The region is just outside Washington State where experts have discovered “very compact sediments” which they say is a sign a huge quake is brewing.
As the land is underwater, such movement could cause tsunamis to threaten the west coast of the US.
The region is known as the Cascadia Subduction zone and is thought to generate a huge quake every 200 to 530 years. The last one arrived in 1700.
Lead author Shuoshuo Han, a postdoctoral fellow at the University of Texas Institute for Geophysics (UTIG), 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.”
After analysing seismic data and sediment samples, the team found sediments are tightly compact around the plate.
This leads to little water gaining access to the pore spaces between the sediments, leaving tectonic plates to build up stress.
Nathan Bangs, a senior research scientist at UTIG and study co-author, said: “That combination of both storing more stress and the ability for it to propagate farther is important for both generating large earthquakes and for propagating to very shallow depths.”
Although it is difficult to pinpoint when exactly an earthquake will hit, the team say it offers a valuable insight and could hold clues when the Big One will strike.
Co-author Demian Saffer, a Penn State University professor, said: “The results are consistent with existing constraints on earthquake behaviour, offer an explanation for differences in structural style along the margin, and may provide clues about the propensity for shallow earthquake slip in different regions.”
Suzanne Carbotte, a research professor at Columbia University, added: “These kinds of long-streamer marine seismic studies provide the best tools available to the science community to efficiently probe subduction zones in high resolution.”
Fears of the Big One have been growing recently as the San Andreas fault has been rocked by a series of minor tremors.
Ten mini quakes have struck along the San Andreas fault, leaving locals worried.
The earthquakes hit Monterey County, just south of San Jose, with the largest registering at 4.6 on the Richter scale – strong enough to be felt 90 miles away in San Francisco – at 11.31 AM local time on Monday 13 November.
However, there were no reports of injuries or damages to buildings.