RUI: Dynamics of Plinian Eruptions - Physical Volcanology of the 1600 Eruption of Volcan Huaynaputina, Southern Peru

Indiana State University, Terre Haute IN

Investigators

Abstract

0087181 DeSilva In attempting to better understand the human, societal, and environmental impacts of volcanic eruptions, scientists are increasingly aware that the fundamental underpinning to this endeavour is knowledge about the physical volcanology of volcanic eruptions. Since plinian eruptions are amongst the most devastating, considerable effort is focused on these phenomena. However, few such eruptions have been observed and documented and our understanding relies heavily on data from eruptions that have occurred in the recent past. Such studies have proved to be the source of much of our insight into the dynamics of plinian eruptions and their local and global effects. A completed study of the 1600 eruption of Huaynaputina, conducted under the auspices of a previous NSF grant, reveals that this eruption is one of the most significant eruptions of historic times. Over 25km3 of tephra was erupted, 90% of which was ejected during a ~20 hour sustained plinian eruption during the first stage of the eruption. Two coeval but distinct deposits formed; a regionally extensive and well-preserved plinian pumice fall deposit, and a much more extensive plinian ash deposit. No caldera collapse occurred despite the large volume erupted allowing the rare preservation of ultraproximal sections and vents. This project will build on the general model of the eruption that we have elucidated to focus on the ultraproximal sections and the proximal pumice fall deposit to increase our understanding of the 1600 Stage I plinian eruption in particular and the dynamics of plinian eruptions in general. Two interrelated objectives are to be addressed. The first is better constrain the evolution of the ~20 hour long plinian eruption, and the second is to better understand the origin and significance of the extremely coarse fall deposits in the ultraproximal sections. These objectives will be addressed through extensive fieldwork to log sections, identify and map key horizons, and map their dispersal. These data will be coupled with existing detailed grainsize and componentry of these horizons throughout the fall deposit to develop a more detailed understanding of the Stage I plinian eruption that breaks down the ~20 hour eruption into several stages. The involvement of graduate and undergraduate students as key players in the team maximises the educational impact of this project.