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SUMMARY:The dynamics of Vulcanian plumes: Insights from laboratory analogu
 e experiments - Jerry Phillips\, Department of Earth Sciences\, University
  of Bristol
DTSTART:20081009T103000Z
DTEND:20081009T113000Z
UID:TALK14268@talks.cam.ac.uk
CONTACT:Dr C. P.  Caulfield
DESCRIPTION:Vulcanian eruptions are small explosive volcanic eruptions\, w
 hich occur frequently at many volcanoes worldwide. This eruptive style pre
 sents a significant natural hazard in terms of ash deposition and pyroclas
 tic flow development\, and may form the initial and waning phases of large
 r more explosive eruptions. The eruption plumes generated by Vulcanian eve
 nts are both unsteady and turbulent\, and difficult to measure directly\, 
 due to their short duration and the low temporal resolution of field monit
 oring methods. An appropriate methodology for investigating the fundamenta
 l dynamics and testing the predictions of theoretical models is the use of
  laboratory analogue experiments. \n            In this study\, appropriat
 ely-scaled laboratory experiments are used to investigate the dynamics of 
 short duration\, high pressure releases of buoyant fluid.  Pressurized mix
 tures of water and alcohol were released into fresh water\, producing shor
 t-lived plumes which exhibited a range of behaviour. The experiments ident
 ified the total momentum and buoyancy of the release as independent contro
 lling parameters over a wide range of initial conditions\, and this was co
 nfirmed by scaling analysis.\n      This presentation focuses on using lab
 oratory observations to constrain the development of predictive models for
  unsteady flows resulting from finite-volume fluid releases. The scaling l
 aws derived from the experimental observations are applied to volcanic haz
 ard prediction to estimate the mass of ash produced in a single eruptive e
 vent\, and form the basis of an algorithm for measuring ash distribution w
 ithin eruption plumes using UV-imaging. These applications are illustrated
  with field observations from Soufriere Hills Volcano\, Montserrat\, and V
 olcan Santiaguito\, Guatemala.\n\n
LOCATION:Open Plan Area\, BP Institute\, Madingley Rise CB3 0EZ
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