Parts of Tacoma, Olympia susceptible to tsunamis. New regulations aim to make them safer
Buildings in Washington might get safer now that new building codes to help protect against tsunamis are in effect.
The codes, for newly built structures in vulnerable areas including Tacoma and Olympia, went in to effect March 15.
Tsunamis are huge, destructive waves that can follow undersea earthquakes and volcanic eruptions. They’ve hit Washington’s coastal areas in the past but long before modern buildings were standing.
Users can access an interactive map that shows where the codes apply. It has handy bookmarks for a number of coastal cities, including Tacoma, Olympia and Seattle as well as smaller towns like Westport and Ocean Shores.
Tsunami hazards
The Washington Geological Survey has studied the potential manifestations and impacts that tsunamis can have on land. WGS has modeled the waves’ potential flooding, velocities and arrival times following an earthquake on the Cascadian Subduction Zone. The fault parallels much of the West Coast about 70-100 miles offshore.
The last major quake from the zone, estimated at 9.0 magnitude, hit Washington in 1700. Its effects were seen and recorded as far away as Japan, but residents there did not know what caused the tsunami.
New codes
In 2021, the state adopted building codes that require engineers and architects to consider tsunami safety in their designs for buildings in what is now officially known as the Washington Tsunami Design Zone.
The WGS recommends zooming in on the map to see specific locations. The hazard zones have a yellow overlay. Details provide estimated inundation levels and other information.
In Tacoma, most of the port and some of the city’s coastline are in the hazard zone. Olympia’s marinas, its port and some of the city’s downtown blocks adjacent to the water are in the map’s hazard zones.
