The morning after a magnitude-7.7 quake -- the strongest in Canada in more than 60 years -- struck the Haida Gwaii archipelago, the 6.3 aftershock occurred at a depth of 5.1 miles and 99 miles south-southwest of Masset, British Columbia, the U.S. Geological Survey said. The epicenter was about 398 miles south of Juneau, Alaska.
The Vancouver Sun reported the area was shaken by 40 other aftershocks of magnitude-4 or more and six at magnitude-5 throughout the day. The newspaper said the strong aftershocks likely would go on for a week or more.
"They will continue for a while," Simon Fraser University geology Professor John Clague told the Sun. "You've got this big shock to the earth and the earth is adjusting to the release of energy and the movement along the fault actually sets up instabilities in the surrounding rocks."
Erin Wilson of Skidegate was speaking to the Canadian Broadcasting Corp. when the big aftershock hit.
"It's non-stop," she said of the incessant tremors. "You hear things creaking and cracking and you hear -- oh, another one right now. It's pretty scary."
Hawaii ended a tsunami warning and evacuations Sunday after the Saturday night quake.
After the warning was posted by the Pacific Tsunami Warning Center, Gov. Neil Abercrombie declared an emergency and officials began evacuating coastal and low-lying areas, KITV News in Honolulu reported.
The first small tsunami waves were seen off Hawaii about 6 hours after the earthquake, CNN said.
Five hours after the evacuations were ordered, the National Weather Service said the threat of a tsunami had decreased and was not expected to rise again.
Regardless, all beaches remained closed and Honolulu Mayor Peter Carlisle urged residents to stay ashore, HawaiiNewsNow reported.
"Right now, we do not feel it is safe for anyone to go into the water," the mayor said.
The USGS said the Saturday quake occurred at a depth of about 10.9 miles. It was centered along British Columbia's coast, about 86 miles south of Masset and about 395 miles south-southeast of Juneau.
A tsunami warning was also issued by the West Coast-Alaska Tsunami Warning Center from the northern tip of Vancouver Island to Cape Decision, Alaska, although it was downgraded to an advisory soon after.
Despite the quake's magnitude, there were no immediate reports of injuries or significant damage in the mostly rural islands of British Columbia.
"We were just sitting down relaxing and all of a sudden -- boom! I thought it was a major landslide," Dave Martynuik, who lives in the village of Queen Charlotte in the Haida Gwaii, told the Toronto Star in a phone interview.