The Pacific Coast of Washington is at risk from tsunamis. These destructive waves can be caused by coastal or submarine landslides or volcanism, but they are most commonly caused by large submarine earthquakes. Tsunamis are generated when these geologic events cause large, rapid movements in the sea floor that displace the water column above. That swift change creates a series of high-energy waves that radiate outward like pond ripples. Offshore tsunamis would strike the adjacent shorelines within minutes and also cross the ocean at speeds as great as 600 miles per hour to strike distant shores.
Tsunami waves can continue for hours.
The first wave can be followed by others a few minutes or a few hours later, and the later waves are commonly larger. The third and fourth waves killed 11 people. That same tsunami destroyed property in many areas along the coast from Alaska to California. That 1964 event was the most recent significant tsunami to reach the Washington coast, but recent geologic investigations indicate that large tsunamis have struck our coast many times in the last few thousand years. On the Pacific Coast, from southern British Columbia to northern California, people and property are at risk both from distantly and locally generated tsunamis.