HR: 11:20h
AN: V42A-05    [Abstracts]
TI: Magma Stagnation and Ascent at Popocatepetl Volcano, Mexico during the last 10 years
AU: * Martin, A L
EM: analil@geofisica.unam.mx
AF: Geofisica,UNAM, Ciudad Universitaria, Mexico D.F., 04510, Mexico
AU: Cifuentes, G
AF: Geofisica,UNAM, Ciudad Universitaria, Mexico D.F., 04510, Mexico
AU: Straub, S
AF: Lamont, 61 Route 9W, Palisades, NY 10964, United States
AU: Mendiola, F
AF: Geofisica,UNAM, Ciudad Universitaria, Mexico D.F., 04510, Mexico
AB: Small eruptions (VEI 1-3) at Popocatepetl have been producing magnesian andesites to dacites (SiO2 56-65; MgO 7-2 wt. percent). since 1994. Since then, continuous multiparameter geophysical and geochemical monitoring (ash sampling and analyses, magnetic recording and processing, spring water analyses and correlation with seismicity) has been carried out. The time series shows that the mafic end-member is a small volume hydrous andesitic melt from the mantle which mixes with an evolved end-member at depths between 4- 13km. The stagnation level appears to be a series of interconnected dykes not a large magma chamber, since during the 10 years of monitoring no time-progressive compositional trend in the ejecta has been observed, therefore implying a steady influx and outflux of melts through the Popo plumbing system in a short timescale. If the reservoir was replenished periodically with mafic melt, a trend towards more mafic compositions would be expected if the evolved melt was to be gradually exhausted. Negative magnetic anomalies (2 to 6nT) correlate with periods of harmonic tremor and decreasing springwater pH, related with successive ascending magma batches. Larger eruptions are associated with influx of deeper magma.
DE: 8414 Eruption mechanisms and flow emplacement
DE: 8419 Volcano monitoring (7280)
SC: Volcanology, Geochemistry, and Petrology [V]
MN: 2007 Joint Assembly