We've seen it in the movies: a massive earthquake causing thousands of deaths, crippling transportation and cutting all communication lines.

A report entitled "The Really Big One" recently published on The New Yorker warns of a similar powerful quake happening in the Pacific Northwest, causing similar devastation.

What would cause this quake? The report points to the Cascadia subduction zone, which runs hundreds of miles between Northern California and ends around Vancouver.

In this zone, a pair of tectonic plates are now grinding up against one another under the Pacific Ocean and are jammed up against each other in the Cascades, instead of normally sliding underneath each other.

These plate movements may soon trigger an earthquake between 8.0 and 8.6 in magnitude, the report warned.

"That's the big one. If the entire zone gives way at once, an event that seismologists call a full-margin rupture, the magnitude will be somewhere between 8.7 and 9.2. That's the very big one," Kathryn Schulz, the report's author, explained.

This earthquake can also trigger a mega-tsunami that would arrive onshore across the Northwestern coast in a span of 15 minutes.

Kenneth Murphy, the director of the division of the Federal Emergency Management Agency in charge of Alaska, Idaho, Oregon and Washington, said an earthquake this powerful can leave devastating effects.

"Our operating assumption is that everything west of Interstate 5 will be toast," Murphy said.

Such a quake is projected to cause 13,000 deaths, and may render a million people homeless.

Some earthquake experts, however, say that the movements in the Cascadia subduction zone should not be the cause of much panic.

"The tsunami won't really be a factor in Seattle or Puget Sound. By the time the swell gets here, it will be pretty small. But the quake could trigger landslides here that cause localised swamping," Sandi Doughton, Seattle Times science writer, said.