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Sensitivity of partial column collapse to exit velocity, ambient wind and particle size

J. W. Campbell1, B. J. Devenish2,3 , M. Herzog1

  • Affiliations: 1Department of Geography, University of Cambridge, Cambridge, UK 2Met Office, Exeter, UK 3Department of Civil Engineering, Imperial College, London, UK

  • Presentation type: Poster

  • Presentation time: Thursday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 85

  • Programme No: 3.12.11

  • Theme 3 > Session 12

Abstract

The eruption of Mt Pinatubo in 1991 in its climactic phase formed the strong case of the volcanic plume model intercomparison study (Costa et al. JVGR 2016) and exhibited partial column collapse in the lower part of the plume. This complex behaviour was captured by three-dimensional (3d) large-eddy simulations (LES) such as those performed by the ATHAM model. Using this model we explore the extent to which this behaviour is determined by the exit velocity and the particle size in addition to the mass flux. We conduct sensitivity tests by systematically varying the exit velocity, ambient wind speed or particle size for the strong case and its companion case in the intercomparison study, the weak eruption, which was based on the eruption of Shinmoe-dake in 2011. We consider how entrainment and mixing are affected by partial column collapse both of which are important in determining whether a plume becomes positively buoyant.