A super-quake on the US-Canada border could potentially kill more than 11,000 people and injure 26,000, according to emergency disaster planners.
The San Andreas fault line in southern California is always discussed as the point where the “Big One” may trigger.
But seismologists say it is the area just north of the US that could produce one “30 times” more powerful.
The last time a mega-quake shook the region was in January 1700 when a magnitude 9 tremor created a massive tsunami which reached as far as Japan.
“This would be a roughly M9 earthquake and would trigger a tsunami”
Alison Bird, Natural Resources Canada
Disaster experts say the rocking caused by the quake might last some three minutes, unlike normal earthquakes which last an average of 15 to 30 seconds.
And if this massive quake were to happen, it could set off other tremors, even triggering the great built-up force of the San Andreas fault line in California.
Around every 14 months the risk of a big earthquake striking in the region is heightened because of episodes where tectonic plates slip due to guilty up pressure.
Now the 14 month period is almost over, and the heightened hazard period at the zone is due in February 2017.
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The 600 mile danger zone runs through northern California, Oregon, Washington, and southern British Columbia which lies within the destructive “Ring of Fire” of tectonic activity around the Pacific.
Concerns are so great that a training programme called “Cascadia Rising 2016” was run earlier this year in the Pacific Northwest to prepare people for the oncoming destruction.
Alison Bird, an earthquake seismologist who works at Natural Resources Canada, told Daily Star Online there is a real threat of an earthquake in the region.
“The worst cast scenario would be for the Cascadia Subduction Zone to fully rupture (from Vancouver Island to northern California, which would be a 1,100 km long rupture).
Pacific Northwest Seismic Network
“This would be a roughly M9 earthquake and would trigger a tsunami, impacting many of our coastal communities.”
She also says that is is possible that other quake prone zones could be set off by aftershocks of a megaquake.
“The megathrust would certainly be followed by numerous aftershocks, both along the rupture plane of the earthquake, and likely within the adjacent plates.
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“But, it is rare that earthquakes are triggered in distant regions, although this is not out of the question.”
Ms Bird also suggests that a megathrust could occur “at any time”.
The dangers of San Andreas are well-known, but many suggest that the power of the Cascadia zone is far more destructive than anything in Southern California.
Last week a cluster of around 10 quakes occurred around the San Andreas fault line, which sparked fears that the cataclysmic megaquake was about to be unleashed.
Experts have said that the US west coast – including major cities such as Los Angeles and San Francisco – is at “high risk” of a major tremor.
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And earthquake watchers have claimed two whopping fault lines “holding hands” off the California coast could spark the largest earthquake in over 90 years.
But Chris Goldfinger, a professor of geophysics at Oregon State University, predicts that Cascadia could be “30 times” more “energetic” than San Andreas and could last as long as three minutes, rather than the average 15 to 30 seconds.
“I’ve been in a 9 in Japan – three minutes is an eternity. It is a very, very long time,” he told CNN.
“We’ll lose a lot of bridges. We’ll lose our highway routes. The coast will probably be closed by down bridges or landslides or both.”