(TNS) - 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.



The damage and casualty estimates in FEMA’s quake scenario are sobering:



• More than 10,000 fatalities, mostly due to the tsunami



• 30,000 injuries



• 7,000 highway bridges and 16,000 miles of highway with high to moderate levels of damage



• 90 percent of port facilities destroyed or damaged



• Natural-gas and refined-fuel pipelines out of service



• 70 percent of electrical power systems damaged



• Serious damage to water-treatment and sewage plants



“For this scenario, we felt we really had to get all the experts in the room and use the best modeling and research that exists,” said Scott Zaffram, FEMA training and exercises branch chief. But the estimates are just that, he cautioned. The number of deaths, for example, would be much lower if the quake struck at 2 a.m. in January than at noon on a summer’s day when beaches are crowded.



During the Cascadia Rising exercise, emergency managers will do their best to deal with the theoretical catastrophe, with the goal of identifying problems and improving response when the real thing happens.



“We’re going to learn something at every level of government … that will help us figure out better ways to plan for this,” Murphy said.



The drill will be conducted mostly at the tabletop level. Workers will staff their posts at emergency-operations centers across Washington, Oregon, Idaho and British Columbia, fielding simulated damage reports, responding to calls for help, coping with power outages and tracking down resources and rescuers.



Phone and Internet services are expected to be knocked out, so teams will practice communicating via satellite phone and emergency radio frequencies.



In Grays Harbor County on the Washington coast, where many towns are in the tsunami inundation zone and ground shaking is expected to be fierce, emergency manager Chuck Wallace has recruited local ham-radio operators to participate.



“They have radios in their trucks,” he said. “They can hook up to a car battery and they’re rolling, so we should be able to get reconnaissance information from them.”



Wallace encouraged organizers to add aftershocks and multiple tsunami surges to the exercise scenario, to make it as realistic as possible. He and his staff are also prepared to consider some grim possibilities, such as a tsunami that completely overtops the cities of Ocean Shores and Westport, killing all public officials.



At the state level, Murphy is challenging elected officials and emergency managers to ask similarly tough questions. “If you have every county in Washington damaged, who gets what first?” he asked.



Several military units will conduct field exercises in conjunction with Cascadia Rising. More than 1,500 members of Washington’s National Guard will set up tactical operations centers, dispatch search and rescue teams, and move supplies, said spokeswoman Karina Shagren.



At least one naval vessel will respond as if to a real disaster, establishing an emergency dock and transporting cargo, equipment and personnel.



The participation of so many state and local governments, agencies and military units is important because the quake and tsunami will affect such a large area, said Jim Mullen, former director of the Washington State Emergency Management Division.



Eastern Washington and Idaho won’t experience much, if any quake damage, but they will be key for relocating refugees, treating victims, and transporting supplies.



Mullen cautioned against the tendency of agencies and organizations to “paper over” their failings in exercises like these. “Identifying gaps is good,” he said. “That means you found something we’re not good at — but now we can fix it.”



And even though the Cascadia Rising exercise is focused on the immediate response to the disaster, officials should also use it as a springboard for discussions about long-term recovery and efforts to get the region’s economy back on track, Mullen said.



The last Cascadia megaquake and tsunami occurred in the year 1700. Estimates of average recurrence intervals vary from 250 to 500 years — but geologists say there’s no doubt the fault will rupture again some day.



Those who weathered the Nisqually quake shouldn’t count on such a mild ride the next time around, Wallace said.



“A Cascadia quake is very different,” he said. “We can’t afford to become complacent.”



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