 Every known type of eruption ( Hawaiian , Strombolian , Plinian , subplinian , phreatic , phreatomagmatic , and Vulcanian ) has occurred at some point in the range . Cerro Azul itself has experienced phreatic , Strombolian , and Plinian activity in human history . The type of eruption tends to correspond with lava composition . Strombolian eruptions at Llaima , Antuco , Villarrica , and elsewhere have been produced by basaltic to basaltic – andesitic activity . Dacitic to rhyolitic lavas have been linked to subplinian and Plinian eruptions , such as those at Quizapu ( 1932 ) and Hudson ( 1991 ) . Because of this variability , volcanic hazards from Cerro Azul and the surrounding region could come in many different forms . Historical eruptions typically have produced lahars , lava flows , and ashfalls . Lava flows and lahars could wipe out entire cities or towns . Ashfall produced by explosive eruptions could interfere with air traffic . Most threatening of all is the risk of pyroclastic flows or avalanches , which have historically traversed as far as 100 kilometers ( 62 mi ) in the region . 
