A flank eruption is an eruption on the slopes of the main volcanic cone. Effusive flank eruptions of basalt are common on shield volcanoes . Explosive flank eruptions can also be called lateral blasts. Parasitic or secondary cones can pepper the sides of volcanoes.
Mt Etna has numerous secondary eruption centres with 60 flank eruptions in the last 400 years and 5 in the last ten.