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Earthquakes in Washington State

Fault Zones

There are 13 major faults known so far in the Puget Sound area. A graphical representation is available from the Pacific Northwest Seismograph Network. Three of the most important faults are the North Whidbey island fault, South Whidbey island fault and the Seattle fault. A discussion about these faults can be found at the "Major Faults of the Puget Sound" webpage.

Technical publications about fault zones

There are several technical publications available from the USGS.

Past Earthquake History

One of the largest earthquakes in Washington is thought to be the 1872 earthquake, magnitude 7.0, that hit near Lake Chelan, Washington. This earthquake was felt from British Columbia, Canada, to Oregon and from the Pacific Ocean to Montana. A very good description can be found on the USGS site about this earthquake. A very detailed historical research report on this earthquake was prepared by Weston Geophysical Research, Inc. in 1976, and is available on-line.

Below are listed other historical earthquakes that have caused damage in Washington state. This information was obtained from a report titled: WHERE HAS EARTHQUAKE DAMAGE OCCURRED IN WASHINGTON STATE? taken from "Washington State Earthquake Hazards", by Linda Noson, Anthony Qamar, and Gerald Thorsen:

  • 1936 Milton-Freewater Earthquake
  • 1939 Puget Sound Earthquake
  • 1945 Puget/Cascades Border Region Earthquake
  • 1946 Puget Sound Earthquake
  • 1949 Olympia and 1965 Seattle-Tacoma Puget Sound Earthquakes

Another compilation of earthquake history in Washington state is available from the USGS.

More recently, three more earthquakes occurred in Washington. A magnitude 5.3 earthquake hit Seattle on May 2, 1996. Information about this earthquake is available from the Pacific Northwest Seismograph Network.

Another earthquake struck Western Washington on July 2, 1999. Information about this earthquake is available from EQE, a consulting company.

The most recent major earthquake, the Nisqually quake, was a magnitude 6.8 quake and struck near Olympia, WA on February 28, 2001.

A list of the most recent earthquakes in Washington state is updated regularly by the Pacific Northwest Seismograph Network.

Earthquake Hazard Information You Should Know