New Tsunami Hazard Maps Published For Anacortes and Bellingham Areas
July 03, 2018
New Tsunami Hazard Maps Published For Anacortes and Bellingham Areas
The Washington Geological Survey has released new tsunami hazard maps for the greater Anacortes and Bellingham area titled “Tsunami Hazard Maps of the Anacortes–Bellingham Area, Washington—Model Results from a ~2,500-year Cascadia Subduction Zone Earthquake Scenario.”
These hazard maps were generated based on models of a ~2,500-year earthquake and tsunami event. This is a conservative (meaning greater inundation) scenario of what might happen during the next great Cascadia earthquake and is a useful tool for evacuation planning and mitigation strategies. These new maps may not resemble the next tsunami to strike the area since as the next tsunami would likely be smaller.
What the model shows is that it is theoretically possible for the height of the tsunami to be up to 18’ in select areas; however the study notes “averages less than 10 feet for most areas.” Within Whatcom County, 12’ is the height used for planning purposes. The model also shows that the velocity of the water may approach 20 knots in restricted waters, such as the Guemes Channel and Eliza Rock.
The study does not include updates for other Whatcom County areas such as the Lummi Reservation, Sandy Point, Cherry Point, Birch Bay, Blaine or Point Roberts. There is a project is underway to model the ~2,500-year earthquake for these areas.
The results from this study are not sufficient to determine site-specific impacts. Earthquake generated landslides or liquefaction are not accounted for in this study.
According to Whatcom County Sheriff Bill Elfo, “The Whatcom County Sheriff’s Office considers the protection of the Citizens of Whatcom County paramount. With the release of this new study, we now have another data point to use in the development and updating of the Whatcom County Tsunami Action Plan. Since 2006 eight tsunami sirens have been installed between Point Roberts and Squalicum Harbor, with a ninth being installed later this summer. We will be fully evaluating our Tsunami Action Plan during the 2021 region-wide catastrophic earthquake exercise. Our participation includes a week long full-scale exercise to simulate the effects of a tsunami and our ability to respond to it.”
Residents of Whatcom County should be aware that if the ground shakes or the sirens sound, a tsunami may be on its way. The tsunami may arrive between 1 hour 45 minutes and 2 hours 30 minutes. Multiple waves are expected and inundation may persist for at least 8 hours. Everyone should stay away from the shorelines and not return to inundated areas until it is safe to do so.
According to Bob Vander Yacht, Interim Emergency Management Coordinator, City of Bellingham, "Tsunami resilience of our coastline cities, residences, and businesses is an extremely important role for local emergency planners. Priority one for planning is the safety of Whatcom County citizens and visitors. Bellingham was fortunate to have been chosen as a participant in the first evolution of tsunami mapping by Washington Geological Survey. The intention of WGS is to complete this process for the entire coastline. We are thankful for our local city and county mapping experts that have been participating in this process."
The Washington Geological Survey “Tsunami Hazard Maps of the Anacortes–Bellingham Area, Washington—Model Results from a ~2,500-year Cascadia Subduction Zone Earthquake Scenario” is available via the following link:
www.dnr.wa.gov/publications/ger_ms2018-02_tsunami_hazard_anacortes_bellingham.zip.
The Washington Geological Survey has released new tsunami hazard maps for the greater Anacortes and Bellingham area titled “Tsunami Hazard Maps of the Anacortes–Bellingham Area, Washington—Model Results from a ~2,500-year Cascadia Subduction Zone Earthquake Scenario.”
These hazard maps were generated based on models of a ~2,500-year earthquake and tsunami event. This is a conservative (meaning greater inundation) scenario of what might happen during the next great Cascadia earthquake and is a useful tool for evacuation planning and mitigation strategies. These new maps may not resemble the next tsunami to strike the area since as the next tsunami would likely be smaller.
What the model shows is that it is theoretically possible for the height of the tsunami to be up to 18’ in select areas; however the study notes “averages less than 10 feet for most areas.” Within Whatcom County, 12’ is the height used for planning purposes. The model also shows that the velocity of the water may approach 20 knots in restricted waters, such as the Guemes Channel and Eliza Rock.
The study does not include updates for other Whatcom County areas such as the Lummi Reservation, Sandy Point, Cherry Point, Birch Bay, Blaine or Point Roberts. There is a project is underway to model the ~2,500-year earthquake for these areas.
The results from this study are not sufficient to determine site-specific impacts. Earthquake generated landslides or liquefaction are not accounted for in this study.
According to Whatcom County Sheriff Bill Elfo, “The Whatcom County Sheriff’s Office considers the protection of the Citizens of Whatcom County paramount. With the release of this new study, we now have another data point to use in the development and updating of the Whatcom County Tsunami Action Plan. Since 2006 eight tsunami sirens have been installed between Point Roberts and Squalicum Harbor, with a ninth being installed later this summer. We will be fully evaluating our Tsunami Action Plan during the 2021 region-wide catastrophic earthquake exercise. Our participation includes a week long full-scale exercise to simulate the effects of a tsunami and our ability to respond to it.”
Residents of Whatcom County should be aware that if the ground shakes or the sirens sound, a tsunami may be on its way. The tsunami may arrive between 1 hour 45 minutes and 2 hours 30 minutes. Multiple waves are expected and inundation may persist for at least 8 hours. Everyone should stay away from the shorelines and not return to inundated areas until it is safe to do so.
According to Bob Vander Yacht, Interim Emergency Management Coordinator, City of Bellingham, "Tsunami resilience of our coastline cities, residences, and businesses is an extremely important role for local emergency planners. Priority one for planning is the safety of Whatcom County citizens and visitors. Bellingham was fortunate to have been chosen as a participant in the first evolution of tsunami mapping by Washington Geological Survey. The intention of WGS is to complete this process for the entire coastline. We are thankful for our local city and county mapping experts that have been participating in this process."
The Washington Geological Survey “Tsunami Hazard Maps of the Anacortes–Bellingham Area, Washington—Model Results from a ~2,500-year Cascadia Subduction Zone Earthquake Scenario” is available via the following link:
www.dnr.wa.gov/publications/ger_ms2018-02_tsunami_hazard_anacortes_bellingham.zip.
