There are fears that the big one could happen along Cascadia Subduction Zone (CSZ) which stretches 1,000km (620 miles) from northern California all the way up to Vancouver.
The subduction zone goes along the Pacific Northwest and caused by a small tectonic plate, named Juan de Fuca, slipping under the North American plate at an unusual angle.
The world’s biggest earthquakes happen in subduction zones which are areas where one tectonic plate dives or “subducts” beneath another plate.
The Cascadia fault lie in the Pacific Ocean, just off the West Coast, is nowhere near as famous as California’s San Andreas Fault.
But there are fears that the Cascadia Subduction Zone could actually give rise to an even bigger earthquake as well as triggering a tsunami.
Chris Goldfinger, a professor of geophysics at Oregon State University, has said that the Cascadia Subduction Zone is capable of delivering a magnitude 9 earthquake.
“Cascadia can make an earthquake almost 30 times more energetic than the San Andreas to start with, and then it generates a tsunami at the same time, which the side-by-side motion of the San Andreas can’t do,” he told CNN in 2016.
“You’re going to have three to five minutes of shaking, and if you’re used to earthquakes in California, they typically last 15 to 30 seconds and before you are really sure of what is happening, it is over.”
The last major earthquake on the Cascadia Subduction Zone caused a tsunami that raced across the Pacific Ocean to Japan in 1700.
An animation from the Pacific Tsunami Warning Center plotted the path of the tsunami as it went from the US to Japan.
Analysis from 2016 found that there were 43 major earthquakes in the past 10,000 years on this subduction zone, sometimes on the entire zone at once and sometimes only on parts of it.
When the entire zone is involved, it’s believed to be capable of producing a magnitude 9.1 earthquake.
In November 2017, a study led by The University of Texas at Austin found that the occurrence of earthquakes and tsunamis may be linked to compact sediments along large portions of the subduction zone.
It found that there was more chance of a big, destructive quake offshore of Washington and northern Oregon than farther south along the subduction zone.
Lead author Shuoshuo Han said: “We observed very compact sediments offshore of Washington and northern Oregon that could support earthquake rupture over a long distance and close to the trench, which increases both earthquake and tsunami hazards.
The Cascadia Subduction Zone is thought to generate a large earthquake roughly every 200 to 530 years.