I agree with Rooster, although I'm not sure it defines a disaster. I guess a definition would be something like "A catastrophically bad outcome to a situation created entirely by human hand". Think of Bhopal.
en.wikipedia.org/wiki/Bhopal_disaster
Define a man-made disaster?
I think the Atomic Bomb is a man made disaster ! It was needed to end WW2 , but it's been a threat to mankind ever since. Someday, someone is going to push a button and create the biggest disaster to man that ever will happen. Another is the escape of a biological weapon ! Total disaster!
