Local Source Generated Tsunami Risks

The Cascadia Subduction Zone (CSZ) is a “megathrust” fault 620 mi long off the west coast, stretching from Northern Vancouver Island to Cape Mendocino, California.

On the night of January 26, 1700, a magnitude 9.0 earthquake shook the region, sending a tsunami almost immediately inland along the west coast of the US and arriving roughly 10 hours after the quake as a 16-foot wave on the shores of Honshu Island, Japan.

Seattle & other Local Fault Earthquakes


Distant Source Generated Tsunami Risks

A tsunami originating from a faraway source. Typically distances greater than 600 miles or more than three hours of tsunami travel time from its source.

Examples include Alaska, Japan, and rare events like the underwater volcanic eruption near Tonga.

The impacts of distance-source tsunamis pose the greatest risk along the outer-coast of Washington.

The Thunderbird & the Whale

The oral history shared by many coastal Tribes in the Northwest tells the story of the Thunderbird and the Whale and the danger of these waves.

Alerts & Warnings

Protect Yourself

1. Drop! Cover! and HOLD ON! Protect yourself during an earthquake.2. Go to high ground or inland! The shaking is your tsunami warning. 3. Stay there until you are informed it is safe to return.

Resources for Suquamish Boaters

Tsunami Maritime Guidance
Guidance for Safe Minimum Offshore Depth for Vessel Movement

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NOAA Electronic Navigational Charts

Bathymetric Data with Water Depths

Tsunamis! What Washington Boaters Need to Know Brochure

Tsunami Sign Installation Information

Please note that currently, these Tsunami Signs in the map below are the proposed locations, and any changes to them will be in the same general area and moved to increase visibility. Once the signs are installed, we will update this map to reflect their actual locations.


Tsunami Scenarios


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