The release of lava and pyroclastic material from a source on the slopes of a volcano, away from its primary central vent or fissure-vent area. The location of a flank eruption is often controlled by local inflation stresses. These initiate fractures within the volcanic pile which propagate outwards from the primary volcanic conduit to feed lava towards the volcanic flanks. A flank eruption occurs where the lava-filled fractures intersect the slope of the volcano.