By Michael Godfried, Senior Planner, UW Institute for Hazard Mitigation Planning & Research
Washington State Emergency Management Division has just released the Manual for Tsunami Vertical Evacuation Structures. The Manual was produced by the University of Washington Institute for Hazards Mitigation Planning and Research and funded by a National Tsunami Hazard Mitigation Grant.
Please go to the following link: https://www.mil.wa.gov/tsunami
The Manual provides a process for communities to follow to plan, fund and build these structures and includes guidance on specific roles, funding sources and recommendations. Over 30 interviews and 2 public meetings in Ocean Shores and Aberdeen helped to inform the content of the Manual. The appendices document the public process and list valuable resources for communities.
From the Manual Executive Summary:
“Washington State has the second-highest earthquake risk in the United States. Western Washington has several active faults that impact communities along its coastlines. The Cascadia Subduction Zone (CSZ), just off the Pacific Ocean coastline, runs from Northern California up to Canada and is capable of generating a magnitude 9 earthquake. Earthquakes are a major source for tsunamis in Washington State. A local CSZ tsunami will leave some coastal communities with as little as 15 to 20 minutes to evacuate and is estimated to cause over 8,000 fatalities. Distant tsunamis, coming from as far away as Alaska and Japan, allow for significantly more warning time.
Coastal communities that lack sufficient natural or artificial high ground are particularly vulnerable. Residents, employees, and visitors will have limited time to evacuate to safety. For at-risk communities, tsunami vertical evacuation structures are a way to save lives. Evacuation structures are designed to withstand an earthquake, aftershocks, liquefaction, and multiple tsunami waves. They can be included as part of a new building or be a standalone tower or berm. Evacuation structures have performed successfully in Japan and have also been built in New Zealand. In 2016, the Ocosta Elementary School was completed with an evacuation area above the gymnasium. This school, located near Westport, Washington, is the first tsunami vertical evacuation structure to be built in North America.
Communities on Washington State’s Pacific Ocean coastline have limited resources. Unlike California and Oregon, Washington State’s major ports, infrastructure and associated funding resources are concentrated in the Puget Sound and along the Columbia River and not along the Washington coast. Tsunami vertical evacuation structures are complex and relatively new. Building these high-performance structures requires a variety of partners and expertise. Communities also have to administer a robust public engagement process to build support, plan, and determine funding options. Given all these factors, Washington State Emergency Management Division (EMD) felt that it was important to provide coastal communities with a manual that could help them navigate this process and protect their communities.”
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