7 Biggest Fault Lines in US

4. Cascadia Megathrust

Length: 620 miles

Cascadia subduction zone or Cascadia megathrust is the fault line on the boundary between North American plate and several smaller plates between it and the Pacific plate. There is strong evidence that Cascadia is somehow connected with San Andreas fault and that its activity predicts San Andrea earthquakes.

 7 Biggest Fault Lines in US

NigelSpiers / Shutterstock.com