Mount Etna spews lava during an eruption seen from Acireale, Italy, on Saturday, November 16. The volcano, found on the Italian island of Sicily, has been active for about 2.6 million years.
Mount Etna: Europe's most active volcano —
Mount Etna spews lava during an eruption seen from Acireale, Italy, on Saturday, November 16. The volcano, found on the Italian island of Sicily, has been active for about 2.6 million years.
Carmelo Imbesi/AP
Mount Etna produces a steam ring, a rare occurrence for volcanoes, on November 11. At approximately 3,350 meters (10,991 feet), Etna is Europe's highest and most active volcano.
Mount Etna: Europe's most active volcano —
Mount Etna produces a steam ring, a rare occurrence for volcanoes, on November 11. At approximately 3,350 meters (10,991 feet), Etna is Europe's highest and most active volcano.
Tom Pfeiffer/Barcroft Media /Landov
A tower of smoke and ash looms over the Sicilian town of Zafferana in January 2012. Etna eruptions are relatively frequent -- the past 12 months have seen a string of powerful lava fountains, flows and ash emissions.
Mount Etna: Europe's most active volcano —
A tower of smoke and ash looms over the Sicilian town of Zafferana in January 2012. Etna eruptions are relatively frequent -- the past 12 months have seen a string of powerful lava fountains, flows and ash emissions.
Carmelo Imbesi/AP
Lava pours down the side of Etna in 2011.
Mount Etna: Europe's most active volcano —
Lava pours down the side of Etna in 2011.
MARCELLO PATERNOSTRO/AFP/Getty Images
Reporters watch lava flow down Etna in 2001.
Mount Etna: Europe's most active volcano —
Reporters watch lava flow down Etna in 2001.
GABRIEL BOUYS/AFP/Getty Images
In this photo provided by NASA, Etna is seen from space spewing smoke and ash in 2001.
Mount Etna: Europe's most active volcano —
In this photo provided by NASA, Etna is seen from space spewing smoke and ash in 2001.
NASA/Getty Images
Lava flows down Etna in 1993.
Mount Etna: Europe's most active volcano —
Lava flows down Etna in 1993.
Francois LOCHON/Gamma-Rapho via Getty Images
A giant mushroom cloud forms over Etna as it erupts in 1989.
Mount Etna: Europe's most active volcano —
A giant mushroom cloud forms over Etna as it erupts in 1989.
Gilles BASSIGNAC/Gamma-Rapho via Getty Images
A man near the village of Sant'Alfio watches lava flow from Etna in 1971.
Mount Etna: Europe's most active volcano —
A man near the village of Sant'Alfio watches lava flow from Etna in 1971.
Keystone/Getty Images
Lava slithers down Etna in 1951.
Mount Etna: Europe's most active volcano —
Lava slithers down Etna in 1951.
Gerard Gery/Paris Match via Getty Images
Villagers pray for help at the foot of Etna as lava advances toward their homes in 1947.
Mount Etna: Europe's most active volcano —
Villagers pray for help at the foot of Etna as lava advances toward their homes in 1947.
Keystone/Getty Images
An illustration shows an Etna eruption in 1669.
Mount Etna: Europe's most active volcano —
An illustration shows an Etna eruption in 1669.
Hulton Archive/Getty Images