A magnitude 5.0 earthquake hit central Canada Wednesday afternoon, rattling buildings from Sudbury to Quebec City, and as far south as New York City.
The epicentre of the quake was in Quebec, about 38 kilometres north of Cumberland, Ont., which is on the Ottawa River, according to the U.S. Geological Survey, and struck at 1:41 p.m. EDT at a depth of 18 kilometres.
There have been two recorded earthquakes with a magnitude over 6.0 in the Western Quebec seismic zone: a 6.1-magnitude quake in 1935 and one measuring 6.2 in 1732.
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"Earthquakes are fairly uncommon here," said Morgan Moschetti, a seismologist with the U.S. Geological Survey. "This isn't totally unheard of, but they are relatively infrequent."
Mr. Moschetti said aftershocks are "definitely a possibility" but that such smaller earthquakes are sometimes so minor they are hardly noticeable.
"After any large event, there's going to be some adjustment in the earth," he said.
Mr. Moschetti said the earthquake was felt in the U.S. from Chicago to western Maine.
An earthquake with a magnitude of 5.0 is considered to be a moderate one but it can cause major damage to poorly constructed buildings over small regions. At the most, it should cause only slight damage to well-designed buildings. However, parts of the Ottawa Valley, including Ottawa, are at greater risk of structural problems because of ground acceleration, a phenomenon in which the type of bedrock amplifies the effects of the tremor, said Alexander Cruden, a professor of geology at University of Toronto.
Glass shattered, pictures fell off walls and a small bridge was damaged near a series of small villages just north of the epicentre, at a dam called Barrage-McLaren.
Mervyn Mallon said traffic is being detoured around an old bridge near Bowman, Que., along Highway 307, about seven kilometres north of the epicentre. Quebec provincial police said a piece of road gave way just before the bridge. A man who was fishing nearby was injured but drove himself to a nearby hospital.
"That's the only report of injury we've had, and it seems quite minor," said Sgt. Claude Denis of the provincial police.
Mr. Mallon, a retired farmer who has lived through a handful of earthquakes in the area about 55 kilometres north of Ottawa, said it was by far the biggest he's seen in his 73 years.
"I was looking at a book when the mirror started swinging on the wall. I caught it before it fell on the floor," said Mr. Mallon.
"The extent of it varies from house to house, depending on foundations and that sort of thing, but so far it's mostly pictures and nick nacks."
"People are a bit shook up because they've never experienced such a thing."
About seven kilometres to the south of the epicentre, in Poltimore, Mr. Mallon's daughter, Valerie Brunet, was gardening when she was surrounded by breaking glass and falling plants.
"I was in an outside shed and I literally thought the building was coming down on me," said the dental assistant who was enjoying a day off.
"The dog was going nuts, running around barking. But there's no real damage to speak of."
Ms. Brunet said there have been a series of smaller aftershocks since the quake.
The quake happened in the western Quebec seismic, near the boundary between the Ottawa-Bonnachere and western seismic boundaries. Geologists have yet to determine which of the two seismic zones the quake happened in, but both areas are known for low to moderate seismic activity, Dr. Alan Baird from Queen's University said.
Early reports on the USGS website labelled the earthquake as 5.5 magnitude. Soon after, it was downgraded to 5.0.
Dr. Baird said that this is because early measures on earthquakes are often inaccurate. "It takes a bit of time to actually process the data to get an accurate measure of the magnitude," he said. Similarly, he said, early reports that the earthquake was 18 kilometres in depth may turn out to be inaccurate.
Environment Minister Jim Prentice was doing an interview with CTV at its Ottawa bureau on the 14th floor of the World Exchange Plaza in downtown Ottawa when the tremor struck.
"I was on the air and suddenly my chair was moving," he said afterwards. "Fortunately I was at the end."
The sidewalks quickly filled with workers who decided to evacuate their buildings. Within minutes of the tremor, cellphone service in Ottawa was down, possibly because callers had overloaded the system, though the exact cause was not known.
Twitter users as far away as Springfield, Mass. and Traverse City, Mich. reported feeling tremors. The quake was felt in Michigan, Vermont and parts of upstate New York.
Sara MacIntyre, a spokeswoman for the Prime Minister, said Stephen Harper was in a car on his way to the Ottawa airport at the time of the earthquake and didn't feel the tremors. Mr. Harper continued with his flight to Toronto to attend an Air India bombing memorial. Ms. MacIntyre said Langevin Block, which houses the Prime Minister's Office, was not evacuated.
"Everyone's okay. We were all not accustomed to the sensations obviously but recognized almost immediately what it was and everyone kind of grouped together," she said, noting that security guards checked in on workers.
On Parliament Hill, where the Commons has adjourned for the summer but the Senate was still in session, Senators felt the Red Chamber shake. Glass windows made a crunching noise, and ornate chandeliers swung.
"I was walking into the chamber, and there was all this crunching noise, and all of a sudden everyone started running," said Senator Marjory LeBreton.
The Senate's black-robed officers poured onto the Parliament lawn, with deputy usher of the black rod carrying the ceremonial staff.
"We're having some contentious debates, so we were wondering if it was a message from the gods," Sen. LeBreton joked.
Parliament Hill was evacuated after the earthquake and Public Works is in the process of inspecting the buildings for possible damage, said Heather Bradley, a spokeswoman for the Speaker of the House of Commons. Employees are being allowed to retrieve their personal belongings and are being asked to go home for the day, she said.
A PMO spokeswoman said the Ottawa headquarters of the National Research Council, which is responsible for monitoring earthquakes in Canada, has been evacuated and officials are taking phone calls from an emergency room.
The Bank of Canada, a few blocks from Parliament Hill, has been closed until the building has been inspected and deemed safe. Core staff will carry on operations out of the bank's second site, which is outside of the downtown core.
Jill Vardy, the Bank of Canada's deputy chief of communications, said this is standard procedure after earthquakes of a significant magnitude.
She said the bank is expected to reopen at its primary site on Thursday.
The tremors were also felt in the Ontario legislature's grand stone building at Queen's Park, prompting one government official to send an email to officials in Quebec, jokingly saying: "If you wanted to separate, why didn't you just say so."
Mike Ansell, manager of a senior citizens home in Cumberland, Ont., said the shaking was "huge" and "felt like forever, but probably just lasted a few minutes."
"Suddenly, I felt the floor moving, and I thought it was an explosion or something," he said. "I immediately thought terrorists or something."
All 65 residents were evacuated safely, he said, and there didn't seem to be any major damage on the streets around him.
The epicentre is roughly on the same longitude as the Chalk River nuclear facility in Eastern Ontario, about 150 kilometres to the west of the quake. The facility was shut down last November because of concerns about a hypothetical earthquake interrupting its electrical power supply, a move that eventually led to the firing of Linda Keen, Canada's former nuclear safety watchdog. The reactor was officially restarted on Dec. 16 after Ottawa intervened.
The Chalk River facility sits on earthquake fault lines. The area has never experienced a major earthquake, but two minor quakes struck in December, registering 3.0 and 3.6 in magnitude.
Tremours from the earthquake hit three of the country's nuclear plants, but caused no damage. The Canadian Nuclear Safety Commission, the federal watchdog agency, said the quake was felt at the Darlington and Pickering stations in Southern Ontario, and the Gentilly-2 plant in Quebec.
The CNSC said the companies operating the plants, Ontario Power Generation and Hydro-Quebec, have confirmed that the stations weren't affected by the earthquake.
The earthquake shook rooftops in neighbourhoods just west of the capital's downtown core for about 20 seconds. It sounded like a squadron of jet fighters rumbling overhead. "The house and the trees were shaking," said Abela Sama, a nanny working in New Edinburgh who recognized it immediately as a minor earthquake. "I lived in the Philipinnes. There are always earthquakes and so I know how it feels."
Several residents on one residential street in the St. Clair West/Christie area of Toronto emerged from their homes within moments of the quake, which struck at about 1:50 p.m., and immediately began questioning one another about what had just happened.
"The house started shaking," said Michelle Mason. "It felt like there was a subway coming under the house. Dave [her husband]said, `I think that was an earthquake." She said there had been no damage inside.
Across the street, Peppe Tozzo, a 26-year-old musician and yoga instructor came out carrying his guitar, having just rescued a wobbling mirror that was about to fall on his way down the stairs. "The house was just flexing," he said. "I thought it was the wind." Meanwhile, his roommate, 27-year-old Ryan Gillies, was upstairs packing his belongings, and thought the shaking had been caused by a passing truck.
Standing on their porch, both men agreed it was a very strange experience. "I felt like it was a sonic wave from the G-20," joked Mr. Tozzo.
Ottawa paramedics were deluged with 911 calls after the quake, spokesman J.P. Trottier told The Globe. "The city was in a bit of a panic, which is to be expected."
He said there were very few injuries because of the quake. Most of them - minor fractures, scrapes and falls - happened in the packed stairwells of office towers downtown.
"Right now, it looks like very, very low numbers of injuries."
Asked whether he felt the quake, Mr. Trottier laughed: "Oh, yes."
He said he felt pretty secure in spite of the shaking.
"We're lucky enough to work out of a five-year-old,100-year-earthquake-proof building. … I did keep an eye on the ceiling tiles, though."
A Toronto Police spokesperson said that there have been no reports of injuries in Toronto, which was later confirmed by the city in a news release.
"It was shaking enough that my blinds were banging against the window," said James Lorimer, a managing director at Ludwig Financial Recruitment in Toronto, which has its offices on the 37th floor of the office tower at First Canadian Place, the country's tallest office building.
He said his mind flashed to the possibility that there was an incident related to the G-20 or terrorism that was causing the building to rock.
"We had a few conspiracy theories going because the University subway was shut down earlier in the day" because of a suspicious package, he said.
With files from Brodie Fenlon, Ann Hui, Jill Mahoney, Les Perreaux, Kate Allen, Shane Dingman, Dennis Choquette, John Ibbitson, Campbell Clark, Bill Curry, Erin Anderssen, Boyd Erman