The first quake measured 6.1 on the Richter scale, strong enough to cause considerable damage to buildings near the epicenter, The Province reported. But it was deep enough and far enough at sea to have no effect on land.
The epicenter was about 130 miles from Bella Bella, British Columbia, the nearest settled area.
"We didn't feel anything," an operator with the Royal Canadian Mounted Police in Bella Bella, said. "And we haven't received any calls."
One of the aftershocks measured 5.0. That's strong enough to damage badly designed buildings.
The seafloor off British Columbia is no stranger to powerful quakes. A 7.7 quake hit in October 2012, and an 8.1 quake, the largest recorded so far in the area, occurred in 1949.