Buaas tipped too far forward in the middle of a jump and slammed face-first into the snow, before limping off the track, and being taken to hospital for a check up.
"It is one of the worst falls I've seen in a long time," Jonas Greve, an expert commentator for TV2 said. "She had too high a speed, and went far too high. I think she flew almost 40 metres before she hit the ground."
Buass is the latest victim of a slopestyle track which many athletes have condemned as dangerously difficult.
"It looks pretty sketchy,” Roope Tonteri, a snowboarder from Finland, told reporters after a training session at Rosa Khutor Extreme Park on Monday. "I think they wanted to make big kickers and it's not really good for riders. It's not really safe anymore."
Torstein Horgmo, a snowboarder on Norway's men's slopestyle team, pulled out of the games this week after breaking his collarbone in training on the track. Finnish snowboarder Marika Enne, and America's Shaun White have also both sustained nasty falls.
Canada's Mark McMorris, tipped by some to take gold in the event, described the run's take-off ramps as "kind of obnoxiously tall," but said he did not believe the course was actually dangerous.
Slopestyle is a fusion of speed and trick snowboarding, with competitors performing jumps and slides as they race down a slope.
On Thursday afternoon, Buaas posted an upbeat picture of herself on Instagram and said she still hoped to be able to compete on Sunday.
"Oh snap…That was a real scare!!!" she wrote. "Good news is that I only ruptured a muscle… I am so grateful it's nothing worse, even though I have some severe pain in my stomach and back.."