Cardiac Ridge today around 1:30pm On the second lap, the seventh track on the slope triggered a large avalanche down to the PWL near the ground. There were 5 people in the vicinity. 1 on the skinner, 1 on the slope and 3 below. It looks like the skier was in an area with deeper graupel pooling from the main shot above. On the third turn, cracks shattered across the slope and the skier was able to see snow moving to his right as he skied left away from the slide. Crown height varied but the part near the skier was around 1' deep. Above in the deeper areas it looked maybe 3' or more. It matched the slide that occurred here 5 weeks ago. I called Alta central and conveyed that nobody was caught and we were all OK. Service was bad, and another party's 911 call activated the slc sheriff's response. I was so impressed by how fast the Powderbirds and DPS responded with members of WBR, Alta and Snowbird ski patrols, rescue dogs. We are all so grateful for you being there for us and so glad nobody got hurt.