Washington earthquakes
Crustal or shallow quakes
Occur in the North American plate at 0-30 km near the crust’s surface along faults. Intense shaking occurs near the epicenter but usually diminishes quickly with distance relative to the other earthquake types. Shallow quakes are the type expected on the Seattle Fault zone, which is the primary but not only source for shallow quakes in Seattle.
- The Seattle Fault
- Simulation of tsunami from a Seattle Fault Earthquake
- Potential tsunami inundation in Tacoma
- Simulation of the Alaskan Way Viaduct
- National Geography: Seattle Fault
Deep or intraplate quakes
Occur at depths of 30-70 km in oceanic crust as it dives under lighter continental crust. Because of the depth, even buildings located right above them are far enough away that ground motions are attenuated. Deep quakes are the most common large earthquakes that occur in the Puget Sound region. Quakes larger than 6.0M occurred in 1909, 1939, 1946, 1949, 1965 and 2001.
- Deep earthquakes
- Nisqually Earthquake February 28, 2001: A look back
- Nisqually earthquake 10th anniversary summary
Subduction zone or megathrust quakes
Occur on the interface between the North American plate and the San Juan de Fuca plate, a small plate extending from northern California to British Columbia. These are the largest type of earthquakes in the world.
- Cascadia subduction zone
- 50 simulations of the ‘Really Big One’ show how a 9.0 Cascadia earthquake could play out (UW News)
- YouTube video about Cascadia
- Watch a 4-minute Discovery News story on the Cascadia earthquake threat
- MegaQuake: Is the United States next? Discovery Channel
- Cascadia subduction zone – Ocean Shores inundation
- Cascadia subduction zone – Long Beach inundation
- UW Seismologist William Steele explains the Cascadia earthquake model
- Reconstruction of Cascadia earthquake
- Cascadia Rising Exercise Scenario Planning Document (2016, PDF, 182-pages)
Other videos about earthquake hazards in Seattle
- Seattle Natural Hazards Explorer
- Amplification and Liquefaction Animation
- Seattle channel earthquakes
- What if? KOMO News on earthquake risks and how to get prepared
- Earthquakes 101 by National Geographic
- Examples of liquifaction Japan
- Information about tsunami
- Japan earthquake: 15 minutes live-cam
- Earthquake awareness and personal preparedness PowerPoint