Environmentally Critical Areas

Volcanic and Seismic Hazard Areas

In 2007, DPD adopted mapping delineating areas of increased hazard due to volcanic and seismic activity including tsunamis, seiches, lahars, and the Seattle fault zone based on the Best Available Science available.  Volcanic and seismic hazard areas are designated in 25.09.020.  THESE DESIGNATIONS ARE ADVISORY.  NO ADDITIONAL REGULATORY REQUIREMENTS APPLY IN THESE AREAS, OTHER THAN THE PROVISIONS IN THE BUILDING CODE OR PROVISIONS THAT MAY APPLY IF OTHER TYPES OF ENVIRONMENTALLY CRITICAL AREAS ARE ALSO PRESENT. 

Maps for these unregulated designations are below:

• Seattle Fault Zone – Seattle Fault Zone Map
• Tsunami Hazard - Tsunami Hazard Map of the Elliott Bay Area
• Lahar Hazard - Volcano Hazards from Mount Rainier Report
• • Full Report
  • Map C & D referencing Seattle

• Adopted Geologic Hazard Areas Ordinance (March 2007): This update designated the Seattle Fault zone and areas of the city that are at risk from tsunamis, seiches, and lahars as environmentally critical areas.
• Geologic Hazard Areas Director’s Report (February 2007): This report provides supporting information on the proposed geologic hazard area ordinance.
• Supplemental Geologic Hazard Areas Best Available Science Report (February 2007): This report provides a compilation and review of the supplemental best available scientific information that has been considered in the proposed code update for new geologic hazard area designations.

For more information on these hazards, go to:

• City of Seattle Office of Emergency Management
• Seattle DPD Emergency Management Page