VANCOUVER - When the "Big One" hit Japan earlier this year, the ground shook, tsunamis struck and tens of thousands of people died.

Scientists know British Columbia will eventually experience its own Big One. The problem is, they just don't know when or where it will strike and how long the shaking will last.

Andrew Calvert, an earth sciences professor at Simon Fraser University, says he may be able to help solve a little piece of that puzzle, following the publication of a recent article in the journal Nature Geoscience.

Calvert and a team of researchers concluded a section of a fault line in the Pacific Northwest — the area where two of the earth's tectonic plates meet — is seven kilometres deeper than previously thought.

The study found the section in question is actually 27 to 42 kilometres deep, not 25 to 35 kilometres, and is under Washington state.

Calvert said that's important. While the new information won't help determine when or where the Big One will come — nothing yet can do that — it will help scientists refine their calculations on any ground shaking that will take place during an earthquake.

"Essentially, what we saw in Japan is what will happen in the Pacific Northwest sooner or later," said Calvert, noting a major earthquake hits B.C. every 500 years. The last quake was in 1700.

"We're building up to a greater likelihood of a very large earthquake that will have minutes of ground shaking and a large tsunami coming in along the coast line."

Calvert said an earthquake in the Pacific Northwest could occur along the fault line and cover an area 100 to 150 kilometres east to west and an area of 500 to 800 kilometres north to south.

Calvert said he's prepared to speculate that the earthquake could even strike south of Vancouver Island, deep underneath Washington state's Olympic Peninsula.

He said the shaking in Vancouver should be less than the shaking in Victoria, but to get an idea of the resulting damage, people need only look at what happened in Japan on March 11.

The magnitude-9.0 earthquake and resulting tsunami hammered the country's northeastern coast. More than 26,000 people were killed or reported missing. The government was forced to pass a $48-billion recovery budget.

Calvert said his team used data that focused on a 200-kilometre-long stretch of fault line between Victoria and southern Washington state.

According to Natural Resources Canada, more than 1,000 earthquakes occur in Western Canada annually.