Tephra Fallout Models: The Effect of Different Source Shapes on Isomass Maps |
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| Authors: | Leng L Lim Winston L Sweatman Robert McKibbin Charles B Connor |
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| Institution: | (1) Institute of Information and Mathematical Sciences, Massey University, Albany Campus, Private Bag 102 904, North Shore, 0745, Auckland, New Zealand;(2) Department of Geology, University of South Florida, Fowler Ave., SCA 528, Tampa, FL 33620, USA |
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| Abstract: | Numerous tephra dispersion and sedimentation models rely on some abstraction of the volcanic plume to simplify forecasts of
tephra accumulation as a function of the distance from the volcano. Here we present solutions to the commonly used advection–dispersion
equation using a variety of source shapes: a point, horizontal and vertical lines, and a circular disk. These may be related
to some volcanic plume structure, such as a strong plume (vertical line), umbrella cloud (circular disk), or co-ignimbrite
plume (horizontal line), or can be used to build a more complex plume structure such as a series of circular disks to represent
a buoyant weak plume. Basing parameters upon eruption data, we find that depositions for the horizontal source shapes are
very similar but differ from the vertical line source deposition. We also compare the deposition from a series of stacked
circular disk sources of increasing radius above the volcanic vent with that from a vertical line source. |
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| Keywords: | Volcanic plume Eruption column Tephra Volcanic hazard Advection– dispersion |
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