I felt one small earthquake while living in Manhattan. Just a quick jerk and that was about it. I was dumbfounded to watch the TV news that night and see that it was actually centered on the Upper East Side. Weird.
In many ways, if you live in NYC, you need to think of earthquakes more like someone who lives in Haiti versus someone from California. Think of how many really OLD, unreinforced masonry buildings there are in NYC. Building collapses are not uncommon events in NYC even during normal times.
Imagine what even a 5.0, especially if it lasted for a bit, could do to those buildings. Probably would kill or injure a lot of people due to getting bonked in the head as the bricks peeled off the building facades and rained down on the sidewalks below. Or remember that unbelievable building collapse on East 62nd back in 2006? The whole building--just rubble. Granted, there was a gas explosion involved, but the same explosion risk exists after an earthquake, too.
As a native Californian, I thought about the possibility of earthquakes there from time to time, but y'know, it's pretty darn hard to do much. Especially when you're already paying much of your paycheck for rent, and there's hardly any space to store a lot of stuff in your cramped apartment anyway. And water? It makes me laugh to think about it, but if everyone in the buildings I lived in stored, say, 20 gallons of water, just the added weight would probably bring the building down!
Then throw in the possibility of some Three Mile Island-type disaster into the mix--eek, that's messy to contemplate!