<P> Volcanic activity first took place at Etna about 500,000 years ago , with eruptions occurring beneath the sea off the ancient coastline of Sicily . About 300,000 years ago , volcanism began occurring to the southwest of the summit ( centre top of volcano ) then , before activity moved towards the present centre 170,000 years ago . Eruptions at this time built up the first major volcanic edifice , forming a stratovolcano in alternating explosive and effusive eruptions . The growth of the mountain was occasionally interrupted by major eruptions , leading to the collapse of the summit to form calderas . </P>
<P> Volcanic activity first took place at Etna about 500,000 years ago , with eruptions occurring beneath the sea off the ancient coastline of Sicily . About 300,000 years ago , volcanism began occurring to the southwest of the summit ( centre top of volcano ) then , before activity moved towards the present centre 170,000 years ago . Eruptions at this time built up the first major volcanic edifice , forming a stratovolcano in alternating explosive and effusive eruptions . The growth of the mountain was occasionally interrupted by major eruptions , leading to the collapse of the summit to form calderas . </P>
when was the first time mount etna erupted
when was the first time mount etna erupted
about 500,000 years ago
about 500,000 years ago