People across Quebec and Ontario say they felt the earth move at about 1:45 p.m. Wednesday.

The U-S Geological Survey initially said the temblor had a magnitude of 5.5 but has now revised that to 5.0.

The tremor was centred about 60 kilometres north of Ottawa in western Quebec but was felt as far away as Windsor, Ontario and also in parts of upstate New York and Vermont.

The quake seemed to last for about 30 seconds in Ottawa and rattled downtown buildings and government offices.

A spokesman for Prime Minister Harper says there are no immediate reports of damage or injury.

Mike White says Harper was enroute to the airport when the quake hit and didn't feel it at all.

Ottawa evacuations

But buildings across downtown Ottawa were evacuated and several Parliament buildings emptied.

A sitting of the Senate was disturbed, as were preparations by the P-M-O for this week's G-8 and G-20 summits.

A gaggle of senators and aides milled about the Parliament Hill lawn after the tremor.

Holly Rockbrune, 25, works for an insurance company. She was home for lunch when she began to notice something strange was happening.

"It was odd because I was in the kitchen making lunch and I could hear banging," Rockbrune said.

"I went into the living room and everything was rattling, but I didn't think much of it so I went back into the kitchen. It only lasted a few seconds."

Stephen Taylor, a political pundit in Ottawa, used his Twitter feed to describe what the tremors felt like.

"I was in an elevator when the earthquake hit," Taylor wrote. "Debris hitting the top of it, walls scraping ... fun stuff."

The website for the USGS displayed a map showing a recent event registering 5.5 magnitude had occurred near the Ontario-Quebec boundary. The USGS said the quake occurred at a depth of 19.2 kilometres.

Big quake for the area

It was one of the most significant quakes ever measured in the region, according to the organization.

The two largest quakes in western Quebec occurred in 1935 at magnitude 6.1 and in 1732 at a magnitude of 6.2, according to the agency.

It said earthquakes east of the Rocky Mountains, although less frequent than in the west, are typically felt over a much broader region.

The survey also said that east of the Rockies, an earthquake can be felt over an area as much as ten times larger than a similar magnitude earthquake on the west coast.

Hundreds of people were milling about on downtown Ottawa streets as the Parliament buildings emptied, along with the Prime Minister's Office across the street at the Langevin Block.

Buildings across downtown Ottawa were evacuated.

A sitting of the Senate was disturbed, as were preparations by the PMO for this week's G8 and G20 summits. PMO staff were forced out onto Wellington Street.

Conservative Senator Lowell Murray said the massive chandeliers of the upper chamber began swaying during a mundane debate on energy issues.

"Initally we thought it might have been an airplane crashing into the building," Murray said.

"But we were standing around wondering what was going on. And I quickly realized it was an earthquake. And then everybody started shouting out, out, out."

Via trains stopped

Those travelling by train along the Quebec City-Windsor corridor were literally stopped in their tracks by the earthquake.

As per normal procedure, Via Rail had to suspend all train travel while it conducted inspections of its tracks.

As a result, passengers were forced to remain on trains with no word of when travel would resume.

With files from The Canadian Press