Fugen-dake erupted on November 17, 1990 after 198 years without a sign
of activity. The volcano then settled down until a second eruption in February
1991. Following this, a major pyroclastic flow occurred on June 3, making Unzen
the scene of the largest volcanic disaster and the largest number of fatalities
and persons missing since the eruption of Tokachi-dake in 1926.
The Ministry of Transport responded with measures to assist victims of the disaster. These measures included ensuring transport safety, replacing land transport with transport by sea, the provision of evacuation vessels and the use of hotels as refuges.
The Meteorological Agency established headquarters for disaster countermeasures both locally and at the Agency headquarters to further strengthen its capacity to survey, supervise and release information on the volcano.
The Maritime Safety Agency established local headquarters for disaster countermeasures and gave warnings through boat patrol inspections.