HR: 0800h
AN: V41D-0802    [Abstracts]
TI: The 1793 Eruption of San Martin Volcano (Los Tuxtlas, Veracruz, Mexico)
AU: * Espindola, J M
EM: jmec@servidor.unaam.mx
AF: Universidad Nacional Autónoma de Mexico, Instituto de Geofísica, Ciudad Universitaria Coyoacan, Mexico, DF 04510, Mexico
AU: Zamora-Camacho, A
EM: zaraceli@yahoo.com.mx
AF: Universidad Nacional Autónoma de Mexico, Instituto de Geofísica, Ciudad Universitaria Coyoacan, Mexico, DF 04510, Mexico
AU: Godinez, M L
EM: lgodinez@servidor.unam.mx
AF: Universidad Nacional Autónoma de Mexico, Instituto de Geografía, Ciudad Universitaria Coyoacan, Mexico, DF 04510, Mexico
AU: Rodriguez-Elizarraras, S
EM: srre@servidor.unam.mx
AF: Universidad Nacional Autónoma de Mexico, Instituto de Geología, Ciudad Universitaria Coyoacan, Mexico, DF 04510, Mexico
AB: San Martin Tuxtla Volcano is located in the State of Veracruz, Eastern Mexico (18.572N, 95.169W, 1650 masl). Its last eruption, which occurred 1793, was described by D. Jose Moziņo, a naturalist sent by the Viceroy-of the then New Spain-to report on the eruption. The activity lasted for several months with distinct events of explosive character, which produced thick ash fall deposits in its vicinity. The explosions were heard, among other places, in the coasts of Tampico some 500km NW from the volcano. The ash fall reached distances up to 200 Km from the crater and covered an area of about 112,000 Km2. Following the description of Moziņo and the results of field studies we make a reconstruction of the eruption. We identified the air fall deposit from this eruption and present an isopach map. We present radiocarbon ages of the paleosoils under the ash bed as an indirect evidence of its age. This data together with present day wind velocities, and a diffusion-advection model of the dispersion of ashes allow to estimate in at least 10km the altitude reached by some of the eruptive plumes. An estimation of the minimum volume of ash erupted, based on the reconstructed isopachs, is of about 1.3 x 108 m3. Microphotographs of the ashes suggest that the activity was of phreatomagmatic and strombolian nature. Finally, we address some aspects of the volcanic risk in the area derived from our study.
DE: 0370 Volcanic effects (8409)
DE: 8404 Volcanoclastic deposits
DE: 8428 Explosive volcanism
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting