HR: 1400h
AN: V33B-01 INVITED     [Abstracts]
TI: Volcano-Ice Interactions in Mexico: Extinction of Glaciers at Popocatépetl and the Fate of the Glaciers of Iztaccíhuatl and Citlaltépetl Volcanoes
AU: * Delgado Granados, H
EM: hugo@tonatiuh.igeofcu.unam.mx
AF: Instituto de Geofísica, Universidad Nacional Autónoma de México, Av. Universidad 3000, Coyoacán, México, DF 04510, Mexico
AB: In spite of the state of activity of the Mexican volcanoes (erupting, fumarolic, or dormant) study of volcano-ice interactions is of key importance because one of the main consequences of these interactions is the generation of lahars. Study of glaciers and volcanic activity help to prevent the possibility of devastating events at volcanoes in Mexico, especially because some explosive events at Popocatépetl volcano generated lahars during the past twelve years. Small-sized glaciers exist or existed at Iztaccíhuatl, Popocatépetl and Citlaltépetl whose volcanic activity is characterized by a different level of activity. The extinction of glaciers of Popocatépetl volcano was eruption-forced. 40% of climatic-related shrinkage occurred in 4 decades whereas 32% of eruption-related shrinkage occurred in 4 years. Long-term effects of glacier extinction include an imbalance between recharge and extraction of groundwater at surrounding aquifers provoked by disappearance of glacier-related melt water. The volcano started to erupt in 1994. Impact of the eruption on the glaciers was in several ways: immediate thermal effect of hot falling ash on snow and ice.; ballistic projectiles are also hot and yield high kinetic energy producing melting restricted to the impact areas; every event depositing 1cm of ash represents a load of ~102-104 tons; fumaroles of <100°C on cracks beneath the glacier provoked continuous melting at the base of the glacier even during the winter; possibly, volcanic gases indirectly affected the glaciers, but greenhouse effect is difficult to assess. Iztaccíhuatl volcano's glaciers have been influenced by the same factors as at Popocatépetl, except the eruption. Citlaltépetl volcano's glaciers have been just affected by climatic changes. Both volcanoes show fumaroles or diffuse degassing. An eruptive event in the short term may cause the same effect as occurred at Popocatépetl volcano. The large ice masses of the world are claimed to be affected by global warming and local climatic variations. Tropical glaciers as those of Mexico are more vulnerable because of their size and exposure to eruptive processes. Even though their extinction might not have a global impact, their disappearance deprives us of important climatic "gauges" at the ~20° north latitude and impacts strongly the local environment. Relations between the volcanic activity and the presence of glaciers in Mexico have still several aspects to study, among them: ice melting provoked by eruptive products and heat flux, glacier extinction, and debris flow generation.
DE: 8408 Volcano/climate interactions (1605, 3309)
DE: 8419 Volcano monitoring (7280)
DE: 8428 Explosive volcanism
DE: 8486 Field relationships (1090, 3690)
DE: 8488 Volcanic hazards and risks
SC: Volcanology, Geochemistry, and Petrology [V]
MN: 2007 Joint Assembly