OCEAN SHORES, Wash. — The 350 children at Ocean Shores Elementary School have practiced their earthquake survival plans, dropping under desks to ride out the convulsions, then racing upstairs to the second floor to await the coming tsunami.
Unless something changes, their preparations will most likely be futile.
The Cascadia fault off the Pacific Northwest coast is poised for a massive, 9.0-magnitude earthquake at some point, scientists say, a rupture that would propel a wall of water across much of the Northwest coast within minutes. Low-lying coastal neighborhoods in Washington, Oregon and Northern California would be under 10 feet or more of water, with the elementary school in Ocean Shores, Wash., facing an inundation that could be 23 feet deep.
The second-floor refuge students rush to in their drills stands 13 feet off the ground — in a structure that was not built to withstand a raging tsunami in the first place.
“The fact of the matter is that if a tsunami occurs tomorrow, we are going to lose all of our children,” said Andrew Kelly, the superintendent of the North Beach School District, which includes Ocean Shores. Mr. Kelly is one of a growing number of local officials who are calling for a network of elevated buildings and platforms along the Northwest coast that could provide an escape for thousands of people who might otherwise be doomed in the event of a tsunami.
Cascadia subduction zone, a 600-mile-long “megathrust” fault that stretches from Vancouver Island, British Columbia, to Cape Mendocino, Calif.
notably in Crescent City, where a tsunami that came all the way from Alaska killed 11 people in 1962.
The question, scientists say, is not if but when. The chance of a 9.0 megaquake on the Cascadia fault in the next 50 years, according to the research, is about one in nine (although the chance of the precise kind of quake envisioned in the planning models used by each state would be less); the odds of a smaller but still powerful earthquake — of a magnitude greater than 7.0 — are one in three. Pressure is continuing to build along the hundreds of miles where the Juan de Fuca plate is pushing under the North American plate.
“Every day, on average, they are being pushed together at about the rate fingernails grow,” said Corina Allen, the chief hazards geologist in Washington State. “Every year that the earthquake doesn’t happen, there’s a higher chance that it will the next year.”
Officials over the years have posted signs for evacuation routes and plotted ways to move people to higher ground. But many communities remain painfully vulnerable.