 Cerro Azul was quiet from 1846 to the beginning of the 20th century . After a possible precursor explosive event in 1903 , Cerro Azul once again erupted in 1907 . Between 1907 and 1914 , plumes and clouds of ash frequently rose out of the caldera , and at least a few of these events were explosive . On September 8 , 1914 , an explosive eruption sent a plume 6 or 7 kilometers ( about 4 mi ) into the air over 8 minutes . By 1916 , these eruptions had produced a caldera nearly identical to the one in existence today . 
