Overview
Slides for the talk entitled "An improved quantitative measure of the tendency for volcanic ash plumes to form in water: implications for the deposition of marine ash beds", given at the Inaugural UK Fluids Conference 2016 in London, UK on 7-9 September 2016. The slide files are available from the gh-pages branch of this repository. The slides are also available to view online.
Abstract
Explosive volcanic eruptions produce vast quantities of searing hot gas and ash, which poses extreme hazards; recent eruptions have resulted in the closure of airports, damage to infrastructure and natural habitats, and loss of life. Predicting and mitigating such events requires knowledge of their frequency, intensity and ash distribution. The layers of ash deposited by past eruptions can uncover a wealth of information pertaining to this. Ash particles either settle slowly and individually, or rapidly and collectively as a plume/density current. Since the settling rate has implications on the accuracy of information inferred from the layer, one needs to determine whether plumes were likely to have formed. Existing theoretical formulae for doing so assume that plumes obey Stokes' law, which is not the case for subaqueous ash plumes. This work presents a new formula for measuring the tendency for subaqueous ash plumes to form. A parameter sweep is undertaken, and a suite of high-resolution, computationally-intensive simulations is produced to evaluate the effectiveness of this new formula. By taking the inertia-dominated nature of plumes into account, the new formula allows settling times to be more accurately and practically determined, thereby permitting improved interpretation of volcanic ash layers.
Journal paper
The details of the journal paper associated with this talk are:
C. T. Jacobs, T. J. Goldin, G. S. Collins, M. D. Piggott, S. C. Kramer, H. J. Melosh, C. R. G. Wilson, P. A. Allison (2015). An improved quantitative measure of the tendency for volcanic ash plumes to form in water: implications for the deposition of marine ash beds. Journal of Volcanology and Geothermal Research, 290:114-124, DOI: 10.1016/j.jvolgeores.2014.10.015