HR: 1400h
AN: V33A-05    [Abstracts]
TI: Emplacement of the Pyroclastic Flows during the 2004-2005 Activity in the Volcan de Colima, Mexico.
AU: * Vargas Gutierrez, V R
EM: volcanovictor@hotmail.com
AF: Centro de Geociencias.UNAM.Juriquilla, Carretera Queretaro-San Luis Potosi, km 15.5, Queretaro, Qro 76230, Mexico
AU: Carrasco Nunez, G
EM: gerardoc@geociencias.unam.mx
AF: Centro de Geociencias.UNAM.Juriquilla, Carretera Queretaro-San Luis Potosi, km 15.5, Queretaro, Qro 76230, Mexico
AU: Varley, N
EM: nick@ucol.mx
AF: Facultad de Ciencias.Universidad de Colima, Bernal Diaz del Castillo No.340 Col. Villa San Sebastian., Colima, Col 28045, Mexico
AB: During its 2004-2005 activity, Volcan de Colima, Mexico produced several pyroclastic flows (PF´s) formed by first an unstable lava dome and then explosive activity. The initial large pyroclastic flow occurred on 06 October 2004, when the large and fast growing andesitic lava dome collapsed towards the southwest flank of the volcano in Barranca La Lumbre.During 2005, the largest episode of pyroclastic flows since the last plinian explosion in 1913, was a product of column collapse of various vulcanian explosions. Between 12 February 2005 and during April at least 7 pyroclastic flow events emplaced meanly in the upper section of the Barranca Montegrande, on the south side of the volcano. After these events the explosive activity increase significantly and on the 15 May 2005 a large vulcanian explosion produced a PF that travelled further than 5 km from the summit, modifying the original topography of the ravine, but the following event on the 30 May was the largest seismically until that moment. On 5th June, the largest explosion to happen in at least the past 20 years, generated flows that travelled more than 5 km and almost filled the upper section of the Barranca Montegrande and San Antonio. On 9th June a change in the principal direction of emplacement occurred when new pyroclastic flow deposition occurred in the Barranca La Arena, located in the southeast section of the volcano The pyroclastic flow front reached 5.40 km. Around one month later (5th July) a smaller deposit emplaced again meanly in La Arena and as a reduced proportion in Montegrande. The next months continued with a decreasing activity and generation of minor PF´s during September and probably December of 2005. During February to July 2005 a total pyroclastic flow volume of 6x10⁶ m³ was generated.The understanding of the behaviour of a pyroclastic flow with its emplacement characteristics and sedimentological pattern and beyond that, the textural, petrography and geochemical variation could give us the opportunity to understand the tendency of the activity in the Volcan de Colima during the next years.
DE: 8404 Volcanoclastic deposits
DE: 8414 Eruption mechanisms and flow emplacement
DE: 8419 Volcano monitoring (7280)
DE: 8428 Explosive volcanism
SC: Volcanology, Geochemistry, and Petrology [V]
MN: 2007 Joint Assembly