At about quarter to two this afternoon, my house shook for several seconds as an earthquake measuring 5.5 struck just north of Ottawa:
H/T to Colby Cosh for the graphic link.
Update: More information from the National Post:
A moderate earthquake was felt in parts of Southern Ontario and as far as Ottawa and Montreal. The U.S. Geological Survey has reported that an earthquake measuring 5.5 struck Southern Ontario, Quebec and a large part of the Eastern U.S. According to the USGS the quake was centered around 49 km from Cumberland, Ont.
According to reports a few tremors can still be felt after minutes after the initial quake but so far there are no reports of damage.