The last damaging earthquake in Washington struck 15 years ago, on Feb. 28, 2001.
The next one is scheduled for June 7.
The ground isn't expected to actually shake this spring. But nearly 6,000 emergency and military personnel will pretend it is during a four-day exercise to test response to a seismic event that will dwarf the 2001 Nisqually quake: A Cascadia megaquake and tsunami.
Called "Cascadia Rising," the exercise will be the biggest ever conducted in the Pacific Northwest. Which is fitting, because a rupture on the offshore fault called the Cascadia Subduction Zone could be the biggest natural disaster in U.S. history.
"It's really going to require the entire nation to respond to an event like this," said Kenneth Murphy, regional director for the Federal Emergency Management Agency, which is coordinating the exercise.
While the Nisqually earthquake measured magnitude 6.8, a Cascadia megaquake is likely to hit magnitude 9 — which is nearly 2,000 times more powerful. It will affect the entire West Coast from British Columbia to Northern California, including Seattle, Portland, Tacoma and Vancouver, B.C. The quake will be closely followed by tsunamis 30 feet high — or bigger — that will slam into oceanfront communities.
Comment: See also: Unexplained loud booms: A compilation from 2015