A disaster can happen at any time. The trigger depends on the kind of disaster.
Prestige oil spill happened in 2002.
lvl 70
Just lucky......
Marchioness disaster happened in 1989.
Feyzin disaster happened in 1966.
Patria disaster happened in 1940.
Eyemouth disaster happened in 1881.
Disaster Report happened in 2002.
Ryongchon disaster happened in 2004.
Kaprun disaster happened in 2000.
Niamiha disaster happened in 1999.