VANCOUVER — The Haida Gwaii region continues to feel the aftershocks of a violent earthquake measuring 7.7 that jolted British Columbia's north-central coast Saturday night, frightening residents and forcing many to temporarily leave their homes for higher ground ahead of a possible tsunami.

The largest, a 6.4 magnitude tremor, struck Sunday afternoon, 136 kilometers south of Masset. There have been over 40 aftershocks in the area.

Tsunami warnings were issued for the North Coast Saturday, the Haida Gwaii islands, parts of the central B.C. coast, the coast of Alaska and as far away as Hawaii.

Early Sunday morning the warnings were downgraded to advisory status, meaning evacuations were no longer necessary, and they were cancelled altogether a few hours later.

Residents near the centre of the quake said the violent jolting lasted for up to a minute, but no injuries or major damage had been reported.

Carsten Ginsburg, who lives in the small community of Bella Coola southeast of Prince Rupert, said the quake lasted about 40 seconds.

"It shook everything. The electricity went out, the power lines were swinging all over the place and stuff was falling off the shelves."

Brent Ward, an earth scientist at Simon Fraser University, said the earthquake was the second largest to hit the country since 1949, when another earthquake was recorded in the same area with a magnitude of 8.1.

"It's an earthquake in an area that gets a lot of earthquakes," he said. "It's a tectonically active area."

Ward said the area is known as the Queen Charlotte fault, where the earth's plates slide horizontally across each other in a strike-slip action, similar to what happens along California's San Andreas fault.

"Stresses build up because of that movement, and every so often we get the release of that stress in the form of an earthquake."

Ward said he wasn't surprised the tsunami warning was shortlived because the strike-slip movement along the fault doesn't generally trigger tsunamis.

"To trigger a tsunami you need to have a vertical movement of the sea floor, and it's that vertical movement that displaces water and triggers the tsunami," he said. "Because it's sliding across each other, you're not generally moving the water."

In fact, hours after the earthquake, Dennis Sinnott, who works at the Institute of Ocean Sciences, said the largest wave hit Langara Island, a northern Haida Gwaii island, and measured just 69 centimetres.

The quake also set off emergency sirens across the Pacific on the islands of Hawaii, but even as people were moving to higher ground, the warning was called off.

In Alaska, the wave surge was just 10 centimetres, much smaller than officials had been forecasting.

Kelli Kryzanowski, manager of strategic initiatives Emergency Management B.C., said the initial earthquake occurred at 8:04 p.m. inland on Haida Gwaii and was initially recorded at a magnitude of 7.1 but was quickly upgraded to a magnitude of 7.7.

Kryzanowski said small waves generated by the quake, measured at 28 centimetres and 44 centimetres, also hit the northern tip of Vancouver Island.