Sydney, Apr 16, (AFP): Australia's Barrier Reef district was rocked by an unusual 5.2-magnitude earthquake today, but laid-back locals said they had barely felt a thing.

The tremor struck about 3.30pm local time (0530 GMT) about 124 kilometres southeast of Townsville at a depth of 10 kilometres, according to the United States Geological Survey.

A low rumbling was felt at Magnetic Island, a 20-minute ferry ride from the mainland and part of the Great Barrier Reef, according to a hotelier at the All Seasons resort, where it briefly interrupted a wedding on the beach.

"Some of the guests felt a bit of a shake, nothing much. It wasn't major, no-one fell over and nothing was damaged," she said.

"It was just like a shudder, my office backs onto the laundry and I said 'Oh, that was a big spin cycle.' It hasn't stopped the world up here.

"We are alive and well at the moment and please God that's how we are going to stay." There were no immediate reports of damage and no tsunami alert was issued.

In Townsville, a tropical city renowned for its easygoing lifestyle, residents said they hadn't felt a thing.

"Look, we're pretty laid-back around here and it'd take something more than that to shake us up!" a publican at the local Molly Malone's Irish Bar told AFP.

"As far as I know there's been no sign of anything like that, no vibrations or nothing. Is this a practical joke?"

Australia rarely experiences earthquakes, its land mass being some distance from the boundary of the Indo-Australian tectonic plate.