As I was watching Obama's speech about firing McChrystal about half an hour ago, I noticed my computer monitor oscillating around in a circle on its stand as if somebody was driving a heavy truck in the aisle past my desk.  I overheard some coworkers talking about an earthquake and sure enough, we were feeling tremors in Detroit from a 5.5 quake up in Ottawa, Canada. 

More info at: earthquake.usgs.gov