Plinian eruption
A large eruption covered parts of the upper edifice with scoria about 15,000 years before present. The Plinian eruption was even more recent, occurring about 10,000 years ago (10,085 ± 45 radiocarbon years ago). After this event four small lava domes formed in the summit region, and partly underwent collapse forming hot avalanche deposits; it is possible that the 1901 eruption was one of these lava dome forming events.