Hazards at ice-clad volcanoes: Phenomena, processes, and examples from Mexico, Colombia, Ecuador, and Chile
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abstract
The interaction of volcanic activity with snow and ice bodies can cause serious hazards and risks. These interactions relate to enhanced heat flow, tephra in contact with the ice and snow resulting in the alteration of surficial ablation, and interaction with pyroclastic flows and incandescent materials. Such interactions can result in the formation of differential ablation, in tephra remobilization and, especially, in the generation of sometimes far-reaching lahars. Disasters resulted from recent events at Mount St. Helens (1980–1986) and Nevado del Ruiz (1985) illustrate the impact these interactions can have. Case studies from Mexico, Colombia, Ecuador, and Chile are described. These descriptions depict the way in which the volcanic activity has interacted with ice bodies in recent volcanic crises (Popocatépetl, Mexico; Nevado del Huila, Colombia; and Llaima and Villarica, Chile) and how the laharic processes have been generated. Reconstruction of historical events (Cotopaxi, Ecuador) or interpretation of events from the geological remains (Citlatépetl, Mexico) helps to document past events which today could be disastrous for people and infrastructure now existing at the corresponding sites. A primary challenge for hazard prevention and risk reduction is the difficulty of making decisions based on imperfect information and a large degree of uncertainty. Successful assessments have resulted in the protection of lives in recent cases such as at Nevado del Huila (Colombia).
