The New York City Earthquake of 1884.

[N2NH]

Almost strong enough to make a Californian look up from his morning coffee.

Yep. In fact, it's more likely to happen in NYC than it is in San Diego.

The problem isn't the magnitude. We had a quake in Quebec that shook us at about a 5, it's the old style buildings that will crack like an egg. The average building is brick and mortar and will literally fall apart in seconds if it goes over a 5. They'll have at least a 5 if things go as they have and they are overdue by 2 decades at this point. The longer it takes, the stronger the quake will likely be.