That compares with 710,000 in last year's Great Washington ShakeOut.
A large earthquake is considered inevitable at some point in the Northwest's future because of shifting plates in the earth's crust. A sudden release would cause an earthquake that could cause significant property damage and loss of life. A large quake also is likely to generate a tsunami, which threatens coastal areas.
The drill is an opportunity for people to practice dropping to the ground, taking cover and holding on until the shaking stops.
Schools, businesses, agencies and families registered for the drill on the Shakeout website.