals associated with rockfalls were also detected. There were also reports of crater incandescence and rumbling sounds. Thermal anomalies were detected over the volcano by satellite, and increased sulphur dioxide emissions were registered.

A further special bulletin (PDF) issued on 16 October reports that the seismic activity has continued, principally characterized by bands of harmonic tremor interspersed with sporadic long-period (LP) events. During an overflight yesterday scientists observed a lava dome within the crater, a lava flow on the north flank of the volcano and blue-ish gas emissions. The emissions reached up to 100 metres above the crater. Explosions and the ejection of incandescent blocks were reported, and the presence of incandescent material on the south flank of the volcano indicated that a lava flow had recently descended that flank. Thermal imagery revealed that incandescent material around the crater was reaching temperatures of 300°C.

Washington VAAC reported an increase in seismic activity at around 19:00 UTC, and emissions and a hotspot at 20:15 UTC today. An ash cloud was reported moving NW at FL150 (15000 feet/4500 metres).

News
Advierten del aumento en la actividad del volcán ecuatoriano Reventador – EFE, 17 October 2009

Information
Global Volcanism Program: Reventador – summary information for Reventador (1502-01=)
Instituto Geofísico – Geophysical Institute of Ecuador

The Volcanism Blog

Reventador: increased activity 24 April 2009

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Reventador, 23 April 2009 (R. Grijalva - SOTE)

Ecuador’s Reventador volcano is showing a significant increase in activity, according to reports in the Ecuadorian press, quoting the country’s Instituto Geofísico. According to the news site Confirmado.net, the seismic signals have included ‘spasmodic and harmonic bands of tremor’ interspersed with long period earthquakes.

UPDATE: A special bulletin from the Instituto Geofísico (PDF) reports the significant activity which occurred at Reventador during 23 April 2009.

  • Gradual but steady increase in seismicity, with spasmodic and harmonic bands of tremor showing periods of high and low activity, interspersed with long period events.
  • Column of water vapour reaching an estimated 2-3 km altitude, with low ash content: satellite imagery indicated that the plume extended approximately 26 km WSW.
  • Persistent thermal anomaly detected on the volcano, increasing in intensity during periods of increased tremor.
  • Loud noises reported from the volcano.
  • No reports of ashfall.

News
Volcán ‘El Reventador’ presenta incremento de actividad – Confirmado.net, 23 April 2009
Aumenta paulatinamente la actividad sísmica del volcán Reventador, en Ecuador – Terra España, 23 April 2009
Reventador reanuda su actividadEl Universo, 24 April 2009

Information
Global Volcanism Program: Reventador – summary information for Reventador (1502-01=)
Instituto Geofísico – Geophysical Institute of Ecuador

The Volcanism Blog

Reventador calms down again, but activity continues 12 November 2008

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Reventador volcano in Ecuador has shown a ‘considerable decline in activity’, reports the Instituto Geofísico in their latest Special Bulletin (PDF), dated 11 November 2008. Seismic activity and volume of gas emission have both declined since 10:00 local time on the morning of 10 November.

During the night of 9/10 November, the report notes, ‘moderate explosive activity (strombolian character) and the emission of two lava flows on the north and south flanks of the central cone of the volcano’ were observed, and ‘during the morning and afternoon of 10 November there was a continual emission of gas without ash content. The lava flows continued their advance, although the distances covered are for the moment less than those reached by the flows of recent eruptions of the volcano’. The Instituto Geofísico indicates that ashfall from the volcano is unlikely over the next few days, but that the lava flows may continue for a few more days, as has been the case with previous eruptions.

The Director of the Instituto Geofísico, Hugo Yepez, ruled out a violent eruption of Reventador in a statement of 10 November, say reports in the Ecuadorian press. However, there is concern that the blockage of watercourses by ash and volcanic debris may cause overflowing of local rivers and possible floods. Reports from the last 24 hours say that incandescence is still visible at the summit of the volcano, and strong explosions have been heard. The alert level for Reventador continues to be yellow.

News
Actividad sísmica del Reventador disminuyó considerablementeEl Comercio, 11 November 2008 (Spanish)
Autoridades de Napo, en alerta por caída de ceniza del ReventadorDiario Hoy, 12 November 2008 (Spanish)
El Reventador sigue en actividadEl Comercio, 12 November 2008 (Spanish)

Information
Global Volcanism Program: Reventador – information about Reventador (1502-01=)
Instituto Geofísico – Geophysical Institute of Ecuador

The Volcanism Blog

Eruptive activity at Reventador, Ecuador 10 November 2008

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Reventador volcano in Ecuador has erupted ash and lava, after a weekend of heightened seismicity. Ecuador’s Instituto Geofísico does not currently regard the activity as dangerous. Reventador’s last eruption was in July this year.

The Spanish newspaper La Vanguardia (see news links below) has some spectacular pictures of this eruption.

Only a brief note here because of time pressures: more Reventador news later. For all our Ecuador coverage: Ecuador « The Volcanism Blog.

News
Reventador volcano spews lava near Ecuador capital – Associated Press, 10 November 2008
IG: Actividad volcánica del Reventador no es peligrosaEl Telégrafo, 10 November 2008 (Spanish)
El volcán Reventador ilumina la noche de los AndesLa Vanguardia, 10 November 2008 (Spanish)
Geofísico descarta gravedad en nueva actividad del ReventadorEl Universo, 10 November 2008 (Spanish)

Information
Global Volcanism Program: Reventador – information about Reventador (1502-01=)
Instituto Geofísico – Geophysical Institute of Ecuador

The Volcanism Blog

Ecuador: Reventador erupting 29 July 2008

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Reventador volcano in north-eastern Ecuador is currently erupting ash and lava. On 27 July 2008 the Instituto Geofísico of Ecuador reported in a special bulletin (PDF) that a progressive increase in seismicity was under way at Reventador volcano. A thermal anomaly was also detected, and overnight incandescence was seen at the crater and ash erupted. Yesterday a second special bulletin (PDF) gave more details of the seismicity:

Since early July the seismic activity of Reventador volcano has shown a progressive and constant increase in the number of events related to the movement of magmatic fluids, especially LP-type events, recording the highest number of such signals on 24 and 25 July with 104 and 96 LP events respectively. On 27 July the seismic activity changes, beginning at 15:00 local time, beginning to register a continuous tremor signal at an amplitude that saturates the volcano’s seismic stations, and is recorded by remote stations such as those at Cayambe, Antisana, Cotacachi and Guagua Pichincha.

With their usual thoroughness, the Instituto Geofísico goes on to document the volcano’s current activity: explosions in the crater, producing an eruption column of ash and incandescent material dispersing to the west and north-west; a lava flow on the south flank; constant roars and rumbles audible in surrounding communities; mild ashfall in Olmedo (50km north-west of Reventador); satellite imaging revealing hot zones within the crater. Based on the volcano’s current behaviour, an explosive eruption similar to that of November 2002 is not expected.

Reventador is one of the most active Ecuadorian volcanoes, with frequent historical eruptions. Between November 2002 and May 2003 the volcano produced a dramatic VEI=4 event, with a 17km eruption column, pyroclastic flows, lava flows, heavy ashfall (Quito was badly affected), and some fatalities. Reventador is located in a fairly remote area of the Cordillera Real, some 90km north-east of Quito, in its own national park; it is not considered a threat to heavily populated areas, but surrounding farmland and agricultural communities can be severely affected by its activity (as in the 2002-3 eruption).

For all our Ecuador coverage: Ecuador « The Volcanism Blog

Information
Global Volcanism Program: Reventador – summary information for Reventador (1502-01=)
Instituto Geofísico – Geophysical Institute of Ecuador

News
Volcano in eastern Ecuador spews ash, lavaInternational Herald Tribune, 29 July 2008
El Reventador volvió a botar ceniza, ayerEl Comercio, 29 July 2008 (Spanish)
El Reventador se reactiva tras 6 años de calmaEl Universo, 29 July 2008 (Spanish)

The Volcanism Blog