Dynamics of a lava fountain revealed by geophysical, geochemical and thermal satellite measurements: The case of the 10 April 2011 Mt Etna eruption

Abstract

Geophysical (tilt, seismic tremor and gravity signals), geochemical (crater SO2flux) and infrared satellite measurements are presented and discussed to track the temporal evolution of the lava fountain episode occurring at Mt Etna volcano on 10 April 2011. The multi‐disciplinary approach provides insight into a gas‐rich magma source trapped in a shallow storage zone inside the volcano edifice. This generated the fast ascending gas‐magma dispersed flow feeding the lava fountain and causing the depressurization of a deeper magma storage. Satellite thermal data allowed estimation of the amount of erupted lava, which, summed to the tephra volume, yielded a total volume of erupted products of about 1 × 106 m3. Thanks to the daylight occurrence of this eruptive episode, the SO2 emission rate was also estimated, showing a degassing cycle reaching a peak of 15,000 Mg d−1 with a mean daily value of ∼5,700 Mg d−1. The SO2 data from the previous fountain episode on 17–18 February to 10 April 2011, yielded a cumulative degassed magma volume of about ∼10.5 × 106 m3, indicating a ratio of roughly 10:1 between degassed and erupted volumes. This volumetric balance, differently from those previously estimated during different styles of volcanic activities with long‐term (years) recharging periods and middle‐term (weeks to months) effusive eruptions, points toward the predominant role played by the gas phase in generating and driving this lava fountain episode.

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

“…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.…”

A year of lava fountaining at Etna: Volumes from SEVIRI

“…It records data in twelve wavebands, including one in the mid-infrared (band IR3.9, 3.48-4.36 mm) and two in the thermal infrared (band IR12.0, 11.00-13.00, and band IR13.4, 12.40-14.40 mm). These two bands have been shown particularly useful in detecting and tracking hot spots associated with effusive activity [Hirn et al, 2008;Bonaccorso et al, 2011b;Ganci et al, 2011Ganci et al, , 2012, and provide data every 15 minutes at a spatial resolution of 3 km. The SEVIRI record for Etna's lava fountaining events of 2011, plus the first event of 2012, is summarized in Table 1.…”

Temporal variations of flux and altitude of sulfur dioxide emissions during volcanic eruptions: implications for long-range dispersal of volcanic clouds

“…This increase is simultaneously measured with the ground network of UV-spectrometers which records similar flux values (up to 600 t h −1 ; (top of Fig. 3 green line), well in excess of background values of ∼ 62 t h −1 recorded between 8 and 9 April 2011 and early morning on 10 April (Bonaccorso et al, 2011). Tremor amplitude, which is commonly used to track changes of the volcanic activity at Etna (Alparone et al, 2003), also indicates a simultaneous increase of the seismicity (bottom of Fig.…”

“…Etna since 2005 (Salerno et al, 2009). On 10 April 2011, three out of the nine spectrometers of the network intersected Etna's plume at a distance of ∼ 14 km from the summit craters (Bonaccorso et al, 2011). If UV radiation received by these instruments is sufficient (i.e.…”

“…during daylight hours, under favourable me- teorological conditions and during eruptive periods emitting an optically thin volcanic plume), such a network allows for monitoring the SO 2 flux emitted by the volcano with a temporal resolution of ∼ 6 min. Hence, on 10 April 2011, Etna SO 2 emission rates could be measured from 7 a.m. to 3 p.m. (Bonaccorso et al, 2011) allowing for the capture of the 10 April eruptive episode which, fortunately, occurred mostly during daylight hours.…”