Laboratory experiments of forced plumes in a density-stratified crossflow and implications for volcanic plumes

摘要

The mass eruption rate feeding a volcanic plume is commonly estimated from its maximum height. Winds are known to affect the column dynamics causing bending and hence reducing the maximum plume height for a given mass eruption rate. However, the quantitative predictions including wind effects on mass eruption rate estimates are not well constrained. To fill this gap, we present a series of new laboratory experiments on forced plumes rising in a density-stratified crossflow. We identify three dynamical regimes corresponding to increasing effect of wind on the plume rise. The transition from one regime to another is governed by two dimensionless velocity scales defined as a function of source and environmental parameters. The results are found consistent with the conditions of historical eruptions and provide new empirical relationships to estimate mass eruption rate from plume height in windy conditions, leading to valuable tools for eruption risk assessment.