Great earthquakes along the Cascadia Subduction Zone (CSZ) have been taking place for thousands of years. The most recent CSZ earthquake (estimated magnitude 9) occurred on January 26, 1700. The exact date was deter- mined from historic records of a tsunami that struck Japan, and confirmed by tree-ring studies of coastal trees killed when land level changes plunged their roots into tidal water.
A search of Native American myths, stories, and traditions has revealed an abundance of accounts from Washington and Oregon that may be connected to Cascadia Subduction Zone earthquakes.