Eruptions of Etna follow a variety of patterns. Most occur at the summit, where there are currently (as of 2019) five distinct craters — the Northeast Crater, the Voragine, the Bocca Nuova, and the Southeast Crater Complex (2). Other eruptions occur on the flanks, which have 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 spectacular but rarely threaten the inhabited areas around the volcano. In contrast, flank eruptions can occur down to a few hundred metres altitude, close to or even well within the inhabited areas. Numerous villages and small towns lie around or on cones of past flank eruptions. Since the year AD 1600, at least 60 flank eruptions and countless summit eruptions have occurred; nearly half of these have happened since the start of the 20th century. Since 2000, Etna has had four flank eruptions — in 2001, 2002–2003, 2004–2005, and 2008–2009. Summit eruptions occurred in 2006, 2007–2008, January–April 2012, in July–October 2012 and again in December 2018.
In 396 BC, an eruption of Etna reportedly thwarted the Carthaginians in their attempt to advance on Syracuse during the Second Sicilian War. A particularly violent explosive (Plinian) summit eruption occurred in 122 BC, and caused heavy tephra falls to the southeast, including the town of Catania, where many roofs collapsed. To help with reconstruction after the devastating effects of the eruption, the Roman government exempted the population of Catania from paying taxes for ten years. The Roman poet Virgil gave what was probably a first-hand description of an eruption in the Aeneid. During the first 1500 years AD, many eruptions went unrecorded (or records have been lost); among the more significant are: (1) an eruption in about 1030 AD near Monte Ilice on the lower southeast flank, which produced a lava flow that travelled about 10 km, reaching the sea north of Acireale; the villages of Santa Tecla and Stazzo are built on the broad delta built by this lava flow into the sea; (2) an eruption in about 1160 (or 1224), from a fissure at only 350–450 m (1,148–1,476 ft) elevation on the south-southeast flank near the village of Mascalucia, whose lava flow reached the sea just to the north of Catania, in the area now occupied by the portion of the city named Ognina.
Courtesy : Wikipedia
