OTTAWA - Windows rattled, walls swayed and knick-knacks toppled from store shelves near the national capital Friday as Canadians across a wide swath of Ontario and Quebec felt the disconcerting tremors of a 5.2-magnitude earthquake.
In the tiny town of Shawville, Que., about 18 kilometres from where Earthquakes Canada located the temblor's epicentre, residents described thinking at first there had been an accident or an explosion.
"There was a loud bang and it sounded like a heavy truck had hit the building," said Katherine Summerfield, who owns and operates Boutique Gwendoline, a women's apparel shop in town.
"The whole building was shaking and then things started falling off the shelving in the back room. So then we instantly knew it was an earthquake."
Less than 10 minutes after the first quake, which was initially reported as a 4.8, Earthquakes Canada registered an aftershock of 4.2.
The original quake was powerful enough to shake the big stone and brick building that houses the municipal offices in Shawville, said Mayor Albert Armstrong.
"The windowsill, the walls seemed to shift up and down," Armstrong told The Canadian Press. "My cabinet behind me was shaking and twisting.
"I've lived here all my life and I've never witnessed one like that before."
Armstrong quickly had maintenance crews check the town's water supply and sewage treatment plant, and then municipal buildings, for damage. But the community appeared to escape unharmed, shy of a few reports of minor residential damage.
One woman said that a furnace pipe was dislodged from her basement ceiling.
But while there was scant physical evidence of the quake near the epicentre, its impact on social media was broad and instantaneous.
The quake touched off an eruption of reaction on Twitter as users reported buildings shaking in Ottawa for several seconds; it was also felt in Toronto and as far away as Waterloo, Ont.
Across the river from Shawville, in Arnprior, Ont., residents reported being startled as buildings began to rumble.
"I thought it was an explosion of some type," said Arnprior resident Susan Eddie. "Everything started to shake so we went outside, and all my neighbours were outside as well.
Added fellow Arnprior resident Julie Engelberts: "My CD player was shaking. It was scary."
Police in Arnprior said they received no reports of damage.
The quake was slightly stronger than the last one of significance to hit the region — a magnitude 5.0 earthquake that was felt on the afternoon of June 23, 2010.
That quake's epicentre was situated in the area of Buckingham, Que., about 56 kilometres north of Ottawa.
Earthquakes Canada said Friday morning's quake followed the one in 2010 relatively quickly, since the region records an earthquake of magnitude 5.0 or higher, on average, only about once every 20 years.