Oh, I'm not saying we will go black, at least not as a direct result. Nor am I saying that anything not on the impacted coast would disappear- the powerplants and stuff would be there and they would continue to work as long as they were able. What I am saying is that I don't think we could absorb that much damage over that little amount of time and not lose critical mass.

As Martin pointed out, 20-30 million dead is a reasonable estimate in this scenario, and figure half that many dislocated, optimistically. Never mind the issues with relocation, that many dead would pose a health crisis the likes of which we haven't seen in this country in living memory. You'd be looking at the loss of major ports (sea and air), stored goods, and economic and communications centers. Add in the loss of records and faith in the US dollar, and you won't see much coming in in the way of imports (ie, oil) even through the intact ports. Even the domestic economy would be hurt in a manner that we haven't seen in 70 years.

It might not be a country breaker, but it would cripple us. It honestly wouldn't be as bad if it hit the West coast, but the loss of everything along I-95 plus the Gulf Coast would put us on the brink. Either way, it would qualify as a TEOTWAWKI scenario, on par with the first sack of Rome- the Empire survived that. For a little while.