America's first tsunami refuge
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Rising above the risk: America's first tsunami refuge
Washington's coast is so close to the seismically active Cascadia Subduction Zone that if a megathrust earthquake were to occur, a tsunami would hit the Washington shoreline in just 25 minutes.
One coastal community is preparing for such a disaster by starting construction on the nation's first tsunami evacuation refuge, large enough to shelter more than 1,000 people who are within 20-minute walking distance.
The vertical evacuation-refuge will be the roof of the gym of the new school in Grays Harbor County, Washington. The Ocosta Elementary School and Tsunami Safe Haven will be the first of its kind in the nation and will be the culmination of 18 years of effort, said Tim Walsh, who is a Chief Hazard Geologist at the Department of Natural Resources and has been working on this project since The National Tsunami Hazard Mitigation Program was formed in 1995.
Walsh will present the project design for the school and structure, along with the detailed tsunami modeling used to find the best location for the refuge, at the Annual Meeting for the Geological Society of America in Vancouver, Canada, on 21 October.
The Cascadia subduction zone is a 700-mile-long (over 1,000 kilometers) fault along the West Coast, where the Juan de Fuca Plate is being forced under the North American Plate. The subduction zone is capable of producing massive earthquakes; scientists have calculated that magnitude-9 earthquakes along this fault line could generate a massive tsunami that would hit the coastlines of British Columbia, Washington, Oregon, and California within 20 to 30 minutes.
"It used to be thought that Cascadia was not an active fault," said Walsh. Not only has Cascadia been found to be an active fault, it has a 10 percent chance that it will cause an earthquake in the next 50 years, he said.
"It is more than 10 times more likely than the chance you will be killed in a traffic accident," said Walsh. "But you aren't looking at the statistics of a single person, but an earthquake that would have an effect on thousands of miles of shoreline." ScienceDaily
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Thursday, October 23, 2014
Grays Harbor County school to build first U.S. vertical-tsunami refuge
A new scenario for a megaquake and tsunami off the Washington coast warns that the death toll could top 10,000 — but Paula Akerlund is doing everything she can to keep her kids safe. All 700 of them.
The Grays Harbor County school district Akerlund oversees on the Washington coast is preparing to build the nation’s first tsunami refuge.
Residents of Westport, Grayland and other communities in the Ocosta School District approved a $13.8 million bond issue earlier this year to replace a flimsy elementary-school building with a complex that includes a gym strong enough to withstand tsunami surges, tall enough to stay dry and big enough to shelter more than 1,000 people on its roof.
“We’re probably less than a mile from the Pacific Ocean, and we have no hills to run up or other natural high ground,” Akerlund said. “Our only alternative is to get as high as we can, as fast as we can.”
In the wake of a magnitude-9 quake on the Cascadia Subduction Zone — a 700-mile-long offshore fault — the resulting tsunami is expected to slam into Westport and other parts of Washington’s outer coast within 20 to 30 minutes.
The new gym will be built on a small hill, and its roof will sit about 55 feet above sea level. That’s well above the tallest surges tsunami modelers predict for the school site, said Chuck Wallace, deputy director of emergency management for Grays Harbor County. “We’re pretty much using our worst-case scenario for height.”
The gym will also provide a refuge for nearby residents." The Seattle Times