The Cascadia subduction zone rarely influences the western portion of Washington state , but the November 1873 M7 .3 shock near the California – Oregon border may have been associated with it . Although activity in the Pacific Northwest ( especially west of the Cascades in Washington ) has occasionally been located near the subduction zone , earthquakes there ( 1949 Olympia , 1965 Puget Sound , 2001 Nisqually ) have mostly been intraslab events . A large M7 earthquake on the Seattle Fault in 900 C.E. may have generated a tsunami in Puget Sound . The 1872 event east of the Cascades is not understood well due to the lack of instrumental records and reliable felt intensity reports
1949 Olympia
1949 Olympia earthquake
1872 North Cascades earthquake