The Pacific Tsunami Warning Center and Environment Canada both issued a tsunami warning for the area from the northern tip of Vancouver Island to Cape Decision, Alaska, extending into Washington, Oregon, Northern California and Hawaii as the evening progressed.
They and other emergency officials advised all coastal residents in those areas to move to higher ground, stay away from all harbours, inlets, including those sheltered from the sea, and not return to such areas until directed to do so by local emergency officials. People were asked to keep phone lines clear and listen to the radio for updates and instructions.
Waves were expected to arrive at Langara by 21:16 PDT and the northern tip of Vancouver Island by 21:17 PDT on October 27, Environment Canada reported.
Emergency Info BC said the first waves seen are usually not the largest, and the waves can go on for several hours. Information about dealing with an emergency is available at their website, as are the latest updates to the tsunami warning:
www.emergencyinfobc.gov.bc.ca
Earthquakes Canada seismologist John Cassidy said the major quake was felt across much of north-central B.C., including Haida Gwaii, Prince Rupert, Quesnel, Houston and Kamloops.
He said no injuries had been reported from the quake itself as it occurred far offshore, though it was large enough to cause extensive damage if located in habited areas. He could not speak to the possible damage from a related tsunami.
The "slip" quake was caused by two tectonic plates — the North American and Pacific plates — sliding past each other along the Queen Charlotte Fault, he added.
Cassidy said that though the Queen Charlotte Fault where this occurred is seismically active, experiencing in recent years earthquakes of magnitude 6 to 6.5, this is the largest quake measured there since a 8.1 magnitude one in 1949.
He said a quake of that size will come with aftershocks over the next few days.
"People should be aware of those and know what to do in the event of an aftershock, which is get under a desk or table and protect yourself from falling objects, mostly."
David McCormack, Director of Hazards Information Services for the NRC, said that this is a "small tsunami," measuring at last tally 43 centimetres from peak to peak, or 21 cm from baseline to peak.
"That's a wave smaller than what you would see in your bathtub, " he said, adding that such waves in confined spaces like ports can still cause a lot of damage, or can pick up steam as they travel.
He explained that sliding plates cause less seabed movement than when tectonic plates are pushed vertically, down under another, as was the case in Japan 2011. "It's the vertical movement that moves the water column and generates a tsunami," he said.
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Evacuation warnings have now been issued in many areas along the Canadian Pacific Coast and Hawaii.