A disaster can happen at any time. The trigger depends on the kind of disaster.
Eyemouth disaster happened in 1881.
Luzhniki disaster happened in 1982.
Ibrox disaster happened in 1971.
Knockshinnoch Disaster happened in 1950.
Marchioness disaster happened in 1989.
HaBonim disaster happened in 1985.
Doñana disaster happened in 1998.
Westfield disaster happened in 1871.
Bocholt Disaster happened in 1895.
Seveso disaster happened in 1976.
Disaster of Curalaba happened in 1598.
Disaster Report happened in 2002.