Causing catastrophe by the act of trying to avoid catastrophe

First of all, the situation you describe -- someone actively trying to avoid a negative outcome, but actually causing the negative outcome -- is the epitome of irony. But I don't think that's the word you're looking for.

Another word that describes this outcome is backfire. If you make a conscious effort to avoid a catastrophe, but you cause the catastrophe as a result, then your effort has backfired.

I don't know if this is exactly what you want but there is an expression used in sociology and economics called self-fulfilling prophecy. Wikipedia http://en.wikipedia.org/wiki/Self-fulfilling_prophecy can explain it better, but I think the name is self-explanatory.

Backfire (“to bring a result opposite to that which was planned or expected: [eg] The plot backfired”), as mentioned in another question's answer, seems appropriate.

Also note the phrase hoist by one's own petard, which means “To be hurt, or destroyed by one’s own plot or device, of one’s own doing which one intended for another; to be “blown up by one’s own bomb”.”