Reventador

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  • Last Known Eruption
  • 0.077°S
  • 77.656°W

  • 3562 m
    11683 ft

  • 352010
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Most Recent Weekly Report: 17 September-23 September 2014


IG reported that vapor plumes with a low ash content rose 1-2 km above Reventador and drifted NW and SW during 17-22 September.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


Most Recent Bulletin Report: June 2013 (BGVN 38:06)


Lava dome's summit rises above rim in late 2012

Introduction. Our last report on Reventador covered activity through 26 April 2012 (BGVN 37:03) and this one covers activity through April 2013.

In its Special Report of 9 November 2012, Ecuador's Instituto Geofísico-Escuela Politécnica Nacional (IG) summarized the new phase of activity that began in February 2012. The Special Report noted that lava flows traveled as far as 2 km from the crater down the N and S flanks. Later reports noted that in November-December 2012, lava flows reached 1.3 km in length; in January 2013 they reached up to 1.1 km in length. During this reporting interval, ash plumes rose as high as 5.2 km altitude both in August 2012 and November 2013.

The lava dome in the interior of the crater continued to grow and between November 2012 and January 2013 established a new summit that reached to at least 100 m above the E rim, having completely filled the crater developed in November 2002. This enabled blocks from the lava dome to roll down the flanks.

Table 6.A non-comprehensive synthesis of Reventador's steam and ash plumes generated during the reporting period. Courtesy of IG and the Washington VAAC.

Date   Plume altitude OR height above (3.5 km a.s.l.) rim / direction / distance   Comments
11 Aug 2012 Ash plume rising to 5.2 km trended W  
20 Sep 2012 Ash plume drifted 22 km SW  
17-18 Oct 2012 Steam and gas plume rose to 1 km and trended W  
3-4 Nov 2012 Steam and ash plume rose to 3 km above the crater.  
5 Nov 2012 Steam and ash plume rose to 3 km; ash plume rose to 2 km and drifted NW  
13 Nov 2012 Gas and ash plume rose to 5.2 km and drifted SE  
16 Nov 2012 Ash plume rose to 4 km above the rim and drifted W and NW Ashfall reported between Reventador and El Chaco (35 km SSW)
22 January 2013 Gas and steam plume rose 1.5 km above the crater; white-to-light grey plumes rose 2 km and drifted W  
24 January 2013 Steam and ash plume rose 2 km  
29 January 2013 Gas plumes rose as high as 1 km and drifted NW and W  
29 January 2013 Overflight revealed steam and ash plume rising to 1.5 km above the lava dome;  
4 February 2013 Ash plume rose to 4 km and drifted NW  
7 February 2013 Ash plume rose to 3 km and drifted S  
2 March 2013 Ash plume rose to 4 km and drifted SW  
8 March 2013 Steam emission rose to 500 above the crater Glow reported
12 March 2013 Emission rose to 2 km and drifted W  
13 March 2013 Ash plumes rose to 3 km  
16 March 2013 Ash plume rose to 1 km and drifted W  
31 March 2013 Steam emission rose to 500 above the crater and trended W  
8 April 2013 Emissions reached to 3 km above the crater  
12 April 2013 Steam emissions reached to 2 km  

Between late April and early August 2012, activity at Reventador remained moderate, and although cloud cover often obscured visual observations, there were occasional reports of steam emissions rising to as high as 1 km above the crater. Long-period (LP) earthquakes occurred with moderate-to-high intensity, a behavior interpreted as the movement of fluids at depths. Seismic signals attributed to rock fall were also prominent, inferred to come from lava flows that descended the N flank, as aerial observers witnessed on both 29 May and 4 June.

Based on analysis of satellite imagery, the Washington Volcanic Ash Advisory Center (VAAC) reported that on 12 August they detected a well-defined thermal anomaly. Thermal images obtained in overflights carried out on 17 and 18 October 2012 revealed a lava flow that descended the flank of the cone and verified that another flow had descended during the preceding days or weeks and at the moment of observation was still warm. The flows did not exceed 1 km in length, and in light of their location within the crater, were not a danger to the public (figure 39).

Figure 39. A) On the left photo, the S flank of Reventador seen on 19 October 2012. A lava flow descending on the upper flank covered much of the flows from previous days and weeks. At right is a corresponding thermal image, permitting definition of the extent of the new hotter flows. Photo and image, courtesy of P. Ramon (Instituto Geofisico).

On 17 and 18 October, IG also verified the presence of a previously known lava dome within the crater, with steep slopes, the top of which was then the highest point of the volcano. Similar observations were carried out on 19 October by IGEPN technicians maintaining the monitoring network, who also stressed the continuous flow of lava blocks spilling off both the fronts of new flows and from the lava dome.

During 31 October-11 December 2012, the IG reported that although cloud cover often prevented visual observations, ash plumes were often seen.

Seismicity increased during this time period. Around 5 November, the seismic network detected an increase in the magnitude of volcanic tremor. IG reported that seismicity indicated falling rock and explosions during 14-15 November. Beginning 16 November IG's seismic network indicated a significant increase in tremor and in signals indicative of emissions and explosions. IG reported that scientists aboard an overflight on 23 November observed intense fumarolic activity and a new crater at the summit of the dome, which contained ash and large blocks. A thermal camera measured temperatures at the dome of ~ 300°C. Lava flows continued to be active on the dome flanks, and elongated block-and-ash deposits were also visible on the flanks. IG reported high seismicity during 5-11 December 2012, indicating multiple explosions almost daily. At least one lava flow was generated between November - December 2012 that descended the N flank to ~1.3 km in length.

2013. Throughout this January-April 2013 reporting period, cloud cover often prevented visual surface observations. The lava dome grew between November 2012 through January 2013 to at least 100 m above the E rim, completely filling the crater generated by the eruption of November 2002. Between November 2002 and 31 January 2013, ~ 20 lava flows had traveled down the N, SE, and S flanks, and affected zones within the caldera.

IG reported moderate seismicity during 16-21 January 2013. During the morning of 22 January seismicity, including tremor, increased significantly, signals indicating that rock falls were detected. Low frequency, high-energy tremor was detected by seismic stations around the volcano with an average of 20 seismic events and an average of 29 explosions. Explosions were heard. Lava flows traveled down the SW and N flanks. Observers reported lava fountains in the crater and lava flows on the flanks, both of which became more intense at 1800. Explosions produced white-to-light-gray plumes that rose 2 km and drifted W (figure 40).

Figure 40. Emission column seen late in the day on 22 January 2013 associated with the explosive activity at Reventador. Courtesy Walter Garcia Synohidro and Instituto Geofisico.

During the night of 22 January a lava flow descending the SE flank had reached a width of 350 m and extended at least 1.1 km (figure 41). Other smaller lava flows up to 200 m long were observed on the N and S flanks.

Figure 41. Thermal image of Reventador on 22 January 2013 shows the dome from which a lava flow descends to the SE. Courtesy S. Vallejo, Instituto Geofisico (IG-EPN).

During 23 January-7 February 2013 seismicity remained high. Lava flows were visible at night. Crater incandescence was observed at night during 29-30 January.

IG reported that seismicity became more moderate during 8-12 February; explosions were detected daily. Ashfall was reported in areas near the volcano on 9 February. Between 16-20 February, activity remained moderate, with continued ash emissions, but an absence of reported ashfall. For the remainder of February 2013, no reports of surface activity were received, and seismic signals ceased transmission.

According to the Washington VAAC, the IG reported that on 2 March lava flows were observed. IG reported that the seismic network recorded multiple explosions during 13-17 March. Observers reported falling and rolling incandescent material on Reventador's S flanks on 12 March. On 15 and 17 March explosions were detected by the seismic network. IG characterized activity as being at a moderate level for most of the remainder of March.

IG noted that moderate activity continued into April 2013 (table 6). Through 12 April seismicity remained moderate. On 15 April IG reported an increase in the number of seismic events. Seismic and surface activity remained moderate to high through 24 April, but became more moderate thereafter and remained so for the remainder of April 2013.

Information Contacts: Instituto Geofísico-Escuela Politécnica Nacional (IG), Casilla 17-01-2759, Quito, Ecuador (URL: http://www.igepn.edu.ec); and Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS E/SP23, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: http://www.ssd.noaa.gov/VAAC/).

Index of Weekly Reports


2014: January | March | April | May | June | July | August | September
2013: January | February | March | April | May | June | July | August | September | October
2012: January | February | March | April | August | September | October | November | December
2011: January | August
2010: February | April | May | August | September | October | November
2009: March | April | May | August | September | October | November
2008: July | August | November
2007: March | April | May | June | October
2005: January | April | May | June | July | August | September | November | December
2004: February | May | December
2003: January | February | March | May | July | October | November
2002: October | November | December

Weekly Reports


17 September-23 September 2014

IG reported that vapor plumes with a low ash content rose 1-2 km above Reventador and drifted NW and SW during 17-22 September.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


10 September-16 September 2014

IG reported moderate volcanic activity including explosions, long-period earthquakes, and tremor at Reventador during 10-16 September. On 10 September continuous steam with minor ash plumes rose 1,000 m above the summit and drifted NW. Cloudy conditions frequently obscured views of the summit.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


3 September-9 September 2014

During 3-9 September IG reported moderate activity including explosions, long-period earthquakes, harmonic tremor, and tremor at Reventador. While cloud cover frequently limited observations, on 5-8 September steam emissions were observed with small quantities of ash. In the morning of 5 September an explosion generated a plume and ejected blocks from the crater that fell ~500 m below the summit on the W flank. A thermal camera detected an explosion on the following day that also included ballistics. Rumbling sounds were heard in the morning of 7 September, and that evening a 1 km plume was observed. The following morning a vapor plume persisted from the summit, and in the afternoon it contained a small amount of ash.

The MODIS sensor onboard the Terra satellite detected thermal anomalies from the region of Reventador’s summit during 4-6 September.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); University of Hawaii MODIS


27 August-2 September 2014

During 27 August-2 September IG reported moderate activity including explosions, long-period earthquakes, harmonic tremor, and tremor at Reventador. On 27 August steam emissions were observed. On most days the volcano was obscured by clouds. On 2 September instruments recorded tremor-related emissions and satellite views showed an ash plume that rose 6 km (19,700 ft) height and drifted W. On 2 September the Washington VAAC reported volcanic ash emissions.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


20 August-26 August 2014

During 20-26 August IG reported moderate to high volcanic activity at Reventador, including explosions, long-period earthquakes, harmonic tremor, and tremor. On 20 August ash plumes, observed through partly cloudy skies, remained near the volcano. On 26 August in the morning hours emissions of water vapor were reported above the crater drifting SW. The volcano was obscured by clouds the other days of the week. On 24 August the Washington VAAC reported an emission with light ash to 6 km (20,000 ft) a.s.l. identified by wind and satellite data, seismic detection, and pilot report.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


13 August-19 August 2014

IG reported moderate volcanic activity including explosions, long-period earthquakes, harmonic tremor, and tremor at Reventador on 13, 14, 18, and 19 August. On 13 August continuous steam with minor ash plumes rose 500 m above the summit and drifted NE. On 14 August clear views of the volcano showed no surface activity, and on 18-19 August the volcano was obscured by clouds.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


6 August-12 August 2014

IG reported moderate volcanic activity including explosions, long period earthquakes, harmonic tremor, and tremor at Reventador during 6-12 August. On 6 August a dark gray plume rose 300 m above the summit and drifted NW. On 7, 8 and 10 August steam and steam-and-minor ash rose 300 to 800 m above the summit and drifted SW and NW. On 9 August views of the volcano were obscured by clouds and no report was available 11 August.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


30 July-5 August 2014

IG reported moderate volcanic activity including explosions, long period earthquakes, harmonic tremor, and tremor at Reventador during 30 July-5 August. On most days IG reported inclement weather with intermittent views of steam-and-ash plumes that rose above the crater and drifted W. On 2 August IG noted a steam-and-ash plume rose 2 km above the crater accompanied by seven emission tremor events. On 31 July Washington VAAC reported on-going ash emissions and detected hotspots at the crater.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


23 July-29 July 2014

IG reported moderate seismicity including explosions, long-period earthquakes, harmonic tremor, and tremor, though cloud cover mostly prevented observations of Reventador during 23-29 July. On 23 July IG reported that a column rose to 1 km above the crater and on 24 July reported strong roaring and a plume that drifted NW. On 27 July an emission was seen in satellite imagery.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


16 July-22 July 2014

IG reported moderate seismicity including explosions, long-period earthquakes, harmonic tremor, and tremor, though cloud cover mostly prevented observations of Reventador during 16-21 July. On 18 July IG noted an emission that rose to 800 m above the crater, and on 22 July a minor ash emission also rose 800 m above the crater; both drifted SW.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


9 July-15 July 2014

IG reported that although cloud cover often prevented observations of Reventador, during 30 June and 2, 4, and 9-12 July ash emissions were seen. In the afternoon of 30 June, a diffuse ash plume was visible rising from the summit. Activity increased on 2 July when 41 explosions were recorded, as well as 27 long-period earthquakes and 15 episodes of tremor associated with emissions. A 2-km-high gas-and-ash plume was observed rising from the summit on the morning of 2 July that drifted SE and later that night an explosion was heard. The IG reported that SOTE (Sistema de Oleoducto Transecuatoriano) personnel heard explosions during the morning of 8 July. The next morning, SOTE personnel noted that the summit was clear and a gas-and-ash plume was rising from the summit up to 2 km above the crater rim. Diffuse ash plumes were also noted on 10 and 11 July that reached 1.5 km above the crater and drifted NW.

The seismic network detected the highest number of explosion signatures during 2-5 July when 34-45 events per day were detected. Up to 12 episodes of harmonic tremor per day occurred during 4 and 5 July. The highest number of long-period earthquakes occurred during 10-11 July: 90 events per day. Tremor signatures associated with emissions had a wide range during this reporting period (0-28 per day), but typically numbered less than 15 per day.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


18 June-24 June 2014

IG reported that although cloud cover often prevented observations of Reventador, during 18-24 June ash plumes were occasionally observed. At night on 17 June incandescence was observed on the S and E flanks. In the morning of 18 June a diffuse ash plume was visible rising ~600 m above the summit that dispersed to the NW. A total of 30 explosion signatures were recorded by the seismic network, along with long-period (LP) earthquakes and tremor.

Incandescence was observed in the morning of 19 June. The infrared webcamera recorded incandescent material descending onto the NE flank. Residents of San Rafael (8 km ESE) reported roaring sounds from the volcano on 19 and 20 June. The seismic network detected >=18 explosions, >20 LP, and >=7 tremor events per day during 18-24 June.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


21 May-27 May 2014

IG reported that although cloud cover often prevented observations of Reventador during 21-27 May ash plumes were occasionally observed. An ash plume was observed from an aircraft on 22 May, and the next day an ash-and-vapor plume rose 1 km and drifted NW.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


30 April-6 May 2014

IG reported that a small pyroclastic flow traveled a few meters below Reventador’s crater on 29 April. Cloud cover occasionally prevented visual observations during 30 April-6 May. An ash plume rose 3-4 km and drifted W on 1 May, and a steam plume with some ash rose less than 1 km the next day. People in Camp San Rafael (8 km ESE) reported that an explosion at 2040 on 4 May ejected a large amount of incandescent material onto the flanks, and generated an ash plume that rose 4-5 km above the crater and drifted NW. Explosions on 5 May produced ash plumes that rose 4 km. At 0925 an explosion vibrated windows in the camp. On 6 May explosions again rattled windows in the camp and a gas plume was observed rising 1 km and drifted W.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


9 April-15 April 2014

IG reported that activity at Reventador remained high on 9-15 April; numerous explosions were detected each day. Steam-and-ash plumes rose less than 1 km above the crater and drifted W during 9-10 April. Lava flows down the SW flank were reported on 9 and 11 April. Clouds obscured views during 12-15 April.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


2 April-8 April 2014

IG reported that cloud cover occasionally prevented visual observations of Reventador during 2-8 April; activity remained high. A steam-and-ash plume rose 3 km and drifted E on 2 April, and a thermal camera detected hot material on the flanks. Four lava flows on the S and SE flanks were observed on 3 April. Ash emissions were observed the next day. On 5 April sporadic ash emissions rose 1 km and drifted W. On 6 April water vapor emissions with low amounts of ash rose 500 m and drifted NW. During 7-8 April lava flows continued to descend the S and SE flanks. On 8 April vapor emissions with small amounts of ash were observed.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


26 March-1 April 2014

IG reported that activity at Reventador increased on 25 March. At 1830 an explosion was followed by a pyroclastic flow that traveled 500 m down the flanks. Strombolian activity produced gas-and-ash plumes that rose 1.5 km above the crater. During 26-29 March continuous tremor was interspersed with explosions and long-period earthquakes. Although cloud cover often prevented crater views, video cameras showed a lava flow traveling down the S flank and incandescent material erupting from the crater. Emissions with small amounts of ash rose 1 km on 28 March. Ashfall was reported in Hosteria El Reventador and camp San Rafael on the flanks. A load roar reported at 0300 on 31 March was followed by observations of incandescent material traveling 1 km down the S flank. Cloud cover prevented visual observations the next day.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


22 January-28 January 2014

Based on information from IG, the Washington VAAC reported that on 22 January an ash plume from Reventador rose to an altitude of km (12,000 ft) a.s.l. Ash was not identified in satellite images. IG noted that an explosions lasting several minutes was recorded.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


1 January-7 January 2014

Based on a pilot observation, the Washington VAAC reported that on 31 December an ash plume from Reventador rose to an altitude of km (16,000 ft) a.s.l. Ash was not identified in satellite images due to weather clouds in the area but an occasional thermal anomaly was detected.

Source: Washington Volcanic Ash Advisory Center (VAAC)


30 October-5 November 2013

During 30 October through 5 November, IG reported that moderate activity from Reventador continued. Elevated seismicity included explosions (8-35 per day), long period earthquakes, and tremor related to emissions and fluid movement in the crust (harmonic tremor). Plumes of steam were frequently observed when the weather permitted; ash plumes were generated on 31 October, 2 November, and 5 November. Ashfall from these events reached the town of San Rafael on 31 October and 2 November; a pilot observed ash on 2 November at an altitude of 6.7 km (22,000 ft). Observers heard roaring noises and sounds resembling "cannon shots" on 31 October and 1 November.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


18 September-24 September 2013

IG reported that seismicity remained elevated at Reventador during 18-24 September. Although cloud cover often prevented observations, ash plumes were occasionally observed. On 19 September an ash plume drifted W, and on 21 September multiple low-energy steam emissions contained small amounts of ash. Deposits from a pyroclastic flow that had descended the S flank were observed on 22 September.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


4 September-10 September 2013

IG reported that seismicity remained elevated at Reventador during 4-10 September. Although cloud cover often prevented observations, ash plumes were occasionally observed rising from the lava dome. On 6 September IG staff observed 1-km-long deposits from a pyroclastic flow that had descended the S flank after an explosion. Ash plumes rose 1-2 km above the lava dome during 6-7 September, and minor ash emissions were noted on 9 September.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


7 August-13 August 2013

IG reported that during 7-8 August explosions at Reventador ejected incandescent material onto the SW flank. Steam emissions were observed on 8 and 9 August, and on 10 August they contained ash and rose 1 km above the crater. Cloud cover prevented observations during 11-13 August; roaring was reported on 13 August.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


24 July-30 July 2013

IG reported that during 24-30 July seismic activity at Reventador remained high and was characterized by explosions, low-intensity emissions, and long-period earthquakes indicting fluid movement. Cloud cover mostly prevented visual observations. On 26 July an explosions generated a low-altitude ash plume that drifted W.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


17 July-23 July 2013

IG reported that during 17-19 July seismic activity at Reventador remained high; at times periods of increased seismicity were followed by relatively quiet episodes. The seismic network recorded long-period signals, rockfalls, explosions, and emissions. Based on reports from observers at camp San Rafael, cloud cover often prevented visual observations, although on 18 July a new lava flow on the E flank was observed with a video camera, and a gas-and-ash plume was observed rising 1 km. During 21-22 July gas plumes with low ash content rose to low heights.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


10 July-16 July 2013

IG reported that during 10-16 July seismic activity at Reventador was high; weather conditions mostly prevented visual observations of the crater. During partially clear views on 13 July, observers noted a new lava flow on the S flank. At 1500 on 15 July continuous tremor was detected, which intensified at 2000, and then decreased at midnight. Intense Strombolian activity during this time was characterized by variable-magnitude explosions and roaring. Explosions generated blocks that rolled down the flanks. Incandescence from the lava flow on the S flank was observed.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


19 June-25 June 2013

According to the Washington VAAC a pilot observed an emission from Reventador that rose to an altitude of 4.9 km (16,000 ft) a.s.l. on 20 June. The VAAC also noted that seismic records from IG were consistent with an emission of ash or gas, and that satellite images did not detect ash.

Source: Washington Volcanic Ash Advisory Center (VAAC)


29 May-4 June 2013

The Washington VAAC reported that on 1 June gas emissions from Reventador possibly contained diffuse ash. Ash was not detected in satellite images.

Source: Washington Volcanic Ash Advisory Center (VAAC)


8 May-14 May 2013

IG reported that during the morning of 8 May incandescence from Reventador's crater was observed in addition to steam-and-ash plumes that rose 1 km above the crater and drifted NW. Cloud cover prevented observations the rest of the day and most of the time during 9-14 May. At 1700 on 10 May a steam plume with low ash content rose 1 km above the crater, and on 11 May a vapor plume rose 500 m and drifted SW.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


1 May-7 May 2013

According to the Washington VAAC, IG reported that on 1 May seismicity at Reventador was elevated, and an ash plume rose to an altitude of 7 km (23,000 ft) a.s.l. A thermal anomaly was visible in satellite images. On 2 May ash was not identified in images and seismicity decreased.

Source: Washington Volcanic Ash Advisory Center (VAAC)


10 April-16 April 2013

According to the Washington VAAC, on 12 April an ash plume from Reventador was observed in visible satellite images along with a corresponding thermal anomaly in short wave infrared images.

Source: Washington Volcanic Ash Advisory Center (VAAC)


13 March-19 March 2013

IG reported that the seismic network at Reventador recorded multiple explosions during 12-17 March. Observers reported falling and rolling incandescent material on the S flank on 12 March. Explosions produced ash plumes that rose more than 1 km and drifted SW. The next day ash plumes rose as high as 3 km. On 15 and 17 March explosions were detected by the seismic network; cloud cover prevented visual observations. On 16 March an ash plume rose 1 km and drifted W.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


27 February-5 March 2013

According to the Washington VAAC, the IG reported that on 2 March lava flows were observed, and a gas-and-ash plume rose to an altitude of 4 km (13,000 ft) a.s.l. and drifted SW. About an hour later a pilot observed an ash plume that rose to the same altitude. No ash plumes were identified in satellite imagery, however a weak thermal anomaly was observed during 2-3 March.

Source: Washington Volcanic Ash Advisory Center (VAAC)


6 February-12 February 2013

IG reported that seismicity at Reventador was high during 6-7 February and moderate during 8-12 February; explosions were detected daily. An ash plume rose 3 km and drifted S on 7 February, and ashfall was reported in areas near the volcano on 9 February. Cloud cover often prevented observations.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


30 January-5 February 2013

During an overflight of Reventador on 29 January scientists observed an explosion and a steam-and-ash plume that rose 1.5 km above the lava dome. Since November the dome had significantly grown to at least 100 m higher than the E rim, and about 20 lava flows had traveled down the N, SE, and S flanks.

During 29 January-5 February seismicity remained high. Cloud cover often prevented observations although emissions were observed; steam-and-ash plumes rose 2-4 km and drifted W and NW on most days. Crater incandescence was observed at night during 29-30 January.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


23 January-29 January 2013

IG reported that in the morning of 22 January tremor at Reventador increased significantly and signals indicating rockfalls were detected. Explosions were heard during the afternoon and evening that same day. After an explosion in the crater a gas-and-steam plume was observed rising 1.5 km above the crater. Lava flows traveled down the SW and N flanks. The lava dome had grown at least 100 m above the crater rim.

During 23-29 January seismicity remained high. Cloud cover mostly prevented visual observations; during 22-23 January lava flow were visible at night, and on 24 January a steam-and-ash plume rose 2 km. Gas plumes rose as high as 1 km and drifted NW and W on 29 January.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


16 January-22 January 2013

IG reported that during 16-21 January seismicity at Reventador was moderate; cloud cover prevented visual observations. Incandescence in the crater was observed at night during 21-22 January. Starting at 0900 on 22 January seismicity at Reventador increased and was characterized by constant low-frequency, high-energy tremor detected by seismic stations around the volcano. Observers reported lava fountains in the crater and lava flows on the flanks, both of which became more intense at 1800. Explosions produced white-to-light-gray plumes that rose 2 km and drifted W.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


5 December-11 December 2012

IG reported that seismicity at Reventador was high during 5-11 December and indicated multiple explosions almost daily. Plumes were observed although cloud cover often prevented visual observations. On 5 December a steam plume rose 1.5 km and drifted NW. The next day a steam-and-ash plume rose 2 km above the lava dome and drifted SE. A steam-and-ash plume rose 1 km on 8 December and drifted WSW, towards Chaco. Another steam-and-ash plume was observed on 11 December.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


21 November-27 November 2012

IG reported that scientists aboard an overflight of Reventador on 23 November observed steam-and-gas emissions with slight amounts of ash rising 500 m above the lava dome and drifting WSW. The lava dome had intense fumarolic activity and there was a new crater at the summit of the dome, which was filled with ash and large blocks. A thermal camera measured temperatures in the dome of about 300 degrees Celsius. Lava flows continued to be active on the dome flanks, and elongated block-and-ash deposits were also visible on the flanks.

According to the Washington VAAC, the IG reported that on 24 November an ash plume from Reventador rose to an altitude of 4.6 km (15,000 ft) a.s.l. Ash was not detected in satellite imagery due to cloud cover, but a thermal anomaly was detected.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


14 November-20 November 2012

IG reported that seismicity at Reventador indicated falling rock and explosions during 14-15 November. Cloud cover prevented visual confirmation.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


7 November-13 November 2012

On 9 November, IG reported that since February Reventador began a new phase of activity characterized by lava flows from the crater, steam plumes, and thermal anomalies detected in satellite images. The lava flows traveled as far as 2 km down the N and S flanks, and steam plumes rose 200-500 m above the crater. Field visits by volcanologists in recent months confirmed that the lava dome in the crater had continued to grow above the rim, becoming the highest point of the volcano. Blocks from the lava dome and lava-flow fronts rolled down the flanks. IG noted that during 3-4 November emissions increased; a steam-and-ash plume rose 3 km above the crater. The seismic network detected an increase in the magnitude of volcanic tremor. Steam-and-gas plumes contained ash within the previous few days.

According to the Washington VAAC, the IG reported that on 9 November an ash emission from Reventador rose to an unknown height. On 13 November a gas-and-ash plume rose to an altitude of 5.2 km (17,000 ft) a.s.l. and drifted SE. Ash was not detected in satellite imagery on either day.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


31 October-6 November 2012

The IG reported that although cloud cover often prevented observations of Reventador, plumes were observed almost daily. During 31 October-1 November and 3 November plumes rose 1.5-3 km above the crater and drifted NW. At about 0400 on 5 November a steam-and-ash plume rose 3 km. An ash plume rose 2 km and drifted NW at 0600.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


19 September-25 September 2012

Based on analysis of satellite imagery, the Washington VAAC reported that an ash plume from Reventador drifted 22 km SW on 20 September.

Source: Washington Volcanic Ash Advisory Center (VAAC)


8 August-14 August 2012

Based on analysis of satellite imagery, the Washington VAAC reported a possible ash emission from Reventador on 11 August. The next day a well-defined thermal anomaly was detected and an ash plume drifted W. According to the VAAC, IG confirmed the ash plume, noting that it rose to an altitude of 5.2 km (17,000 ft) a.s.l.

Source: Washington Volcanic Ash Advisory Center (VAAC)


18 April-24 April 2012

IG reported that on 18 April a plume with low ash content rose 2 km above Reventador's crater and drifted NW. A steam plume rose 100 m above the crater the next day. Weather conditions prevented observations during 20-23 April.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


21 March-27 March 2012

IG reported that during 21-25 March storm clouds prevented observations of Reventador. During 25-26 March incandescence from a high part of the volcano was observed. On 26 March a steam emission rose 500 m above the crater. Based on analysis of satellite imagery and seismic data, the Washington VAAC reported that an ash plume drifted 25 km NNW on 26 March. Later that day the ash had dissipated and seismicity decreased.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


15 February-21 February 2012

IG reported that activity continued at Reventador during 15-21 February. Satellite images showed a thermal anomaly on the NE flank from the lava flow that was observed on 12 February. Clouds prevented views on 17, 19, and 21 February. Based on analysis of satellite imagery, the Washington VAAC reported an ash plume that drifted 19 km SE on 16 February. IG observed an ash plume that rose 100 m above the crater on 18 February.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


8 February-14 February 2012

IG reported that during 10-13 February new activity from Reventador was detected. Satellite images showed a thermal anomaly on 10 February. Based on pilot observations, the Washington VAAC reported an ash plume that rose to an altitude of 5.2 km (17,000 ft) a.s.l. and drifted NW. On 11 February ash-and-steam emissions drifted NW. Seismicity increased on 12 February and a lava flow descended the NE flank during 12-13 February. Crater incandescence was observed during 10-13 February.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


4 January-10 January 2012

IG reported that staff conducting fieldwork at Reventador during 6-7 January observed constant emissions of gas-and-steam rising about 300 m above the crater and drifting WNW. The emissions originated from a growing lava dome that was a few tens of meters above the crater rim and almost filled the base.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


3 August-9 August 2011

The IG reported that scientists conducting an overflight of Reventador on 14 July noted that the lava dome at the top of the 2008 cone continued to grow, filling the crater. The dome had reached the same height as the highest part of the crater rim, formed during 2002. Intense fumarolic activity produced continuous plumes. The dome was thought to have formed during 2011, growing at a rapid rate and producing high temperatures. IG also noted that seismicity had increased starting in May but was more pronounced during the previous few weeks. During 3-9 August cloud cover prevented observations of the lava dome, but the seismic network detected long-period and explosion-type earthquakes.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


5 January-11 January 2011

Based on a pilot observation, the Washington VAAC reported that on 4 January an ash plume from Reventador rose to an altitude of 5.2 km (17,000 ft) a.s.l. Cloud cover prevented clear satellite observations of the volcano. A subsequent report stated that IG noted low seismicity, no reports of ashfall, and that satellite imagery showed no ash emissions.

Source: Washington Volcanic Ash Advisory Center (VAAC)


3 November-9 November 2010

Based on a pilot observation, the Washington VAAC reported that on 2 November an ash plume from Reventador rose to an altitude of 4.6 km (15,000 ft) a.s.l. Cloud cover prevented clear satellite observations of the volcano.

Source: Washington Volcanic Ash Advisory Center (VAAC)


6 October-12 October 2010

Based on analyses of satellite imagery and information from IG, the Washington VAAC reported that on 6 October a small ash cloud from Reventador drifted NE. IG also reported that a steam plume rose 1 km above the crater on that same day.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


29 September-5 October 2010

According to the Washington VAAC, the IG reported ash over Reventador on 30 September. The VAAC stated that a diffuse plume was observed in satellite imagery drifting NW, although ash was not identified.

Source: Washington Volcanic Ash Advisory Center (VAAC)


22 September-28 September 2010

The IG reported that on 28 September three seismic events from Reventador were recorded. Cloud cover prevented observations during the first event. During the second period of increased seismicity, observers noted that a steam plume with a small amount of ash rose 400-500 m above the crater and drifted N. The third episode was accompanied by a steam-and-ash plume that rose 2 km above the crater and drifted NW. Ash fell on Reventador.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


8 September-14 September 2010

The Washington VAAC reported that on 9 September an ash plume from Reventador at an altitude of 5.5 km (18,000 ft) a.s.l. was observed by a pilot.

Source: Washington Volcanic Ash Advisory Center (VAAC)


25 August-31 August 2010

The Washington VAAC reported that on 30 August an ash plume was observed near Reventador by a pilot. Ash was not seen in satellite imagery.

Source: Washington Volcanic Ash Advisory Center (VAAC)


26 May-1 June 2010

The IG reported a lahar on Reventador's E flank, detected for 90 minutes by the seismic network on 25 May. It destroyed a bridge over the Marker River, disrupting the route from Baeza to Lago Agrio.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


5 May-11 May 2010

The IG reported that during 5-9 May observations of Reventador were not possible because of weather. The Washington VAAC reported that on 7 May an ash plume seen by a pilot rose to an altitude of 5.2 km (17,000 ft) a.s.l. Cloud cover prevented satellite observations of the area. On 8 May the IG noted a small lahar inside the caldera.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


28 April-4 May 2010

The IG reported that on 29 April an explosion from Reventador produced a steam plume with low ash content. Meteorological clouds mostly prevented observations during 30 April-4 May.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


21 April-27 April 2010

The IG reported that on 20 April scientists conducting an overflight of Reventador saw steam-and-gas emissions. They also observed an explosion generate a pyroclastic flow that traveled 200 m down the S flank. Deposits from previous pyroclastic flows were seen on the same flank. Explosions generated steam-and-gas plumes with low ash content during 20-22 April. Weather clouds prevented views of the volcano in satellite imagery on 23 April, although a pilot reported that an ash plume rose to an altitude of 4.9 km (16,000 ft) a.s.l. On 26 April a steam-and-ash plume rose 500 m above the crater.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


7 April-13 April 2010

The IG reported that during 7-13 April observations of Reventador were not possible because of weather. The Washington VAAC reported that on 8 April an ash plume seen by pilots rose to altitudes of 4.6-6.7 km (15,000-22,000 ft) a.s.l. and drifted W. Cloud cover prevented satellite observations of the area. The VAAC also noted that seismicity was elevated.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


17 February-23 February 2010

The MODIS satellite detected a thermal anomaly over Reventador on 14 February. Based on information from the Guayaquil MWO, the Washington VAAC reported an ash emission on 18 February. Ash was not identified in satellite imagery. IG reported that seismic signals indicated an emission that day, but weather conditions prevented visual observations.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts Team; Washington Volcanic Ash Advisory Center (VAAC)


18 November-24 November 2009

Based on a pilot observation, the Washington VAAC reported that on 20 November an ash plume from Reventador rose to an altitude of 6.1 km (20,000 ft) a.s.l. A thermal anomaly was detected on satellite imagery.

Source: Washington Volcanic Ash Advisory Center (VAAC)


11 November-17 November 2009

Based on analyses of satellite imagery, the Washington VAAC reported that on 14 November ash plumes from Reventador drifted 10-20 km WNW and W. An intermittent thermal anomaly was also detected.

Source: Washington Volcanic Ash Advisory Center (VAAC)


4 November-10 November 2009

Based on a pilot observation, the Washington VAAC reported that on 5 November an ash plume from Reventador rose to an altitude of 7 km (23,000 ft) a.s.l. and drifted NE. Ash was not seen in satellite imagery, although meteorological clouds were present. IG reported that an ash plume rose 500 m above the crater on 7 November.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


21 October-27 October 2009

The IG reported that on 21 October, steam-and-gas plumes from Reventador with little to no ash content rose 2-4 km above the crater and drifted NW, W, and S. An explosion that day ejected incandescent material from the crater; blocks rolled down the flanks. On 22 October, a few explosions generated ash-and-steam plumes with little to no ash content that rose 4 km and drifted NW, E, and SE. Observations during an overflight revealed a small lava flow on the N flank and a larger flow with four branches on the S flank. Some of the base of the lava dome had been removed, and small spines were present, especially on the S side of the dome. Thermal images revealed that material in the crater was 400 degrees Celsius and the lava-flow fronts were 250 degrees Celsius. Cloudy weather prevented visual observations during 23-26 October. Roaring noises were heard on 25 October.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


14 October-20 October 2009

The IG reported that field observations of Reventador on 16 and 17 September confirmed the presence of a lava flow on the S flank of the cone. Gas and steam emissions were noted, as was growth of the lava dome. Thermal anomalies over the crater area were detected in satellite imagery on 6, 11, and 13 October. On 14 October, seismicity increased and harmonic tremor was detected. A seismic station on the NE flank of the cone detected rockfalls. Several people living in the area reported roaring noises and observed slight incandescence from the crater during the previous few nights.

During an overflight on 16 October, scientists saw the lava dome and a lava flow on the N flank. Bluish gases were emitted. According to a thermal camera, the incandescent parts in the crater were about 300 degrees Celsius. Other observers heard roaring noises and sounds resembling "cannon shots." Incandescent blocks were ejected from the crater, and steam and gases rose 100 m and drifted SW. Incandescent material was seen on the S flank. On 17 October, incandescence on the S flank was seen and noises similar the previous day were again heard. A small gray plume was seen the next day. On 19 October, thermal anomalies were again detected on satellite imagery. During an overflight, blue gas plumes were seen. The lava flow on the S flank occupied a large area and was divided into two branches.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


30 September-6 October 2009

Based on information from IG, the Washington VAAC reported that on 4 October an ash plume from Reventador drifted W. Ash was not seen in satellite imagery, although meteorological clouds were present. An occasional thermal anomaly was seen, however.

Source: Washington Volcanic Ash Advisory Center (VAAC)


16 September-22 September 2009

Based on a pilot observation, the Washington VAAC reported that on 21 September a plume from Reventador rose to an altitude of 7.6 km (25,000 ft) a.s.l. Ash was not seen in satellite imagery, although meteorological clouds were present.

Source: Washington Volcanic Ash Advisory Center (VAAC)


12 August-18 August 2009

The IG reported that seismic tremor from Reventador was sporadically detected during 21 July-3 August. On 4 August, seismicity increased and periods of tremor frequently saturated the seismic stations. Thermal anomalies detected in satellite imagery on 1 and 2 August became more intense on 4, 5, and 10 August. On 6 August, a steam plume rose 1.2 km above the crater and drifted W. Incandescent blocks were ejected from the crater and fell onto the flanks. Thermal images taken from a location 7 km E of Reventador revealed a linear area of higher temperatures, confirming the presence of a new lava flow on the S flank. Incandescence in the crater was seen during observations on 9 August. According to the Washington VAAC, IG reported that an ash plume rose to an altitude of 3.6 km (11,700 ft) a.s.l. and drifted NW on 15 August.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


20 May-26 May 2009

Based on a pilot observation and a SIGMET notice, the Washington VAAC reported that on 26 May a diffuse ash plume from Reventador rose to an altitude of 6.4 km (21,000 ft) a.s.l. and drifted SW. Thermal anomalies were intermittently seen on satellite imagery. Gas plumes with some possible ash were noted later that day.

Source: Washington Volcanic Ash Advisory Center (VAAC)


13 May-19 May 2009

The Washington VAAC reported that, although ash from Reventador was observed by IG on 15 May, an ash signature or a thermal anomaly was not detected in satellite imagery.

Source: Washington Volcanic Ash Advisory Center (VAAC)


29 April-5 May 2009

Based on analysis of satellite imagery, the Washington VAAC reported that on 1 May a thermal anomaly over Reventador was noted along with a possible low-level plume drifting W. The IG reported to the VAAC lava and gas emissions, and possible smoke from burning vegetation, but little to no ash.

Source: Washington Volcanic Ash Advisory Center (VAAC)


22 April-28 April 2009

The IG reported that seismicity from Reventador decreased to low levels on 26 March, after the seismic network had detected an earthquake swarm the same day. On 23 April, increased seismicity was characterized by long-period events interspersed with bands of spasmodic and harmonic tremor. Observers reported that steam plumes with low ash content rose to altitudes of 5.6-6.6 km (18,400-21,700 ft) a.s.l. and drifted W. Intense noises from the volcano were also reported. A thermal anomaly and a steam plume drifting 26 km WSW were detected on satellite imagery.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


25 March-31 March 2009

The IG reported that seismicity from Reventador increased during 25-26 March. On 26 March, the seismic network detected an earthquake swarm consisting of long-period and hybrid events, interspersed with bands of harmonic tremor. Observers reported steam emissions with low ash content.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


19 November-25 November 2008

Inclement weather prevented observations of Reventador during 19-23 November. A seismic station situated on the NE flank of the central cone recorded a high number of rockfall signals that presumably originated from the active lava-flow fronts.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


12 November-18 November 2008

The IG reported that slight incandescence from Reventador's crater was seen at night during 11-12 November. Inclement weather prevented observations during 13-16 November. On 17 and 18 November, a seismic station situated on the NE flank of the central cone recorded a high number of rockfall signals that presumably originated from the active lava-flow fronts. Steam emissions rose from the crater.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


5 November-11 November 2008

The IG reported that SOTE (Sistema de Oleoducto Transecuatoriano) personnel and residents near Reventador observed incandescence in the crater on 7 November. The reports were confirmed by the presence of thermal anomalies in satellite imagery. The next day, seismicity increased and a steam-and-ash plume rose to an approximate altitude of 5.6 km (18,400 ft) a.s.l. and drifted SW. Incandescent blocks were ejected from the inner crater to the S. Residents in El Chaco (about 35 km SE) and in the Quijos area heard strong explosions and saw steam plumes with low ash content. A pilot reported that a steam plume with little ash content at an altitude of 7.6 km (25,000 ft) a.s.l. drifted NW. On 9 November incandescent blocks were ejected 100 m into the air, and roaring and "cannon shot" sounds were reported. Strombolian activity and two lava flows that descended the N and S flanks of the central cone were observed using a permanent camera. Slight ashfall was noted in Cayambe, about 55 km WNW. A thermal anomaly was detected by satellite imagery on 9 and 10 November. On 10 November, seismicity considerably decreased and gas emissions continued. The lava flows continued to advance.

According to a news article, officials suspended flights into Quito airport due to ash plumes on 10 November for three hours as a preventative measure.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC); Associated Press


6 August-12 August 2008

The IG reported that steam-and-gas from Reventador was emitted during 6-8 August. Incandescence from the crater was observed at night on 8 August.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


30 July-5 August 2008

The IG reported that seismicity from Reventador decreased during 30-31 July. On 31 July, steam-and-gas plumes with a low ash content were detected on satellite imagery and drifted W and SW. On 1 August, steam-and-gas plumes were emitted and a lava flow in the caldera was active. Diffuse ash emissions were noted on 2 August. On 3 August, IG scientists observed the lava flow in the caldera and estimated that it advanced at a rate of 100 m per day. They also heard sporadic roaring noises. Gas-and-steam plumes were noted on 5 August.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


23 July-29 July 2008

The IG reported that the number of earthquakes per day from Reventador increased during July and were the greatest on 24 and 25 July. At 1500 on 27 July, continuous seismic tremor was registered and was followed by observations of incandescence around the crater. Thermal anomalies were also identified on satellite imagery. At 1900 explosions produced ash plumes and ejected incandescent material that fell onto and rolled down the flanks. On 28 July, ash plumes drifted NW and W. Ashfall was reported in Olmedo, about 50 km NW. Later that day, ash plumes rose to altitudes of 4-6 km (13,100-19,700 ft) a.s.l. and drifted NW. On 29 July, steam plumes rose from the crater and drifted NW. A sulfur smell was reported at areas around the volcano. A lava flow traveled S.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


10 October-16 October 2007

Based on information from the Guayaquil MWO, the Washington VAAC reported that an eruption from Reventador on 11 October produced an ash plume that rose to an altitude of 4.6 km (15,000 ft) a.s.l. and drifted S. Ash was not observed on satellite imagery due to cloud cover.

Source: Washington Volcanic Ash Advisory Center (VAAC)


20 June-26 June 2007

Based on seismic interpretation, IG reported that lahars occurred on the flanks of Reventador on 20, 21, and 23 June. Clouds inhibited visual observations during 20-24 June.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


13 June-19 June 2007

Based on seismic interpretation, IG reported that lahars occurred on the flanks of Reventador on 15 and 19 June. According to the Washington VAAC, the IG reported that activity on 18 June possibly produced ash plumes that drifted NW. Ash was not visible on satellite imagery.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


23 May-29 May 2007

Based on information from IG, the Washington VAAC reported that an ash plume from Reventador rose to an altitude of 3.7 km (12,000 ft) a.s.l. on 18 May and drifted NW. Ash was not observed on satellite imagery.

Source: Washington Volcanic Ash Advisory Center (VAAC)


16 May-22 May 2007

On 16 May, IG reported that a steam plume from Reventador rose to an altitude of 3.6 km (11,900 ft) a.s.l. and drifted to the NW. The plume was visible on satellite imagery. On 18 May, strong rains resulted in a lahar that lasted approximately 40 minutes. A lahar was also noted on 22 May. Visual observations were hindered during most of the reporting period due to inclement weather.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


25 April-1 May 2007

On 27 April, a steam plume from Reventador rose to an altitude of 3.7 km (12,000 ft) a.s.l. Later that night, incandescent material was ejected from the crater. On 30 April, a steam plume was observed on satellite imagery drifting NW. Based on the Guayaquil MWO and satellite imagery, the Washington VAAC reported that an ash plume rose to an altitude of 3.7 km (12,000 ft) and drifted NW. Visual observations were hindered during 25 April-1 May due to inclement weather.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


18 April-24 April 2007

On 18, 20, and 23 April, steam-and-gas emissions from Reventador hung near the summit. On 18 April, a plume was seen drifting NW on satellite imagery. On 20 April, a bluish haze of gases was observed. Clouds occasionally inhibited views of the summit during 18-24 April.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


11 April-17 April 2007

On 11 April, a steam plume from Reventador rose to an altitude of 3.8 km (12,500 ft) a.s.l. Visual observations were hindered during 12-17 April due to inclement weather. On 13 April, the lava flow on the S flank, first observed on 28 March, was 15 m thick and possibly active.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


4 April-10 April 2007

Incandescent blocks ejected from the summit of Reventador that subsequently rolled down the S flanks were observed at night during 3-4 April. Satellite imagery revealed ash plumes drifting W and a large thermal anomaly over the crater. On 4 April, a plume rose to an altitude of 4.6 km (15,100 ft) a.s.l. Crater incandescence was observed on 4 and 6 April and "cannon shots" were heard on 6 April. Ash-and-steam emissions were observed during 8-9 April. Steam emissions from the flanks on 8 April possibly originated from a lava flow.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


28 March-3 April 2007

On 28 March, observers reported roaring noises and an ash column from Reventador that rose to an altitude of 5.6 km (18,400 ft) a.s.l. and drifted W. A small lava flow traveled 200 m down the S flank. Incandescent material and ash emissions were observed during 29-31 March. On 1 April, ash plumes rose to an altitude of 7.6 km (24,900 ft) a.s.l. and incandescent rocks were ejected about 50 m above the crater. Incandescent material was again seen at the summit on 2 April. The Washington VAAC reported that a strong hotspot was present on satellite imagery during 1-3 April. Based on pilot reports, IG reported that a steam-and-gas plume with little ash content rose to an altitude of 6.1 km (20,000 ft) a.s.l. and drifted W on 3 April.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


21 March-27 March 2007

IG reported that during early March, the number of tectonic earthquakes from Reventador increased. Steam-and-ash plumes were sporadically visible and rose to altitudes of 4 km (13,000 ft) a.s.l. occasionally during 8-22 March. On 21 March, noises were reported. The next day, seismic signals changed and indicated possible emissions. On 24 March, local people saw ash plumes and incandescent material near the crater and heard roaring noises. An explosion produced a plume that rose to an altitude of 6.6 km (21,700 ft) a.s.l. and drifted W. Based on reports from IG, the Washington VAAC reported an ash plume to altitudes of 3.7-7 km (12,000-23,000 ft) a.s.l. that drifted NE and WNW during 26-27 March. A thermal anomaly was present on satellite imagery during 24-27 March.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


28 December-3 January 2006

IG reported that during 19-25 December, seismicity was at low levels at Reventador and several small explosions occurred. According to the Washington VAAC, satellite imagery showed an ash plume at a height around 7.6 km (25,000 ft) a.s.l. extending NW on 29 December.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


16 November-22 November 2005

During 7-13 November, the number of earthquakes at Reventador increased slightly in comparison to the previous week. Small explosions produced ash plumes that rose to a height of ~4.6 km (15,000 ft) a.s.l.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


9 November-15 November 2005

During 31 October to 6 November, seismicity was at low levels at Reventador and several small explosions occurred. Based on information from IG, the Washington VAAC reported that ash from an explosion on 12 November rose to a height of ~3.7 km (12,000 ft) a.s.l.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


28 September-4 October 2005

During 19-25 September, several small explosions occurred at Reventador. An explosion on 20 September produced an ash plume to a height of ~5.8 m (19,000 ft) a.s.l. Small amounts of ash fell in the towns of El Chaco, San Francisco de Borja, and Baeza. During the report week, there was a reduction in the number of earthquakes at the volcano.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


21 September-27 September 2005

During 21-27 September, there were intermittent emissions of ash from Reventador, with the highest rising plumes reaching ~8.5 km (28,000 ft) a.s.l. on 24 September. Hot spots were occasionally visible on satellite imagery during the report week.

Source: Washington Volcanic Ash Advisory Center (VAAC)


14 September-20 September 2005

On 1 and 2 September, lahars traveled down Reventador's flanks. During 5-11 September, there was a substantial decrease in seismicity at Reventador, except for tremor, in comparison to the previous week. Pilots reported ash clouds on 13 and 15 September at a height of ~7 km (23,000 ft) a.s.l. No ash was visible on satellite imagery.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


31 August-6 September 2005

During 22-28 August, there was a decrease in activity at Reventador in comparison to the previous week. Seismicity and gas emissions decreased at the volcano, and no surficial changes were observed. On 1 September a pilot reported an ash cloud to the Washington VAAC, but no ash was visible on satellite imagery.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


17 August-23 August 2005

Volcanic activity continued at Reventador during 18-21 August, with ash plumes rising to a maximum height of ~5.8 km (19,000 ft) a.s.l. on 18 August. A hotspot was occasionally visible on satellite imagery during the report period.

Source: Washington Volcanic Ash Advisory Center (VAAC)


10 August-16 August 2005

A pilot observed ash from Reventador on 11 August at 1150 at heights between 3.7 km and 6.4 km (12,000 and 21,000 ft.) a.s.l. IG reported that on 13 August a narrow plume of ash was visible drifting W.

Source: Washington Volcanic Ash Advisory Center (VAAC)


3 August-9 August 2005

Based on information from IG, the Washington VAAC reported a possible ash cloud over the volcano at 1818 on 4 August. No ash was detected in satellite imagery through 1815 due to cloud cover.

Sources: Washington Volcanic Ash Advisory Center (VAAC); Instituto Geofísico-Escuela Politécnica Nacional (IG)


27 July-2 August 2005

Ash emissions occurred at Reventador during 27 July to 2 August, with plumes rising to 5.2 km (~17,000 ft) a.s.l.

Source: Washington Volcanic Ash Advisory Center (VAAC)


20 July-26 July 2005

During 7-17 July, scientists noted that a lava flow (lava number 5) was no longer flowing in a direction that threatened a highway or pipe lines. In addition, plumes of steam, gas, and ash rose to heights of 0.5-2 km above the crater (13,300-18,200 ft a.s.l.) and typically drifted NW.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


13 July-19 July 2005

Based on information from IG, the Washington VAAC reported that an ash eruption at Reventador on 18 July at 1115 produced a plume to ~3.7 km (~12,100 ft) a.s.l. Ash was not visible on satellite imagery.

Source: Washington Volcanic Ash Advisory Center (VAAC)


6 July-12 July 2005

As of 6 July, harmonic tremor, occasional explosions, and long-period and volcano-tectonic earthquakes continued at Reventador. Strong Strombolian fountaining was observed during the evening and one of the lobes of a lava flow (Lava number 5) was advancing down the caldera wall following the Río Marker. The flow abruptly slowed to ~20 m/day in comparison to flow-front velocities of ~70 m/day during 19-23 June, and ~50 m/day during 23-30 June. Lava number 5 was ~1.2 km from a steep incline, where it could begin to rapidly descend to the alluvial fan where the highway and petroleum pipeline are located.

Based on information from IG, the Washington VAAC reported that an ash plume extended N of the volcano's summit on 11 July. No ash was visible on satellite imagery.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


29 June-5 July 2005

During 30 June to 5 July, gas-and-ash emissions continued at Reventador. Plumes rose to a maximum height of 7 km (23,000 ft) a.s.l.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


22 June-28 June 2005

On 24 June the Geophysical Institute observed ash over the volcano moving NW. No ash or hot spot activity was visible in satellite data, but detection may have been hindered by low-level weather clouds.

Sources: Washington Volcanic Ash Advisory Center (VAAC); Instituto Geofísico-Escuela Politécnica Nacional (IG)


15 June-21 June 2005

According to IG, during 11-12 June lobes of a lava flow traveled down Reventador's S and SE flanks. A lava flow that was traveling SE earlier in June had ceased to move. Plumes of gas-and-ash rose 1-2 km above the volcano's crater and typically drifted NW. The Washington VAAC reported that low-level gas-and-ash emissions continued during 15-21 June.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


8 June-14 June 2005

During the last week of May, there was an increase in the number of long-period earthquakes at Reventador associated with a new lava flow. A lava flow emitted previously continued to travel SE towards the Marquer and Montana rivers. During 2-3 June, incandescence was visible in the crater. On 6 June ash-and-gas plumes were emitted from the volcano.

Source: Washington Volcanic Ash Advisory Center (VAAC)


18 May-24 May 2005

Based on information from IG, the Washington VAAC reported that an eruption at Reventador on 19 May around 0900 produced a NW-drifting ash plume to 3.7-4.9 km (12,000-16,000 ft) a.s.l. Ash was not visible on satellite imagery due to meteorological clouds near the volcano.

Source: Washington Volcanic Ash Advisory Center (VAAC)


20 April-26 April 2005

Based on a pilot report to the Guayaquil MWO, the Washington VAAC reported that ash from Reventador was seen on 25 April around 0826 at a height of ~7.9 km (~26,000 ft) a.s.l. drifting S. Ash was not visible on satellite imagery.

Source: Washington Volcanic Ash Advisory Center (VAAC)


6 April-12 April 2005

A change in seismic behavior was noted at Reventador during 1-8 April that was marked by episodes of tremor. About 45 tremor episodes occurred regularly during the week. During the evening of 6 April, incandescence was visible at the volcano. Based on information from IG, the Washington VAAC reported that ash from Reventador was visible on 8 April around 1430 at a height of ~4.6 km (15,000 ft a.s.l.). Ash was not visible on satellite imagery.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


12 January-18 January 2005

On 14 January at 0700, the Washington VAAC reported that an ash plume was observed at Reventador. The plume rose to a height of ~4.5 km a.s.l. On 16 January at 0430, satellite imagery indicated a brief emission of steam and very light ash that rose to ~6 km a.s.l. and moved E.

Source: Washington Volcanic Ash Advisory Center (VAAC)


6 January-12 January 2005

On 4 June, a hotspot and a steam-and-gas plume extending NW of Reventador were visible on satellite imagery. The plume was below 6.1 km (20,000 ft) a.s.l.

Source: Washington Volcanic Ash Advisory Center (VAAC)


22 December-28 December 2004

During 19-26 December, seismic signals at Reventador revealed that lava emission that began in early November continued. Seismic signals also suggested that mudflows occurred on 17 and 19 December.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


15 December-21 December 2004

On 16 December, a block lava flow from Reventador extended more than 1.5 km from the 2002 crater through a breach in the S portion of the crater wall. The flow front was ~600 m below the central vent and extended to the ESE. Lava extrusion from a vent in the crater likely began in early November, accompanied by a dramatic increase in volcano-tectonic earthquakes.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


1 December-7 December 2004

According to the Washington VAAC, satellite imagery on 2 December showed an ash plume from Reventador at a height of ~5 km extending W of the volcano. Also, IG reported to the VAAC that ash was seen drifting NW on 4 December. A hot spot was visible on infrared satellite imagery. On 4 December, Strombolian activity was seen in Reventador's crater. Since 9 November, volcanic material continued to gradually fill the crater and generate a lava flow down one flank. Activity was accompanied by a gas column that reached a maximum height of 3 km.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


19 May-25 May 2004

Strong rain on 15 May caused several lahars to travel down Reventador's flanks. They persisted through 16 May.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


12 May-18 May 2004

During 3-9 May, the level of seismicity at Reventador did not change significantly. During 7-8 May, lahars traveled down Reventador's flanks, disrupting travel on the Chaco-Lumbaquí road for about a day.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


25 February-2 March 2004

During 16-22 February, the average number of long-period earthquakes (4.1) and volcano-tectonic earthquakes (17) at Reventador nearly doubled in comparison to the previous week. Satellite imagery on 21 February showed a plume from Reventador drifting NNE.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


5 November-11 November 2003

Many unconsolidated deposits remain on Reventador's flanks following its sudden eruption on 3 November 2002, and strong rain fell there during 7 and 9 November 2003. During those days seismometers recorded signals interpreted as lahars. In addition, after these signals diminished, the seismometers detected the more subtle signals of tremor. Multiple volcanic earthquakes per day also occurred.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


15 October-21 October 2003

During 13-19 October at Reventador, 77 volcano-tectonic and 17 long-period earthquakes were recorded, averaging eleven and two earthquakes per day, respectively. Lahars were reported on 13, 14, and 19 October. The lahar on 13 October was the largest of the week, lasting ~75 minutes.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


16 July-22 July 2003

Rainfall at Reventador during 7-13 July remobilized ash on the volcano's flanks, causing lahars down Montana River. Travel on the Baeza highway was interrupted. Permanent tremor associated with degassing was recorded.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


7 May-13 May 2003

Heavy rainfall (200 mm in less than 24 hours) at Reventador on 6 May led to the remobilization of ash that was deposited on the volcano's flanks during the November 2002 eruption. Lahars traveled down the volcano's SE flank via Marker and Reventador gorges. According to IG, seismic signals indicated that lahars occurred in seven main pulses, with the longest pulse lasting ~2 hours. Lahars crushed a portion of the sole petroleum pipeline in Ecuador, located on the volcano's SE flank, and dragged it 22 m. According to news reports, about 5,600 barrels of crude oil escaped the damaged pipeline and entered Reventador River. News reports also stated that a large area of the Amazon jungle was polluted. Lahars also destroyed a bridge and blocked a highway that crosses the Amazon.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); IRIB News; El Comercio; Reuters


5 March-11 March 2003

During 1-7 March, lahars continued to travel down Reventador's flanks as they had for several weeks. On 2 March lahars descended Marker Gorge, disrupting travel in the area. On the 3rd lahars traveled down Marker and Reventador gorges. Flooding occurred on the 4th. During the report period, seismicity and gas emissions remained at low levels, and there was no indication of increased volcanism.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


26 February-4 March 2003

Heavy rain fall at Reventador caused lahars to flow down Márker gorge on 23 February, affecting travel in the area. On the 24th, lahars traveled mainly down Márker and Reventador gorges. On the 28th, rain caused small lahars in Márker, Reventador, and Montana gorges. During 22-28 February, seismicity remained at low levels, only small amounts of steam were emitted from the volcano, and there was no indication of increased volcanism.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


19 February-25 February 2003

During 20-21 February, heavy rain mixed with fine volcanic material on Reventador's flanks, generating mudflows that traveled down the Montana River. The mud flows obstructed travel on a highway. During 15-21 February, seismic activity remained at low levels and there was no indication of increased volcanism. IG stated that since the rainy season is beginning near Reventador, residents must be aware of the danger of possible mudflows.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


8 January-14 January 2003

During 10-14 January, volcanic and seismic activity were relatively low at Reventador. On the 10th several lahars traveled down the Marquer and Reventador rivers. Lava flows continued to slowly advance and steam plumes were seen rising above the volcano.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


18 December-24 December 2002

During 18-23 December, volcanic and seismic activity were low at Reventador. Seismicity was characterized by low-frequency tremor. No new activity was recorded at the volcano.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


11 December-17 December 2002

During 12-15 December, volcanic and seismic activity was low at Reventador; however, weather clouds thwarted visual observations.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


4 December-10 December 2002

Low-level seismicity continued at Reventador through 8 December. White emission columns were observed on the afternoon of 3 December, but meteorological clouds prevented observations during most of the week. White steam-and-gas emissions were seen again on 7 December rising about 500 m above the summit. There were no reports of lahars.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


27 November-3 December 2002

During 26 November- 1 December, Reventador mainly emitted gas and steam and occasionally small amounts of ash, and seismicity was low. IG stressed to the public that the sulfuric odor in the city of Quito was not indicative of renewed volcanism. During a flight over the volcano on 27 November, IG scientists determined that reports of a second lava flow made the previous week were false; rather, a pyroclastic flow had descended the volcano's NE flank. They also confirmed that a lava flow on the volcano's E flank had been emitted from a small crater that opened ~600 m below the volcano's summit. They believe it began to flow on 24 November and was accompanied by the emission of ash and incandescent rocks. On 2 December incandescence was visible on the E flank of the cone, which was thought to be from a new pulse of lava emitted from the 24 November flow the night of 1 December. On 2 December mudflows traveled down the Montana River, causing problems at a highway.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


20 November-26 November 2002

IG reported that during 20-25 November seismicity decreased at Reventador in comparison to the previous week and mostly gas-and-steam emissions occurred with little ash content. On 20 and 21 November 16 earthquakes were recorded each day, whereas about 150 earthquakes were recorded on each of the previous days. At this time gas-and-steam plumes reached to 2 km above the volcano and incandescence was sometimes visible within the crater. Lahars traveled down the volcano's flanks into Montana and Marker gorges. There were many reports of a strong scent of sulfur in the city of Quito, caused by the large amount of SO2 being emitted from Reventador (15,000-29,000 tons of SO2 measured by satellite on the 21st). Eruptions on 24 and 25 November produced ash-and-gas clouds that rose ~1 km above the volcano.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


13 November-19 November 2002

During 12-16 November, seismic and volcanic activity continued at Reventador. Constant tremor, and hybrid and volcanotectonic earthquakes were recorded. On 12 November a column of steam and ash was seen rising 6-7 km above the volcano and drifting to the W. There was only a moderate amount of ash in the cloud, therefore there was not much ashfall. Mudflows traveled down Reventador's flanks and during several evenings incandescence was visible on the NE flank. During a flight over the volcano on the 18th, a lava flow was seen on the crater's S wall advancing slowly. Also, pyroclastic-flow deposits were seen that IG warned may be remobilized during heavy rain, becoming dangerous mud flows.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC)


6 November-12 November 2002

Volcanic activity decreased following the large eruption at Reventador on 3 November, but small-to-moderate eruptions continued during 5-12 November. IG reported that on the 5th, explosions produced SW-drifting ash-and-gas clouds to heights between 3 and 6 km. Ash fell in the town of Chaco. On the 7th an eruption sent an ash-and-gas cloud to 7 km that drifted W. Rain during the evening of the 9th caused mudflows to travel down the volcano's flanks, closing the Chaco-Reventador highway. According to the Washington VAAC, the maximum height reached by ash clouds during the report period was ~10 km a.s.l. On 10 November the Quito airport was reopened, after being closed for a week. Ash from previous eruptions descended on Quito on 11 November, causing officials to close schools and warn residents to protect themselves from inhaling ash.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); Washington Volcanic Ash Advisory Center (VAAC); Associated Press; Reuters; Reuters


30 October-5 November 2002

After 26 years with no explosive activity, a large eruption began at Reventador on 3 November that sent pyroclastic flows down the volcano's flanks. Based on seismic data and observations made by people near Reventador, IG reported that the first pyroclastic flows produced from the eruption occurred on the 3rd around 0900. Then, during 1000-1900 continuous tremor was recorded that may have been associated with continuous ash emissions and small explosions. Between 2000 on the 3rd and 0100 on the 4th, there was an increase in the amount and intensity of the tremor. After 0100 the activity level decreased, but a pulse of activity occurred between 0200 and 0300. A new cycle of activity began during 0700-0800. Small-to-moderate explosions occurred during the day and small pyroclastic flows descended the volcano's flanks. On the morning of the 5th explosive sounds were not heard, no ash fell in towns near the volcano, and meteorological clouds obscured Reventador. In addition, seismicity was low, but some small earthquakes and low-amplitude volcanic tremor occurred.

According to the Washington VAAC, the first eruption on 3 November produced an ash cloud that reached a height of ~16.8 km a.s.l. Subsequent explosions generated more ash clouds and satellite imagery showed discrete ash clouds on the 5th; a thin area of ash at ~16.8 km a.s.l. was located over S Colombia and N Brazil moving E, and a thicker ash cloud drifted W over the Pacific Ocean towards the Galapagos Islands at a height of ~10.7 km. In addition, a nearly stationary area of ash was observed over the Pacific Ocean off the coast of Ecuador at a height of ~9.1 km a.s.l.

According to OCHA, pyroclastic flows on the 3rd reached the Baeza-Lumbaqui highway, blocking inter-city traffic. Ash fell in the towns of Baeza, Cayambe, Yaruqui, El Quinche, Tumbaco, Pifo, Sangoqui, and Quito, Ecuador's capital ~70 km W of Reventador. Quito was paralyzed by ash fall; schools and businesses were closed, residents were told to remain indoors, and all operations at the Mariscal Sucre airport in Quito were suspended. The approximately 3,000 people living in towns at the base of the volcano were evacuated and no deaths or injuries were attributed to volcanic activity.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG); UN Office for the Coordination of Humanitarian Affairs (OCHA); Washington Volcanic Ash Advisory Center (VAAC); El Universo; El Comercio


Index of Bulletin Reports


Reports are organized chronologically and indexed below by Month/Year (Publication Volume:Number), and include a one-line summary. Click on the index link or scroll down to read the reports.

01/1974 (CSLP 09-74) Mid-December 1973 eruption from cone in SW corner of caldera

03/1974 (CSLP 09-74) Explosive activity every 20-30 minutes in late February

01/1976 (NSEB 01:04) Explosive eruption begins on 4 January; lava flows enter the jungle

09/1990 (BGVN 15:09) Low-temperature fumarolic activity

11/2002 (BGVN 27:11) Strong, sudden 3 November eruption; 8-km-long pyroclastic flow

02/2003 (BGVN 28:02) Ashfall in January, mudflows in February-March; additional data from November

06/2003 (BGVN 28:06) Lahars, mudflows, and steam emissions continue through mid-July

11/2003 (BGVN 28:11) Variable seismicity, degassing, and recurring lahars

11/2004 (BGVN 29:11) Late 2004 visits find renewed venting and thick intracaldera lava flows 2 km long

05/2005 (BGVN 30:05) Lava flow reaches 4 km from summit, approaching road and petroleum pipeline

08/2005 (BGVN 30:08) Generally, activity shifting from effusive towards explosive

03/2008 (BGVN 33:03) Eruptive episode during March-May 2007, another ash plume in October

04/2008 (BGVN 33:04) Quiet, January 2006-February 2007; emissions, March-October 2007

08/2008 (BGVN 33:08) Eruptions, seismicity, and hot spots in late July and early August 2008

03/2009 (BGVN 34:03) Lava extrudes down two flanks during November 2008-April 2009

09/2009 (BGVN 34:09) Lava flows seen and SO2 fluxes recorded during 16-17 September 2009

03/2012 (BGVN 37:03) Dome growth; lava and pyroclastic flows; lahar takes bridge

06/2013 (BGVN 38:06) Lava dome's summit rises above rim in late 2012




Bulletin Reports

All information contained in these reports is preliminary and subject to change.


01/1974 (CSLP 09-74) Mid-December 1973 eruption from cone in SW corner of caldera

Card 1774 (11 January 1974) Mid-December 1973 eruption from cone in SW corner of caldera

Minard Hall reported the following by cable. "Visited Reventador on 15 December 1973 for one hour. Cone (1,000 feet high) in SW corner of caldera in eruption. Vapor plume, 1 km long, heads SW. Considerable noise from crater, no explosions, no material being ejected. Small lava lake in crater. Narrow lava flow 1.5 km long leaves lake, flows due E down cone and out onto plain. Flow began November 1973 and is in motion. It is a blocky flow of olivine-rich basaltic andesite. The flow is dark black in color, but grey on sides due to fresh exposure of new material by avalanching. Flow steadily heading E for main road, oil pip line, and Rio Coca. To N, extensive mud flow (3 km long, 1 km wide), grey in color, flowed NE. Black basalt flow of July 1972 lies immediately N of lahar, flowed NE from cone. N side of cone: grey and black blocky flows up to 5 km long. W side: grey blocky flows one-half km long abut against caldera wall. S side: same as W side. SE side: old overgrown flows, green in color. From border of caldera outward, dense green jungle. Area of recent activity, and not overgrown by jungle, approximately 4 km in diameter. Plan expedition for longer stay in February 1974."

Information Contacts: Minard Hall, Escuela Politécnica Nacional, Quito.

03/1974 (CSLP 09-74) Explosive activity every 20-30 minutes in late February

Card 1813 (12 March 1974) Explosive activity every 20-30 minutes in late February

The volcano El Reventador is a 1,500-m-high composite cone that is growing in the calder of the older El Reventador. After many years of only fumarolic activity, major flows of lava occurred in June-August 1972 that had a volume of approximately six million cubic meters. The volcano remained relatively inactive until November 1973 when a smaller flow left that crater and traveled on e and one-half kilometers to the southeast. Numerous laharic flows related to this activity have carried boulders up to five meters in length up to three kilometers from the cone.

Six days (23-28 February 1974) were recently spent on the volcano studyng the present activity. The blocky lava flow of November 1973 has backed off the flanks and remains still active halfway up the cone. The explosive nature of the volcano has increased dramatically. When visibility permitted, explosive activity was recorded every 20-30 minutes. It was accompanied by loud explosions that, at times, shook our campsite 3 km distant, by red flashes from the crater, by gray-brown eruption clouds that rose a kilometer above the crater, and by incandescent red ejecta (often blocks up to 5 m in diameter) that rolled down the sides of the cone. This explosive activity was not observed in December 1973 and marks an important change in the nature of the activity. Inaccessibility and poor weather condition preclude frequent monitoring of this volcano.

Information Contacts: Minard Hall, Escuela Politécnica Nacional, Quito.

01/1976 (NSEB 01:04) Explosive eruption begins on 4 January; lava flows enter the jungle

An explosive eruption began during the early morning of 4 January. At dawn an ash column 1 km high was observed. Fine ash was carried W and SW over the Andes, dusting Quito through 10 January. Bombs blown 100 m vertically from the crater were large enough to be seen by the naked eye from a distance of 3 km. Strange seismic signatures, detected 90 km away (at Quito) and attributed to Reventador, began at 0115 on 4 January and continued until 0900 on 9 January. A portable seismograph 10 km from the cone measured continuous harmonic tremor.

Two lava flows descended from the breached crater and divided into three lobes at the base of the cone. During the first 40 hours flows traveled approximately 1.5 km E at 37 m/hour. By 9 January the three lobes had traveled 2.5 km and were advancing approximately 5 m/hour over lahar deposits and jungle. As of 27 January the lava flows had stopped, but infrequent explosive activity, including nuées ardentes, was continuing. The continual ash column had terminated by 25 January. The flows were a black basaltic andesite with olivine, augite, hypersthene, and oxyhornblende.

Reventador had similar eruptions in July 1972 and November 1973. When last visited before the current eruption, on 10 December 1975, it was producing a large steam column.

Further Reference. Hall, M.L., 1980, El Reventador, Ecuador: un volcán activo de los Andes Septentrionales: Revista Politécnica, v. 5, no. 2, p. 123-136.

Information Contacts: M. Hall, Escuela Politécnica, Quito.
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09/1990 (BGVN 15:09) Low-temperature fumarolic activity

Abundant small fumaroles were observed 17-19 August, within the crater and in concentric cracks near the rim. These fumaroles emitted little gas and were fairly quiet. Fumarole temperatures, measured using infrared thermometry, reached 71.0°C (figure 1).

Figure 1. Sketch map of the crater of Reventador showing fumarole locations (solid circles), sizes, and temperatures, August 1990. Courtesy of Sean Hodges.

Information Contacts: S. Hodges, Univ of Oxford. The Oxford field team also included J. Bass, S. Crampton, J. Dinares, S. Hart, R. Hartley, C. Mandeville, M. More, K. Ogden, J. Scarrow, and A. Whittingham.
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11/2002 (BGVN 27:11) Strong, sudden 3 November eruption; 8-km-long pyroclastic flow

After a 26 year repose without signs of unusual activity, Reventador burst unexpectedly into a VEI 4 eruption on 3 November 2002. Seismometers, including some located 15 and 24 km away, only began to detect anomalous seismicity 4 hours prior to the eruption's visual confirmation. A preliminary evaluation implies that this was one of Ecuador's most powerful eruptions of the past 100 years.

A vertical aerial photograph of Reventador's edifice taken in 1983 (figure 2) has been annotated by Minard (Pete) Hall to show the age and distribution of lava flows. During the 2002 eruption onlookers took a series of photos; a side view captured at an early stage appears in figure 3.

Figure 2. Aerial photo of Reventador caldera taken in 1983. Top of photo lies to the N; the walls of the E-breached caldera are 3-4 km apart. The bottom image is the same photo with map overlays of lava flows and key features. Although cut off in this cropped figure, the caldera's W wall is intact. Courtesy of Instituto Geografico Militar de Quito and Instituto Geofisico, Escuela Politecnica Nacional, Quito, Ecuador (IG).

The following tentative chronology of the eruption is based upon IG seismic and NOAA data, as well as eyewitness accounts and photos. The chronology of the events on 3 November is detailed in table 1. At press time editors were unable to learn the latest details regarding timing but these will appear in a subsequent report.

Table 1. Chronology of events that took place at Reventador on 3 November 2002. Courtesy IG and NOAA.

    Time           Activity

    0300           Beginning of seismic swarm of 100 events, most of a
                     hybrid tendency characterized by frequencies of 1.8 to
                     4.2 Hz and seismic tremor of low frequency (0.7-1.0
                     Hz). Workers at base camp located 8 km from cone were
                     awakened by earthquakes.
    0530           At daylight workers reported a steam column 2-3 km high
                     above cone.
    0715           Pilots from TAME Airline reported ash plume in the
                     direction of Reventador.
    0715-0745      NOAA GOES images first show eruption cloud.
    0745           Witnesses reported increased intensity of eruptive
                     column, now reaching ~6 km above the cone and drifting
                     to the SW.
    0803           Photos show that eruption column had reached 7,300 m
                     above cone and suggest small pyroclastic flows.
                     Successive explosions and a constant roar were heard
                     at 8 km distance, but not at closest town at 15 km
                     distance.
    0815           GOES images show eruption cloud beginning to travel to
                     SW.
    0912           Main eruption begins. Column soon rises to 16-17 km
                     above cone.
    1415 and       Other important pulses of the eruption.
    1615-1715
    1300 approx.   Ash cloud reaches InterAndean Valley and Quito, ~100 km
                     from the volcano, causing almost total obscurity by
                     late afternoon. It left a layer up to 3-5 mm thick of
                     fine gray ash everywhere. Some closer towns received
                     up to 3 cm of ash. Most residents of the region
                     complained about the strong odor of both SO2 and H2S.
    2005           Another intensification of eruptive activity (which
                     continued until 0100 on 4 November).

On 6 October 2002 a M 4.1 seismic event occurred beneath the volcano, accompanied by nine smaller VT events; the tentative epicenter was slightly SW and W of the cone. Around 20 October a local guide with tourists reached the top of the cone and saw only normal fumarolic activity. No anomalous activity was detected by satellite monitoring during this period.

Table 1 summarizes seismic, visual, and satellite observations of the initial eruptions on 3 November that led to the main eruption's starting at 0912. In that energetic phase a column rose 16-17 km above the intracaldera cone. At least five significant pyroclastic flows (PFs) were produced. A photo sequence showed PFs descending SE along the southern caldera floor and obliquely overriding the 200-400-m-high southern caldera rim (figure 3).

Figure 3. A photo showing the young intracaldera cone and main eruption column (on right) of Reventador at 0912 (local time) on 3 November 2002. The view is looking SW from the town of Reventador, 14 km to the volcano's NE. The shot captured a pyroclastic flow traveling along the S side of the caldera floor and overtopping the caldera rim; a topographic boundary 200-400 m high. Note the expansive ash cloud above the pyroclastic flow. Photo taken by R. Saca; provided courtesy IG.

The longest PF traveled 8 km; it flowed out of the breached caldera and down steep slopes to reach the Quijos river. In doing so, it crossed important oil and gas pipelines, pushing them ~20 m downslope without inducing failure. It destroyed an oil pipeline still under construction, and carried away small bridges on the main dirt highway leading to the oilfields. The PF buried one small house and 20 head of cattle. No casualties were reported.

Two segments of the ash column took different paths. The segment of the column that rose up to 16 km high blew to the SW and WSW toward Quito and the populated InterAndean Valley, traveling at 30-45 km/hour. The ash cloud above 16 km moved E and reached southern Colombia and northwestern Brazil. J.L. LePennec (IRD) estimated that ~282 x 106 m3 of pyroclastic material was erupted.

This eruptive event largely destroyed the old summit crater in the intracaldera cone. It was left with two deep notches in its uppermost NNW and SSW sides. These notches apparently served as the source of both the PFs and lava flow number 1. An eyewitness observed rock ejection during this episode. The eruptive event that began at 0912 lasted ~45 minutes, but eyewitnesses indicated that most of the PF activity lasted only 10 minutes.

Throughout the day on 3 November seismic activity was pronounced and included seismic tremor (1-2 Hz), long-period (LP) events (1.5-1.7 Hz), a few volcano-tectonic (VT) events (2-4 Hz and 12-14 Hz), but mainly hybrid events (with initial phases at 2-8 Hz, followed by a main phase at 1-2 Hz).

On 4 November, during 1200-1300, explosions continued but with much less intensity. Ash and steam continued to rise. During the day, TOMS satellite measured up to 60,000 metric tons/day of SO2 (figure 4). In subsequent days, TOMS estimates remained around 5,000 to 20,000 metric tons/day through 21 November (figure 4).

Figure 4. Reventador's SO2 output based upon TOMS satellite data reflecting the interval 4-26 November 2002. Courtesy of Simon Carn and Arlin Krueger.

The next day, on 5 November, small explosions continued, but at 1300 a significant explosion may have generated PFs. Debris flows formed in the days following the PF emplacement mainly covered parts of the PF deposits and also reached the Quijos river, ~8 km from the crater.

During 6-7 November the volcano continued to emit ash, gases, and steam, but at reduced levels. Lava flow number 1 was presumed to have begun during this time, which was later confirmed by NOAA thermal images to have begun at 1900 on 7 November. The lava flow, several hundred meters wide, left the crater area and cone, and traveled SE down the caldera floor near the S caldera wall. An 8 November overflight by Jorge Anhalzer visually confirmed a 4-km-long lava flow, overriding the PF deposits and lahar plain. By 3 December it had traveled 5 km, but it was advancing at only ~1-3 m/day. Through late December observers confirmed that the lava flow continued to move.

During 8-21 November a short eruption column continued, but with increasingly more steam and gas relative to ash. No clear explosions were heard. Variable debris-flow activity occurred, depending upon the intensity of local rainfall. Sulfur gases were occassionally noted in the InterAndean Valley and in Quito.

On 21 November a second lava flow broke out on the lower SE foot of the cone at ~2,600 m elevation and descended to the ESE. By 3 December it had traveled 2 km and was accumulating against the side of the first lava flow.

From 21 November until 3 December there was no additional explosive or PF activity, the steam-rich plume rose to only 1-2 km, and the two lava flows continued moving at a rate of a few meters/day. Debris flows remained a threat to the workers repairing the pipelines and travelers along the main highway.

Setting and sketch map. Reventador stratovolcano is on the E flank of the Ecuadorian Andes in jungles of the western Amazon basin. It contains a 3-km-wide caldera with a young, unvegetated cone that rises ~1,300 m above the caldera floor. The caldera is breached to the E and frequent lahars in this region of heavy rainfall have constructed a debris plain on the E caldera floor. No population centers exist nearby; however, the principal oil and gas pipelines and an important highway cross the lower flanks of the volcano, precisely where most flows exited the caldera (figure 5).

Figure 5. Sketch map showing deposits resulting from the November 2002 eruption of Reventador. PF signifies pyroclastic-flow deposits; stippled area shows downed trees and burned vegetation caused by PF's. The map shows the lava flow's advance as of 25 November. Note the oil and gas pipeline near the terminal ends of the PFs. This map omits the debris-flow deposits, which largely covered the PF deposits. Courtesy M. Hall.

The young andesitic cone is within an older caldera (figures 2 and 5). The caldera's interior walls reach heights of 200-400 m, especially at its higher W end. Traces of an older somma rim lie concentrically outside the present W walls of the caldera. The caldera contains older lava flows and pyroclastic-flow and debris-flow deposits; the resulting caldera floor is higher in its W corner, slopes downward to the SE, and drains into the Quijos river.

The symmetrical composite cone of Reventador is presently at an elevation of ~3,500 m, 1,500 m above the lowest point at the SE end of the caldera. The slopes of the young cone average 34 degrees. The cone is slightly higher than the adjacent caldera rim, although a 1931 report stated that it was lower than the rim. Prior to this eruption the summit crater had a diameter of ~200 m and typically displayed mild fumarolic activity. Recent magmas are typically 56-58% SiO2 and carry olivine, two pyroxenes, and plagioclase.

Some 14 eruptions of sufficient magnitude to have been detected at appreciable distances occurred between 1541 and 1926 (Hall, 1977). The volcano was first visited in 1931, following its 1926-1929 eruption period. K.T. Goldschmid, a Shell Oil Company geologist, visited the volcano during its 1944 eruption. Eruptive activity occurred in 1960. Another cycle began in July 1972 and lasted until 1976, during which lava flows, small PFs, and debris flows were generated in four eruptive episodes; however, neither ashfalls nor strong sulfur gases were noted in the InterAndean Valley. A detailed listing of past eruptions is available from IG upon request.

Monitoring. Just months prior to the eruption, in April 2002, IG staff installed two new seismic stations (1 Hz, vertical, telemetered). With respect to the crater, the new stations sit 15 km ENE and at 24 km SW. They were operating during the November 2002 crisis (figure 6). After 3 November two similar stations were installed 7.5 km SE and 8 km E of the crater. Older stations important in monitoring the eruption include the two Cayambe stations, located ~40 km NW of Reventador, and Pino station on Guagua Pichincha, located about 100 km WSW. Most locatable earthquakes had shallow hypocenters beneath either the caldera's outer western flanks or under the young cone.

Figure 6. A histogram showing the daily number of all types of earthquakes registered at Reventador during November 2002. Courtesy Instituto Geofisico.

Daily numbers of seismic events detected in November are show graphically on figure 6. Prior to the current eruption, the volcano averaged ~7 events/day. During the eruption, the average stood at ~142 events/day, chiefly hybrid earthquakes that began with higher frequencies and after a few seconds dropped to lower frequencies.

The eruption's first day was associated with more than 188 events, while the 2nd thru 5th days had only 50-100 events. By 8 November, the number of events generally remained above 200/day, dropping on 17 November to under 150/day, and dropping still further by 20 November. This abrupt decline was possibly associated with the eventual breakout of the second lava flow on 21 November.

No deformation or chemical monitoring was being carried out on the volcano prior to this eruption. TOMS SO2 monitoring as well as thermal monitoring by satellite have been extremely important, given the remoteness and inaccessibility of Reventador. Flights by an UltraLight and light planes have resulted in some photographic coverage and thermal imaging with a FLIR camera.

Effects of the 2002 eruption. Widespread ashfall to the W and SW caused visibility problems, respiratory ailments, some roof collapses, an undisclosed number of deaths and injuries to people attempting to clean their roofs of ash, crop damages, cattle illnesses, closure of Quito's airport for eight days, and power outages in some areas for up to four days. Legally enforced cleaning of all public streets and sidewalks by broom-wielding residents limited the amount of ash entering sewer systems. Lower speed limits were put in place to reduce airborne ash kicked up by passing vehicles. Ecuador's principal crude oil pipeline, although not severed, remained threatened by daily debris flows. One approach to this problem may be to bury the pipeline where it traverses the volcano's vulnerable E slopes.

References. Belloni, L.C., 1989, Slope failures on the volcano "El Reventador" in eastern Ecuador (discussions on volcanic debris), in Proceedings of the Twelfth international conference on Soil mechanics and foundation engineering—Comptes rendus du douzieme congres international de Mechanique des sols et des travaux de foundations, no. 12, v. 5, p. 2851.

Hall, M.L., 1980, El Reventador, Ecuador; un volcan activo de los Andes Septentrionales (El Reventador, Ecuador; an active volcano in the northern Andes): Politecnica 5, p. 123-136.

Hall, M.L., 1979, Volcan Reventador, Ecuador.Volcano News, v. 1, p. 1-3.

Hoyt, D.V., 1978, An explosive volcanic eruption in the Southern Hemisphere in 1928. Nature (London). 275; 5681, Pages 630-632.

Salazar, M.E., 1983, Expedicion vulcanologica el Volcan Reventador (Volcanologic expedition to Reventador Volcano): Flysch, v. 4, p. 1-4.

Information Contacts: P. Ramon, M. Hall, P. Mothes, and H. Yepes, Instituto Geofísico (IG), Escuela Politécnica Nacional, Quito (URL: http://www.igepn.edu.ec/, Email: geofisico@accessinter.net); J.P. Eissen and Jean-Luc LePennec, French IRD (Institut de recherche pour le Développement) Representatives, Mission IRD-Whimper 442 y Corúa -Apartado Postal 17-12-857, Quito, Ecuador (Email: eissen@ird.fr; lepennec@ecnet.ec); Franz Böker, BGR (Bundesanstalt für Geowissenschaften und Rohstoffe), Alfred-Bentz-Haus, Stilleweg 2, D-30655 Hannover, Germany (Email: franz.boeker@bgr.de); George Stephens, Operational Significant Event Imagery (OSEI) team, World Weather Bldg., 5200 Auth Rd Rm 510 (E/SP 22), NOAA/NESDIS, Camp Springs, MD 20748USA (Email: osei@noaa.gov) ; Arlin Krueger and Simon A. Carn, Joint Center for Earth Systems Technology (NASA/UMBC), University of Maryland-Baltimore County, 1000 Hilltop Circle, Baltimore, MD (Email: scarn@umbc.edu; akrueger@umbc.edu).
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02/2003 (BGVN 28:02) Ashfall in January, mudflows in February-March; additional data from November

On 3 November 2002, an unexpected eruption occurred at Reventador (BGVN 27:11). The following report provides an update on recent activity and additional information about the November eruption, including discussion of a site visit after the eruption and satellite data.

Recent activity. Seismicity was low during mid-December 2002. On 10 January, Instituto Geofísico (IG) reported that several lahars occurred that day in the Marquer and Reventador rivers. Ashfall was reported in the N sector of Quito, ~90 km to the WSW. In the afternoon a bluish gas column was observed exiting the crater. IG personnel stated that lava was slowly advancing and that 80-90% of the 3 November 2002 pyroclastic-flow deposits were covered by lahars.

During late February, rain generated mudflows that ended near the Montana River and disrupted traffic on a highway. White steam exited the volcano. Seismicity remained low, and was characterized by bands of harmonic tremor and volcano-tectonic (VT) earthquakes.

Intense rains during the first few days of March caused mudflows and again disrupted traffic. A gas column reached 300-500 m above the summit. Low-level seismicity was characterized by bands of harmonic tremor and a few isolated earthquakes. The seismic station in Copete registered high-frequency signals associated with lahars.

Site visit during 17-19 November 2002. The following report of an investigation of the 3 November 2002 explosion (BGVN 27:11) was submitted by Claus Siebe (Instituto Geofísico (IG), UNAM). Siebe, Jesús Manuel Macías, and Aurelio Fernández were able to fly to Quito on 17 November. On 18 November they interviewed Ing. Marcelo Riaño (general manager of the Trans-Equatorian Oil-Pipeline) as well as Patricia Mothes, Minard Hall, and Hugo Yepes (IG).

On 19 November they arrived in El Chaco (~34 km from Reventador) and traveled to the confluences of the Ríos Marker and Montana with the Río Coca (both are located 8 km from the crater). A small apron of fresh lahar deposits ~300 m wide covered the area adjacent to the Río Marker where the road had been before the 3 November eruption. Several dozens of workers with heavy machinery were trying to make a temporary passage over the gravel and boulder surface for the waiting trucks. For a few minutes they could see for the first and only time a ~1-km-high brownish ash column rising from the crater before incoming clouds hindered further visual contact.

"At the time of our visit, the Río Marker was diminished to such an extent that we could jump from boulder to boulder from one side to the other of the stream without getting wet. The vegetation around the confluence of the rivers was completely destroyed, and surviving trees were scorched and defoliated. The base layer of the fresh deposits consisted of up to 2.5-m-thick, partly matrix-supported, partly clast-supported pyroclastic-flow deposit with abundant wood and charcoal fragments (abundant scoriaceous boulder- and gravel-sized clasts were subrounded while dense clasts were angular). This was overlain by a sequence of several sandy-gravelly lahar units with abundant charcoal supporting larger boulders as well as clasts from the underlying pyroclastic-flow deposit.

About 400 m from the Río Marker, after passing a narrow zone of unaffected vegetation, we were able to reach the Río Montana, where a similar situation was encountered (figure 7). Here, at places the lahar deposits were still steaming with a sulfurous smell. The bridge over the river was destroyed, but the oil pipeline was still basically intact (figure 8). Since the area did not seem safe (the last lahar had been emplaced less than 24 hours prior) the team returned to El Chaco, where they interviewed several people and obtained photographs of the pyroclastic flow and its deposits taken on 3 November 2002 (figures 9-11).

Figure 7. Fresh lahar deposits at Reventador near the confluence of Río Montana with Río Coca on 19 November 2002. According to workers trying to repair the road the still-warm and steaming surface of the lahar deposit shown in the photo was produced during the afternoon of 18 November after heavy rain. This was the 10th lahar event since 3 November. Courtesy of Claus Siebe.
Figure 8. Photo looking downstream near the confluence of Río Montana with Río Coca on the ESE flank of Reventador. In the foreground are the fresh lahar deposits. In the middle ground is the destroyed concrete bridge over the Río Montana as well as the oil-pipeline immediately behind. The bulldozer is trying to built a temporary passage for hundreds of trucks waiting on both sides of the road. In the background is the Río Coca with distal-debris avalanche deposit (19,000 Y BP) forming the vegetated hills behind the river. Photo taken on 19 November shortly after 1300 by Claus Siebe. Courtesy of Claus Siebe.
Figure 9. Pyroclastic flow descending Reventador's SE slopes during the morning of 3 November 2002. Photo was taken from the E (Transoceanic road in the foreground). This anonymous photo was purchased at a small hotel in El Chaco. Courtesy of Claus Siebe.
Figure 10. Fresh pyroclastic-flow deposits from Reventador, produced on 3 November 2002, ponding against the bridge over the Río Montana. This anonymous photo was purchased at a small hotel in El Chaco. Courtesy of Claus Siebe.
Figure 11. Distal pyroclastic-flow deposits from Reventador and scorched vegetation along the Transandean oil-pipeline near the confluence of the Río Montana with the Río Coca. This anonymous photo was purchased at a small hotel in El Chaco. Courtesy of Claus Siebe.

At about 2200 we drove to the summit of a hill (2,959 m elevation) N of Sta. Rosa, 27.5 km from the summit of Reventador. Although the night was clear and we had a good view, the summit was covered by clouds and no incandescence from an advancing lava flow could be seen.

From conversations with personnel from PETROECUADOR, road workers, peasants, etc., the team obtained the following information. Workers from TECHINT, an Argentinian company building a second pipeline parallel to the existing one, were at their campsite near the Río Montana when the eruption started in the early hours of 3 November (it was still dark). The eruption came without prior warning, but they were able to evacuate before strong explosions around 0900 sent pyroclastic flows along the Ríos Montana and Marker. These flows destroyed the road and parts of the new pipeline still under construction. The old pipeline was displaced several meters horizontally but never broke. At places the pyroclastic-flow deposits came to rest in direct contact with the tube. Temperature measurements at points of contact yielded values of 80°C. In subsequent days several lahars came down the Ríos Montana and Marker after heavy rains, further damaging the road (but not the pipeline). The pipeline has continued its operation; it delivers more than 400,000 barrels of oil per day to the Pacific coast.

Inhabitants of the small village of El Reventador, located ~12 km downstream from the confluence of the Ríos Montana and Coca voluntarily evacuated their homes when they heard the explosions around 0900.

One of the scoriaceous juvenile rock samples collected near the confluence of Río Marker with Río Coca was analyzed by X-ray fluorescence and thin sections were made of the same sample. The results revealed that the rock is an andesite (SiO2= 58.1%) similar in composition to those erupted in 1976 (55-58% SiO2).

Satellite data. Simon Carn (NASA/UMBC) reported that TOMS observations of the Reventador eruption clouds during 3-4 November suggest modest SO2 burdens and spatial separation of the emitted SO2 and ash. Carn, with input from Andy Harris, also constructed a timeline of notable events during 3-6 November along with potentially useful satellite images and overpasses (table 2).

Table 2. Preliminary timeline of the November 2002 eruption of Reventador, compiled using satellite imagery and information from IG and the Washington VAAC. Courtesy of Simon Carn and Andy Harris.

    Date         Time    Satellite       Event
                 (UTC)

    3 Nov 2002   0700                    Seismic events recorded
    3 Nov 2002   0945    GOES-8          Clear - no hot spot
    3 Nov 2002   1000                    Eruption begins; 3 km ash column,
                                           incandescent ejecta
    3 Nov 2002   1015,   GOES-8          Clear-no hot spot
                 1045,
                 1115
    3 Nov 2002   1245,   GOES-8          Ash
                 1315,
                 1345
    3 Nov 2002   1400                    Main eruption phase; pyroclastic
                                           flows reported
    3 Nov 2002   1415    GOES-8          Ash, ring-shaped cloud?
    3 Nov 2002   1445    GOES-8          Ash
    3 Nov 2002   1510    MODIS Terra     Ash
    3 Nov 2002   1515    GOES-8          Ash
    3 Nov 2002   1530    GOME            SO2
    3 Nov 2002   1543    EP TOMS         SO2, ash
    3 Nov 2002   1545,   GOES-8          Ash
                 1615,
                 1645
    3 Nov 2002   1707    NOAA-16 AVHRR   Ash
    3 Nov 2002   1715    GOES-8          Ash
    3 Nov 2002   1722    SeaWiFS         Ash
    3 Nov 2002   1745    GOES-8          Ash
    3 Nov 2002   1810                    Ash begins to fall in Quito
    3 Nov 2002   1815,   GOES-8          Ash
                 1845,
                 1915,
                 1945
    3 Nov 2002   2000                    Ash covers large area of Ecuador,
                                           reaching coast
    3 Nov 2002   2015    GOES-8          Ash, gravity waves?
    3 Nov 2002   2045,   GOES-8          Ash, gravity waves
                 2115,
                 2145,
                 2215
    4 Nov 2002   0345,   GOES-8          Cloud-covered
                 0415,
                 0445,
                 0515,
                 0545,
                 0615
    4 Nov 2002   0625    MODIS Aqua      Ash, SO2
    4 Nov 2002   0645    GOES-8          Cloud clearing- possible hot spot
    4 Nov 2002   0710    NOAA-16 AVHRR   Ash
    4 Nov 2002   0715,   GOES-8          Hot spot
                 0745
    4 Nov 2002   0815,   GOES-8          Strong hot spot and plume
                 0845
    4 Nov 2002   0915    GOES-8          Strong hot spot and minor plume
    4 Nov 2002   0945,   GOES-8          Strong hot and detached minor plume
                 1015
    4 Nov 2002   1045    GOES-8          Hot spot
    4 Nov 2002   1115    GOES-8          Ash, strong hot spot and main plume
    4 Nov 2002   1145,   GOES-8          Ash, main plume extends W
                 1215,
                 1245,
                 1315,
                 1345,
                 1415
    4 Nov 2002   1445    GOES-8          Ash, main plume (N arm) reaches coast
    4 Nov 2002   1515    GOES-8          Ash
    4 Nov 2002   1530    GOME            SO2
    4 Nov 2002   1555    MODIS Terra     SO2
    4 Nov 2002   1632    EP TOMS         SO2, ash
    4 Nov 2002   1715    GOES-8          Plume still attached to hot spot
    4 Nov 2002   1835    NOAA-16 AVHRR   Ash
    4 Nov 2002   1845    MODIS Aqua      SO2
    5 Nov 2002   1645,   GOES-8          Low-level ash
                 1715,
                 1745
    5 Nov 2002   1815,   GOES-8          Low-level ash
                 1845,
                 1915
    6 Nov 2002   1530    GOME            SO2
    6 Nov 2002   1544,   EP TOMS         SO2
                 1634,
                 1545,
                 1634,
                 1546

The TOMS overpass at 1543 UTC on 3 November captured the early phase of the eruption. An ash signal was localized over the volcano and a more extensive SO2 cloud containing ~12 kilotons SO2 was spreading E and W.

At 1632 UTC on 4 November, TOMS detected several distinct cloud masses. A cloud containing no detectable ash and ~11 kilotons SO2 was situated E of Ecuador on the Perú/Colombia border, a maximum distance of ~600 km from Reventador beyond which a data gap intervened. A second cloud containing ~42 kilotons SO2 and a weak ash signal was observed over the Pacific Ocean around 700 km from the volcano. The highest ash concentrations were detected in a cloud straddling the coast of Ecuador ~260 km W of the volcano that covered ~70,000 km2. This cloud contained little SO2. It is assumed that these clouds (total ~53 kilotons SO2) were erupted on 3 November.

A plume was also detected extending ~200 km W of Reventador, containing ~10 kilotons SO2. Based on high temporal resolution GOES imagery this plume first appeared sometime between 1045 UTC and 1115 UTC on 4 November. Nearby Guagua Pichincha was also reported active at this time by the Washington VAAC, and may have contributed some SO2; the highest SO2 concentrations in the Reventador plume were measured in the TOMS pixel covering Guagua Pichincha.

On 5 November neither SO2 nor ash were detected by TOMS, although a ~700-km-wide data gap occurred off the coast of Ecuador. The TOMS orbit was better placed on 6 November but no SO2 or ash were apparent. However, renewed SO2 emissions were detected on 7 November.

Information Contacts: P. Ramon, M. Hall, P. Mothes, andH. Yepes, Instituto Geofísico (IG), Escuela Politécnica Nacional, Quito (Email: geofisico@accessinter.net, URL: http://www. igepn.edu.ec/, ); Simon A. Carn, Joint Center for Earth Systems Technology (NASA/UMBC), University of Maryland-Baltimore County, 1000 Hilltop Circle, Baltimore, MD (Email: scarn@umbc.edu, URL: http://www.jcet.umbc.edu/); Andy Harris, HIGP/SOEST, University of Hawaii at Manoa, HI 96822 USA (Email: harris@pgd.hawaii.edu, URL: http://goes. higp.hawaii.edu/); Claus Siebe and Gabriel Valdez Moreno, Instituto de Geofísica, UNAM, Mexico, D.F (Email: csiebe@tonatiuh.igeofcu. unam.mx, valdezm@servidor. unam.mx); Jesús Manuel Macías, CIESAS-Mexico, Juarez 87, Tlalpan, DF. CP14000 (Email: macserr@att.net.mx); Aurelio Fernández Fuentes, Centro Universitario de Prevencion de Desastres, Universidad de Puebla, Mexico (Email: aurelioff@hotmail.com); Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS E/SP23, NOAA Science Center Room 401, 5200 Auth Road, Camp Springs, MD 20746, USA (URL: http://www. ssd.noaa.gov/).
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06/2003 (BGVN 28:06) Lahars, mudflows, and steam emissions continue through mid-July

After a 26-year repose without signs of unusual activity, Reventador burst unexpectedly into a VEI 4 eruption on 3 November 2002 (BGVN 27:11). A preliminary evaluation indicated that this was one of Ecuador's most powerful eruptions of the past 100 years. The following report provides an update on activity since March 2003 (BGVN 28:02) through mid-July 2003. Available seismic records are incomplete for this period (table 3). However, by late April all types of recorded seismic events had declined to very low levels.

Table 3. Summary of seismic activity at Reventador, 8 March-13 July 2003. Note that data are incomplete. Courtesy of the Instituto Geofísico.

    Date (2003)    Long-period / Hybrid    Volcano-tectonic

    08-14 Mar      120 avg. daily          15 avg. daily

    24-31 Mar      50-60 daily             20-30 daily
    01-06 Apr      42-98 daily             5-13 daily
                   26-65 daily
    07-12 Apr      63.5 avg. Daily         2.33 avg. daily
                   30 avg. daily
    13 Apr                58                     6
    14 Apr                29                     3
    15 Apr                35                     8
    16 Apr                37                     6
    17 Apr                31                     8
    18 Apr                22                     8
    19 Apr                20                     6

    28 Apr-02 May       0 daily               0 daily
    03 May                 1                     1
    04 May                 0                     0

    30 Jun-06 Jul          1                     4
    07-13 Jul              2                     2

Heavy rains in March 2003 mixed with ash on Reventador's flanks, causing mudflows and lahars that disrupted traffic along routes crossing rivers draining the volcano (figure 12). A gas column reached 300-500 m above the summit early in the month. Low-level seismicity was characterized by bands of harmonic tremor and a few isolated earthquakes; long-period (LP) seismic events were possibly associated with gas discharges. The seismic station in Copete registered high-frequency signals associated with lahars; however, only a few lahars were observed. Activity during the last week of March was characterized by persistent low-energy emissions of white steam and yellowish gases. Seismicity was also low during this time. The reference seismic station was moved nearer to the volcano, allowing detection of smaller magnitude earthquakes.

Figure 12. Map showing drainages from Reventador and the location of roads and pipelines SE of the volcano. Courtesy of the Instituto Geofisico.

When the weather permitted in April and May 2003, observers saw continuous low-level emissions of white steam and yellow gases rising several hundreds of meters above the volcano's cone. This was corroborated by the seismicity recorded at station LAVA2 (inside the caldera near the lava front). Rains have been frequent, generally of short duration, and accompanied by some lahars. Low-frequency tremor on 12 April was recorded at LAVA2 (0.9 Hz) and CONE (1.3 Hz), in the caldera NE of the cone near the head of the Rio Reventador. During April, rivers swelled with water and mud that blocked river crossings. Seismicity was characterized by a fairly constant number of long-period (LP)/hybrid and volcano-tectonic (VT) events, with a slight diminution in the number of LPs (table 1). Lahars on 18-19 April produced significant flooding in Rio Reventador and Rio Marker. Seismic activity stayed at very low levels.

On 1 May strong rains in the area of the volcano generated mud flows or lahars that destroyed the highway in the Rio Reventador sector. Heavy rainfall of up to 200 mm in less than 24 hours on 6 May led to the remobilization of ash from the November 2002 eruption. Lahars traveled down the SE flank via the Rio Marker and Rio Reventador gorges. Seismic signals indicated that lahars occurred in seven main pulses, with the longest pulse lasting ~2 hours. Lahars crushed a portion of the petroleum pipeline on the SE flank and dragged it 22 m. Lahars also destroyed a bridge and blocked a highway. On 8 May, satellite images showed a plume that extended ~50 km NW.

During much of June and July 2003, the volcano was not visible due to cloudiness. Seismic activity during June was characterized by bands of continuous tremor, some related to increased volume of the rivers and/or mud flows. On 19 June, a steam plume reached a height of ~300 m. Seismic tremor was associated with flowing gas and observed emissions. Small seismic events (magnitudes less than 3.4) occurred on 23 and 25 June. During 30 June-1 July a gas column was observed that rose ~200 m and drifted W. Seismicity was at low levels in early July, but continuous tremor occurred associated with degassing.

Information Contacts: Geophysical Institute, National Polytechnical School, Campamento, San Rafael, Ecuador (URL: http://www.igepn.edu.ec).
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11/2003 (BGVN 28:11) Variable seismicity, degassing, and recurring lahars

This report contains updates from Reventador for July through November 2003. During this time seismicity varied from generally low to occasionally high. Lahars recurred, as rain and drainage systems continued to move tephra left after the eruptions that began on 3 November 2002 (BGVN 27:11, 28:02, and 28:06). Except for degassing, steam plumes, and the cooling of lava flows, further eruptive behavior (or cessation of activity) was not mentioned.

Activity during July-August 2003. Rainfall at Reventador during 7-13 July caused renewed movement of ash on the volcano's flanks. This led to lahars down the Montana River, and a consequent interruption in highway travel. Tremor associated with degassing was noted, with an increase during the last week of July and early August. Steam plumes were noted on 30 July and 2 August and lahars coincident with tremors were observed on 30 July. Seismicity was moderate, with about five volcano-tectonic (VT) events per day and a total of four tectonic events between 30 July and 3 August. These four events were located between 5.4 and 35 km away. The tectonic earthquake on 3 August registered the highest magnitude, M 3.2.

On 9 August detectors in three locations registered a lahar; this was later confirmed by staff from the Chaco-Santa Rosa station. Seismicity was low between 4 and 10 August, with six local tectonic events. Three of these occurred on 8 August, at varying depths, but all were within 10-12 km of the volcano. The second of these was the largest of any event that week, M 2.9. Seismicity stayed low through the end of the month, with an average of one VT event per day during the last week of August. Small fracture events related to the cooling of lava flows were noted. However, no rains capable of generating lahars were recorded, and there were no reports of steam or gas emissions.

Activity during September-October 2003. Reports were not available for the first three weeks of September and the first two weeks of October. During the week of 22-28 September, two lahar signals were registered, as well as 44 hybrid events, 43 VT events, and seven long-period (LP) events. During the following week, hybrid and LP events dropped to 17 and two events, respectively, but the number of VT events increased considerably, to 78. Lahars lasting ~ 4 hours each were recorded on 30 September and 1 October, following moderate rain on the 30th. During 13-19 October instruments registered 77 VT and 17 LP earthquakes (i.e., averaging 11 VT earthquakes and two LP earthquakes per day). Lahars were reported on 13, 14, and 19 October. During the following week, seismicity stayed at similar levels. Due to intense rains, more lahars were registered, on 20 and 22 October and again on 28 and 29 October. Traffic was again affected as a route had to be closed. Also between 27 October and 2 November, there was a small increase in the number of volcano-tectonic events.

Activity during November 2003. Seismicity remained constant, averaging 8-9 earthquakes each day. Following strong rains on 7 and 9 November, seismometers detected signals attributed to lahars. After the lahar signals had diminished, tremor was again detected. Lahar signals were also recorded on 11, 12, 14, and 26 November.

Information Contacts: Geophysical Institute (IG), Escuela Politécnica Nacional, Apartado 17-01-2759, Quito, Ecuador (URL: http://www.igepn.edu.ec/).
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11/2004 (BGVN 29:11) Late 2004 visits find renewed venting and thick intracaldera lava flows 2 km long

A 16 December 2004 report from the Instituto Geofísico (IG) of the Escuela Politécnica Nacional calls attention to renewed lava effusion from the crater that lies within Reventador's large summit cone (figure 13). A block-lava flow escaped the cone's crater. It ran out at a breach in the S wall, and by 16 December it had advanced ~ 2 km farther. The flow advanced SE along a narrow, E-curving path, remaining atop lavas from 2002. Thus far in 2004, lava flows remained well within the larger caldera.

Figure 13. An aerial photo of Reventador's 4-km-diameter caldera as a base for mapping the lava flows of 2002 and those of 2004 through mid-December. The 2002 flows are labeled Lava 1 and Lava 2. The 2004 lava flow followed and partly covered Lava 1. At a distance of ~ 1 km from the vent, the 2004 lava flow bifurcated into two closely spaced parallel lobes. The caldera has an E-tilting floor, is open on its E side, and contains a prominent cone on its W side. The cone forms the volcano's summit, and contains an elongate crater that hosts the 2004 vent ("active vent"). The crater has a rim that is indicated by a solid curving line; the crater's inward-sloping walls are indicated by light shading and lines resembling the trends of gullies. The cone's floor at its southern breach lies at ~ 3,200 m elevation. The aerial photo was taken by Instituto Geográfico Militar in 1983. Figure courtesy of IG.

Reports in 2003 chiefly discussed events outside the caldera. A road, one gas pipeline, and two oil pipelines traverse Reventador's flanks 7 km ESE of the active vent. All of these installations were affected in 2003 (but not appreciably since then). The pipelines were destroyed due to heavy lahars coming down the Reventador river on 6 May 2003 (BGVN 28:06). Our last report (BGVN 28:11) discussed events during July through most of November 2003.

Lava venting in the crater likely began in early November 2004, a time when seismic station CONE registered dramatic increases in volcano-tectonic events (figure 14). In response to the elevated seismicity, the IG-EPN began more intensive monitoring, including overflights with thermal imaging, repeat visits to the remote volcano, and on 9 November 2004, installation of the additional short-period seismic station LAV3, ~ 2 km from the crater's vent.

Figure 14. Seismicity (number of earthquakes) versus time registered at Reventador (station CONE) during mid-February 2003 through mid-December 2004. Anomalously elevated seismicity consisting mainly of volcano-tectonic began in August 2004. Activity increased on 4 November 2004 and included hybrid events. Previously unseen emergent, extended-duration, broad-band earthquakes began on 22 November 2004. Courtesy of IG.

A helicopter overflight by IG-EPN staff on 10 November 2004 confirmed the presence of a small lava dome, which appeared then to be confined to the crater floor. This feature was not present on photos taken during an IG overflight on 19 October 2004. During the 10 November overflight, a continuous 2.5 km-high gas column escaped from the crater, accompanied by sulfurous odors detected by personnel in the helicopter.

The date when lava began escaping the crater was not precisely known, but it was thought to have been around 22 November, coincident with the emergence of distinct seismic signals not previously observed at Reventador (figure 11). The signals occurred in swarms and consisted of low-frequency (1-10 Hz) waves of relatively low-amplitude. Their seismic records were emergent (i.e. growing in amplitude with time) and of long duration (up to 60 seconds). They are thought to have been possibly associated with rock falls from lava flowing down the cone's southern flank. As many as 200 of these events were recorded each day at station CONE.

A return visit to the crater rim on 28 November (this time on foot) documented abundant fresh lava in the crater (figure 15), a dramatic increase in the volume of lava there. At least 0.5 x 106 m3 of new lava then covered the entire crater floor and appeared to be already flowing out of the southern breach and into the surrounding caldera. Because of cloudy weather, the exact extent of the flow remained indeterminate. The surface of this lava flow also extended to the N and reached a level ~ 20 m below the northern breach. Continuous lava extrusion or flowing or both were heard within the crater, making sounds akin to glass breaking, and vigorous roaring gas emissions originated from the crater's western margin. These gas emissions and other smaller fumaroles contributed to a plume that was continuously present, extending at least 1 km above the vent.

Figure 15. Reventador's 2004 lava flow/dome as seen on 28 November 2004. The photo was taken looking W and downward from the cone's eastern crater rim (see vantage point indicated by the star on figure 11). Courtesy of IG.

IG observers estimated that the total mid-December lava flow volume was ~ 3 x 106 m3. The inferred 22 November date of flow onset would imply a steady-state extrusion rate of ~ 0.1 x 106 m3 per day and a flow front advancing at ~ 80 m per day. These observations appear to conform with satellite thermal infrared observations, which noted no significant anomalies until the end of November, due presumably in large part to the lava being confined within the steep-walled crater. Inclement weather occurred and also may have impeded some of the satellite thermal observations.

The most recent visit to the crater rim, on 11 December 2004, traced the source of degassing and lava outflow to the most elevated portion of a small dome-like feature at the central western margin of the crater. Figure 16 shows how instrumentally aided nighttime incandescence observations disclosed both the vent area and surficial flow-textures extending S towards the southern breach of the cone. Figure 14 also documents a comparatively narrow arm of lava trending towards the cone's northern breach. Nighttime incandescence from the lava flow was also visible from local communities such as El Chaco, ~ 20 km distant.

Figure 16. Thermal image of the lava flow in the interior of Reventador crater taken with a Forward Looking Infrared (FLIR) imager at 2000 on 11 December 2004. Courtesy of IG.

Figure 17 illustrates the scene on 12 December 2004 during a visit to the front of the most advanced lobe of lava (for location, see star at end of flow lobe, figure 9). IG-EPN staff estimated the flow front at ~ 20 m high and saw incandescent blocks falling off of it.

Figure 17. A N-looking view of Reventador's gray-colored lava-flow front taken on 12 December 2004 at ~ 2,600 m elevation. Person at right indicates scale of the advancing flow front. The lava flow emanated from the breach in the S side of the cone's crater, a spot seen in the photo's upper left. Courtesy of IG.

Information Contacts: Patricio Ramón, Daniel Andrade, David Rivero, Alexandra Alvarado, Sandro Vaca, and Pete Hall, Geophysical Institute (IG), Escuela Politécnica Nacional, Apartado 17-01-2759, Quito, Ecuador (URL: http://www.igepn.edu.ec/, Email: pramon@igepn.edu.ec; dandrade@igepn.edu.ec; mhall@igepn.edu.ec); Jeffrey B. Johnson, Dept. of Earth Sciences, James Hall University of New Hampshire, Durham, NH 03824 (jeff.johnson@unh.edu); MODIS Thermal Alert System, Hawaii Institute of Geophysics and Planetology (HIGP), School of Ocean and Earth Science and Technology, University of Hawaii at Manoa (URL: http://www.modis.higp.hawaii.edu).
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05/2005 (BGVN 30:05) Lava flow reaches 4 km from summit, approaching road and petroleum pipeline

Crisis escalates. Instituto Geofísico (IG) members noted that eruptions at Reventador in Ecuador's eastern cordillera continued into at least early July 2005. Observers documented thick blocky lava flows, occasional Vulcanian explosions, new fumarolic activity on the N flank of the cone, and venting of vapor, gases, and fine ash. This followed a spate of increased seismicity during April to early June 2005. Lava flows had extended 4 km from the summit vent toward the SE, in the direction of the main highway across this region, a route that links the important oilfields in the Amazon basin with Quito, the capital. The lava flows were sequentially numbered (Lava ##3, ##4, etc.).

Lava ##3, a flow that began in November 2004 (BGVN 29:11), advanced slowly and ceased movement by early January 2005. Following relatively low seismic activity in late 2004 and early 2005, the IG monitoring network began to register bands of harmonic tremor starting 1 April (figure 18). Through 8 April 2005, instruments recorded 45 tremor episodes, each lasting 10 to 60 minutes. Dominant frequency peaks were between 1 and 1.5 Hz. Given that strong incandescence was observed by a guard of PetroEcuador from 14 km away, the tremor was interpreted to signal the rise of magma into the upper part of the cone through an open conduit.

Figure 18. Seismic events registered at Reventador since August 2004. Courtesy of IG.

Lava ##4 erupted coincident with this strong tremor and was the most important surface manifestation. It was first observed in an overflight on 12 April, escaping from a summit crater conduit that had formed a carapace. It was seen flowing down the SW crater notch onto the cone's flanks and then onto the SW and SE caldera floor. The flow partially covered Lava ##3 (figure 19), resulting in layers of recent lava in some places reaching more than 50 m thick. This emplacement was observed during several days of work on the seismic instrumentation and sampling within the caldera carried out by IG personnel during 19-22 April. During the same overflights, a new fumarole field was observed on the lower S flank of the cone, a spot very close to the upper Reventador River, in the same place where thermal anomalies were observed on 11 March 2005.

Figure 19. Location of lava flows related to eruptive activity within the Reventador caldera since 2002. Photo taken looking at the SE flank on 6 May 2005 by P. Ramón. Provided courtesy of IG.

Starting on 15 May there was an important increase in the intensity of harmonic tremor, often preceded by low frequency (< 1 Hz) long-period events, a conspicuous aspect of behavior that was absent in April. Many of the long-period events, particularly those occurring during 17-21 May, were of such magnitude that they registered at seismic stations on other volcanoes (e.g., Cerro Negro and Guagua Pichincha) more than 100 km distant. After this elevated activity in mid May, there was a decrease in the number of events, dropping to an average of 88 per day. During this period Lava ##4 continued to flow, moving at the rate of about 20 m/day, advancing particularly strongly along the caldera's S wall in a stream channel (Rió Marker) cut through the 2002 pyroclastic deposits. Lava reached 25 meters thick when seen during a 22-23 May visit, during which time strong roars and the sounds of 'many jet planes' blared from the vent. These sounds indicated a strong gas flux, although little vapor was observed. At this time, there was an absence of both explosions and incandescence in the summit crater.

An overflight on 25 May confirmed the emergence of a new flow (Lava ##5). It followed the same route as ##4, but was comprised of three principal lobes. The middle lobe, which represented the most conspicuous and largest volume, advanced down the Río Marker's channel (figure 20).

Figure 20. Lavas 4 and 5 flowing down the Marker's stream channel along the SE margin of Reventador's caldera. Photo taken on 17 June 2005 by P. Ramón. Provided courtesy of IG.

Reventador's activity in June 2005 began with an important swarm of volcano-tectonic and hybrid seismic events—starting on the 2nd and continuing through the 3rd. Of particular note, tremor continued for more than 10 hours, and provided background to the discrete volcano-tectonic and hybrid events Hybrid events had not been registered since November 2004. Following these important swarms, instruments registered strong, full-amplitude bands of spasmodic tremor, comprised to some extent by packages of long-period events lasting for hours to days on end.

During these early days of June, there was an intensification of incandescence in the crater and later, the emission of gases and slight ash. On 8 June, a 100 km long vapor/ash column extended from the volcano into the S part of Quito at ~ 7 km altitude and caused a very slight powdering of ash, which was brought down by a gentle rain and left cars dappled with circular spots.

A trip by IG volcanologists into the caldera on 11-12 June disclosed strong Strombolian fountaining in the summit crater. Lava ##5 continued to flow atop the stalled Lava ##4. Measurements of SO2 flux with a mini-DOAS (differential optical absorption spectroscopy) resulted in an estimate of ~ 2,500 metric tons/day.

Three other seismic stations were installed around the caldera with the helicopter help of the petroleum company OCP during 16-19 June. One broad-band seismograph and infrasound system was also installed, thanks to collaboration with Jeff Johnson of the University of New Hampshire. During this period no Strombolian activity was observed, but Vulcanian explosions (figure 21) occurred with little warning. A 24-hour period during 18-19 June included at least seven discrete explosions, producing strong infrasound and seismic responses. Many of these explosions discharged columns that rose 2-3 km above the summit (and some, up to as high as ~ 6 km above the summit) and were clearly heard within the caldera. Large incandescent blocks could be seen thrown several hundreds of meters into the air, falling on the cone's upper slopes. Ash content in the columns was moderate. Explosions were discrete and often terminated within 4 minutes. Thermal alerts were identified by the Hawaii Institute of Geophysics and Planetology (HIGP). Observations on 30 June and 1 July noted recent lava flows in the upper Marker river valley (figure 22).

Figure 21. One of Reventador's discrete Vulcanian explosions observed during a 19 June 2005 helicopter flight. The view is from the E of Reventador caldera looking toward the W. Photo taken on by P. Ramón; provided courtesy of IG.
Figure 22. A photo of Reventador's Lava ##4 flow front (which had reddish hues) overtopped by Lava ##5 (more nearly white). The shot was taken in the Río Marker at 1100 on 30 June 2005. By 1 July, Lava ##5 had still not advanced beyond the terminus of Lava ##4. Photo by P. Ramón, provided courtesy of IG.

The 4-6 discrete explosive degassing events/day observed in June led the IG authors to surmise that there were a series of temporary plugs in the upper part of the conduit. This behavior was thought to reflect magma becoming more crystal rich.

As of 6 July, harmonic tremor, occasional explosions, and long-period and volcano-tectonic signals all continued to register at Reventador on the IG's telemetered monitoring network. Strong Strombolian fountaining was observed from distances of 6.5 and 14 km during the evening and one of the lobes of Lava ##5 was advancing down the caldera wall (following the Río Marker), but abruptly slowed to perhaps only ~ 20 m/day. In comparison, this flow-front velocity had earlier attained ~ 70 m/day (during 19-23 June) and ~ 50 m/day (during 23-30 June). The diminished rate of advance and continuing high-amplitude tremor suggested that perhaps a new lava flow (Lava ##6) had broken out high on the flanks, a conjecture yet to be confirmed by press time. Lava ##5 was still 1.2 km from the steep incline, a point where it could begin rapid descent to the alluvial fan where the highway and petroleum pipeline are located.

Information Contacts: Patricia Mothes, Patricio Ramón, Pete Hall, Daniel Andrade, and Liliana Troncoso, Geophysical Institute (IG), Escuela Politécnica Nacional, Apartado 17-01-2759, Quito, Ecuador (URL: http://www.igepn.edu.ec/, Email: pmothes@igepn.edu.ec; pramon@igepn.edu.ec; mhall@igepn.edu.ec; dandrade@igepn.edu.ec; ltroncoso@igepn.edu.ec); Jeffrey B. Johnson, Dept. of Earth Sciences, James Hall University of New Hampshire, Durham, NH 03824, USA (Email: jeff.johnson@unh.edu).
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08/2005 (BGVN 30:08) Generally, activity shifting from effusive towards explosive

Reventador ceased extruding significant new lava flows in early July 2005. Subsequent activity through this report interval, late September, was manifested as intermittent explosive eruptions. These were characterized alternately as Strombolian activity and short-duration Vulcanian events.

After the post-effusive phase and during the explosive phase a significant Vulcanian event took place at 2058 on 12 September, producing an ash column more than 5 km above the summit. Large bombs were ejected more than 2 km from the vent and small pyroclastic flows were evident in gullies descending from the cone. This event was preceded by more than a week of relative quiescence, indicating that future Vulcanian eruptions may occur with little warning.

This report was submitted by Jeffrey B. Johnson (University of New Hampshire), who collaborated with colleagues including Patricio Ramón, Liliana Troncoso, Guillermo Viracucha, Jaime Lozada, Daniel Andrade, David Rivero, Gorky Ruiz, Pete Hall, and Wilson Enriquez (Geophysical Institute, Escuela Politécnica Nacional, IG-EPN). They adhered to the practice of numerically naming lava flows, for example Lava ##5.

End of significant lava effusions. BGVN 30:05 provided a detailed overview of recent active lavas erupted by Reventador between April 2005 and the end of June 2005. Visits to the caldera on 1 July revealed dramatic diminution in the advance rate of Lava ##5 along the southern caldera margin. Within the first few days of July, Lava ##5 had stagnated. Its furthest extent was ~ 4.5 km from the vent and about 50 m short of the furthest extent of Lava ##4 (erupted in May 2005), which it was overriding.

Since the first few days in July, major lava extrusion had terminated. Despite intermittent MODIS thermal alerts (~ 1 per week from University of Hawaii (HIGP)), no significant lava flows have been directly observed by IG-EPN personnel or reported by the local populace. During July, it is likely that small lava flow(s) (under 1 km in length) were extruded from the southern breach of the cone during short-lived events lasting a few days or less. For instance, a photo taken on 1 August (figure 23) indicates a short, fresh lobe (named Lava ##6), which was no longer incandescent during a night-time visit on 3 August.

Figure 23. Photograph of a fresh lava flow at Reventador on 1 August 2005. The flow, which appears as a white lobe, was stagnant. Courtesy of J. Johnson and the Geophysical Institute.

Explosive activity. Pyroclastic explosions, which first occurred in early June 2005, continued intermittently until 25 September 2005. Significant Strombolian activity was noted at night by the local populace in the first few days of July, coincident with the decline of Lava ##5 extrusion. In mid-July, explosive activity was minimal, but increased towards the end of the month and during August. Between explosions, voluminous vapor plumes were often observed and loud degassing sounds were often audible, but at times the volcano was also completely silent. Incandescence was also often visible in the cone, suggesting an open-vent configuration. Periods of quiescence separated explosive activity and generally lasted hours to days. Typical eruptive events, which occurred as many as 26 times a day (i.e., on 15 September), are identified clearly by seismic records. These emissions tend to alternate between discrete pyroclastic-laden, ash-rich explosions and extended-duration Strombolian-type fountaining (figure 24). Both types of events were capable of erupting large blocks up and over the crater rim (~ 200 m above the vent), which were often sufficiently massive to be visible from the highway ~ 7.5 km distant.

Figure 24. Strombolian activity at Reventador depicted in a sequence of still images taken at one-minute intervals along with accompanying infrasonic and seismic traces (signals recorded ~ 1.8 km from the vent). Courtesy of J. Johnson and the Geophysical Institute.

A period of relative quiescence, marked by an absence of large ash-generating plumes, was evident at the end of August and during first days of September. Vent incandescence was also notably absent during several days up until the large explosion at ~ 2058 on 12 September.

Preceded by a swarm of small volcano-tectonic events, the explosion was manifested by very short-duration transient signals, with arriving infrasonic and seismic waves lasting less than ~ 1 minute. However, peak-to-peak amplitudes the respective signals (~ 211 Pa and 4.9 mm/s) were substantially greater than other explosive events occurring at the volcano during recent months.

As previously mentioned, this short-duration explosion generated a more than 5 km-high ash-cloud and ejected large bombs aerially to more than 2 km. Small pyroclastic flows were confined to gullies on the cone and reached at least 1.5 km from the vent (figure 25).

Figure 25. Photos of Reventador cone taken 12 days apart (13 and 25 September 2005, from different angles) show the channels and deposits of small pyroclastic flows. Arrow connects same location on cone in both frames. Courtesy of J. Johnson and the Geophysical Institute.

Since this large event, incandescence has been routinely present in the crater and explosions have occurred with greater frequency (figure 26). Further large explosions occurring in the morning of 24 September were likely responsible for more pyroclastic deposits evident on the upper cone and in upper-flank gullies (figure 25, right-hand photo).

Figure 26. Summary of explosion counts at Reventador as identified by the IG-EPN seismic network between 1 June and 23 September 2005. Courtesy of J. Johnson and the Geophysical Institute.

Monitoring. Reventador continues to be closely monitored by the IG-EPN (figure 27). A telemetered seismic network, consisting of three local short-period seismometers, is used to quantify the eruptive chronology of the volcano, including the quantities of volcano-tectonic events (VT), long-period events (LP), hybrid events, and harmonic and spasmodic tremor, and explosion events. Three temporary stand-alone dataloggers with broad-band seismometers and infrasonic microphones, installed with collaboration from the University of New Hampshire and the University of North Carolina, have supplemented this network throughout the summer.

Figure 27. Summary of Reventador seismicity since 1 June 2005. Many of the tremor events were associated with vigorous degassing at the vent. Courtesy of J. Johnson and the Geophysical Institute.

Additionally, field visits by IG-EPN personnel have been conducted regularly. During an expedition on August 28, Differential Optical Absorption Spectroscopy (DOAS) and Forward Looking Infrared (FLIR) measurements were made to assess gas and thermal flux, respectively. DOAS measurements revealed a continuing flux of SO2 estimated at ~ 850 tons/day. The FLIR measurements confirmed near-magmatic temperatures at the vent. It also confirmed stagnation of all lava flows on the volcano since their maximum surface temperatures had cooled into the range of ~ 50°C.

Information Contacts: Jeffrey B. Johnson, Dept. of Earth Sciences, University of New Hampshire, Durham, NH 03824, USA (Email: jeff.johnson@unh.edu); Patricio Ramón, Liliana Troncoso, Guillermo Viracucha, Jaime Lozada, Daniel Andrade, David Rivero, Gorky Ruiz, Pete Hall, and Wilson Enriquez, Geophysical Institute (IG), Escuela Politécnica Nacional, Apartado 17-01-2759, Quito, Ecuador (URL: http://www.igepn.edu.ec/, Email: pramon@igepn.edu.ec).
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03/2008 (BGVN 33:03) Eruptive episode during March-May 2007, another ash plume in October

An apparent hiatus in activity starting in late 2005 ended with an eruption during March 2007. Previous reports documented intermittent explosive eruptions through September 2005, with Strombolian activity and short-duration Vulcanian events (BGVN 30:08). These events were accompanied by small pyroclastic flows, small lava flows, large bombs, and ash columns.

According to the Instituto Geofísico (Escuela Politécnica Nacional) (IG), seismicity at Reventador was at a low level at the end of December 2005. No IG reported were received between January 2006-March 2007. In early March 2007 the IG noted that the number of tectonic earthquakes from Reventador had increased. Steam-and-ash plumes were sporadically visible and occasionally rose to altitudes of 4 km during 8-22 March. On 21 March, noises were reported. The next day, seismic signals changed that indicated possible emissions. On 24 March, local people saw ash plumes and incandescent material near the crater and heard roaring noises. An explosion produced a plume to an altitude of 6.6 km that drifted W. Based on reports from IG, the Washington VAAC reported an ash plume during 26-27 March that reached an altitude of 3.7-7 km and drifted NE and WNW. A thermal anomaly was present on satellite imagery during 24-27 March.

On 28 March 2007, observers reported roaring noises and an ash column that rose to an altitude of 5.6 km and drifted W. A small lava flow traveled 200 m down the S flank. Incandescent material and ash emissions were observed during 29-31 March. On 1 April, ash plumes rose to an altitude of 7.6 km and incandescent rocks were ejected about 50 m above the crater. Incandescent material was again seen at the summit on 2 April. The Washington VAAC reported that a strong hotspot was present on satellite imagery during 1-3 April. Based on pilot reports, IG reported that a steam-and-gas plume with little ash content rose to an altitude of 6.1 km and drifted W on 3 April.

On 3-4 April 2007, incandescent blocks ejected from the summit subsequently rolled down the S flanks. Satellite imagery revealed ash plumes drifting W and a large thermal anomaly over the crater. On 4 April, a plume rose to an altitude of 4.6 km. Crater incandescence was observed on 4 and 6 April and "cannon shots" were heard on 6 April. Ash-and-steam emissions were observed during 8-9 April. Steam emissions from the flanks on 8 April possibly originated from a lava flow.

On 11 April, a steam plume rose to an altitude of 3.8 km. Visual observations were hindered during 12-17 April due to inclement weather. On 13 April, the lava flow on the S flank, first observed on 28 March, was 15 m thick and possibly active. On 18, 20, and 23 April, steam-and-gas emissions hung near the summit. On 18 April, a plume was seen drifting NW on satellite imagery. On 20 April, a bluish haze of gases was observed. Clouds occasionally inhibited views of the summit during 18-24 April.

On 27 April, a steam plume from Reventador rose to an altitude of 3.7 km. Later that night, incandescent material was ejected from the crater. On 30 April, a steam plume was observed on satellite imagery drifting NW. Based on the Guayaquil MWO and satellite imagery, the Washington VAAC reported that an ash plume rose to an altitude of 3.7 km and drifted NW. Visual observations were hindered during 25 April-1 May due to inclement weather.

On 16 May the IG reported that a steam plume rose to an altitude of 3.6 km and drifted to the NW. An ash plume on 18 May rose to an altitude of 3.7 km and drifted NW, but ash was not observed on satellite imagery. Strong rains that day resulted in a lahar that lasted approximately 40 minutes. A lahar was also noted on 22 May. Visual observations were hindered during most of the reporting period due to inclement weather.

Lahars occurred on the flanks on 15, 19, 20, 21, and 23 June. An eruption on 11 October 2007 produced an ash plume that rose to an altitude of 4.6 km and drifted S. Ash was not observed on satellite imagery due to cloud cover.

Information Contacts: Washington Volcanic Ash Advisory Center, Satellite Analysis Branch (SAB), NOAA/NESDIS E/SP23, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: http://www.ssd.noaa.gov/VAAC/); P. Ramón, Instituto Geofísico-Departamento de Geofísica (IG), Escuela Politécnica Nacional, Casilla 17-01-2759, Quito, Ecuador (Email: pramon@igepn.edu.ec).
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04/2008 (BGVN 33:04) Quiet, January 2006-February 2007; emissions, March-October 2007

Our previous report on Reventador documented intermittent explosive eruptions through September 2005, with Strombolian activity and short-duration Vulcanian events. These events were accompanied by small pyroclastic flows, small lava flows, large bombs, and ash columns (BGVN 30:08). This report discusses reported events into 2008.

According to the Instituto Geofísico (Escuela Politécnica Nacional) (IG), seismicity at Reventador was low at the end of December 2005. There were no reports on this volcano during January 2006 through February 2007. The volcano was apparently only weakly eruptive or non-eruptive around this interval. MODVOLC thermal alerts were absent during late December 2005 to late March 2006.

In early March 2007, however, the IG reported an increase in the number of tectonic earthquakes at Reventador. Steam-and-ash plumes were sporadically visible and occasionally rose to altitudes of 4 km during 8-22 March. On 21 March, noises were reported. The next day, seismic signals changed that indicated possible emissions. On 24 March, local residents saw ash plumes and incandescent material near the crater and heard roaring noises. An explosion produced a plume that rose to an altitude of 6.6 km and drifted W. Based on reports from IG, the Washington VAAC reported an ash plume during 26-27 March that reached an altitude of 3.7-7 km and drifted NE and WNW. A thermal anomaly was present on satellite imagery during 24-27 March.

On 28 March, observers reported roaring noises and an ash column from Reventador that rose to an altitude of 5.6 km and drifted W. A small lava flow traveled 200 m down the S flank. Incandescent material and ash emissions were observed during 29-31 March. On 1 April, ash plumes rose to an altitude of 7.6 km and incandescent rocks were ejected about 50 m above the crater. Incandescent material was again seen at the summit on 2 April. The Washington VAAC reported that a strong hotspot was present on satellite imagery during 1-3 April. Based on pilot reports, IG reported that a steam-and-gas plume with little ash content rose to an altitude of 6.1 km and drifted W on 3 April.

On 3-4 April, incandescent blocks ejected from the summit subsequently rolled down the S flanks. Satellite imagery revealed ash plumes drifting W and a large thermal anomaly over the crater. On 4 April, a plume rose to an altitude of 4.6 km. Crater incandescence was observed on 4 and 6 April and "cannon shots" were heard on 6 April. Ash-and-steam emissions were observed during 8-9 April. Steam emissions from the flanks on 8 April possibly originated from a lava flow.

On 11 April, a steam plume from Reventador rose to an altitude of 3.8 km. Visual observations were hindered during 12-17 April due to inclement weather. On 13 April, the lava flow on the S flank, first observed on 28 March, was 15 m thick and possibly active.

On 18, 20, and 23 April, steam-and-gas emissions from Reventador hung near the summit. On 18 April, a plume was seen drifting NW on satellite imagery. On 20 April, a bluish haze of gases was observed. Clouds occasionally inhibited views of the summit during 18-24 April.

On 27 April, a steam plume from Reventador rose to an altitude of 3.7 km. Later that night, incandescent material was ejected from the crater. On 30 April, a steam plume was observed on satellite imagery drifting NW. Based on the Guayaquil Meteorological Watch Office (MWO) and satellite imagery, the Washington VAAC reported that an ash plume rose to an altitude of 3.7 km and drifted NW. Visual observations were hindered during 25 April-1 May due to inclement weather.

On 16 May, the IG reported that a steam plume from Reventador rose to an altitude of 3.6 km and drifted to the NW. The plume was visible on satellite imagery. On 18 May, strong rains resulted in a lahar that lasted approximately 40 minutes. A lahar was also noted on 22 May. Visual observations were hindered during most of the reporting period due to inclement weather.

On 18 May, an ash plume from Reventador rose to an altitude of 3.7 km and drifted NW. Ash was not observed on satellite imagery. Lahars occurred on the flanks of Reventador on 15, 19, 20, 21, and 23 June. Clouds inhibited visual observations during 20-24 June.

MODVOLC thermal alerts were frequent during late March and throughout April 2007. One alert occurred in late May 2007; two also appeared on 6 August 2007 (local dates and times). No further alerts were issued in data accessed 9 June 2008.

A VAAC report noted an eruption on 11 October 2007. It emitted an ash plume that rose to an altitude of 4.6 km and drifted S. Ash was not observed on satellite imagery due to cloud cover.

Information Contacts: Washington Volcanic Ash Advisory Center, Satellite Analysis Branch (SAB), NOAA/NESDIS E/SP23, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: http://www.ssd.noaa.gov/VAAC/); P. Ramón, Instituto Geofísico-Departamento de Geofísica (IG), Escuela Politécnica Nacional, Casilla 17-01-2759, Quito, Ecuador (Email: pramon@igepn.edu.ec).
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08/2008 (BGVN 33:08) Eruptions, seismicity, and hot spots in late July and early August 2008

Eruptions from Reventador (figure 28) occurred between March and May 2007, and an ash plume was reported in October 2007. The eruptions were characterized by steam-and-ash plumes that rose to altitudes as high as 7.6 km, thermal anomalies on satellite imagery, roaring noises, and a small lava flow (BGVN 33:03 and 33:04).

Figure 28. Map of Ecuador showing Reventador and selected other volcanoes. Courtesy of USGS.

MODVOLC thermal alerts were issued on 28 and 31 July 2008 (local dates). Mapping of the MODIS anomaly locations indicated that thermally radiant material was within the crater (no anomalies outside the crater).

According to the Instituto Geofísico-Escuela Politécnica Nacional (IG), seismic activity showed a progressive and constant increase from the beginning of July. The number of earthquakes per day were the greatest on 24 and 25 July. On 27 July continuous seismic tremor was followed by incandescence around the crater. Thermal anomalies were also identified on satellite imagery. In the evening, explosions produced ash plumes and ejected incandescent material that rolled down the flanks. On 28 July ash plumes rose to altitudes of 4-6 km and drifted NW and W; ashfall was reported in Olmedo, ~ 50 km NW. On 29 July, ash-free steam plumes rose from the crater and drifted NW, and a sulfur smell was noted near the volcano. A lava flow directed S from the caldera halted but the location of the flow front was ambiguous in the reporting.

According to the IG, seismicity from Reventador decreased during 30-31 July, and remained low thereafter. A lava flow within the caldera was observed. On 31 July, steam-and-gas plumes with a low ash content were detected on satellite imagery and drifted W and SW. On 1 August, steam-and-gas plumes were emitted and a lava flow in the caldera was noted. Diffuse ash emissions were noted on 2 August. On 3 August, IG scientists observed the lava flow in the caldera and estimated that it advanced at a rate of 100 m per day. They also heard sporadic roaring noises.

On 2 August, the Washington Volcanic Ash Advisory Center (VAAC) began to advise that light ash and gas was being emitted. An occasional hotspot was observed on 3 August. By 4 August, the VAAC reported that emissions had ceased and seismicity was decreasing.

According to the IG, during 5-8 August, gas-and-steam plumes were noted. By 7 August the lava flow had ceased. On 8 August, incandescence from the crater was observed at night. There were no further reports through 1 October.

During July-August 2008 the government did not believe the risk to human health was sufficient to increase the alert status or evacuate the residents. However, officials activated some emergency responses in nearby towns.

Information Contacts: P. Ramón, Escuela Politécnica Nacional, Casilla 17-01-2759, Quito, Ecuador (Email: pramon@igepn.edu.ec, URL: http://www.igepn.edu.ec); Washington Volcanic Ash Advisory Center, Satellite Analysis Branch (SAB), NOAA/NESDIS E/SP23, NOAA Science Center Room 401, 5200 Auth Road, Camp Springs, MD 20746, USA (URL: http://www.ssd.noaa.gov/).
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03/2009 (BGVN 34:03) Lava extrudes down two flanks during November 2008-April 2009

Our previous report covered activity through early August 2008, a period that included extrusions of lava flows (BGVN 33:08). This report continues through late April 2009, including a hiatus for much of August into November 2008. In early November observers saw repeated small eruptions emitting plumes with generally minor ash, Strombolian eruptions, and lava flows down two flanks. What follows summarizes reports from the Instituto Geofísico-Escuela Politécnica Nacional (IG).

The last paragraph of the main section of this report discusses an important temporal and spatial correlation made at the volcano on 23 April 2009. The IG correlated satellite thermal data and ground-based observations with high tremor and acoustical noise.

An IG daily report issued 8 August 2008 noted a lack of movement in the lava flows and the emission of gas plumes without ash. That night, glow was observed from the crater. On 18 August, amid rainy conditions, a possible lahar was noted. Except for ongoing seismicity, relative calm prevailed until early November.

The IG noted glow from the crater the night of 7 November, an observation confirmed in satellite thermal data. At 1900 on 8 November high-amplitude seismic signals saturated the seismic stations. Local observers saw an ash-and-steam column that evening to 2 km above the crater. The ash content was moderate. Another IG report noted that in the settlements of Chaco and Quijos residents could hear strong explosions and see gas plumes with low ash content. A pilot report stated the plume blew NW and reached an approximate estimated altitude of 7.6 km.

Special Report 6 (9 November) included a plot of seismicity since 1 February 2007 (figure 29). Long-period (LP) earthquakes began to dominate in March 2008 and the large spike around 8-9 November 2008 was outstanding compared to the recent pattern. Another larger spike in seismicity had been seen during mid-March 2007, but it was composed of volcano-tectonic (VT) earthquakes.

Figure 29. A histogram of daily seismicity for Reventador during 1 February 2007 to 8 or 9 November 2008. The plot includes harmonic tremor (TR. ARM.) and special kinds of tremor (TR. ESP.) in addition to more typically plotted event types (LP earthquakes, VT earthquakes, and hybrid (HB) earthquakes). Courtesy of IG (from their Special Report No. 6, issued 9 November 2008).

A follow up report on 11 November stated that Reventador had discharged moderate strombolian explosions on 9-10 November, with ongoing lava flows on the N and S flanks of the central cone. Both the summit eruptions and the flank flows were conspicuous at night.

SO2 emissions were clear in Aura/OMI imagery of 9 and 10 November (figure 30). About a day later, Reventador calmed considerably (with seismicity dropping strongly after 1000 on 11 November). The escalating activity drove IG to install two more seismometers, two infrasonic sensors, and a monitoring camera.

Figure 30. Spectroscopic measurements of SO2 taken by the Aura/OMI satellite on 9 November 2009 from eruptions at Reventador. The smaller plume to the N is from Galeras. Courtesy of Simon Carn and the OMI Sulfur Dioxide Group.

The IG's Special Reports of 10 and 11 November (Numbers 7 and 8) offered further information. Lava flows had descended to below 2,600 m elevation (the summit is at 3,562 m elevation but the vent elevation was not stated). During the night of 9 November incandescent ejecta rose 100 m above the crater, along with continuous roars and canon-shot noises. Although light ash fell in Cayambe on 9 November, other towns in the region had not been affected. Strombolian emissions had calmed some on the night of 10 November. After 1000 on 11 November, both gas emissions and seismicity calmed.

Seismicity increased starting on 15 December 2008, and remained elevated through 8 January 2009. During 3-8 January there were almost constant gas emissions (with ash contents moderate to low), small-to-moderate explosions, and tremor lasting several hours. The tremor was accompanied by roaring noises and the ejection of blocks that landed near the summit. Explosions and emission tremors were of variable intensity, causing windows in nearby towns to vibrate. Ash rose 2 km above the summit and drifted W, causing ashfall in the towns of El Manzano, Choglontus, Palictahua, and Cahuají.

After 8 January 2009, the IG reported the steady decrease of seismic activity. There were a few explosions and water vapor emissions with low ash content reaching heights of 1-1.5 km above the crater. These plumes drifted W and SW, with reported minor ashfall in the towns mentioned above. Associated with these emissions, observers heard sporadic roaring noises. Seismic activity continued to decrease during the latter part of January 2009 and into February 2009. Although in mid-February 2009 there was a mild increase in seismicity, overall the level remained low. A single observation revealed the presence of a small column of steam and gas.

During 16-22 February seismic activity remained low, with few seismic events and signals associated with fluid movements at depth. The number of rockfalls was significant, even compared to that seen during cooling of the lava flow from November 2008. During this week there were various episodes of harmonic tremor and explosions. During 23 February-15 March 2009 there was a slight increase in the number of low-intensity seismic events attributed to fluids at depth. There was a later decrease in seismicity

IG's 2009 Special Report Number 1 (26 March) noted a seismic increase on 26 March, which they again attributed to fluids moving within the volcanic edifice. After 1000 on the 26th, instruments detected a seismic swarm consisting of both LP and hybrid earthquakes, intercalated with banded tremor, the later of which had a 4-hour duration. From past experience, the IG inferred these signals could reflect the onset of new lava approaching the surface.

Special Report Number 2 (23 April) noted that later on the 26th the signals dropped off and remained low through at least early 23 April. Despite low seismicity, there were both episodes of banded tremor and intercalated LP earthquakes.

The tremor was of variable amplitudes, including some that saturated local seismic stations, particularly between 0500 and 0700 on 23 April 2009. On that day, a low, gas-rich cloud blew W from Reventador. Several residents living near the volcano also heard loud noises. A satellite-detected thermal hotspot on the volcano beginning at 0300 continued, with high intensity, between 0500 and 0700. The presence of the highest intensity thermal anomalies coincided with the highest tremor amplitudes and audible noises. Multiple MODVOLC thermal alerts were detected on 24-25 April and on 8 and 10 May 2009.

Information Contacts: Geophysical Institute (IG), Escuela Politécnica Nacional, Apartado 17-01-2759, Quito, Ecuador (URL: http://www.igepn.edu.ec/); Simon Carn, Dept of Geological and Mining Engineering and Sciences, Michigan Technological University, 1400 Townsend Dr., Houghton, MI 49931, USA (URL: http://www.volcarno.com/, http://so2.umbc.edu/omi/, Email: scarn@mtu.edu); Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://hotspot.higp.hawaii.edu/).
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09/2009 (BGVN 34:09) Lava flows seen and SO2 fluxes recorded during 16-17 September 2009

Activity at Reventador between August 2008 and late April 2009 was a period of generally low seismicity (BGVN 34:03). During early November 2008 repeated small eruptions occurred with steam-and-ash plumes, Strombolian eruptions, and lava flows. This report continues coverage through October 2009, an interval that included new lava flows advancing ~ 500 m by mid-September 2009.

Based on analysis of satellite imagery, the Washington Volcanic Ash Advisory Center (VAAC) reported that on 1 May a thermal anomaly over Reventador occurred along with a possible low plume drifting W. The Instituto Geofísico-Escuela Politécnica Nacional (IG) reported to the VAAC the presence of lava and gas emissions and possible smoke from burning vegetation, but little to no ash.

On 15 May, the IG observed an ash emission, although neither an ash signature nor a thermal anomaly was detected in satellite imagery. On 26 May, a diffuse ash plume rose to an altitude of 6.4 km and drifted SW. Thermal anomalies were intermittently seen on satellite imagery.

On 21 July-3 August, tremor was sporadic. On 4 August, seismicity increased and periods of tremor frequently saturated the seismic stations. Thermal anomalies, detected in satellite imagery on 1 and 2 August, became more intense on 4, 5, and 10 August. On 6 August, a steam plume rose 1.2 km above the crater and drifted W. Incandescent blocks were ejected from the crater and fell onto the flanks. Thermal images taken from a location 7 km E of Reventador revealed a linear area of higher temperatures, confirming the presence of a new lava flow on the S flank. Incandescence in the crater was seen on 9 August. According to the Washington VAAC, based on information from the IG, an ash plume on 15 August rose to an altitude of 3.6 km and drifted NW.

Field observations on 16-17 September 2009. IG scientists visited Reventador during 16-17 September 2009; among their objectives was to map, sample, and collect thermal images of the new lava flows and to measure the sulfur dioxide (SO2) concentrations with a mobile DOAS.

The team noted that recent lava flows had descended the flanks in a SE to E direction, continuing the same pattern that had begun with the 2005 eruption (figure 31). A dome within the crater showed constant growth (figure 32). Gas was emitted to a height of less than 200 m and drifted mainly W. A small lava flow originating in the dome area had descended ~ 500 m from the cone's S flank.

Figure 31. Panoramic view from the sequential camera of lava flows at Reventador. Courtesy of S. Vallejo.
Figure 32. At Reventador, a photo taken on 16-17 September 2009 of the actively growing dome in the summit crater. Courtesy of J. Bourquin.

Thermal images and SO2 measurements were collected near the caldera, and lavas were sampled. SO2 flux measurements (table 4) were collected both by helicopter and by car (figure 33). A telescope for the SO2 measurements sat below the helicopter blades and those spinning blades may have interfered with the measurements. The values presented may thus underestimate the SO2 fluxes.

Table 4. Reventador SO2 data collected from helicopter on 16 and 17 September 2009. The transects in the first column are indicated on figure 33. Transect 34 measurements clearly indicated that the SO2 gas plume had divided (bifurcated) and the two plumes appear as 34a and 34b. For this transect, the SO2 fluxes were calculated separately for each lava plume segment, than added to get the total emission. Land-based measurements, transects 43 and 46, were collected S and W of the vent. Courtesy of IG.

    Transect   Wind      Wind       Data    Offset   SO2 flux   Plume   Traverse   Intensity
     /Route    speed   direction   number             (t/d)     Width    Length      Limit
               (m/s)                                             (km)     (km)

    31          5        281        191      -28        811      1.9      52.2         7
    34a         5        270         95       -1      1,425      3.6      22.2         7
    34b         5        326        124       -8        795      2.5      49.2         7
    34 Total   --         --        215       --      2,220       --       --         --
    35          5        337         84      -28        616      1.6      22.8         5
    36          5        349        147      -16        557      2.1      30.2         8

    43          5        202        471      -14        283      5.2      42.8         5
    46          5        236       1222      -14      1,264      16       116          5
Figure 33. Map of Reventador illustrating transects made (in colored version, each transect is in a different color). Transects 31 and 34 were conducted on 16 September; transects 35, 36, 43 and 46 were conducted on 17 September. Courtesy of IG.

Based on a pilot observation, the Washington VAAC reported that on 21 September a plume rose to an altitude of 7.6 km. An ash plume on 4 October drifted W. In both cases, ash was not seen in satellite imagery, although meteorological clouds were present. In the latter case, an occasional thermal anomaly was observed.

Thermal anomalies over the crater area were detected in MODIS satellite imagery on 6, 11, and 13 October. On 13 October, the OMI satellite sensor indicated that the SO2 concentration in the atmosphere near the volcano had increased. On 14 October, seismicity increased and harmonic tremor was detected. A seismic station located at ~ 2,600 m elevation on the NE flank of the cone detected rockfalls. Several people living in the area reported roaring noises and had observed slight incandescence from the crater during the previous few nights.

During an overflight on 16 October, scientists saw the lava dome and a lava flow on the NE flank (figure 34). Bluish gases were being emitted. According to a thermal camera, the incandescent parts in the crater were about 300°C. Other observers heard roaring noises and sounds resembling "cannon shots." Incandescent blocks were ejected from the crater, and steam and gas rose 100 m and drifted SW. Incandescent material was seen on the S flank.

Figure 34. Aerial photo taken on the N side of Reventador on 16 October 2009 showing the lava dome amid weather clouds and some heavy steaming from the NE-flank lava flow. Courtesy of IG.

On 17 October, long period (LP) earthquakes and volcanic explosions lasting up to 10 hours were registered, incandescence on the S flank was noted, and noises similar to the previous day were again heard. A small gray plume was seen the next day. On 19 October, thermal anomalies were again detected on satellite imagery. During an overflight, blue gas plumes containing SO2 were seen (figure 35). The lava flow on the S flank occupied a large area and was divided into two branches.

Figure 35. Photograph of the E side of Revantador's cone taken the morning of 19 October 2009. Note steam rising from dome summit and lava flows on volcano's flanks. Courtesy of IG.

According to the IG, on 21 October, steam-and-gas plumes with little to no ash rose 2-4 km above the crater and drifted in various directions. An explosion that day ejected incandescent material from the crater and blocks rolled down the flanks. On 22 October, a few explosions generated ash-and-steam plumes that rose 4 km. Observations during an overflight revealed a small lava flow on the N flank and a larger flow with four branches on the S flank (figure 36). Part of the lava dome base had disappeared and small spines were present, especially on the S side of the dome. Thermal images revealed that material in the crater was 400°C and the lava-flow fronts were 250°C. Cloudy weather prevented visual observations during 23-26 October. Roaring noises were heard on 25 October.

Figure 36. Aerial photograph displaying the distribution of lava flows on the N side of Reventador's caldera on 22 October 2009. Courtesy of S. Vallejo.

Information Contacts: Geophysical Institute (IG), Escuela Politécnica Nacional, Apartado 17-01-2759, Quito, Ecuador (URL: http://www.igepn.edu.ec/); Washington Volcanic Ash Advisory Center, Satellite Analysis Branch (SAB), NOAA/NESDIS E/SP23, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: http://www.ssd.noaa.gov/VAAC/); Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), University of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://hotspot.higp.hawaii.edu/).
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03/2012 (BGVN 37:03) Dome growth; lava and pyroclastic flows; lahar takes bridge

Reventador discharged a series of small eruptions and lava flows during 2007-2009 (BGVN 33:04; 33:08; 34:03; and 34:09). Our last report (BGVN 34:09) discussed events through 26 October 2009. Since then seismicity generally remained moderate to low through at least April 2012, and ash emissions accompanying lava-dome growth intermittently occurred. Much of this report stems from work by the Instituto Geofísico-Escuela Politécnica Nacional (IG). The andesitic volcano contains a 4-km summit caldera that opens to form a large U-shaped scarp that funnels material SE (see map in BGVN 28:06). A VEI 4 eruption on 3 November 2002 (BGVN 27:11) occurred unexpectedly after a 26-year repose.

During this reporting interval, October 2009-April 2012, small plumes with occasional ash emissions accompanied dome growth (table 5). In August 2011, the top of the growing lava dome first reached the same height as the highest part of the rim. MODVOLC thermal alerts, which are satellite based using the MODIS instrument, were absent during 2011, possibly due to masking effects of cloud cover. The two tallest plumes noted in table 5 rose to approximately 7 km altitude. In addition, as discussed below in text, pyroclastic flows were also seen during the reporting interval. Lahars were common, including one that destroyed a bridge over a river on the SE flank on 25 May 2010.

Table 5. Summary of behavior and plumes at Reventador between mid-October 2009 and 18 April 2012. Some aspects of the October 2009 activity were previously reported (BGVN 34:09). Cloud cover frequently prevented observations of the volcano, and minor plumes may not have been recorded or were omitted. Heights above crater were converted to altitude by adding the summit elevation of 3.6 km. ‘-’ indicates data not reported. Data provided by the Instituto Geofísico-Escuela Politécnica Nacional (IG), the Guayaquil Meteorolgical Watch Office (MWO) in Ecuador, and the Washington Volcanic Ash Advisory Center (VAAC).

Date              Plume          Plume drift     Remarks               altitude (km)      direction                                                 On the 14th, increased seismicity and harmonic tremor.                                                 Residents during the middle of October heard roaring                                                   and booming noises and saw glowing.14, 16-17,                                       An IG field party saw a lava flow on the cone’s 19 Oct 2009          -                -            S flank on the 16th and 17th.                                                 An overflight on the 16th also revealed a lava flow on                                                   the N flank.                                                 On the 19th an areal infrared (FLIR) camera took images                                                   of S flank lava flows that covered a large area.                                                 A plume with little or no ash rose to 7.5 km altitude                                                   and drifted NW, W, and S.                                                 An explosion ejected glowing material from the crater                                                   and blocks rolled down the flanks.21-22                                            Aerial infrared observations again imaged the N flank lavaOct 2009             -                -            flow, and detected multiple lobes in the S-flank flows.                                                 A part of the lava dome’s base had been removed but                                                   the dome itself had gained some small spines, especially                                                   towards the S.                                                 Material near the crater had temperatures up to 400°C.5 Nov 2009           7                NE         Pilot report. Ash not seen in satellite imagery, although                                                   weather clouds were present.7 Nov 2009           4                -          -14 Nov 2009          -          10-20 km W, WNW  -20 Nov 2009          6.1              -          -18 Feb 2010          -                -          Ash not identified in satellite imagery.8 Apr 2010           4.6-6.7          W          Pilot report. Cloud cover prevented satellite observation.20-23                                            200 m long pyroclastic flow seen during IG flight on 20thApr 2010             4.9-5.5          S            (see text).                                                 Plume height and direction from aviation reports on 23rd.26 Apr 2010          4                -          -29 Apr 2010          -                -          Low ash content.7 May 2010           5.2              -          Pilot report. Cloud cover prevented satellite observation.8 May 2010           -                -          IG reported lahars including some that later destroyed a                                                   bridge over Marker river (see text).30 Aug 2010          -                -          Pilot report. Ash not seen in satellite imagery.9 Sep 2010           5.5              -          Pilot report.28 Sep 2010          5.6              NW         Ash fell on Reventador amid seismic episodes (see text).30 Sep 2010          -                NW         Satellite detected diffuse plume but no ash. IG reported                                                   ash over Reventador.6 Oct 2010           -                NE         Steam plume also emitted that day.2 Nov 2010           4.6              -          Cloud cover prevented satellite observation.4 Jan 2011           5.2              -          Ash not detected by satellite, and no reports of ashfall.                                                 IG later inferred extensive dome growth during 2011 (see text).                                                 An IG flight revealed the dome’s top had reached as high                                                   as the highest point on the rim (figure REV1).14 Jul 2011          -                -          Plumes were continuous though fumarolic (probably not ash bearing).                                                 Seismicity had started in May 2011 but became more pronounced                                                   around the start of July.3-9 Aug 2011         -                -          Cloud cover hid the lava dome but IG seismic instruments recorded                                                   both long-period and explosion earthquakes.6-7 Jan 2012         -                -          IG field inspection revealed constant steam-and-gas emissions from                                                   a lava dome that rose ten’s of meters above crater rim.11 Feb 2012          5.2              NW         Pilot report. IG noted that on the 12th, seismicity increased and                                                   a lava flow was detected on the NE flank.16 Feb 2012          -             19 km SE      Ash detected by satellite.18 Feb 2012          3.6              -          -26 Mar 2012          -             25 km NNW     -18 Apr 2012          5.6              NW         -

On 20 April 2010, IG scientists flying over Reventador saw an explosion that generated a pyroclastic flow. It traveled ~200 m down the S flank. Recent deposits from earlier pyroclastic flows were also seen on the same flank. Steam-and-gas emissions also continued. On 8 May 2010, IG noted a small lahar inside the caldera.

On 25 May a destructive lahar took place that was detected for 90 minutes by the seismic network. It traveled down the SE flank and destroyed a bridge over the Marker River, ~8 km SE of the summit area. The loss of the bridge disrupted travel along Route E45 between Baeza (~34 km SSW) to Lago Agrio (also called Nueva Loja, ~121 NE).

On 28 September 2010, IG recorded three seismic episodes from Reventador. Cloud cover prevented observations during the first episode. The second seismic episode was accompanied by a steam plume containing a small amount of ash that rose 400-500 m above the crater. The third episode occurred in conjunction with a steam-and-ash plume that rose 2 km above the crater. Ash fell on the flanks.

In May 2011, seismicity began to increase and became more pronounced by early July.

During an overflight on 14 July 2011, IG scientists noted that the lava dome at the top of the 2008 cone had continued to grow (figures 37 and 38). The dome had reached the same height, or higher, as the highest part of the crater rim formed during 2002 (figures 37 and 38). Intense fumarolic activity produced continuous plumes.

Figure 37. Annotated photo of Reventador taken looking NW on 14 July 2011. The green lines trace the topographic margin of the summit caldera initially formed in the sudden 2002 eruption. The conical structure outlined in orange is a scoria or tephra cone (which includes some lavas) and spills out of the breach toward the viewer. The red line outlines the dome, initially seen in 2004, that grew substantially in 2011. Courtesy of J. Bustillos/Instituto Geofísico-Escuela Politécnica Nacional.
Figure 38. Thermal image of Reventador crater for comparison with the visual image (figure 37), also taken 14 July 2011. The measured temperature of the growing dome was ~150°C. Courtesy of S. Vallejo/Instituto Geofísico-Escuela Politécnica Nacional.

During 3-9 August cloud cover prevented observations of the lava dome, but the seismic network detected long-period and explosion-type earthquakes.

During a field trip on 6-7 January 2012, IG staff observed constant emissions of gas and steam that originated from the growing lava dome. At this point in time the dome had broadened and stood a few ten’s of meters above the crater rim.

During 10-13 February 2012, IG detected new activity, including a thermal anomaly, an ash plume, and crater incandescence. This elevated activity continued during 15-21 February. Incandescence near the summit was again observed during 25-26 March but seismicity decreased around this time.

In accordance with these other observations, occasional MODVOLC thermal alerts were posted. Between 1 November 2009-1 April 2012, there were 12 days with MODVOLC thermal alerts. No thermal alerts were detected in 2011. As of 26 April 2012, six days in 2012 had thermal alerts (10, 13, 22, 26 February, 18 March, and 26 April).

Information Contacts: Instituto Geofísico-Escuela Politécnica Nacional (IG), Casilla 17-01-2759, Quito, Ecuador (URL: http://www.igepn.edu.ec); Guayaquil Meteorological Watch Office (MWO); Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS E/SP23, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: http://www.ssd.noaa.gov/VAAC/); Hawai'i Institute of Geophysics and Planetology (HIGP), MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://hotspot.higp.hawaii.edu/).
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06/2013 (BGVN 38:06) Lava dome's summit rises above rim in late 2012

Introduction. Our last report on Reventador covered activity through 26 April 2012 (BGVN 37:03) and this one covers activity through April 2013.

In its Special Report of 9 November 2012, Ecuador's Instituto Geofísico-Escuela Politécnica Nacional (IG) summarized the new phase of activity that began in February 2012. The Special Report noted that lava flows traveled as far as 2 km from the crater down the N and S flanks. Later reports noted that in November-December 2012, lava flows reached 1.3 km in length; in January 2013 they reached up to 1.1 km in length. During this reporting interval, ash plumes rose as high as 5.2 km altitude both in August 2012 and November 2013.

The lava dome in the interior of the crater continued to grow and between November 2012 and January 2013 established a new summit that reached to at least 100 m above the E rim, having completely filled the crater developed in November 2002. This enabled blocks from the lava dome to roll down the flanks.

Table 6.A non-comprehensive synthesis of Reventador's steam and ash plumes generated during the reporting period. Courtesy of IG and the Washington VAAC.

Date   Plume altitude OR height above (3.5 km a.s.l.) rim / direction / distance   Comments
11 Aug 2012 Ash plume rising to 5.2 km trended W  
20 Sep 2012 Ash plume drifted 22 km SW  
17-18 Oct 2012 Steam and gas plume rose to 1 km and trended W  
3-4 Nov 2012 Steam and ash plume rose to 3 km above the crater.  
5 Nov 2012 Steam and ash plume rose to 3 km; ash plume rose to 2 km and drifted NW  
13 Nov 2012 Gas and ash plume rose to 5.2 km and drifted SE  
16 Nov 2012 Ash plume rose to 4 km above the rim and drifted W and NW Ashfall reported between Reventador and El Chaco (35 km SSW)
22 January 2013 Gas and steam plume rose 1.5 km above the crater; white-to-light grey plumes rose 2 km and drifted W  
24 January 2013 Steam and ash plume rose 2 km  
29 January 2013 Gas plumes rose as high as 1 km and drifted NW and W  
29 January 2013 Overflight revealed steam and ash plume rising to 1.5 km above the lava dome;  
4 February 2013 Ash plume rose to 4 km and drifted NW  
7 February 2013 Ash plume rose to 3 km and drifted S  
2 March 2013 Ash plume rose to 4 km and drifted SW  
8 March 2013 Steam emission rose to 500 above the crater Glow reported
12 March 2013 Emission rose to 2 km and drifted W  
13 March 2013 Ash plumes rose to 3 km  
16 March 2013 Ash plume rose to 1 km and drifted W  
31 March 2013 Steam emission rose to 500 above the crater and trended W  
8 April 2013 Emissions reached to 3 km above the crater  
12 April 2013 Steam emissions reached to 2 km  

Between late April and early August 2012, activity at Reventador remained moderate, and although cloud cover often obscured visual observations, there were occasional reports of steam emissions rising to as high as 1 km above the crater. Long-period (LP) earthquakes occurred with moderate-to-high intensity, a behavior interpreted as the movement of fluids at depths. Seismic signals attributed to rock fall were also prominent, inferred to come from lava flows that descended the N flank, as aerial observers witnessed on both 29 May and 4 June.

Based on analysis of satellite imagery, the Washington Volcanic Ash Advisory Center (VAAC) reported that on 12 August they detected a well-defined thermal anomaly. Thermal images obtained in overflights carried out on 17 and 18 October 2012 revealed a lava flow that descended the flank of the cone and verified that another flow had descended during the preceding days or weeks and at the moment of observation was still warm. The flows did not exceed 1 km in length, and in light of their location within the crater, were not a danger to the public (figure 39).

Figure 39. A) On the left photo, the S flank of Reventador seen on 19 October 2012. A lava flow descending on the upper flank covered much of the flows from previous days and weeks. At right is a corresponding thermal image, permitting definition of the extent of the new hotter flows. Photo and image, courtesy of P. Ramon (Instituto Geofisico).

On 17 and 18 October, IG also verified the presence of a previously known lava dome within the crater, with steep slopes, the top of which was then the highest point of the volcano. Similar observations were carried out on 19 October by IGEPN technicians maintaining the monitoring network, who also stressed the continuous flow of lava blocks spilling off both the fronts of new flows and from the lava dome.

During 31 October-11 December 2012, the IG reported that although cloud cover often prevented visual observations, ash plumes were often seen.

Seismicity increased during this time period. Around 5 November, the seismic network detected an increase in the magnitude of volcanic tremor. IG reported that seismicity indicated falling rock and explosions during 14-15 November. Beginning 16 November IG's seismic network indicated a significant increase in tremor and in signals indicative of emissions and explosions. IG reported that scientists aboard an overflight on 23 November observed intense fumarolic activity and a new crater at the summit of the dome, which contained ash and large blocks. A thermal camera measured temperatures at the dome of ~ 300°C. Lava flows continued to be active on the dome flanks, and elongated block-and-ash deposits were also visible on the flanks. IG reported high seismicity during 5-11 December 2012, indicating multiple explosions almost daily. At least one lava flow was generated between November - December 2012 that descended the N flank to ~1.3 km in length.

2013. Throughout this January-April 2013 reporting period, cloud cover often prevented visual surface observations. The lava dome grew between November 2012 through January 2013 to at least 100 m above the E rim, completely filling the crater generated by the eruption of November 2002. Between November 2002 and 31 January 2013, ~ 20 lava flows had traveled down the N, SE, and S flanks, and affected zones within the caldera.

IG reported moderate seismicity during 16-21 January 2013. During the morning of 22 January seismicity, including tremor, increased significantly, signals indicating that rock falls were detected. Low frequency, high-energy tremor was detected by seismic stations around the volcano with an average of 20 seismic events and an average of 29 explosions. Explosions were heard. Lava flows traveled down the SW and N flanks. Observers reported lava fountains in the crater and lava flows on the flanks, both of which became more intense at 1800. Explosions produced white-to-light-gray plumes that rose 2 km and drifted W (figure 40).

Figure 40. Emission column seen late in the day on 22 January 2013 associated with the explosive activity at Reventador. Courtesy Walter Garcia Synohidro and Instituto Geofisico.

During the night of 22 January a lava flow descending the SE flank had reached a width of 350 m and extended at least 1.1 km (figure 41). Other smaller lava flows up to 200 m long were observed on the N and S flanks.

Figure 41. Thermal image of Reventador on 22 January 2013 shows the dome from which a lava flow descends to the SE. Courtesy S. Vallejo, Instituto Geofisico (IG-EPN).

During 23 January-7 February 2013 seismicity remained high. Lava flows were visible at night. Crater incandescence was observed at night during 29-30 January.

IG reported that seismicity became more moderate during 8-12 February; explosions were detected daily. Ashfall was reported in areas near the volcano on 9 February. Between 16-20 February, activity remained moderate, with continued ash emissions, but an absence of reported ashfall. For the remainder of February 2013, no reports of surface activity were received, and seismic signals ceased transmission.

According to the Washington VAAC, the IG reported that on 2 March lava flows were observed. IG reported that the seismic network recorded multiple explosions during 13-17 March. Observers reported falling and rolling incandescent material on Reventador's S flanks on 12 March. On 15 and 17 March explosions were detected by the seismic network. IG characterized activity as being at a moderate level for most of the remainder of March.

IG noted that moderate activity continued into April 2013 (table 6). Through 12 April seismicity remained moderate. On 15 April IG reported an increase in the number of seismic events. Seismic and surface activity remained moderate to high through 24 April, but became more moderate thereafter and remained so for the remainder of April 2013.

Information Contacts: Instituto Geofísico-Escuela Politécnica Nacional (IG), Casilla 17-01-2759, Quito, Ecuador (URL: http://www.igepn.edu.ec); and Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS E/SP23, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: http://www.ssd.noaa.gov/VAAC/).
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Reventador is the most frequently active of a chain of Ecuadorian volcanoes in the Cordillera Real, well east of the principal volcanic axis. The forested, dominantly andesitic Volcán El Reventador stratovolcano rises to 3562 m above the jungles of the western Amazon basin. A 4-km-wide caldera widely breached to the east was formed by edifice collapse and is partially filled by a young, unvegetated stratovolcano that rises about 1300 m above the caldera floor to a height comparable to the caldera rim. It has been the source of numerous lava flows as well as explosive eruptions that were visible from Quito in historical time. Frequent lahars in this region of heavy rainfall have constructed a debris plain on the eastern floor of the caldera. The largest historical eruption took place in 2002, producing a 17-km-high eruption column, pyroclastic flows that traveled up to 8 km, and lava flows from summit and flank vents.

Summary of Holocene eruption dates and Volcanic Explosivity Indices (VEI).

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
2008 Jul 27 2014 Sep 22 (continuing) Confirmed 2 Historical Observations
2007 Mar 15 ± 7 days 2007 Oct 11 (?) Confirmed 2 Historical Observations
2004 Nov 7 ± 3 days 2006 Mar Confirmed 2 Historical Observations
2002 Nov 3 2003 Jan 10 (?) Confirmed 4 Historical Observations Summit and SE flank (2600 m)
1976 Jan 4 1976 May Confirmed 2 Historical Observations
1973 Nov 1974 Jul Confirmed 3 Historical Observations
1972 Jul 1972 Sep Confirmed 2 Historical Observations
1960 Jun Unknown Confirmed 3 Historical Observations
1958 Nov Unknown Confirmed 3 Historical Observations
1955 Unknown Confirmed 2 Historical Observations
1944 Feb 24 1944 Mar 1 Confirmed 3 Historical Observations
1936 Aug 27 Unknown Confirmed 3 Historical Observations
1929 Unknown Confirmed 3 Historical Observations
1926 Jan 5 ± 4 days 1926 May Confirmed 3 Historical Observations
1912 Feb 1912 Mar Confirmed 3 Historical Observations
1898 Apr 8 1906 Confirmed 3 Historical Observations
1894 Unknown Confirmed 3 Historical Observations
1871 Jan 30 Unknown Confirmed 2 Historical Observations
1856 Dec 12 1856 Dec 13 Confirmed 3 Historical Observations
1844 Unknown Confirmed 3 Historical Observations
1843 Dec 7 Unknown Confirmed 3 Historical Observations
1843 (in or before) Unknown Confirmed 2 Historical Observations
1797 Jan Unknown Confirmed 3 Historical Observations
1691 Unknown Confirmed 3 Historical Observations
1590 Unknown Confirmed 3 Historical Observations Volcano Uncertain: possibly Antisana
1541 Apr Unknown Confirmed 3 Historical Observations

This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.


Synonyms

Reventador, El | Pisambilla

Domes

Feature Name Feature Type Elevation Latitude Longitude
Copete, El Dome
A steam plume, seen in a 1944 aerial view from the SE, rises above the summit crater of Reventador volcano. An eruption during February 24 to March 1, 1944 caused ashfall in the Andes and produced a lava flow down the Río Ouijos. The steaming El Reventador stratovolcano is nestled within the rim of an arcuate caldera that is breached widely to the east. It rises 1300 m above the caldera floor and is one of Ecuador's most active volcanoes.

Photo courtesy of Minard Hall (Escuela Politécnica Nacional, Quito), 1944.
The remote and inaccessible Reventador volcano rises above the jungles of the western Amazon basin. El Reventador, a young stratovolcano constructed within the 3-km-wide breached caldera of Volcán Reventador, is the most frequently active of a N-S chain of Ecuadorian volcanoes that lies well east of the principal volcanic axis. Fresh-looking lava flows descending from El Reventador extend east across the caldera floor in this late-1960s photo. Explosive eruptions during historical time have been visible from Quito.

Photo by Juan Elizalde (courtesy of Minard Hall, Escuela Politécnica Nacional, Quito).
The 1976 eruption of Reventador volcano began on January 4 with explosions that sent ash west over the Amazonian jungle. At the same time lava flows from the summit crater descended the eastern flank of the cone. They split into several lobes and reached a length of 3 km before stopping at the end of the 3rd week of the eruption. Pyroclastic flows began between the 2nd and 3rd weeks and continued for several months, traveling at speeds up to 135 km/hr across the caldera floor. The eruption ended in May.

Photo courtesy of Minard Hall (Escuela Politécnica Nacional, Quito), 1976.
An ash column rises above the summit crater of Reventador volcano during the 1976 eruption. This view across the north caldera rim in the foreground shows a small pyroclastic flow descending the flank of the summit cone into the clouds. Pyroclastic flows began between the 2nd and 3rd weeks of the eruption, which started on January 1. They originated from collapse of the vertical eruption column and traveled down the flanks of the volcano onto the floor of the breached caldera. Pyroclastic-flow activity continued for several months.

Photo by Minard Hall, 1976 (Escuela Politécnica Nacional, Quito).
The steaming summit crater of Reventador volcano in northern Ecuador is seen in this aerial view from the north on April 21, 2005. The black area in the center of the crater is a new lava dome that began growing inside the crater during an eruption that had begun in November 2004. Lava flows from the crater periodically descended a notch in the far crater wall and flowed down the southern flank of the cone. Conical Sumaco volcano is seen in the background.

Photo by Patricio Ramon, 2005 (Instituto Geofisca, Escuela Politecnica Nacional).
A steam-and-gas plume rises from the central cone of Reventador volcano in this March 11, 2005 aerial view from the SE. Several lava flows generated during eruptions in 2002 and 2004-2005 are visible on the south and SE flanks of the central cone. The 3562-m-high central cone was constructed within the large 4-km-wide horseshoe-shaped caldera breached to the east (lower right). The caldera was formed during a major collapse of the volcano, which produced a massive debris avalanche that swept into the Amazon basin.

Photo by Patricio Ramon, 2005 (Instituto Geofisca, Escuela Politecnica Nacional).

The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title.

Almeida E, Cruz M, 1986. Estudio geologico del Volcan Reventador. Inst Ecuatoriano Electrificacion (INECEL), Quito, unpublished rpt, 43 p.

Hall M L, 1977. El Volcanismo en El Ecuador. Quito: Biblioteca Ecuador, 120 p.

Hall M L, 1980. El Reventador, Ecuador, un volcan activo de los Andes septentrionales. Rev Politecnica, Quito, 5: 123-136.

Hall M L, 1987. . (pers. comm.).

Hall M, Ramon P, Mothes P, LePennec J L, Garcia A, Samaniego P, Yepes H, 2004. Volcanic eruptions with little warning: the case of Volcan Reventador's surprise November 3, 2002 eruption, Ecuador. Rev Geol Chile, 31: 349-358.

Hantke G, Parodi I, 1966. Colombia, Ecuador and Peru. Catalog of Active Volcanoes of the World and Solfatara Fields, Rome: IAVCEI, 19: 1-73.

Johnson J, Ramon P, Andrade D, Hall M L, 2006. Reventador volcano: 2002 to present, explosive and effusive activity. Cities on Volcanoes 4, Quito, Ecuador, 23-27 Jan, 2006, Field trip A5: 1-15.

Samaniego P, Eissen J-P, Le Pennec J-L, Robin C, Hall M L, Mothes P, Chavrit D, Cotten J, 2008. Pre-eruptive physical conditions of El Reventador volcano (Ecuador) inferred from the petrology of the 2002 and 2004-2005 eruptions. J Volc Geotherm Res, 176: 82-93.

Volcano Types

Stratovolcano
Caldera
Lava dome(s)

Tectonic Setting

Subduction zone
Continental crust (> 25 km)

Rock Types

Major
Andesite / Basaltic Andesite
Basalt / Picro-Basalt
Dacite

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km
484
963
4,403
2,619,647

Affiliated Databases

Large Eruptions of Reventador Information about large Quaternary eruptions (VEI >= 4) is cataloged in the Large Magnitude Explosive Volcanic Eruptions (LaMEVE) database of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).
WOVOdat WOVOdat is a database of volcanic unrest; instrumentally and visually recorded changes in seismicity, ground deformation, gas emission, and other parameters from their normal baselines. It is sponsored by the World Organization of Volcano Observatories (WOVO) and presently hosted at the Earth Observatory of Singapore.
EarthChem EarthChem develops and maintains databases, software, and services that support the preservation, discovery, access and analysis of geochemical data, and facilitate their integration with the broad array of other available earth science parameters. EarthChem is operated by a joint team of disciplinary scientists, data scientists, data managers and information technology developers who are part of the NSF-funded data facility Integrated Earth Data Applications (IEDA). IEDA is a collaborative effort of EarthChem and the Marine Geoscience Data System (MGDS).
Smithsonian Collections Search the Smithsonian's NMNH Department of Mineral Sciences collections database. Go to the "Search Rocks and Ores" tab and use the Volcano Name drop-down to find samples.