Ash and steam eruption on April 1. Column rises to approximately 4000 m, then is blown downwind. Heavy ash fallout close to the crater is typical of the phreatic eruption style observed over the period March 30 to April 12, 1980. (The sharp black/white breaks on the slopes of the volcano are areas of ash and snow, respectively.) Correlation spectrometric analysis of this and other plumes revealed little magmatic contribution to the eruptions during the first 16 days of activity.