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Products and dynamics of lava-snow explosions: the 16 March 2017 explosion at Mt Etna (Italy)
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  • Raffaello Cioni,
  • Daniele Andronico,
  • Lorenzo Cappelli,
  • Alvaro Aravena,
  • Pietro Gabellini,
  • Antonio Cristaldi,
  • Rosa Anna Corsaro,
  • Massimo Cantarero,
  • francesco ciancitto,
  • Emanuela De Beni
Raffaello Cioni
Università di Firenze

Corresponding Author:raffaello.cioni@unifi.it

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Daniele Andronico
Istitutio Nazionale di Geofisica e Vulcanologia - Osservatorio Etneo
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Lorenzo Cappelli
Département Géosciences Environnement et Société Université Libre de Bruxelles, Brussels, Belgium
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Alvaro Aravena
Universidad Catolica del Maule
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Pietro Gabellini
Dip.to Scienze Terra, Università di Firenze
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Antonio Cristaldi
Istituto Nazionale di Geofisica e Vulcanologia
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Rosa Anna Corsaro
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Massimo Cantarero
Istituto Nazionale di Geofisica e Vulcanologia
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francesco ciancitto
Istituto Nazionale di Geofisica e Vulcanologia, sezione di Catania
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Emanuela De Beni
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Volcanic hazards associated with lava flows advancing on a snow cover are often underrated. On 16 March 2017, during a mild effusive-explosive eruption at Mt Etna (Italy) a slowly advancing lava lobe interacted with the snow cover producing a sudden, short-lasting sequence of explosions. White vapor, brown ash and coarse material were suddenly ejected, and the products hit a group of people, injuring some of them. The proximal deposit formed a continuous mantle of ash, lapilli and decimetric-sized bombs, and the ballistic material reached up to 200 meters away from the lava edge. A total deposit mass of 7.1 ± 0.8 × 104 kg was estimated, corresponding to a lava volume removed by the explosion of 32.0 ± 3.6 m3. Textural and morphological data on the ejected clasts were used to constrain a model of lava-snow interaction. Results suggest that the mechanism responsible for the explosions was the progressive pressure build-up due to vapor accumulation under the lava flow, while no evidence was found for the occurrence of fuel-coolant interaction processes driving the explosions. Although these low-intensity explosions are not too frequent, the collected data represent a unique dataset which provides useful information on the involved processes and the associated hazard, but also on possible measures of mitigation to prevent potentially dramatic accidents at volcanoes like Etna, recording up to thousands of visitors per day.