The nine-year activity of the volcano is divided into four stages, with names that come from the Purépecha language. The first phase (Quitzocho) extended from February 22 to October 18, 1943, with activity concentrated in the cracks that formed in the Cuiyusuro Valley, forming the initial cone. During this time, the ejected material was mostly lapilli and bombs. In March, the eruption became more powerful, with eruptive columns that extended for several kilometers. In four months, the cone reached 200 meters and in eight months 365 meters. During this time period, there was some lava flow. On June 12, lava began to advance towards the village of Parícutin, forcing evacuations the next day.