Mount Etna is thought to have started as a submarine volcano that slowly grew above sea level as it erupted, time and again, gradually increasing its height with solidified lava, according to NASA's Earth Observatory.

What caused Mount Etna to erupt in 2013?

The working explanation boils down to indigestion: how volcanic gases build up inside Etna's underground plumbing. As with all volcanoes, the magma inside Etna holds gas bubbles, such as carbon dioxide, sulfur dioxide and water.

Why did Mount Etna erupt in 2001?

Etna, Italy, 21 July 2001 - Lava crawls towards Etna village Nicolosi, Sicily - Thick rivers of lava crawled down the sides of Mount Etna towards a village as Europe's most active volcano rumbled for a third straight day.