Late-Pleistocene flank collapse triggered by dome growth at Tacaná volcano, México-Guatemala, and its relationship to the regional stress regime

During late Pleistocene time, the extrusion of an andesitic dome at the summit of Tacaná volcano caused the collapse of its northwestern flank. The stratocone collapse was nearly parallel to the σ min stress direction suggesting that failure was controlled by the regional stress field. The event pro...

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Bibliographic Details
Published in:Bulletin of volcanology 2010, Vol.72 (1), p.33-53
Main Authors: Macías, J. L., Arce, J. L., García-Palomo, A., Mora, J. C., Layer, P. W., Espíndola, J. M.
Format: Article
Language:English
Subjects:
Crystalline rocks
Earth and Environmental Science
Earth Sciences
Earth, ocean, space
Engineering and environment geology. Geothermics
Exact sciences and technology
Geological time
Geology
Geophysics
Geophysics/Geodesy
Igneous and metamorphic rocks petrology, volcanic processes, magmas
Lava
Mineralogy
Natural hazards: prediction, damages, etc
Plate tectonics
Research Article
Sedimentology
Volcanoes
Volcanology
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Summary:During late Pleistocene time, the extrusion of an andesitic dome at the summit of Tacaná volcano caused the collapse of its northwestern flank. The stratocone collapse was nearly parallel to the σ min stress direction suggesting that failure was controlled by the regional stress field. The event produced a debris avalanche that was channelized in the San Rafael River and moved 8 km downstream. The deposit covered a minimum area of 4 km 2 , had a volume of 0.8 ± 0.5 km 3 , with an H/L (vertical drop to horizontal transport distance ratio) of ~0.35, defining a degree of mobility that is atypical for volcanic debris avalanches. The flank failure undermined the summit dome leading to its collapse and the generation of a series of block-and-ash flows that were emplaced in quick succession and covered the avalanche surface. The collapse event left a 600-m-wide summit amphitheatre with a 30-degree opening to the northwest, and >200 m thick debris that blocked the San Rafael River. Remobilization of this material produced debris flows that eroded the primary deposits and cascaded into the Coatán River. After the collapse, the activity of Tacaná continued with the emission of the Agua Zarca lava flow dated at 10 ± 6 ka ( 40 Ar/ 39 Ar), and pyroclastic surges dated at 10,610 + 330/−315 yr BP ( 14 C), which provide a minimum age for the collapse event. During the Holocene, Tacaná has been very active producing explosive and effusive eruptions that ended with the extrusion of two summit domes that today occupy the amphitheatre. The 1950 and 1986 phreatic outbursts occurred along the Pleistocene collapse scar. Currently ~300,000 inhabitants live within a 35 km radius of Tacaná, and could conceivably be impacted by future events of similar magnitude.
ISSN:0258-8900
1432-0819
DOI:10.1007/s00445-009-0303-9