Mount Etna, towering above Catania, Sicily's second largest city, has one of the world's longest documented records of historical volcanism, dating back to 1500 BC. Historical lava flows cover much of the surface of this massive volcano, which makes it the highest and most voluminous in Italy. Ever since ancient times, the volcano seems to have been in near-constant activity. It is considered, after Kilauea on Hawaii, the second most active, i.e. productive volcano on earth.
Two styles of eruptive activity typically occur at Etna: (1) persistent explosive eruptions, sometimes with minor lava emissions, from one or more of the 4 prominent summit craters, the Bocca Nova, Voragine (the former Central Crater), NE Crater, and SE Crater (the latter formed in 1978). (2) Flank eruptions, typically with higher effusion rates, are less frequent and originate from fissures that open on the volcano's flanks. Such flank eruptions, such as the spectacular recent ones in 2001 and 2002-03 commonly form cinder cones, that dot the volcano in their hundreds.