Generally speaking, 5-6 things have to go wrong for an incident to occur. Furthermore, these events or failures have to occur in a certain sequence.
The characteristics of mega disasters is that 5-6 events with fairly low probabilities of occurrence line up.
Such rare incidents are referred to by many names within the risk management community – black swans, perfect storms, aligning of stars.
Why are these rare events difficult to identify? I would love to hear your comments.
Here is Jon Stewart on frequency of the perfect storms: