Major effusive eruptions and recent lava fountains: Balance between expected and erupted magma volumes at Etna volcano

Abstract

Over the last four decades Etna has shown a high output rate through numerous eruptions. The volcano has displayed two eruptive behaviors. The first is characterized by effusive eruptions that efficiently drained the storage system and emitted large volumes of magma; the second behavior is related to lava fountains, erupting small magma batches, which are normally with high frequency and have been considered as precursors of major effusive eruptions. In this paper, we present an updated estimation of emitted volumes from Etna eruptions, which include the 38 lava fountain episodes that occurred from January 2011 to April 2013. These recent explosive episodes have been frequent, discharging significant magma volumes. Observing the steady trend of magma output over time, we present insights on expected erupted volumes. We highlight that the January 2011 to April 2013 lava fountains efficiently drained the intermediate‐shallow storage system and favored a balance between the incoming and outgoing magma.

Why Does a Mature Volcano Need New Vents? The Case of the New Southeast Crater at Etna

“…Best fit is achieved by adjusting the area of cooling lava until the measured and theoretical curves match. This technique was tested using ground-based thermal camera images collected during the 12 August 2011 event , and the volumes found for all the 2011-2013 events at Etna are in good agreement with field measurements (Behncke et al, 2013;De Beni et al, 2015) and strain meter data processing results (Bonaccorso and Calvari, 2013). Applying the cooling curve modeling we retrieve the lava volume for the six events spanning from 1.15 to 2.18 × 10 6 m 3 , as given in Table 1.…”

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

“…Likely, the structural discontinuity between the Hyblean platform and Apennine -Maghrebide chain, facilitates magma ponding. In this intermediate storage, due to the almost continuous magma input from depth (Bonaccorso Calvari and Calvari, 2013), the magma can accumulate, producing the observed inflation phases. During ponding, differentiation processes are also observed (Cannata et al, 2018).…”

“…However, during 2011-2014, the high frequency of the NSEC lava fountain episodes erupted a total volume (pyroclastics products plus effusive flows) of ∼150 × 10 6 m 3 (De Beni et al, 2015). Over this 2011-2014 time interval, this total erupted volume gives an average magma eruption rate similar (even higher) to the long-term output rate in the last decades through the usual effusive eruptions that is 25 × 10 6 m 3 per year (Harris et al, 2011;Bonaccorso Calvari and Calvari, 2013). In other words, the 2011-2014 NSEC activity was characterized by an unusually high frequency of explosive episodes compared to Etna's activity in past decades, although the average magma erupted rate in this interval is close to the long-term output rate of the volcano mainly emitted through major effusive eruptions.…”

Topographic Maps of Mount Etna’s Summit Craters, updated to December 2015

“…Etna: (1) the Voragine (VOR), or Chasm, earlier called Central Crater (CC), is the oldest, and has been observed at least since 1858 (Behncke, Neri, & Sturiale, 2004;Lyell, 1858); (2) the NE-Crater (NEC) is a cinder cone that built up from 1911 (McGetchin et al, 1974); (3) the Bocca Nuova (BN) started as a pit crater next to VOR in 1968, and collapsed in 1970 to form a large depression, now joined to VOR (Calvari et al, 1995;Chester, Duncan, Guest, & Kilburn, 1985;Giammanco, Sims, & Neri, 2007;Slatcher et al, 2015), and (4) the SE-Crater (SEC), which formed during the 1971 eruption (Behncke et al, 2006;Calvari, Coltelli, Muller, Pompilio, & Scribano, 1994;Guest, 1973), and has been the most active summit crater over recent decades (Behncke et al, 2006;Bonaccorso & Calvari, 2013;Calvari et al, 2011). Finally, the New SE-Crater (NSEC) (the fifth and youngest summit crater) has formed at the eastern base of the SEC, starting from a little pit crater that opened in late 2007 (Acocella et al, 2016;Behncke et al, 2016;Del Negro et al, 2013).…”

“…From these data, we can obtain the output rate and evaluate the state of the volcano and its potential of producing future eruptions (e.g. Bonaccorso & Calvari, 2013;Harris, Steffke, Calvari, & Spampinato, 2011Wadge & Guest, 1981). In addition, since the summit area of Etna is visited by thousands of tourists every year, the availability of updated topographic maps is essential for both monitoring and civil protection purposes (e.g.…”