A magnitude-7.7 earthquake struck off the west coast of Canada, with residents in parts of British Columbia evacuated, but the province appeared to escape the biggest quake in Canada since 1949 largely unscathed, with no reports of major damage.
A tsunami alert triggered by the quake set off alarms in Hawaii, with authorities forcing a state-wide evacuation.
The US Geological Survey said the powerful quake hit the Queen Charlotte Islands just after 8pm local time on Saturday at a depth of about five kilometres and was centred 155 kilometres south of Masset, British Columbia.
The USGS said the quake shook the waters around British Columbia and was followed after several minutes by a 5.8-magnitude aftershock. Several other aftershocks were reported.
The governor of Hawaii, Neil Abercrombie, said that the islands were lucky to avoid more severe surges after the earthquake struck. Abercrombie said beaches and harbours were still closed across Hawaii.
Lenore Lawrence, a resident of Queen Charlotte City on the Haida Gwaii, off the coast of British Columbia, said the quake was "definitely scary", and she wondered if "this could be the big one". She said the shaking lasted more than a minute. While several things fell off her mantle and broke, she said damage in her home was minimal.
Many on the BC mainland said the same. Joan Girbav, manager of the Pacific Inn in Prince Rupert, British Columbia, said: "I was sitting at my desk and everything just started to move. It was maybe 20 seconds. "It's very scary. I've lived here all my life and I've never felt that."
In Hawaii, the tsunami warning spurred residents to stock up on essentials at petrol stations and grocery stores and sent tourists in beachside hotels to higher floors in their buildings. The bus service into Waikiki was cut off an hour before the first waves, and police in central Honolulu shut down a Halloween block party. In Kauai, three schools used as evacuation centres quickly filled to capacity.
Fryer said the largest wave in the first 45 minutes of the tsunami was measured in Maui at about 60 centimeters higher than normal sea levels.
Alan Wong, a Hongkonger on vacation in Hawaii, said people appeared pretty calm in the region despite tsunami warnings that came hours before he was scheduled to fly back.
He was staying in a hotel in Puako on Hawaii's "Big Island". People staying on the first and second storeys needed to be evacuated, but Wong, on the fourth, could stay in his room, he said.
Reuters, Associated Press, Agence France-Presse