26/01/2016 7:54 PM AEDT | Updated 15/07/2016 12:51 PM AEST

Australian Man Dave Hannagan And Companion Cathy Grimes Killed In Avalanche In Jackson Hole, Wyoming


An Australian man and his American companion who died in an avalanche just outside the boundary rope of the US ski resort of Jackson Hole were not properly prepared for the back country, a resort spokeswoman has said.

Sydney man Dave Hannagan -- a 46-year-old surfer and real estate agent from Bondi known as "Big Wave Dave" -- and his American companion Cathy Grimes, 36, were both killed by an avalanche which it appears they triggered.

“It’s upsetting because these folks... we don’t think they were properly prepared for the back country,” said Jackson Hole spokesperson Anna Cole.

“They didn’t have transceivers and they apparently didn’t know the terrain very well.”

There has been a spate of recreational skier and snowboarder deaths caused by avalanches in both the US and Europe in recent years, as adventurous snow-lovers seek challenges beyond the patrolled slopes inside resort boundaries. Yet many skiers still fail to carry avalanche equipment like shovels and tranceivers, which allow people to find them under the snow.

This is the area where Mr Hannagan and Ms Grimes are believed to have ventured before triggering a fatal avalanche.

Jackson Hole, which is situated on a particularly steep-sided, dramatic offshoot of the Rocky Mountains known as the Teton Range, is renowned for its steep back country, or "side country" as locals often call it.

The Tetons are not to be treated lightly

Multiple warning signs alerting skiers to all manner of dangers dot the boundary ropes. It appears that the two skiers paid insufficient respect to the signs and ventured out to an area which is crossed by a band of cliffs and had an unstable snowpack after recent snowfalls and wind.

Mike Rheam, a forecaster for the Bridger-Teton Avalanche Center, told local news outlet the Jackson Hole News & Guide that there had been fatalities in that region in the past.

“People who aren’t familiar with the terrain … it gets steeper and the avalanche breaks over them … they were carried over the cliff," he said.

The 60 metre-wide avalanche occurred just after 2pm on Sunday afternoon local time, after the resort had received about 12cm of new snow the day prior. Rescuers probed the snow and had found both skiers by 3.32 pm. One was found under a metre of snow, the other just 30 cm. Both were apparently killed by trauma, the News & Guide reported.

A third skier in the group "grabbed a tree and was not carried over the cliff or buried,” Mr Rheam said.

Mr Hannagan's boss and friend Ric Serrao told Fairfax Media that Dave Hannagan was "a bit of an icon" around Bondi.

"He was just one of those real true blue people, he was just so genuine," Mr Serrao said. "He loved to travel, he loved to surf, at work he was one of our secret smoking guns. We called him the deadly weapon because he had this smile and people just loved to work with him."