Everyone knows about the San Andreas fault located in western California. The fault line is one of the most famous in the world and was responsible for such earthquakes as the 1906 San Francisco earthquake, the 1992 Landers earthquake, and even delayed the World Series with the 1989 Loma Prieta earthquake. However, an even bigger treat looms off the northwest coast of the United States.
The New Yorker published an article this week about the potential hazards of the Cascadia Subduction Zone. The Cascadia Subduction Zone is formed from the Juan De Fuca plate subducting under the North American plate, and spans from northern California to Vancouver. The subduction zone caused the Cascade Mountains to form via volcanic activity. Some notable peaks in the Cascades are Mt. St. Helens, Mt. Hood, and Mt. Rainier.
The Cascadia Subduction Zone produces an earthquake about once every 243 years and the Pacific Northwest is 72 years past due. Now this doesn't mean that an earthquake will occur this year, or next year. But remember, the longer a fault goes without an earthquake, the more stress that gets built up, thus causing a stronger earthquake. The best-case-scenario for fault zones is to have many small earthquakes over a short span of time, rather than one big one every couple hundred years.
The United States Geological Survey predicts that if a major earthquake occurs within the Cascadia Subduction Zone, that it could likely be a magnitude 8-9.2. The earthquake will likely cause a tsunami which will produce a second round of fatalities. Cities from Sacramento, Portland, and Seattle are at risk.