The Sakurajima Volcano Research Center, Disaster Prevention Research Institute (DPRI), Kyoto University celebrated the completion of the third observation tunnel in Kokuminshukusha Rainbow Sakurajima, Kagoshima Prefecture on 29 August 2016.
The completion of the third observation tunnel, Koumon, makes Sakurajima volcano to be the one and only volcano in the world to have three observation tunnels. Other two observations tunnels are Haruta observation tunnel (completed in 1985) and Arimura observation tunnel (completed in 2006 by the Ministry of Land, Infrastructure and Transport Management). These will facilitate the research of early warning of movements and prediction of eruptions. The completion of the tunnel was considered an urgent task as a major eruption of the volcano is expected in the near future.
Further details in Japanese, click link..