Check out the web page of the Pacific Northwest Seismic Network and click on the markers for recent earthquakes.
You'll be surprised to see that they happen all the time... it's just that few of them are strong enough for us to feel.
The Cascadia Subduction Zone in which we live poses a constant threat of big earthquakes, and other features can also contribute to powerful Earth movements.
Seismic Network president John Vidale lectures this week at Southwestern Oregon Community College on temblors in the Northwest. He gives us a preview on The Exchange.