island in the Northern Mariana Island group in north Pacific Ocean; one of 17 islands within a self-governing commonwealth; largest of purely volcanic islands at 8 mi (13 km) long by 2 ¹/₂ mi (4 km) wide; evacuated after the severe volcanic eruption of Mt. Pagan (574 m) in the northeast in 1981; population (which was 54 at the time) was moved to Saipan and has never returned, although the island is sporadically populated; island is still regarded as volcanic and peaks in the southwest corner emit steam; rugged terrain, lack of adequate soil cover, and insufficient rain make island generally unsuitable for habitation.