Usu volcano, Hokkaido, Japan started eruption on 31 March 2000. The last eruption of Usu volcano was in 1977-78.Since 27 March 2000, very vigorous earthquake swarm began. Japan Meteorological Agency (JMA) issued 'Volcanic Alert' since 29 March.
Phreatic eruption continued at Nisiyama and Kompirayama craters in NW frank of Usu volcano. A cryptodome had formed near Nishiyama crater. The magmatic activity had stopped and the eruption stopped until September 2001.
