V. Evaluating volcanic hazards  

V.4 Just add water: hazards variation in lava flows, steam-driven and hydromagmatic explosive eruptions

Pranabendu Moitra, University at Buffalo, New York; pranaben@buffalo.edu
Cristian Montanaro, University of  Auckland, New Zealand;c.montanaro@auckland.ac.nz
Emma Liu, University of Cambridge, UK
Karen Strehlow, GEOMAR, Kiel, Germany
Bettina Scheu, Ludwig-Maximilians-Universität, Munich, Germany
Samuel A Soule, Woods Hole Oceanographic Institution, US
Bernd Zimanowski, University of Wuerzburg, Germany
James White, University of Otago, NZ

Volcanic and hydrothermal activity produces eruptions ranging from lava flows, to hydromagmatic (phreato-magmatic, surtseyan) and steam-driven (phreatic and hydrothermal) events. During the interaction of magma/lava with water, the extent and rate of heat transfer may influence i) the eruption explosivity and the efficiency in fine ash production, ii) the cooling time scales of lava flows, and iii) the hydrothermal activities along mid-ocean ridges. Other steam-driven eruptions are generated solely by the sudden flashing to vapor of hot and pressurized water. For explosive events, the properties and dispersal characteristics of fragmented material (juvenile or lithic) provide important information on the mechanisms of fragmentation and on the energy budgets. However, there remain outstanding questions. How does magma-water heat transfer influence lava flow dynamics? What is the range of possible dynamic interplay between magmatic vesiculation and magma-water interaction? What is the role of explosive expansion of propelling fluids in controlling the fragmentation intensity during these eruptions? In this session, we aim to bring together observational, experimental and numerical analysis-based contributions that investigate the physical controls on i) eruptive processes and/or the resulting deposits, and ii) the hazards, for any eruption involving external water in various geological settings (from subaerial to subaqueous).