Boiler Bay Beacon
SALEM — The Oregon Department of Emergency Management on Wednesday released new guidance to help coastal communities plan tsunami vertical evacuation structures.
TSUNAMI VERTICAL STRUCTURE GUIDANCE
The document is a planning tool, not a requirement to build. Officials say it is aimed at places where walking to natural high ground after a Cascadia earthquake may not be fast enough.
“Oregon’s coastal communities face some of the most urgent tsunami risks in the nation, and this guidance provides several considerations for tsunami safety that can inform locally driven solutions,” OEM Director Erin McMahon said.
A Cascadia Subduction Zone earthquake may shake for three minutes or longer. State scientists say a locally generated tsunami can begin to inundate the coast in as little as 10 minutes after shaking starts. Ground shaking is the warning. There may be no time for an official alert.
Vertical evacuation structures are towers, earthen berms, elevated platforms or buildings built to stand above the expected flood. They are engineered to survive strong shaking, debris and more than one wave so people can wait out the first hours.
Oregon has one completed example. The Gladys Valley Marine Studies Building at Oregon State University’s Hatfield Marine Science Center in Newport opened in 2020. The rooftop is about 47 feet high and is designed as a refuge for more than 900 people. Access includes stairs, a ground-level ramp and an emergency elevator with backup power. The building was designed for a magnitude 9-plus earthquake and an extra-extra-large Cascadia tsunami.
Most of Lincoln City can reach high ground at a moderate walking speed if people leave as soon as they can move, according to Department of Geology and Mineral Industries evacuation studies. Cutler City and the Siletz Spit are harder. Distances are longer and routes are limited. City code already allows vertical evacuation structures if they put people above the largest mapped local tsunami.
OEM developed the guidance with DOGAMI. Support came from NOAA’s National Tsunami Hazard Mitigation Program and FEMA’s Emergency Management Performance Grant program.
The guide covers hazard science, evacuation timing, structure types, case studies, public engagement, funding options and Oregon rules, including tsunami design standards and the Tsunami Hazard Overlay Zone.
Maps and routes are at OregonTsunami.org. If the ground shakes hard and long on the coast, drop, cover and hold, then walk inland or uphill. Do not wait for a siren.
