Skinned up far Lookers R uptrack of nosehairs moving towards far out ridge. About 2/3 way up the track (unsure of elevation) on a 33 to 36 degree SW facing slope we experienced a lound WHOOMPH with 200 foot shooting crack that broke at my feet (the second on the skin track). The crack propagated roughly 75 feet in front of me and 125 feet behind me. Very luckily (and I unsure how) the slope did not slide despite an ideal slope angle for avalanches and little support from below. All 4 skinners who were spaced by roughly 35 to 40 feet were on the slab that failed.
We dug a pit and profile of the crack. Crack depth was 1 to 2 feet deep. The majority of the slab was 40 cm of 4 finger (presumably storm snow) sitting on a thin 1 finger crust. Below this was a thin layer of facets (the weak layer that failed) on top of again 4 finger cohesive snow.
Snow pit dug just above the failed crack on a 36 degree slope showed ECTN26 on the lase failedlayer that produced our crack / whoomph. On shovel sheer after the test the slab failed to break free from the rest of the column).