1. ASH PLUME STREAMS FROM MT. ETNA, SICILY. When this photograph was taken from Space Station Alpha on July 22, 2001, Mt. Etna's ash cloud reached about 5.2 kilometers into the atmosphere. Etna's record of volcanism is one of the longest in the world, dating back to 1500 BC. Two styles of volcanism are typical: explosive eruptions from the summit and flows from fissures on the volcano's flanks. (Photo courtesy of NASA.) Click here to learn more about Italy's volcanoes.   Click here to learn more about volcanoes all over the world.

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