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Questão FC689033

READ TEXT I AND ANSWER THE FOLLOWING QUESTION: TEXT I Products and dynamics of lava-snow explosions: The 16 March 2017 explosion at Mount Etna, Italy Abstract Volcanic hazards asso

Interpretação de Textos (Understanding)

FGV · 2025

READ TEXT I AND ANSWER THE FOLLOWING QUESTION:

 

TEXT I

 

Products and dynamics of lava-snow explosions: The 16 March 2017 explosion at Mount Etna, Italy

 

Abstract  

Volcanic hazards associated with lava flows advancing on snow cover are often underrated, although sudden explosions related to different processes of lava-snow/ice contact can occur rapidly and are only preceded by small, easily underrated precursors. On 16 March 2017, during a mildly effusive and explosive eruption at Mount Etna, Italy, a slowly advancing lava lobe interacted with the snow cover to produce a sudden, brief sequence of explosions. White vapor, brown ash, and coarse material were suddenly ejected, and the products struck a group of people, injuring some of them. The proximal deposit formed a continuous mantle of ash, lapilli, and decimeter-sized bombs, while the ballistic material travelled up to 200 m from the lava edge. The deposit was estimated to have a mass of 7.1 ± 0.8 × 104 kg, which corresponds to a volume of 32.0 ± 3.6 m3 of lava being removed by the explosion. Data related to the texture and morphology of the ejected clasts were used to constrain a model of lava-snow interaction. The results suggest that the mechanism causing the explosions was the progressive build-up of pressure due to vapor accumulation under the lava flow, while no evidence was found for the occurrence of fuel-coolant interaction processes. Although these low-intensity explosions are not particularly frequent, the data set collected provides, for the first time, quantitative information about the processes involved and the associated hazard and suggests that mitigation measures should be established to prevent potentially dramatic accidents at worldwide volcanoes frequented by tourists and with fairly easy access, such as Etna.

 

Source: GSA Bulletin (2024) 136 (5-6): 2325–2342. Available at

https://pubs.geoscienceworld.org/gsa/gsabulletin/article/136/5-6/2325/628546/Products-and-dynamics-of-lava-snow-explosions-The

 

Based on Text I, mark the statements below as TRUE (T) or FALSE (F).

 

I) The eruption resulted in no casualties.

 

II) Fragments were launched high above the edge of the lava.

 

III) Fuel and coolant interaction caused the explosion at Mount Etna.

 

The statements are, respectively

  1. T, F, T.
  2. F, F, T.
  3. F, T, F.
  4. F, T, T.
  5. T, T, F.
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Gabarito

Certo

Comentário do professor

A sequência correta é F, T, F.

I — Falso. O texto afirma que os produtos ejetados atingiram um grupo de pessoas, “injuring some of them”, o que indica que houve feridos; portanto não é verdade que não houve vítimas.

II — Verdadeiro. Há menção explícita de “ballistic material travelled up to 200 m from the lava edge”, ou seja, fragmentos foram projetados a partir da borda da lava, compatível com a afirmação.

III — Falso. O estudo declara que “no evidence was found for the occurrence of fuel-coolant interaction processes” e atribui o evento à acumulação de pressão por vapor sob a lava, não a uma interação combustível-refrigerante.

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