HR: 0830h
AN: V51F-0340    [PDF]
TI: Volcanic Hazards Associated with the NE Sector of Tacan\'{a} Volcano, Guatemala.
AU: * Hughes, S R
EM: simon@strumble.com
AF: SUNY at Buffalo, Department of Geology, 876 Natural Science Complex, Buffalo, NY 14260 United States
AU: Saucedo, R
AF: Universidad Aut\'{o}noma de San Luis Potos\'{i}, Salvador Nava, Zona Universitaria, San Luis Potos\'{i}, SLP 78240 Mexico
AU: Macias, J
AF: UNAM, Instituto de Geof\'{i}sica, Ciudad Universitaria, Del Coyoac\'{a}n, M\'{e}xico, DF 04610 Mexico
AU: Arce, J
AF: UNAM, Instituto de Geof\'{i}sica, Ciudad Universitaria, Del Coyoac\'{a}n, M\'{e}xico, DF 04610 Mexico
AU: Garcia-Palomo, A
AF: UNAM, Instituto de Geof\'{i}sica, Ciudad Universitaria, Del Coyoac\'{a}n, M\'{e}xico, DF 04610 Mexico
AU: Mora, J
AF: UNAM, Instituto de Geof\'{i}sica, Ciudad Universitaria, Del Coyoac\'{a}n, M\'{e}xico, DF 04610 Mexico
AU: Scolamacchia, T
AF: UNAM, Instituto de Geof\'{i}sica, Ciudad Universitaria, Del Coyoac\'{a}n, M\'{e}xico, DF 04610 Mexico
AB: Tacan\'{a} volcano, with a height of 4,030 m above sea level, straddles the southern Mexico/Guatemala border. Last active in 1986, when there was a small phreatic event with a duration of a few days, this volcano presents an impending hazard to over 250,000 people. The NE sector of the volcano reveals the violent volcanic history of Tacan\'{a} that may be indicative of a serious potential risk to the area. Its earliest pyroclastic history appears to consist of fall, flow, and surge deposits, together with lavas, that have formed megablocks within a series of old debris avalanche deposits. This sector collapse event is overlain by a sequence of pumice fall and ash flow deposits, of which the youngest, less-altered pumice fall deposit shows a minimum thickness of $>$ 4 m, with a dispersal axis trending toward the NE. A second debris avalanche deposit, separated from the above deposits by a paleosoil, is dominated by megablocks of lava and scoriaceous dome material. The current topography around the northeastern flank of the volcano is determined by a third, and most recent debris avalanche deposit, a thick ($>$ 20 m) sequence of six block and ash flows dated at around 16,000 years BP, each separated by 1-10 cm thick ash cloud surge deposit, together with secondary lahar deposits. These are followed by a at least 4 lava flows that extend 2 km down the flank of the volcano. It appears that the most recent pyroclastic event at Tacan\'{a} is also recorded in this sector of the volcano: above the block and ash flows occurs a $>$ 1 m thick ash flow unit that can be seen at least 5 km from the vent. Lastly, the Santa Maria Ash fall deposit, produced in 1902, has capped most of the deposits at Tacan\'{a}.
DE: 8400 VOLCANOLOGY
DE: 8404 Ash deposits
DE: 8499 General or miscellaneous
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting