When an earthquake rips along the Cascadia Subduction Zone fault, much of the U.S. west coast could shake violently for five minutes, and tsunami waves as tall as 100 feet could barrel toward shore.

The Cascadia Subduction Zone, a major fault that runs offshore from Northern California to British Columbia, is best known for putting the coast in danger of large earthquakes and tsunamis. A new study sounds another alarm: A big earthquake on the fault could cause land along the coast to sink permanently,