Fig. 5: Inferred buoyancy flux as a function of fissure length, illustrating the transition from a point-source model for the plume stem to a line-source model.
From: Rapid heat discharge during deep-sea eruptions generates megaplumes and disperses tephra
The blue shading represents the range of inferred values of the buoyancy flux at the plume source F0 given the full range of umbrella fluxes, \({Q}_{umb}^{(min)}\,<\,{Q}_{umb}\,<\,{Q}_{umb}^{(max)}\), predicted by Eq. (4), as a function of the length of the source l. For a point source, or sufficiently small fissure lengths (l ≲ l*), the details of the source are unimportant to good approximation and the predictions conform to those of a point-source model, as given by Eq. (9). For sufficiently long sources (l ≳ l*), a model assuming a planar source becomes more applicable in accordance with the prediction of Eq. (11). The lengthscale l*, given by Eq. (12) and indicated by a dashed curve, represents the fissure length on which the predictions of the two theories are equivalent.
