A Model for Buoyant Tephra Plumes Coupled to Lava Fountains With an Application to the 29th of August 2011 Paroxysmal Eruption at Mount Etna, Italy

Explosive basaltic eruptions pose significant threats to local communities, regional infrastructures and international airspace. They produce tephra plumes that are often associated with a lava fountain, complicating their dynamics. Consequently, source parameters cannot be easily constrained using traditional formulations. Particularly, mass flow rates (MFRs) derived from height observations frequently differ field deposit-derived MFRs. Here, we investigate this discrepancy novel integral plume model explicitly accounts for which is represented as hot, coarse-grained inner co-flowing finer-grained outer plume. The new shows fountain has higher variability in rise than standard the same initial MFR depending on conditions. grain-size distribution relative size of compared surrounding primary controls final they determine strength coupling between two plumes. We apply August 29, 2011 paroxysmal eruption Mount Etna, Italy. modeled profile indicates field-derived does not correspond at vent, but rather just above top. High fallout results much erupted solid material reaching top This deposits form proximal cone dispersing atmosphere. With our model, discrepancies types observation-derived can investigated understood.