'Doomsday tsunami' is ready to strike the US

A 100ft mega tsunami could hit the US at any moment - and that's only the beginning

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The Cascadia Subduction Zone, a massive fault line stretching from northern California to British Columbia, has been eerily quiet for 300 years. When it finally ruptures, it's expected to trigger a colossal earthquake that could rattle the Pacific Northwest for minutes.

Even worse, tsunami waves up to 30m (100ft) high will likely crash to the shore, unleashing destruction along the coast.

But according to a new study published in the Proceedings of the National Academy of Sciences, that will only mark the beginning of Cascadia's cataclysm.

If a wave the same size as Indonesia's 2004 Boxing Day mega tsunami wasn't bad enough, the new analysis reveals that land along the coast could drop by more than 2.5m (8ft) in a matter of minutes.

"We talk about climate-driven sea level rise, which is occurring at three to four millimetres (0.11-0.15in) a year, and that does eventually add up," Dr Tina Dura, lead author of the study, told BBC Science Focus. “But here we'll have two metres (6.5ft) of sea level rise in minutes. Why aren’t we talking about that more?”

WHEN CASCADIA RUPTURES

The Cascadia Subduction Zone marks the boundary where the oceanic Juan de Fuca Plate is slipping beneath the North American Plate. But rather than moving smoothly, these plates tend to get stuck — and as they lock together, the strain grows over centuries.

When it finally releases, the result is a powerful earthquake.

Cascadia is capable of producing quakes of magnitude 9.0 or more, with major events thought to strike every 450 to 500 years. The last one occurred on 26 January 1700, and based on geological records and contemporary reports, its magnitude was likely between 8.7 and 9.2.

According to the US National Seismic Hazard Model, there’s now a 15 per cent chance of a magnitude 8.0 or greater earthquake along the zone’s margin in the next 50 years.