How often does mount etna erupt ?
Eruptions of Etna are not all the same. Some occur at the summit, where there are currently (as of 2008) four distinct craters–the Northeast Crater, the Voragine, the Bocca Nuova, and the Southeast Crater. Other eruptions occur on the flanks, where there are more than 300 vents, ranging in size from small holes in the ground to large craters hundreds of metres across. Summit eruptions can be highly explosive and are extremely spectacular, but are rarely threatening for the inhabited areas around the volcano. On the contrary, flank eruptions can occur down to a few hundred metres altitude, close to or even well within the populated areas. Numerous villages and small towns lie around or on cones of past flank eruptions. Since the year 1600 A.D., there have been at least 60 flank eruptions and countless summit eruptions; nearly half of these have occurred since the start of the 20th century, and the 3rd millennium has seen five flank eruptions of Etna so far, in 2001, 2002–2003, 2004–2005