The quake struck around 12:41 PDT just off the west coast of Vancouver Island, south of Port Hardy.
The quake was initially thought to have a magnitude of 6.7, but was later downgraded by the U.S. Geological Survey (USGS).
There were no reports of injuries or damage, and no tsunami warning was issued.
“To get a tsunami we need to disrupt the ocean floor,” explained Dr. Brent Ward, an Earth Sciences Professor at Simon Fraser University. “The fault actually has to move the sea floor (and cause displacement)”.
The quake was felt in Vancouver, where tall buildings swayed gently and shaking reportedly lasted for nearly one minute.
In Campbell River, schools were evacuated as per earthquake emergency plans.
Ward said many quakes of magnitude 5 and higher occur off Vancouver Island, where the Juan de Fuca plate dives beneath the North America plate.
The strongest earthquake ever recorded in Canada occurred on that fault line in 1946. The 7.4-magnitude quake caused extensive damage in Campbell River, Comox and Courtenay.
“Chimneys were broken and fell through houses, brick facades were cracked off buildings and there were quite a few landslides,” Ward said.
Fortunately, the island was very sparsely populated in those days, so no casualties were reported.
“If we had a 7.4 (quake) now, under Vancouver Island -- or, even worse, under Vancouver -- we would see substantial damage and certainly some loss of life,” Ward said.
The reality that B.C. could experience “the Big One” at any time means communities and individuals have to be prepared. The province regularly participates in emergency simulations with other earthquake-prone areas, including California, and an organization called ShakeOut holds an annual earthquake drill so individuals will know how to respond when quakes do strike.
With files from Jill Colton