Eruptive processes leading to the most explosive lava fountain at Etna volcano: The 23 November 2013 episode

Abstract

The 23 November 2013 lava fountain at Etna volcano was the most explosive of the last 44 episodes that have occurred at Etna in 2011-2013. We infer the total magma volume erupted by thermal images analysis and show that it was characterized by a very high time-averaged-discharge-rate (TADR) of 360 m 3 s À1 , having erupted~1.6 × 10 6 m 3 of dense-rock equivalent magma volume in just 45 min, which is more than 3 times the TADR observed during previous episodes. Two borehole dilatometers confirmed the eruption dynamics inferred from the thermal images. When compared to the other lava fountains, this episode can be considered as the explosive end-member. However, the erupted volume was still comparable to the other lava fountain events. We interpret that the 23 November explosive end-member event was caused by more primitive and gas-rich magma entering the system, as demonstrated by the exceptional height reached by the lava fountain.

Satellite and Ground Remote Sensing Techniques to Trace the Hidden Growth of a Lava Flow Field: The 2014–2015 Effusive Eruption at Fogo Volcano (Cape Verde)

“…Comparing this episode with lava fountains observed at Mt Etna, we assume that the cinder cone was mainly formed by proximal ballistic fallout during the lava fountain phase of the eruption [63][64][65]. Given that the cone built up in seven days (between 23 and 30 November 2014), the DRE TADR [49] for its growth is ~9.7 m 3 s −1 .…”

Coupled Short- and Medium-Term Geophysical Signals at Etna Volcano: Using Deformation and Strain to Infer Magmatic Processes From 2009 to 2017

“…Despite the long-term drift characterizing the instruments during the first years of setup, clear strain changes were revealed during the short duration of the lava fountain episodes at NSEC (Bonaccorso et al, , 2014. Soon after their installation, the borehole dilatometers detected the short-term variations produced by the lava fountains with high accuracy (Figure 2).…”

“…In the Hawaiian cases the lava fountains typically range from ∼ 10 to 100 m in height, and occasionally reach more than 500 m. Most of the material returns to the surface to form pyroclastic cones, rootless flows or lava ponds (Head and Wilson, 1987). Lava fountains at Etna are often different from the Hawaiian style for their more explosive power and for the formation of a several kilometers high, sustained eruptive column causing widespread ash fallout (e.g., Calvari et al, 2011;Bonaccorso et al, 2014). It is for this reason that they have often been referred as "paroxysmal" (e.g., Bonaccorso et al, 2011aBonaccorso et al, ,b, 2013Gambino et al, 2016) to highlight their greater power when compared to the Hawaiian lava fountains.…”

“…This sustained a several kilometer-high eruptive column expanding well beyond the lava fountain portion and causing widespread ash fallout (e.g., Calvari et al, 2011;Bonaccorso et al, 2014;Bonaccorso and Calvari, 2017). The short lived activity of lava fountains, although spectacular, emitted limited volumes of magma (∼ 2.5 × 10 6 m 3 per event) compared to the prolonged effusive flank eruptions, which usually emit from 1.0 × 10 7 to 2.0 × 10 8 m 3 .…”

Tephra From the 3 March 2015 Sustained Column Related to Explosive Lava Fountain Activity at Volcán Villarrica (Chile)

“…They typically emit lava fragments to heights extending tens to hundreds of meters (Bonaccorso et al, 2011). Most lava fountains reach 500-600 m above the crater (e.g., Houghton and Gonnermann, 2008;Taddeucci et al, 2015), but the highest reach ∼2.0 km and are infrequent, violent and short-lived (e.g., Bonaccorso et al, 2014;Andronico et al, 2015). Their evolution is commonly initiated by Strombolian activity (resumption phase) followed by lava fountaining, and typically the formation of an eruption column (paroxysmal phase), which ends with the waning of the eruption (conclusive phase) (Andronico et al, 2015).…”