The volcano also erupted phreatically several times, as recorded by Vogel in 1913 and 1920, with its activity increasing from 1916 to 1926. During these years, the eruptions grew more frequent and more violent. A major outburst on November 2, 1927 started a period of nearly continuous violent eruptions that lasted until 1929. During this period, Cerro Azul sometimes erupted daily, sending columns of ash as far as 6 or 7 kilometers (about 4 mi) into the air. Quizapu Crater grew slightly during this eruptive period.