A new tsunami strategy launched for Bainbridge Island
The Washington Emergency Management Division has completed a Tsunami Maritime Response and Mitigation Strategy for the City of Bainbridge Island’s Eagle Harbor.
It’s the first strategy that includes a look at potential impacts from the nearby Seattle earthquake fault and is geared to help the region understand the tsunami risk, build resilience, and figure out protective actions to take to enhance life safety and protect property.
“Although rare — only one such event has been recorded in the geologic record over the past 16,000 years — a large earthquake on the Seattle Fault has a high potential to generate a tsunami,” the report notes. “A tsunami could reach Eagle Harbor in less than 10 minutes, bringing strong currents and large-scale inundation along the shoreline and low-lying areas.”
This graphic represents maximum current speeds above normal for a Seattle Fault Zone earthquake and tsunami at the mouth of Eagle Harbor. The darker purple colors represent speeds of 9 knots and more above background current speeds.
The strategy also looks at potential impacts from a tsunami that originates from the Cascadia Subduction Zone, noting tsunami waves could enter the Strait of Juan de Fuca and reach Eagle Harbor about 2 hours and 20 minutes later.
Residents of Bainbridge Island who feel an earthquake are encouraged to drop, cover and hold on and then head to high ground immediately after the shaking stops, said Ethan Weller, tsunami program coordinator at Washington Emergency Management Division (EMD).
Developed in partnership with EMD, Washington Geological Survey, the City of Bainbridge Island and key stakeholders, the Tsunami Maritime Response and Mitigation Strategy offers a comprehensive framework to understand, mitigate, and respond to the tsunami risks posed to the maritime community around Eagle Harbor. This strategy reflects a collaborative process between the state’s tsunami team and the City of Bainbridge Island, which included engaging local expertise, facilitating workshops, and fostering open dialogue with stakeholders.
Anne LeSage, the city’s emergency management coordinator, expressed her pride in the collective effort. “Completing the Tsunami Maritime Response and Mitigation Strategy is a testament to the resilience and dedication of Bainbridge Island,” LeSage said. “I’m incredibly proud of how invested the city and state are in the safety and emergency response of our community, and I want to thank our partners at Bainbridge Prepares and the Washington Emergency Management Division for their unwavering commitment to preparedness. Emergency management is truly a community effort and we couldn’t achieve this milestone without the help and collaboration of everyone involved.”
Eagle Harbor is a vital maritime and community hub for Bainbridge Island, serving the island’s main town, Winslow. At its eastern end is the Seattle-Bainbridge Island ferry terminal. There’s also a network of private marinas as well as Waterfront Park and City Dock.
Bainbridge Island already boasts a preparedness culture, including a Community Emergency Response Team. Among its key efforts, the Bainbridge Prepares Flotilla mobilizes private vessels to support the community during emergencies, particularly when conventional transportation routes are disrupted. Work has already been done to improve its maritime infrastructure on the City Dock, especially when it comes to sea level rise, which will also help mitigate for tsunami damage.
“The work Bainbridge Island and its residents have already done in preparing for disasters is admirable – something other communities should look to and replicate,” Weller said. “I’m confident they will continue to work on these challenges.”
This shows the water-level changes over time for a Seattle Fault Zone earthquake and tsunami scenario.
It’s recommended Bainbridge Island continue its public education, incorporating the results of the strategy so people in tsunami inundation areas understand the risks. For instance, the existing wildfire response and evacuation plans could serve as a template to address the evacuation challenges the community could face from a tsunami.
The strategy also calls for the city to shut down harbor infrastructure before a tsunami arrives. The City Dock was upgraded five years ago which included electrical systems that automatically shut down the flow of electricity upon detection of a stray current or faulty wiring.
The lead marine officer for the City of Bainbridge Island’s Police Department, Jonathan Bingham, outlined a potential idea for constructing a dock that may house maritime response assets for the city. This earthquake and tsunami-resistant structure would protect city assets, allowing for faster response times and better coordination with surrounding communities in a tsunami.
“Going through this process, we realized our marine assets, like all the marine infrastructure in Puget Sound, are vulnerable to a tsunami,” Bingham remarked. “It became clear how self-reliant we as a city would have to become in any circumstance where the City of Bainbridge Island could be cut off from all assistance. The idea would be to protect essential marine assets that will be critical in a post-earthquake/tsunami response.”
Other recommendations call for the city to secure moorings of city-owned vessels, restrict traffic entering the marina by land and aid in traffic evacuation, pre-stage emergency equipment outside affected areas, install more tsunami evacuation route signs and more.
The strategy also identified potential sources of funding to help the city pay for maritime mitigation efforts.
The above figures are inundation (on-land flooding) for a Cascadia Subduction Zone earthquake and tsunami. It takes about an hour and a half for the water-level changes to occur in the area.
This is the fifth maritime strategy created by EMD. Other strategies have been done for the Ports of Neah Bay, Anacortes, and Bellingham, as well as Grays Harbor's Westport Marina.
Read the report at this link. Learn more about Bainbridge Island.