New State Tsunami Modeling Puts Real Numbers on the Wave Threatening Kitsap's Navy Bases

A tsunami born nearly 1,500 miles away in the Gulf of Alaska could still be swelling three feet at the Navy's Trident submarine base in Bangor and surging to 14 feet by the time it reaches the dead end of Hood Canal near Belfair, three and a half hours after the ground stops shaking on the other side of the Pacific. That is the headline finding of the first state modeling ever done of a tsunami generated along the Alaska-Aleutian Subduction Zone, released this month by the Washington Geological Survey and the state Emergency Management Division. The scenario re-creates the 1964 Good Friday earthquake that killed 131 people in Alaska, but moves its epicenter closer to Kodiak Island to aim the strongest wave energy squarely at Washington's coast. For Kitsap County, where the Navy runs the West Coast's only dry dock large enough for an aircraft carrier, the modeling puts hard numbers on a threat that state officials say is more likely to strike in anyone's lifetime than the long-feared Cascadia earthquake that sits directly beneath Puget Sound.

How State Scientists Built a Worse Version of the 1964 Alaska Quake

The Washington Geological Survey and Washington Emergency Management Division built the scenario as a joint project, and it is the first time the state has modeled a tsunami sourced from the Alaska-Aleutian Subduction Zone rather than the Cascadia fault closer to home. Researchers started with the magnitude-9.2 earthquake that struck Alaska on Good Friday in 1964, then repositioned its epicenter nearer Kodiak Island so the resulting wave train would point more directly at the Washington coast than the original event did. The output is not a single number but a full set of maps: onshore flooding zones, offshore wave heights, arrival times at dozens of towns, and current speeds in narrow waterways, all now published through the Department of Natural Resources' Geologic Information Portal. State officials say the Alaska-sourced scenario matters precisely because it is the more probable one. Washington has never recorded a Cascadia rupture in the modern instrumental era, but the Alaska-Aleutian zone produces a major earthquake somewhere along its length every few decades, and each one sends some amount of tsunami energy toward the Pacific Northwest. Modeling a worst-case version of that recurring hazard, rather than the rarer local one, was the point of the exercise. The survey says more than 175,000 residents and visitors currently live or work inside Washington's tsunami inundation zones, spread across roughly 3,000 miles of shoreline, which is the population the new maps are meant to help protect.

Hood Canal Would Swell for Hours, Right at Bremerton's Doorstep

The model's timing table reads like a countdown clock for the Kitsap Peninsula. The first wave reaches La Push in three hours and 30 minutes, Port Angeles in four hours, Seattle in five hours and 40 minutes, and Olympia in seven hours. Along the outer coast at Westport, in Grays Harbor County, offshore waves could top 20 feet. Inside Hood Canal, the numbers are smaller but still consequential for a body of water most Kitsap residents think of as sheltered: three feet at Bangor, home to the Navy's Trident ballistic-missile submarine fleet, four feet at Hoodsport, and as much as 14 feet once the wave funnels down to the dead end at Lynch Cove, near Belfair. What caught the modelers off guard was not the coast. It was the interior. Researchers had not expected hazardous currents to develop this far inside Puget Sound's protected waterways, but the simulation shows dangerous current speeds in the San Juan Islands, Guemes Channel, Port Gamble and Hood Canal itself, all places where boat traffic and shoreline development assume calm water. The tsunami does not behave like a single wave and vanish. State scientists say the disturbance can keep sloshing through these enclosed channels for 24 hours or longer, and that the first wave to arrive is frequently not the largest one, a detail that matters enormously for anyone tempted to return to the waterfront once the initial surge has passed.

Why the Navy's Only Carrier Dry Dock Is Already on a Separate Watch List

The Alaska scenario is not the only tsunami study bearing on Bremerton's waterfront. A separate, earlier round of state modeling focused on the closer and more destructive threat: a magnitude-9.0 rupture of the Cascadia Subduction Zone itself. That analysis found Puget Sound Naval Shipyard in Bremerton and Naval Base Kitsap-Bangor squarely exposed, with waves "eclipsing 20 feet" battering waterfront structures and Hood Canal expected to "slosh back and forth like a bathtub, all the way to Belfair," subjecting the shoreline to what that analysis called multiple wakes for hours. The two studies model different earthquakes with different arrival times, and this newsroom is not conflating them; they describe the same vulnerable stretch of shoreline from two different directions, which is exactly why Kitsap's Navy installations keep surfacing in tsunami planning regardless of which fault ruptures. Puget Sound Naval Shipyard is not a replaceable facility. It is the only shipyard on the West Coast that can dry-dock an aircraft carrier, and reporting on the Cascadia modeling noted it is also the only place in the world where the Navy can properly handle nuclear components pulled from decommissioned vessels. What happens to that work in the hours after a tsunami warning is less clear. Coverage of the earlier study found the Navy's own contingency plans center on standing up "a dedicated post with base leadership and emergency management officials," without spelling out exactly how nuclear-material handling would be paused or secured, a gap that has nothing to do with which subduction zone eventually ruptures.

Officials Say the Distant Threat Is the More Likely One

Elyssa Tappero, tsunami program manager for the Washington Emergency Management Division, has been the state's public face for the new modeling, and her framing is deliberate: a Cascadia earthquake captures public imagination because it is catastrophic and close, but a Cascadia rupture is also, by the geologic record, a once-in-several-centuries event. Alaska is a different story. Tappero told reporters that "a large, distant tsunami...is much more likely to happen in our lifetimes" than a local Cascadia event, because Alaska's Aleutian arc produces large, tsunami-generating earthquakes far more frequently than Washington's own fault does. She has also framed the modeling as reassurance rather than alarm, telling one outlet that "understanding what that looks like for Washington...can really help dispel some of the fears" around tsunami risk generally, by replacing an abstract worry with an actual map and an actual number of hours. That distinction matters for how Kitsap County should weigh the two hazards against each other. The Cascadia scenario remains the more violent one for anything close to the fault line, but the Alaska scenario is the one state planners now say residents are statistically more likely to actually live through, which is why it received the more detailed modeling treatment this year rather than being treated as a secondary case.

What Actually Buys Kitsap Residents Those 3.5 Hours

A 3.5-hour warning window is generous by tsunami standards. Coastal communities on the outer Pacific coast often have just 10 to 20 minutes for a locally generated wave, and Washington's preparedness system is built to use the extra time a distant source provides. The state maintains 121 tsunami sirens positioned along vulnerable coastal areas, paired with smartphone alerts pushed through the same wireless emergency-alert system used for Amber Alerts, so a distant-source tsunami like an Alaska-generated one triggers a phone notification well before any siren would need to sound locally. Residents can register directly for state alerts at mil.wa.gov/alerts, and emergency managers also recommend keeping a battery- or hand-crank-powered NOAA weather radio on hand, since cell networks are not guaranteed to survive an event of this scale intact. For anyone actually on the water in Hood Canal or the inner Sound when a distant earthquake strikes, the practical advice does not wait for an official alert at all. A strong or prolonged earthquake felt locally, a sudden and unusual recession of water from the shoreline, or an unexplained roaring sound from the ocean are all treated as natural warnings that mean move to higher ground immediately, without waiting for a siren. Because modelers found the first wave in Hood Canal is often not the largest, the state's standing guidance is to stay away from the shoreline for the full duration officials clear the area, not just until the initial surge recedes, a detail that runs directly against the instinct to go check on a boat or a dock the moment the water looks calm again.

The Federal Money Trail Behind Tsunami Readiness

The new modeling lands the same year Congress is moving to renew the federal law that funds the warning system underneath it. The Senate Commerce Committee in March advanced the Tsunami Warning, Research, and Education Act of 2026, a bipartisan reauthorization led by Washington Senator Maria Cantwell and co-sponsored by Alaska Senators Lisa Murkowski and Dan Sullivan, a pairing worth noting given that Alaska is the very source zone this new Washington modeling is built around. The bill would reauthorize NOAA's tsunami programs at $30 million annually through 2030, a roughly 16 percent increase over current funding, and it directs the agency to strengthen fail-safe warning communications and run annual joint drills with state, local and tribal emergency managers, the same chain of agencies that produced this month's Puget Sound modeling. The legislation also instructs the Government Accountability Office to separately evaluate the nation's readiness for a Cascadia Subduction Zone event, effectively formalizing at the federal level the same two-hazard framing Washington's own scientists are already using: prepare seriously for the rare, catastrophic local quake, while building out real infrastructure for the more frequent, distant one. The bill still needs a full Senate floor vote and House action before it becomes law, and its fate over the coming months will determine whether the warning network Kitsap County would actually depend on gets the funding increase state officials say it needs.