A massive earthquake may be brewing beneath North America

No one knows when it will strike... but everyone agrees it will be a huge rupture

- 

A hidden tectonic fault in Canada's Yukon could be gearing up to unleash a major earthquake of at least magnitude 7. 5, according to a new study.

The Tintina fault, which runs from northeastern British Columbia through to central Alaska, has been quietly accumulating strain for at least 12,000 years. Previously thought to be relatively benign, new analysis suggests it's still very much active.

Worryingly, scientists can't say when the next major quake will strike – only that it almost certainly will.

LARGER RUPTURES

"Our findings indicate that the fault is active and continues to accumulate strain," Dr Theron Finley, lead author of the study published in Geophysical Research Letters, told BBC Science Focus. "And so we anticipate that in the future, it will rupture again."

Tintina is what's known as a 'right-lateral strike-slip fault' – a type of fault where two blocks of the crust slide past each other horizontally. If you stand on one side of this fault and the other side moves to your right during an earthquake, it's called right-lateral.