The Seattle Fault ( and the related Tacoma Fault ) is not the only source of earthquake hazard in the Puget Lowland . Other faults in the near surface continental crust , such as the South Whidbey Island Fault ( near Everett ) , and the yet to be studied Olympia Fault ( near Olympia ) , though historically quiescent , are suspected of generating earthquakes of around magnitude 7 . Others , such as the 2001 Nisqually earthquake , originate about below Puget Sound in the Benioff zone of the subducting Juan de Fuca Plate ; being so deep their energy is dissipated . And there are the infrequent but very powerful great subduction events , such as the magnitude 9 1700 Cascadia earthquake , where the entire Cascadia subduction zone , from Cape Mendocino to Vancouver Island , slips
1700 Cascadia earthquake
1700 Cascadia earthquake
Seattle Fault