About a dozen Whitehorse residents reported feeling an earthquake Sunday afternoon.

The magnitude 5.1 earthquake, which occured at 4:24 p.m. PST, originated about 87 kilometres southwest of Haines, Alaska and approximately 200 kilometres southwest of Whitehorse.

"The 5.1 is a big enough earthquake if you're close to it, you would be frightened," John Cassidy,a seismologist for the Geological Survey of Canada, told the Star this morning.

Most people, however, felt a slight swaying for a few seconds, he said. One woman felt the ground abruptly shake while she was outside her Wolf Creek home.

Sunday's earthquake was caused by the North American Plate and the Giant Pacific Plate pushing the Yakatak Plate into the corner of North America.

The effects felt in Whitehorse were caused by the earthquake's surface waves, which travel along the surface of the Earth, making the ground move up and down once every 10 or 20 seconds.

Surface waves can cause the upper floors of a high-rise building to shake, or can make people dizzy, said Cassidy.

"Certainly, earthquakes shouldn't be a surprise at any time," said Cassidy. "That's a very active region along the coastal region."

Cassidy said Alaska has a magnitude five earthquake every year, with the most active regions being the Yukon's southwest corner near Haines Junction and the northeast.

The Whitehorse area has had earthquakes of magnitude five or six in the past, but the most dramatic sensation comes from larger earthquakes in Alaska.

A recent example of this is a Denali, Alaska earthquake in 2002, which had a magnitude of 7.9.