Eruptive HistoryEruptions at Galeras are typically of Andesitic composition and characterized as Vulcanian-style. Carbon dating places an age date of approximately 5,000 years on the active cone. During this time, Galeras has experienced six periods of activity, in which 45 separate volcanic events consisting of pyroclastic flows, tephra falls, lava flows, and lahars have been documented. The stratigraphy around the volcano records the most prominent activity of the volcano to be pyroclastic flows and is what makes up the most bulk of the hazards surrounding the volcano (Artunduaga, 1997).
Eruption in 1993 After 10 years of dormancy, in 1988 Galeras became active. In 1993, during a Decade Volcano conference that was being held in Pasto, Colombia, an eruption occurred without warning. Tragically,a group of tourists and scientists had ventured into the caldera and during the eruption six scientist and three tourists were killed. The event remains controversial to this day, because the expedition leader, reportedly ignored data that showed there may be a possible eruption (Baxter, 1997). Figure 5: The active cone with steam clouds escaping from the vent, as seen from the south. Photo by Norm Banks, 1989 (USGS). Retrieved from: http://www.volcano.si.edu/world/volcano.cfm?vnum=1501-08=&volpage=photos&photo=043076
Other Documented Eruptions
1535, December 1580, July 1616, 1641, 1670, 1754, November 1796, June 1823, October 1828, 1834, October 1865, July 1889, 1891, December 1923, October 1924, October 1932, February 1936, July 1947, January 1950, 1974, February 1989, January 1990. Reported incidents with no official proof occurred in 1836, 1930, 1933, and 1973 ( Vervaek, 2012). Eruption Documented on Webcam, January 17th, 2008
(Retrieved from http://www.astrogeodata.it/id310.htm) Figure 7: Beginning of eruption 20:06:03, local time.
Figure 8: Eruption continues 20:06:25, local time.
Figure 9: Eruption continues 20:06:36, local time.
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Figure 4: Photo of a large eruption at Galeras on August 27, 1936 Photo courtesy of Marta Calvache, 1936 (INGEOMINAS-Observatorio Vulcanológico del Sur)
Eruptions 2000-2010
After a period of roughly seven years of dormancy, Galeras returned to life in March of 2000. A VEI 1 eruption occurred at the central vent, that was questionably phreatic. Again, in 2002 the volcano produced the same style eruption. In 2004, a VEI 3 eruption took place, which was also centered at the main vent. This eruption was explosive and forced local residents to evacuate, and only caused land and property damage. A lava dome began extruding in November of 2005, which led to an VEI 2 eruption and more evacuations. In 2007 and 2008 the volcano experienced a VEI 3 and in 2010 a VEI 2 eruption. These ost recent eruptions were explosive and were centered around the main vent. Throughout 2011, the volcano experienced increased seismic activity and SO2 emission, but did not produce an eruption. Since 2011, the volcano has been characterized by fluctuating seismicity, SO2 emissions and increased inflation near the central vent. There have been various ash and steam plumes that have risen between 500-1000m since mid-September (Smithsonian institution global volcanism program, n.d.). Figure 6: Thermal images of Galeras, retrieved from reconnaissance missions by INGEOMINAS on December 6th, 2012. In the FLIR image on the right, three maximum temperatures were captured: 116.8°C, 98.7°C, and 74.4°C. Image courtesy of INGEOMINAS. Retrieved from: http://www.volcano.si.edu/reports/bulletin/contents.cfm?issue=3704&display=complete
Figure 10: Steam plume emanating from Galeras on February 15th, 2007. Picture was taken from the town of Pasto, Colombia. Retrieved from: http://en.wikipedia.org/wiki/File:Volcán_Galeras_-_Pasto_-_Colombia.jpg
Figure 11: Image of the central vent of Galeras on August, 25th, 2010. Retrieved from: http://www.headlines24x7.com/general/colombia-announces-red-alert-after-the-galeras-volcano-erupted
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