How did a giant, gaping hole tear through the massive Oroville Dam’s main concrete spillway last week, setting in motion the chain of events that could have led to one of America’s deadliest dam failures? Dam experts around the country are focusing on a leading suspect: Tiny bubbles.The prospect is simple, yet terrifying and has been the culprit in a number of near disasters at dams across the globe since engineers discovered it about 50 years ago.