We heard this too.
Hard to believe a 6 range earthquake could sway buildings in Louisville and up and down the east coast.
My wife called from Dayton Ohio. She is on a fifth floor and said the building swayed dramatically.
Most of DC was built on swamp land that was drained and filled...there are no tall office buildings in DC....and when the Wash Monument was constructed..they may not have known about how to handle a big load, over a small foorprint, on a soft foundation...