Piton de la Fournaise has two semi-circular craters, surrounding older craters. The volcano experiences a mix of Hawaiian eruption and Strombolitian eruption types and typically has highly liquid lava flows. When cooled, Piton de la Fournaise lavas form basalt enriched in labradorite with almost no olivine. Historic evidence indicates that the volcano erupts on a 20 to 40-year cycle.