GALERAS Colombia 1.22°N, 77.37°W; summit elev. 4,276 m; All times are local (= UTC - 5 hours) Reports from 2004: | July | August | September | October | November | Reports from 2005: | January-February | May | June | July | August | November | December| Reports from 2006: | January | February | March | April | May | Galeras Eruptive History Information from the USGS Global Volcanism Program (Oldest to Newest) "Report provided courtesy of the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program." -------------------------------------------------------------------------------- 21-27 July 2004 Based on information from IG, the Washington VAAC reported that an activity increase at Galeras during several days prior to 24 July consisted of emissions that rose ~600 m above the volcano's summit. Ash was not visible on satellite imagery. According to a news report, a wide area around the volcano was declared off limits to visitors. Sources: Washington VAAC, Associated Press -------------------------------------------------------------------------------- 28 July- 3 August 2004 Satellite imagery showed a faint ash plume emitted from Galeras on 29 July around 0745. The height and direction of the plume was unknown. Source: Washington VAAC -------------------------------------------------------------------------------- 4-10 August 2004 According to the Washington VAAC, several ash plumes emitted from Galeras were visible on satellite imagery during 7-10 August. The highest rising plume reached about 6 km a.s.l. Source: Washington VAAC -------------------------------------------------------------------------------- 11-17 August 2004 INGEOMINAS reported that volcanic and seismic activity increased at Galeras on 11 August at 2349 when an eruption began that sentan ash-and-gas cloud to an unknown height and generated visible incandescence. According to the Washington VAAC, satellite imagery showed that an ash plume rose to a height of ~10.7 km a.s.l. It spread in all directions, but mainly to the NE, E, and SW. Later in the day, a thin plume at a height of ~7.3 km a.s.l drifted SW into northern Ecuador. A plume also drifted NW at a height of ~6.1 km a.s.l. By 1315 ash was no longer visible on satellite imagery. Fine ash was deposited in villages near the volcano including, La Florida (~10 km NW of the volcano), Nariño, Sandoná, and Consacá, and farther afield in Ancuya, Linares, and Sotomayor (~ 40 km NW of the volcano). News articles reported that ~230 families were evacuated mainly from the volcano's N flank. Ash contaminated potable water in some villages, impacted farm animal's health, and left hundreds of dead fish floating in rivers. The village of La Florida was most strongly impacted by the eruption. On 16 August, ash emissions continued, depositing ash in several villages. A thin plume was visible on satellite imagery extending ~75 km NW. Sources: Instituto Colombiano de Geología y Minería, Washington VAAC, El Spectador, El Pais -------------------------------------------------------------------------------- 18-24 August 2004 INGEOMINAS reported that gas-and-ash emissions continued at Galeras as of 18 August. Ash fell in villages near the volcano, including La Florida, Sandoná, El Ingenio (within 15 km of the volcano), and farther afield in Samaniego and Sotomayor (between 20 and 40 km from the volcano). Sources: Instituto Colombiano de Geología y Minería, Washington VAAC -------------------------------------------------------------------------------- 25-31 August 2004 INGEOMINAS reported that at Galeras during 19 August to 1 September, there was a decrease in the level of seismicity and the number of ash emissions. Gas-and-steam emissions continued. Source: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 22-28 September 2004 During 23-27 September, tremor associated with ash-and-gas emissions was recorded at Galeras. On the 23rd, ash deposits were seen on the upper portions of the volcano's N flank. By the 27th the amount of tremor had decreased significantly, which may have coincided with a decrease in ash emissions. Source: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 6-12 October 2004 During 8-11 October, emissions of gas and fine ash continued at Galeras. Plumes rose to a maximum height of ~1.5 km above the volcano. Small-amplitude tremor associated with gas-and-ash emissions was recorded. Source: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 17-23 November 2004 Galeras volcano erupted explosively on 21 November at 1544, Instituto Colombiano de Geología y Minería reported. The eruption produced a shock wave felt as far away as Cimarrones (18 km N of the volcano), Chachagui (17 km N of the volcano), and Laguna de La Cocha (20 km SW of the volcano). Effects of the shock wave varied from a loud roar, to the vibration of large windows, to the feeling of an earthquake. Ballistic rock blocks were expelled and fell nearly 3 km from the volcano on its eastern flank, producing short-lived forest fires. The eruption produced an ash-and-gas column that rose to an estimated height of 9-10 km a.s.l and drifted to the S and W. The Washington VAAC reported that satellite imagery through 2015 on 21 November revealed that high level ash estimated to be near 9 km a.s.l had moved to the W, while low level ash estimated to be near 4-5 km a.s.l remained in the vicinity of the summit of the volcano and showed little motion. Sources: Instituto Colombiano de Geología y Minería, Washington VAAC -------------------------------------------------------------------------------- 26 January- 1 February 2005 During 25-31 January, low-level relatively shallow seismicity continued at Galeras, and a small amount of deformation towards the W portion of the volcanic cone occurred. On 30 January an emission of gas and ash rose ~800 m above the volcano. Sources: Instituto Colombiano de Geología y Minería, Washington VAAC -------------------------------------------------------------------------------- 2-8 February 2005 During 31 January to 7 February, small gas-and-ash emissions continued at Galeras. Ash was deposited in the sectors of Consacá (~15 km W of the volcano) and La Florida (~10 km NW), and in the city of Pasto (~ 10 km E). Low-level seismicity and a small amount of deformation were recorded. Sources: Instituto Colombiano de Geología y Minería, Washington VAAC -------------------------------------------------------------------------------- 18-24 May 2005 According to a news article, on 24 May the Colombian government ordered the evacuation of ~9,000 people living near Galeras due to an increase in volcanic activity. INGEOMINAS reported that during 16-23 May, small shallow earthquakes occurred beneath the volcano. There was an increase in earthquakes associated with fracturing within the volcano during the night of 21 May to the morning of 22 May. Gas emissions slightly decreased on 17 and 20 May in comparison to 29 April and 2 May, and slightly increased around 23 May. Deformation continued to be recorded at the volcano's summit. There were no ash emissions. Galeras remained at Alert Level 2 (probable eruption in terms of days or weeks) as it has since 19 April 2005. Sources: Instituto Colombiano de Geología y Minería, Reuters -------------------------------------------------------------------------------- 1-7 June 2005 During 30 May to 6 June, there was a decrease in seismicity and deformation at Galeras in comparison to the previous week. The number and magnitude of earthquakes decreased and there were smaller changes in deformation. The level of alert was decreased from 2 (probable eruption in days or weeks) to 3 (changes in the behavior of volcanic activity have been noted). Sources: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 8-14 June 2005 At Galeras during 6-13 June, there were low levels of seismicity, small amounts of deformation, and moderate gas emissions from the main crater. The alert remained at level 3 (changes in the behavior of volcanic activity have been noted). Sources: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 6-12 July 2005 During 4-11 July, seismicity remained at low levels at Galeras. An M 2.5 volcano-tectonic earthquake on 4 July was felt in sections of some towns near the volcano. During the report period, small amounts of deformation were recorded and low rates of gas discharge were noted. Sources: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 10-16 August 2005 During 8-15 August, seismicity remained at low levels at Galeras and small amounts of deformation were recorded. The Alert Level remained at 3 (changes noted in the behavior of volcanic activity). Sources: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 17-23 August 2005 During 19-21 August, 30 volcano-tectonic earthquakes were recorded at Galeras. The earthquakes occurred 3-4 km NW of the volcano's active cone, near the towns of Santa Bárbara, Nariño, and La Florida. About five earthquakes felt by nearby populations occurred at depths of 8-6 km, with the largest (M 4.7) occurring at a depth of 6 km on 21 August. No significant deformation was observed at the volcano during the report period, and gas emission continued from the main and secondary craters. Sources: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 24-30 August 2005 Volcano-tectonic earthquakes that began at Galeras around 19 August continued through 29 August. The earthquakes occurred at depths of 5-8 km and reached M 4.6. No surficial changes were observed at the volcano. Sources: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 2-8 November 2005 During 31 October to 7 November, low-level seismicity occurred at Galeras, including several tornillo earthquakes (long-period seismic events related to pressurized fluid flow at shallow depth). In addition, small amounts of deformation were recorded at the volcano. Galeras remained at Alert Level 3 (changes in the behavior of volcanic activity have been noted). Sources: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 9-15 November 2005 INGEOMINAS reported that during 9-14 November, a large number of tornillo earthquakes (long-period seismic events related to pressurized fluid flow at shallow depth) continued to occur below Galeras. In the previous 2 weeks, 25 tornillos were recorded. The earthquakes had characteristics similar to those that occurred before eruptions in 1992-1993. A small amount of deformation was recorded at Galeras during the report period. Activity in the previous month suggested that the volume of magma beneath the volcano was greater than that inferred to have been present during the 1992-1993 eruptions. Due to the increased activity at Galeras, the Alert level was raised from 3 (changes in the behavior of volcanic activity have been noted) to 2 (probable eruption in days or weeks). According to new reports, on 14 November local authorities recommended the voluntary evacuation of as many as 9,000 people living in towns near the volcano, including in parts of Pasto (to the W), La Florida (to the N), and Nariño (to the N). Sources: Instituto Colombiano de Geología y Minería, El Tiempo, IOL News -------------------------------------------------------------------------------- 16-22 November 2005 Heightened seismic activity continued at Galeras during 16-22 November. According to news articles, only ~1,000 of the ~9,000 residents who were ordered to evacuate had left as of 18 November. Sources: Instituto Colombiano de Geología y Minería, Associated Press -------------------------------------------------------------------------------- 23-29 November 2005 On 24 November at 0246 seismicity was recorded at Galeras that was associated with the beginning of an eruption. Ash from the eruption fell in the towns of Fontibon, San Cayetano, Postobon, and in north Pasto (E of the volcano). INGEOMINAS raised the Alert Level from 2 (probable eruption in days to weeks) to 1 (eruption imminent or occurring). The Washington VAAC observed a small puff of ash NE of the volcano at a height around ~4.6 km (15,000 ft) a.s.l. Activity decreased by the next day, so the Alert Level was reduced to 2. Thousands of people had been evacuated from the vicinity of the volcano during the week prior to the eruption. Sources: Instituto Colombiano de Geología y Minería, Associated Press, Reuters -------------------------------------------------------------------------------- 30 November-6 December 2005 The hazard status at Galeras was at Level III as of 5 December. Low levels of seismicity and deformation were continuing. Although poor weather conditions obscured the volcano most of the time, steam and gas emissions were photographed on 2 December coming from several locations on the active cone, including the main crater. The plume rose 1 km above the summit on 3 December. Sources: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 7-13 December 2005 Due to a decrease in volcanic activity at Galeras, on 28 November INGEOMINAS reduced the Alert Level at the volcano from 2 (probable eruption in days to weeks) to 3 (changes in the behavior of volcanic activity have been noted). Through 12 December, seismicity was recorded that was indicative of fluids moving within the volcano, small changes in deformation occurred, and emitted gas rose to a height of ~500 m above the volcano (or 15,700 ft a.s.l.). Source: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 21-27 December 2005 Based on information from the US Geological Survey, the Washington VAAC reported that a pilot observed an ash plume from Galeras on 23 December at a height of ~7.3 km (24,000 ft) a.s.l. drifting W. Source: Washington Volcanic Ash Advisory Center -------------------------------------------------------------------------------- 28 December 2005- 3 January 2006 During 23 December to 2 January, Galeras emitted gas and small amounts of ash. On the 23rd, four events produced ash plumes that rose to ~3 km above the volcano (or 23,900 ft a.s.l.) and drifted toward the sector of Consacá, ~13 km WSW. A cluster of 33 volcano-tectonic earthquakes occurred beneath the volcano's crater during 29-30 December. The earthquakes reached a maximum magnitude of 1.2. The sulfur-dioxide flux at the volcano varied between 300 and 1,500 tons per day. Galeras remained at Alert Level 3 ("changes in the behavior of volcanic activity have been noted"). Source: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 4-10 January 2006 During 2-9 January, Galeras emitted gas and small amounts of ash. In addition, heightened seismicity continued and small changes in deformation were measured. The sulfur-dioxide flux from the volcano varied between 490 and 1,500 metric tons per day. Galeras remained at Alert Level 3 ("changes in the behavior of volcanic activity have been noted"). Source: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 11-17 January 2006 During a flight over Galeras on 13 January, scientists saw a lava dome in the volcano's main crater. Around this time, there was an increase in the amount of seismicity and deformation. Galeras remained at Alert Level 3 ("changes in the behavior of volcanic activity have been noted"). Source: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 25-31 January 2006 During 23-30 January, a lava dome continued to grow in the main crater of Galeras, and strong degassing occurred in several areas of the active cone and around the dome. Seismicity continued that was associated with the movement of fluid within the volcano, and slight deformation was recorded. Galeras remained at Alert Level 3 ("changes in the behavior of volcanic activity have been noted"). Source: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 1-7 February 2006 During 30 January to 6 February, seismicity continued at Galeras, with an average of 200 small earthquakes occurring per day. In addition, slight deformation was recorded at the volcano. A flux of about 300 metric tons of sulfur dioxide was measured per day. Strong degassing occurred in several sectors of the active cone and around the lava dome. Steam rose to ~900 m above the volcano (or ~17,000 ft a.s.l.). Galeras remained at Alert Level 3 ("changes in the behavior of volcanic activity have been noted"). Source: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 8-14 February 2006 INGEOMINAS reported on 10 February that a lava dome was growing inside the main crater of Galeras. The lava dome was not seen during the previous observation flight on 16 January. Seismicity was dominated by long-period earthquakes, with an average of 150 occurring daily during 13 January to 8 February. On 5 February, strong degassing was visible from different parts of the active cone and around the lava dome. Cracks were visible on the high parts of the lava dome. During a field visit on 8 February, scientists found fall material [originally incorrectly reported in the WVAR as pyroclastic-flow deposits] high on the SE flank of the volcano. The exact date of the small emission was not known, but it occurred after 26 November when scientists previously visited the area. Galeras remained at Alert Level 3 ("changes in the behavior of volcanic activity have been noted"). Source: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 15-21 February 2006 During 13-20 February, seismicity continued at Galeras, with an average of about 190 small earthquakes occurring per day. A flux of about 200 metric tons of sulfur dioxide was measured daily. Steam and gas rose to ~1.1 km above the volcano (or ~17,600 ft a.s.l.) on 19 February. Incandescence was visible at parts of the lava dome. The volume of the lava dome in the main crater was approximately 1.5 times larger than when it was first observed on 13 January. Galeras remained at Alert Level 3 ("changes in the behavior of volcanic activity have been noted"). Note: It was incorrectly reported in the 8-14 February Weekly Volcanic Activity Report that on 8 February pyroclastic-flow deposits were found at Galeras. Pyroclastic-fall deposits were observed. Source: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 22-28 February 2006 During 20-27 February, seismicity continued at Galeras, with an average of 280 small earthquakes occurring per day. On 26 February seismic stations detected a cluster of earthquakes. A shallow M 4.8 volcano-tectonic earthquake was registered below the volcano at 1009, followed by 35 smaller earthquakes. Slight deformation was recorded at the volcano. A flux of about 600 metric tons of sulfur dioxide was measured per day. Steam and gas rose to ~700 m above the volcano (or 16,300 ft a.s.l.). Galeras remained at Alert Level 3 ("changes in the behavior of volcanic activity have been noted"). Source: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 1-7 March 2006 During 27 February to 6 March, there were variations in the rate of degassing at Galeras and an increase in the volume of the lava dome located in the main crater in comparison to the previous week. Galeras remained at Alert Level 3 ("changes in the behavior of volcanic activity have been noted"). Source: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 15-21 March 2006 During 13-20 March, seismicity at Galeras decreased in comparison to previous weeks and deformation was measured at the volcano. Plumes of mainly steam, gas, and small amounts of ash were emitted from the volcano and rose to a maximum height of 1.2 km above the volcano (or 18,000 ft a.s.l.). Galeras remained at Alert Level 3 ("changes in the behavior of volcanic activity have been noted"). Source: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 22-28 March 2006 Due to an increase in tremor at Galeras beginning on the morning of 28 March, INGEOMINAS raised the Alert Level from 3 ("changes in the behavior of volcanic activity have been noted") to 2 ("likely eruption in days or weeks"). On the 28th, energetic signals and tremor began that had been absent during previous weeks. In addition, seismic instruments detected very shallow low-energy hybrid signals, similar to ones recorded during 1991-1993 when dome emplacement occurred on the main crater's floor. Sources: Instituto Colombiano de Geología y Minería, Reuters -------------------------------------------------------------------------------- 29 March-4 April 2006 An increase in the energy of earthquakes at Galeras, which began on 28 March, ended on the 29th. The number of earthquakes beneath the volcano decreased during 28 March to 3 April (an average of 66 earthquakes was recorded daily), in comparison to the previous week (an average of 89 earthquakes was recorded daily). During the report period, steam columns rose up to ~500 m above the volcano (or 15,700 ft a.s.l.) and the outer layer of the lava dome at the volcano's summit cooled in comparison to previous weeks. Galeras remained at Alert Level 2 ("likely eruption in days or weeks"). Source: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 5-11 April 2006 INGEOMINAS reported that Galeras remained at a critical state during 5-10 April, with a partially solidified lava dome in the main crater. Decreases were observed in various measured parameters at the volcano, including seismicity, deformation, gas emissions, and temperatures. According to INGEOMINAS, most of the explosive eruptions at Galeras in the past 17 years occurred when parameters were at similarly low levels. In addition, the current lava dome has a significantly greater volume than the dome that was destroyed during an eruption in 1992. Also, the volume of magma in the interior of the volcanic system is greater than during 1989-1993. Galeras remained at Alert Level 2 (likely eruption in days or weeks). Source: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 12-18 April 2006 INGEOMINAS reported that Galeras remained at a critical state during 10-17 April, with a partially solidified lava dome in the main crater. Seismicity continued to decrease, with an average of 70 small earthquakes occurring at the beginning of the report week, and an average of 45 occurring at the end of the week. In addition, there were small gas emissions from the volcano. Galeras remained at Alert Level 2 (likely eruption in days or weeks). Source: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 19-25 April 2006 INGEOMINAS reported that Galeras remained at a critical state during 18-24 April, with a partially solidified lava dome in the main crater and low levels of seismicity. Galeras remained at Alert Level 2 (likely eruption in days or weeks). Source: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 26 April to 2 May 2006 INGEOMINAS reported that Galeras remained at a critical state during 21 April to 1 May, with a partially solidified lava dome in the main crater and low levels of seismicity. The sulfur-dioxide flux continued at low levels. Galeras remained at Alert Level 2 (likely eruption in days or weeks). Source: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 3-9 May 2006 INGEOMINAS reported that Galeras remained at a critical state during 1-8 May, with a partially solidified lava dome in the main crater and low levels of seismicity. The sulfur-dioxide flux continued at very low levels. Galeras remained at Alert Level 2 (likely eruption in days or weeks). Source: Instituto Colombiano de Geología y Minería -------------------------------------------------------------------------------- 10-16 2006 INGEOMINAS reported that during 9-15 May, a partially solidified lava dome remained in Galeras' main crater. Seismicity and the sulfur-dioxide flux continued at low levels. Gas and sporadic ash emissions rose to low levels. Galeras remained at Alert Level 2 (likely eruption in days or weeks). Source: Instituto Colombiano de Geologia y Mineria -