Powerful Silicic Explosive Volcanism: Understanding Abrupt Shifts in Eruption Style and Intensity in the 181 AD Taupo Eruption

公元181年陶波火山口的喷发是至少在过去5000年中全球最强大的喷发。尽管与这些异常高的喷发率相关的惯性很大，陶波的特点是喷发的形式和力量反复突然变化。喷发强度的这种突然变化是许多强烈爆炸性喷发的基本组成部分，但研究很少。在我们对火山稳态喷发过程的模型变得越来越优雅和复杂的时候，这种变化的原因仍然鲜为人知。如果这种变化能够得到解释，甚至可以预见，那么危险建议和喷发预报的质量将会显著提高。该项目的主要目标是了解这种“不稳定”的机制和来源，长期目标是改善对未来大型火山喷发的准备。研究计划有四个方面：a)在比以前在陶波描述的更精细的尺度上量化喷发强度的变化，或对任何其他强大的硅质爆炸性喷发，精确地限制所有7个喷发阶段/单元的喷口位置；b)记录跨越风格、单元之间的一级转变和强度的二级转变的样品的气泡度(和结晶度)；c)测量同一样品喷发前和同时喷发时的挥发物含量；d)完善现有的强大硅质喷发的脱气、上升和喷发模型，重点解释喷发过程的突然变化。该项目将汇集来自火山学4个国际机构和4个分学科的5名学生和研究人员。

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.