Hidden Dangers Lurking Beneath the Emerald City A new study published in GSA Bulletin reveals that smaller secondary faults beneath Seattle may be far more active than previously thought, rupturing approximately every 350 years.
This finding is a stark reminder that Seattle's earthquake threat extends far beyond the Cascadia subduction zone, which has long been considered the primary concern.
The Seattle Fault Zone (SFZ) is an east west fault system that stretches through Bainbridge Island and Seattle, absorbing strain caused by compression in the Earth's crust between Portland, Oregon, and Vancouver, British Columbia.