Alaska earthquake highlights tsunami risk for coastal communities

A major earthquake late Saturday night off the coast of Alaska briefly caused concern about the possibility of a tsunami along the British Columbia coast.

The 7.2 magnintude quake struck about 100 kilometres from the community of Sand Point on the Alaskan peninsula at 10:48 local time.

Tsunami warning sirens could be heard in several communities -- sending people to shelters.

"When a tsunami is imminent you need to get to high ground," said Michael Bostock, a UBC professor in the Earth, Oceans and Atmospheric Sciences department. "High ground will save you and you want to be several tens of metres above shoreline."

Within minutes of the quake, the B.C. government used its Emergency Info BC Twitter account to announce the quake was being evaluated.

About an hour after the shaking had stopped, the same account tweeted that there was "No tsunami threat to #BC."

If there had been a tsunami, it would have taken three to five hours to reach portions of the B.C. mainland and parts of Vancouver Island.

According to Bostock, tsunamis can move across deep ocean water at over 700 km/h.

In the event of a quake closer to the west coast of Vancouver Island, the first waves could reach coastal communities like Tofino within minutes.

"Everybody plans for the worst case scenario, which is a large subduction quake just off the coast, and that would give us 20 minutes approximately," Tofino Mayor Dan Law said.

In partnership with Ottawa, the B.C. government is in the process of setting up an earthquake early warning system able to predict quakes in the moments before they happen.

"In particular, early warning for the big one off our shores is becoming a reality," said Bostock. "You'll be hearing very shortly about the implementation of early warnings so people can download apps and so on. I understand that's sort of within the time frame of the next year or so."

The system may only provide seconds of warning, but that could be enough for people to take shelter from potential hazards.

It is expected to be live some time in 2024.