This first recorded eruption of Cerro Azul was effusive, and formed the volcanic vent at Quizapu. Hornblende-dacite lava erupted with small masses of tephra, which had been degassed shortly before the eruption. Lava flowed over the Estero Barroso Valley and westward into the Río Blanquillo Valley. By November 28, the volcano appeared at rest, and the herdsman returned to the place of first observation. There, they found a blocky lava field. The lava was still hot, fuming and crackling with gas and flame. Fascinated by the volcano, Ignacy Domeyko traveled to Chile to study the field and found its width to be . By 1992 the field had grown to twice that size.