Yesterday's (2011-08-23) 5.8 mag quake in Virginia produced this interesting video that actually shows the seismic wave moving across North America. (for more info click HERE)
Just to keep things in perspective, the 9.0 quake that hit Japan on March 11th was over 1,000,000,000 (one billion) times stronger at the epicenter. Every whole number increase in magnitude is 1,000 times stronger than the lower whole number.
I've read that there is an identified fault that crosses the mid-line of Manhattan Island with the potential of generating a 6.5 quake. I don't know when (or if) NYC has upgraded their building codes to account for this hazard but it is easily conceivable that if/when it does occur the structural loss within the city could easily be in the 78%-90% range. The regional effect would be devastating, with major damage extending over a far greater range than we typically have in California.
Oh, yeah. In California a 5.8 is what considered "coffee stirring strength." Nothing to get excited about. Feces occurs.
"Let's all be careful out there!"