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

Abstract

We have developed a new integral model that accounts for the coupling between 11 a tephra plume and a lava fountain. 12• The initial grain-size distribution and radius of a lava fountain control the rise height 13 of the surrounding tephra plume. 14• The model can explain the relationship between the tephra plume and cone de-15 posits and the observed plume and lava fountain height.

A New Radar‐Based Statistical Model to Quantify Mass Eruption Rate of Volcanic Plumes

“…It is notable as all these cases fall within the natural variability of the paroxysmal phase of basaltic volcanoes as Etna (Andronico et al., 2021). Interesting to note that tephra plumes coupled with lava fountains are associated with higher variability of the Q M ‐ H TP relationship compared to standard plumes (Snee et al., 2021). The DB12 and MA09 models estimates are all consistent with the sampled Q M values for the testing data; however, the median Q M from our model is systematically lower than the DB12 and MA09 estimates (Figure 4).…”

“…Nonetheless, our statistical model provides key innovative features: first, it has been entirely developed, for the first time, on self‐consistent radar‐based H TP and Q M estimates allowing to eliminate the uncertainty in the definition of parameters; second, being based on lava‐fountain fed tephra plumes at Etna, it can better capture the high variability in rise height typical of these plumes. In fact, the MCMC approach is especially appropriate for the description of the Q M ‐ H TP relation for this eruptive style, which is especially impacted by the combination of various parameters of lava fountains (Snee et al., 2021); Third, it propagates the uncertainty on both the input data ( H TP and v w ) and the model parameter values. In this way, uncertainty on Q M estimates can be propagated and accurately quantified.…”

Examples of Multi-Sensor Determination of Eruptive Source Parameters of Explosive Events at Mount Etna

“…The exit velocity is a critical parameter to determine MER [4,13,15,30,66] and to constrain eruptive column dynamics [77][78][79][80][81]. Direct evaluation of exit velocities at Etna comes from the fixed-pointing near-source Doppler radar V2B at very high time resolution [12,30].…”

“…Paroxysms at Etna are generally composed of two main components, i.e., a lava fountain and a tephra plume which is mostly fed by the lava fountain [4,30,35,81]. The contribution of each component to the TEM, MER, and TGSD of the cumulative event can be explored using different sensors.…”

“…In fact, it is important to bear in mind a few shortcomings of deposit sampling at Etna. First, the very proximal fraction deposited <0.5 km from the vent and contributing to building the eruptive cone, i.e., the lava fountain tephra deposit, is never sampled [35,36,81]. Second, the proximal fraction deposited <5 km and corresponding to the coarsest part of the tephra plume GSD is also rarely sampled because of access difficulties (i.e., presence of La Valle del Bove horseshoe-shaped depression) and problems in discriminating individual deposits in periods of frequent activity [26,69].…”