The tsunami warning issued for the British Columbia coast after a major magnitude 7.7 earthquake struck the Queen Charlotte Islands region, has been downgraded to an advisory.
The earthquake occurred at 8:04 p.m. local time on Saturday night, 198 kilometres south-southwest of Prince Rupert at a depth of 10 km in a seismically active region, said the U.S. Geological Survey and Earthquakes Canada, who measured the quake at a magnitude of 7.7.
Earthquake Canada initially measured it at magnitude 7.1 but altered their report later Saturday.
“This was a big earthquake, the biggest earthquake we’ve had in Canada since 1949,” Simon Fraser University (SFU) geologist John Clague told the Sun.
“I think we were fortunate that the epicenter was in a very sparsely populated area. Had that occurred close to an urban area it would have been a total disaster.”
Before Saturday, the largest quake in the last 40 years was a 6.6 earthquake in 2009.
The U.S. Geological Survey also measured two aftershocks at magnitude 5.8 at 8:14 p.m. and magnitude 4.8 at 8:52 p.m. PDT.
Although Saturday’s quake is the strongest to hit Canada since an 8.1 quake rattled the Queen Charlotte Islands in 1949, it isn’t likely that a large tsunami will affect the north coast of Vancouver Island, said Brent Ward, a geologist with the Department of Earth Sciences at SFU.
“I don’t think we have to worry about a tsunami,” said Ward, noting that the epicenter of the strike slip quake was under land, making it less severe than the subduction movement that caused so much destruction in Japan last year.
Following the quake, the Alaska 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.
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
Warnings of a tsunami have spread throughout the U.S. As far as Hawaii, officials are closely monitoring any developments and preparing for the worst.
According to the Honolulu Star Advertiser, tsunami warning sirens have sounded throughout Hawaii and people are being advised to evacuate inundation zones.
That said, SFU geologist John Clague said he would be surprised if the Haida Gwaii temblor had such a far reaching impact.
“The tsunami can be directed west across the pacific but I’d still expect some significant waves here if it was going to be an issue in Hawaii,” Clague told the Sun.
“They were talking about three to seven foot waves – that just doesn’t seem reasonable to me given the lack of any significant run-ups on our coast.”
In Tofino, tsunami sirens sounded for at least an hour Saturday night as residents evacuated to higher ground.
Paul and Lisa Jarvis, of the band Mojave, live in Tofino and first learned of the earthquake in an emergency text.
“My wife and I are on emergency social services and we got a text saying ‘please unlock the community centre, people are evacuating there,'” said Paul Jarvis, who, along with his wife is a volunteer in emergency social services and lives close to the community centre. While it’s on the highest ground in Tofino, Jarvis said their house is close to the beach.
“The sirens were going off for at least the last hour — then they went on again for about five minutes,” he said.
Paul said soon cars had overfilled the small community centre parking lot and were parked along the road as some 200 people rushed to the centre, parents with children bundled in coats over their pyjamas and people carrying water and food supplies.
“People got their supplies and got out to the community centre,” said Paul, adding that another 200 went to the local school, also on high ground and the site that had previously had been designated for evacuations.
“It is just an advisory, not actually a warning. People are just being safe,” he said.
Paul said Tofino Mayor Perry Schmunk was the community centre speaking to residents who had evacuated there.
Shortly after the quake struck, Schmunk posted a warning on Twitter and on his Facebook page: “Tofino has activated Tsunami Warning system if your in a low lying area of Tofino please proceed to the community hall ASAP.”
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.
Story Credit: Kirstin Endemann, Gillian Shaw, Marc Miquel Helsen, Ottawa Citizen, Vancouver Sun
Published: Saturday, October 27, 2012