- View All
For Reporting Year
Submitted by Tobias Fischer, October 2015
Galeras' last activity cycle started with a first episode on August 11th 2004 followed by a second event less than one hour later, erupting ash volume of about 1.2 million cubic meters. Pasto Volcanological and Seismological Observatory reported (http://intranet.ingeominas.gov.co/pasto/Boletines_mensuales) an emplaced dome in the main crater at Galeras volcano with a volume of 700,000 cubic meters, which was observed from helicopter on January 13th 2006.
Sulphur dioxide fluxes have been measured at Galeras volcano since November 2007 until July 2012 and an ash eruption registered on January 17th 2008. The eruption was followed by an SO2 increase beginning in the second half of 2008 reaching values up to of 13,600 tonnes per day. Increases of sulphur dioxide fluxes from fumaroles at Galeras volcano in 2008 can be explained as a magma intrusion based on the relative high solubility of sulphur gases in the volume of Galeras magmas. Movement from the depth to the surface of relative high volume of Galeras magma will facilitate sulphur dioxide exsolution with decrease of lithostatic pressure reaching the surface with more and more open fractured conditions. Since February 14th till January 2nd 2010 ten explosive eruptions destroyed the dome. Just after the high SO2 emissions in 2008 a sealing process occurred in Galeras, which reduced gas flows into the atmosphere and therefore increased the internal pressurization of the volcanic chimney. Product of this high pressurization in the Galeras conduits were the consecutive eruptions since 2009.