 Cerro Azul 's April 1932 eruption was one of the largest of the 20th century . Releasing 9 @.@ 5 cubic kilometers ( 2 cu mi ) of lava , the volcano ejected primarily dacitic tephra , accompanied by rhyodacite , andesite , and minuscule amounts of andesitic and basaltic scoria . At least one eruptive period lasted for 18 hours , creating an " exceptionally uniform " deposit . Eruption columns , extending 27 – 30 kilometers ( 17 – 19 mi ) into the air , were sighted . <unk> were similar to the effusive eruption in 1846 . Soon after , both the <unk> and Descabezado Grande volcanoes began erupting , sending clouds of ash 800 kilometers ( 500 mi ) into Argentina . The eruption had a Volcanic Explosivity Index ( VEI ) of at least 5 . 
