Rise of Volcanic Eruption Clouds: Relationship Between Cloud Height and Eruption Intensity
Mark Settle
Jan 1976 · Air Force Geophysics Laboratory, Air Force Systems Command, United States Air Force
Ebook
37
Pages
About this ebook
The rise of eruption clouds is produced by the upward momentum and thermal buoyancy of volcanic dust and gas, processes which play important roles in other phenomena. The expansion of a turbulent jet in free flow is controlled by the rate at which the forward momentum of the jet is dissipated. Thermal buoyancy of industrial waste gases provides a mechanism for moving such wastes upward through the atmosphere and ensuring their dispersal over a wide area. The rise of volcanic eruption clouds can be modelled after these 2 analogous phenomena. In this report average ejection velocities at a volcanic vent ranging from 20 m/sec to 200 m/sec are assumed to represent a wide range of eruption intensity, from Strombolian to Vulcanian types. For eruption velocities varying from 20 m/sec to 200 m/sec, cloud heights estimated by the turbulent jet model range from 1500 m to 6500 m (mid-latitude eruption) while cloud heights estimated by the industrial plume models range from 900 m to 10,000 m. These estimates are considered to be roughly comparable in view of the assumptions and extrapolations involved in applying these models to explosive eruption conditions and agree quite well with reported heights of eruption clouds. The fact that comparable estimates of cloud height are produced by 2 very different models suggests that both momentum and thermal buoyancy play an important role throughout the main portion of an eruption cloud's trajectory.
The rise of eruption clouds is produced by the upward momentum and thermal buoyancy of volcanic dust and gas, processes which play important roles in other phenomena. The expansion of a turbulent jet in free flow is controlled by the rate at which the forward momentum of the jet is dissipated. Th...
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