U.S. Navy Closes Four Drydocks at Puget Sound Shipyard Over Quake Risk

The U.S. Navy is temporarily idling four submarine repair drydocks in Washington due to earthquake risk, the service announced Sunday. 

The Navy recently commissioned a seismic assessment for Puget Sound Naval Shipyard as part of its long-term Shipyard Infrastructure Optimization Program. The objective was to assess any risks associated with the occurrence of an earthquake while a nuclear sub is undergoing maintenance in one of the docks. The Navy did not go into details on the outcome of the assessment, but three drydocks at Puget Sound Naval Shipyard in Bremerton and one drydock at the Trident Refit Facility in Bangor will be kept empty until the conclusion of further investigations.

“Our public shipyards are essential to our national defense,” said Vice Adm. Bill Galinis, commander, Naval Sea Systems Command. “We will begin implementing these mitigations immediately and safely return our dry docks to full capacity as soon as possible.”

Aircraft carrier maintenance will not be affected. The service is examining the impacts on upcoming sub maintenance availabilities - already plagued by extended delays - and all options are being evaluated, including continuation of any work that can be done pierside.

The Pacific Northwest's coastal areas are exposed to significant risk of a major quake from the Cascadia Subduction Zone, which last ruptured about 320 years ago. Washington State's Department of Natural Resources estimates that the odds of a magnitude 9.0 quake within the next 50 years are about 10-17 percent. Tsunami flooding depths along Northwest beaches are expected to range from 60-100 feet, but Bremerton is far inland enough that it would not be substantially affected.