Here is what I heard the cause was,
“Residents of Washington DC do not be alarmed. That quaking you feel is the entire country moving to the right.” – (comment seen circulating on FB)
Evidently the quake occurred on a little known fault line outside of DC called “Bush’s Fault”
“It has been confirmed that the shaking felt around the washington area and along the east coast was actually our Founding Fathers all rolling in their graves!”