Abstract
AbstractExplosive 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 from field deposit‐derived MFRs. Here, we investigate this discrepancy using a novel integral plume model that explicitly accounts for a lava fountain, which is represented as a hot, coarse‐grained inner plume co‐flowing with a finer‐grained outer plume. The new model shows that a plume associated with a lava fountain has higher variability in rise height than a standard plume for the same initial MFR depending on initial conditions. The initial grain‐size distribution and the relative size of the lava fountain compared to the surrounding plume are primary controls on the final plume height as they determine the strength of coupling between the two plumes. We apply the new model to the August 29, 2011 paroxysmal eruption of Mount Etna, Italy. The modeled MFR profile indicates that the field‐derived MFR does not correspond to that at the vent, but rather the MFR just above the lava fountain top. High fallout from the lava fountain results in much of the erupted solid material not reaching the top of the plume. This material deposits to form the proximal cone rather than dispersing in the atmosphere. With our novel model, discrepancies between the two types of observation‐derived MFR can be investigated and understood.
Highlights
Explosive basaltic volcanism can generate ash-rich plumes that can cause significant local and regional disruption (Barsotti et al, 2010; Scollo et al, 2013; Andronico et al, 2015)
The new model shows that a plume associated with a lava fountain shows higher variability in rise height than a standard plume for the same initial mass flow rates (MFRs) depending on initial conditions
We randomly sample a parameter space that consists of initial velocity, temperature, gas mass fraction, grain-size distribution (GSD), MFR and partition coefficient (ε), to assess the impact of a lava fountain on plume height
Summary
Explosive basaltic volcanism can generate ash-rich plumes that can cause significant local and regional disruption (Barsotti et al, 2010; Scollo et al, 2013; Andronico et al, 2015). Many of these plumes are characterised by a hot inner core that is defined as a lava fountain. The climactic phases of these eruptions, where the lava fountain and tephra plume co-exist, are referred to as paroxysmal eruptions (Alparone et al, 2003). Such eruptions have occurred at volcanoes including Mount. While the dynamics of ash-rich, buoyant plumes are well studied, the impact of a hotter, coarser, inner core inside the plume needs to be considered (e.g., first phase of the 2010 eruption of Eyjafjallajökull, Iceland (Kaminski et al, 2011))
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
