The 181 AD eruption of Taupo caldera was the most powerful eruption globally in at least the last 5000 years. Despite the great inertia associated with these exceptionally high eruption rates, Taupo was characterized by repeated abrupt changes in the form and power of the eruptions. Such abrupt shifts in eruptive intensity are a fundamental, yet little studied, part of many intense explosive eruptions. The causes of such shifts remain poorly understood, at a time when our models for steady state eruptive processes at volcanoes become increasingly elegant and sophisticated. The quality of hazard advice and eruption forecasts would be significantly improved if such changes could be explained, and even anticipated.
The main goal of this project is to understand the mechanisms for, and origin of, such 'unsteadiness' with a long-term aim to improve preparedness for future eruptions at large volcanoes. The research plan is fourfold: a) to quantify changes in eruption intensity on a scale finer than previously described at Taupo, or for any other powerful silicic explosive eruption and constrain vent position precisely for all 7 eruptive phases/units; b) record the vesicularity (and crystallinity) of samples that span both the first order transitions in style, between units, and second order shifts in intensity; c) measure pre- and syn-eruptive volatile content of the same samples; and d) refine existing degassing, ascent and eruption models for powerful silicic eruptions with emphasis on explaining abrupt shifts in eruption processes. This project will bring together 5 students and researchers from 4 international institutions and 4 four sub-disciplines in volcanology.
