The VEI 2 Christmas 2018 Etna Eruption: A Small But Intense Eruptive Event or the Starting Phase of a Larger One?

The Etna flank eruption that started on 24 December 2018 lasted a few days and involved the opening of an eruptive fissure, accompanied by a seismic swarm and shallow earthquakes, significant SO2 flux release, and by large and widespread ground deformation, especially on the eastern flank of the volcano. Lava fountains and ash plumes from the uppermost eruptive fissure accompanied the opening stage, causing disruption to Catania International Airport, and were followed by a quiet lava effusion within the barren Valle del Bove depression until 27 December. This was the first flank eruption to occur at Etna in the last decade, during which eruptive activity was confined to the summit craters and resulted in lava fountains and lava flow output from the crater rims. In this paper, we used ground and satellite remote sensing techniques to describe the sequence of events, quantify the erupted volumes of lava, gas, and tephra, and assess volcanic hazards.Publishedid 9056V. Pericolosità vulcanica e contributi alla stima del rischioJCR Journa

Monitoring the December 2015 summit eruptions of Mt. Etna (Italy): Implications on eruptive dynamics

A lengthy period of eruptive activity fromthe summit craters ofMt. Etna started in January 2011. It culminated in early December 2015 with a spectacular sequence of intense eruptive events involving all four summit craters (Voragine, Bocca Nuova,NewSoutheast Crater, and Northeast Crater). The activity consisted of high eruption columns, Strombolian explosions, lava flows andwidespread ash falls that repeatedly interferedwith air traffic. The most powerful episode occurred on 3 December 2015 from the Voragine. After three further potent episodes fromthe Voragine, activity shifted to the NewSoutheast Crater on 6 December 2015, where Strombolian activity and lava flow emission lasted for two days and were fed by the most primitive magma of the study period. Activity once more shifted to the Northeast Crater, where ash emission and weak Strombolian activity took place for several days. Sporadic ash emissions from all craters continued until 18 December, when all activity ceased. Although resembling the summit eruptions of 1998–1999, which also involved all four summit craters, thismultifaceted eruptive sequence occurred in an exceptionally short time window of less than three days, unprecedented in the recent activity of Mt. Etna. It also produced important morphostructural changes of the summit area with the coalescence of Voragine and Bocca Nuova in a single large crater, the “Central Crater”, reproducing themorphological setting of the summit cone before the formation of Bocca Nuova in 1968. The December 2015 volcanic crisis was followed closely by the staff of the Etna Observatory to monitor the on-going activity and forecast its evolution, in accordance with protocols agreed with the Italian Civil Protection Department.Published53-695V. Dinamica dei processi eruttivi e post-eruttiviJCR Journa

MT. ETNA FEBRUARY-APRIL 2013 ERUPTION

European FP7 MED-SUV (MEditerranean SUpersite Volcanoes). Grant Number: 308665 European Research Council European FP7 (FP/2007-2013)/ERC. Grant Number: 279802 SIGMA (Sistema Integrato di sensori in ambiente cloud per la Gestione Multirischio Avanzata

On the transition from strombolian to fountaining activity: a thermal energy-based driver

International audienc

Coupling between magmatic degassing and volcanic tremor in basaltic volcanism

Magmatic degassing, typically measured as SO2 flux, plays a fundamental role in controlling volcanic eruption style and is one of the key parameters used by volcano observatories to assess volcanic unrest and detect eruption precursors. Volcanic tremor, the integrated amplitude of seismic energy release over a range of frequencies, is also a key parameter in volcano monitoring. A connection between volcanic degassing and tremor has been inferred through correlations between the signals which are often, but not always, observed during periods of unrest or eruption. However, data are often equivocal and our understanding of the physical processes, which couple degassing with tremor are still evolving. New insights into degassing-tremor coupling can be made by investigation of the long-term relationship between degassing and tremor, focusing on the frequency-dependence of tremor and passive degassing behavior. In this study, we examine how long-term SO2 emission rates and volcanic tremor on Mt. Etna, track rapid variability in eruptive dynamics. Correlations between SO2 flux and tremor are explored in both quiescent and eruptive periods, comparing the two parameters at both long and short time-scales (< < 1 day) for ∼2 years. Our analysis reveals that over ∼month-long timescales passive degassing of SO2 and tremor tend to be well-correlated, but these correlations are lost over shorter timescales. This reflects a coupling process between passive degassing and tremor, produced by a combination of gas flow through permeable magma and the convective flow of magma within the conduit. Short-term correlations are lost because variations in the continuous degassing process are relatively small compared with the overall degassing rate and fall below measurement noise. During eruptive periods strong correlations are observed between degassing and tremor, with a significant contribution of higher frequency signal in tremor, controlled by eruptive style. These observations suggest that in syn-eruptive periods the tremor source is dominated by the coupling between the eruption column and the ground through infrasonic waves, rather than conduit processes. Our results demonstrate the importance of high quality long-term observations and offer new insights into the physical mechanisms which couple degassing and volcanic tremor at active volcanoes

Crater Gas Emissions and the Magma Feeding System of Stromboli Volcano

International audienc

A New Degassing Model to Infer Magma Dynamics from Radioactive Disequilibria in Volcanic Plumes

Mount Etna volcano (Sicily, Italy) is the place where short-lived radioactive disequilibrium measurements in volcanic gases were initiated more than 40 years ago. Almost two decades after the last measurements in Mount Etna plume, we carried out in 2015 a new survey of 210Pb-210Bi-210Po radioactive disequilibria in gaseous emanations from the volcano. These new results [ ( 210 Po / 210 Pb ) = 42 and ( 210 Bi / 210 Pb ) = 7.5 ] are in fair agreement with those previously reported. Previously published degassing models fail to explain satisfactorily measured activity ratios. We present here a new degassing model, which accounts for 222Rn enrichment in volcanic gases and its subsequent decay into 210Pb within gas bubbles en route to the surface. Theoretical short-lived radioactive disequilibria in volcanic gases predicted by this new model differ from those produced by the former models and better match the values we measured in the plume during the 2015 campaign. A Monte Carlo-like simulation based on variable parameters characterising the degassing process (magma residence time in the degassing reservoir, gas transfer time, Rn-Pb-Bi-Po volatilities, magma volatile content) suggests that short-lived disequilibria in volcanic gases may be of use to infer both magma dynamics and degassing kinetics beneath Mount Etna, and in general at basaltic volcanoes. However, this simulation emphasizes the need for accurately determined input parameters in order to produce unambiguous results, allowing sharp characterisation of degassing processes

Hyperpectral infrared imaging of volcanic plume at Mt Etna during IMAGETNA campaign

International audienceKnowledge of the composition and the spatial evolution of volcanic plumes provides insights to processes occurring in the Earth's interior. On the other hand, quantification of gaseous emission fluxes is also a fundamental task in the framework of climate change in order to refine the contribution of natural emissions. UV cameras allow us to image volcanic plumes and evaluate SO2 fluxes, although can be subject to uncertainties in the retrieval. Another technique of imaging is now available in the infra-red. Such infrared hyperspectral imager (pixel-by-pixel spectra) might represent a major step forward in volcanology due to its potential to allow SO2 flux measurements during the night and gives access to additional relevant species but has to be tested and validated as a first step. In June 2015 a campaign of measurements - IMAGETNA - was performed at Mt Etna (Pizzi Deneri Volcano Observatory) with the intent to explore the application of these techniques for volcanic gas measurements all together. Over five days the volcanic plume was remotely observed simultaneously by employing three different hyperspectral imagers (commercial and under development), FTIR instrument, UV LWIR cameras, and radiometer. Results gathered from IR hyperspectral imageur will be presented and compared to SO2 UV-Vis camera measurements