Photo taken on Dec. 24, 2018 shows the Mount Etna volcano during the eruption in Catania, Sicily, Italy. Sicily's Mount Etna volcano erupted on Monday, the National Institute of Geophysics and Vulcanology (INGV) said in a statement. Eruptions are fairly frequent occurrences at Mount Etna, with the last large eruption taking place in 2009, according to the INGV. (Photos: Xinhua)

Photo taken on Dec. 24, 2018 shows the Mount Etna volcano during the eruption in Catania, Sicily, Italy. Sicily's Mount Etna volcano erupted on Monday, the National Institute of Geophysics and Vulcanology (INGV) said in a statement. Eruptions are fairly frequent occurrences at Mount Etna, with the last large eruption taking place in 2009, according to the INGV.

Photo taken on Dec. 24, 2018 shows the Mount Etna volcano during the eruption in Catania, Sicily, Italy. Sicily's Mount Etna volcano erupted on Monday, the National Institute of Geophysics and Vulcanology (INGV) said in a statement. Eruptions are fairly frequent occurrences at Mount Etna, with the last large eruption taking place in 2009, according to the INGV.

Photo taken on Dec. 24, 2018 shows the Mount Etna volcano during the eruption in Catania, Sicily, Italy. Sicily's Mount Etna volcano erupted on Monday, the National Institute of Geophysics and Vulcanology (INGV) said in a statement. Eruptions are fairly frequent occurrences at Mount Etna, with the last large eruption taking place in 2009, according to the INGV.