Explosive volcanic eruptions can inject voluminous amounts of ash into the atmosphere potentially crippling global infrastructure as witnessed by the recent eruption of Eyjafjallajökull in Iceland. While significant improvements have been made in the development of ash dispersal models and in the conceptual understanding of processes that govern the transport of ash far from the volcanic vent, much of the uncertainty in current forecasts of ash dispersal occurs due to limited description of particle dynamics in the conduit and near the vent. The proposed work will examine the physical processes that modify the grain size distribution of particles across a spectrum of energies due to eruptive processes in the conduit and multiphase interaction in the plume using computational, field and laboratory approaches.
Ash dispersal models have focused on long-range dispersal, incorporating conditions from atmospheric models. Due to the investment and advances in these fields, one of the goals of this work is to provide improved source terms and physical understanding that can be readily adopted into any dispersal model. To develop an integrated framework, we will address the following questions, objectives and related hypotheses: 1. How do post-fragmentation conduit processes play a role in setting the exit conditions into the atmosphere? 2. How do vent conditions and entrainment physics contribute to grain size sorting in plumes? 3. What role does hydrous aggregation play in the proximal distribution of ash? All of these questions will be closely linked and will make use of carefully chosen field examples, laboratory experiments, numerical simulations and visualization tools. This work will also develop an integrated set of fluid dynamics modules, teaching at a distance tools, and web based tools to enable high school students to learn more about volcanology and earth sciences in general. This approach has been designed to reach a broad high school audience, and in its first phase will reach several schools with large minority populations. Additionally these tools will be promoted to the broader public through web applications and through interactive three-dimensional visualizations tools that can be used in museum displays.
