Lived in LA a few years ago and was through 3. They measured 4.3, 5.4 and 7.1 and can tell you a 5.4 while not 'severe' by LA standards would, probably cause alot of damage in NYC. Had the epicenter been within 20 miles of Manhattan, say. Supposedly, the largest e.q. to have happened in the North American continent happened in the Mississippi River basin. The ground liquified and it lasted for over a month. Someone correct me if I'm wrong, please as I remember seeing a TV show years ago in reference to the Mississippi River quake.