On this day in history (within living memory) a disaster occurred which killed over 2,600 people. What was it, where was it, and when was it?

Hint: It was the worst disaster of its kind in history.

The Vaiont dam disaster

http://www.aber.ac.uk/iges/cti-g/hazards2000/massmovement/human2.html

Yeah, I gotta stop lobbing these slow pitches.