With waves capable of reaching 100 feet high and traveling at speeds up to 600 mph, tsunamis are one of the most powerful forces the earth.
Typically caused by powerful earthquakes under the ocean floor, tsunamis push tremendous and potentially destructive volumes of water across the surface of the ocean, presenting catastrophic dangers to coastal communities. With the North America tectonic plate and the Juan de Fuca plate converging at the Cascadia subduction zone off Washington’s coast, our state faces particular danger from tsunamis.
There is no way to prevent tsunamis. But you can prepare.
You would have at least 25 minutes to get out of the way of a tsunami caused by a megathrust earthquake, like the one off the coast of Japan in 2011.
As part of Earth Science Week 2014, Washington State Department of Natural Resources encourages residents, officials, and visitors to communities near the Pacific coast to review plans in order to be prepared when a tsunami hits.
DNR and its Division of Geology and Earth Resources works closely with the Washington Emergency Management Division, federal agencies, and local governments to prepare maps of recommended tsunami evacuation routes for many coastal Washington communities. Local and state emergency officials rely on maps of earthquake faults, tsunami inundation zones, and other information to plan their responses to earthquakes, tsunamis, and other natural disasters.
Even after the initial tsunami wave hits, you should follow evacuation routes. The first wave is often not the largest; successive waves may be spaced many minutes apart and continue to arrive for several hours. Return only after emergency officials say it is safe.
DNR is also helping communities prepare for tsunamis with research and evacuation maps. TsuInfo Alert is a bi-monthly newsletter published by the Division of Geology and Earth Resources that links scientists, emergency responders, and community planners to the latest tsunami research.
DNR geologists were among the experts who advised local officials and participated in public workshops with residents about tsunami dangers in Westport and other at-risk communities on Washington’s outer coast.
In addition, DNR geologists were part of the planning process for one of the first large tsunami refuges in the U.S. With their community less than a mile from the ocean, voters in the Ocosta School District at Westport last year approved a $13.8 million bond issue to replace an aging elementary school and build a gymnasium that will double as the nation’s first tsunami refuge structure.
The new gym’s roof, designed to withstand earthquakes and the impact of a tsunami, will sit about 55 feet above sea level, well above the highest surges predicted for the school site, and be able to hold 1,500 people. Elevated refuges can be the most practical and affordable options to survive a tsunami in communities where rapid evacuation is not possible.
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