Massive earthquake in B.C. could trigger larger tsunami than expected: study

A new study is questioning whether current scientific models are underestimating the potential size of tsunamis off British Columbia's coast in the event of a large-scale earthquake.

Earthquake scientist John Cassidy says that an ocean plate off the B.C. coast is moving a few centimetres towards Vancouver Island each year, and when that happens sediment builds up.

"If you think of a bulldozer driving through the sand or through some soil, it sort of pushes everything forward and it stacks stuff up," he said. "[That's] exactly the same thing as the ocean plate."

The study published in the journal Earth Science Reviews looks at how that sediment would affect earthquakes in subduction zones around the world.

CASCADIA SUBDUCTION ZONE

Southern B.C. is located on the Cascadia Subduction Zone, which spans from northern Vancouver Island down to northern California.

"What this study is saying is that not only will the tsunami be generated by the movement of the fault, but also potentially the movement of the faults in the sediment that’s been scraped off over the years," said Kate Moran, CEO of Ocean Networks Canada.

"And so really, there could be higher waves generated in various locations on the planet," she said.

A beach is pictured on Vancouver Island, B.C. (CTV News)

Local experts say that while the study is an important reminder of tsunami risks, researchers here are unlikely to change their current predictions.

"It's not something we would change our models or risk estimates at this time because it’s one piece of a very complicated puzzle," said Cassidy.

Still, the earthquake scientist says all information about how to accurately predict what to expect from tsunamis can help protect people and property.