The guys in the top picture digging what I thought to be because of slope on the mountain seem to be digging a bit deep. But due to Teddys falling tree theory is there any chance this could have been their den or labaz.
I am guessing that you are talking about the photo with one of the group holding a ski looking at the camera and the others crouching and digging , the back packs are on the slope to the right and all the skis and ski poles are sticking out of the snow on the slope above the trench that's being dug. If this is the photo you mean , then there are at least 5 hikers along the trench line . Allowing 1 meter for each hiker to dig and rotate, then that equals a 5 meter trench minimum.
Teddy does suggest that this may have been the labaz but I would have to argue that 5 meters is too big for a labaz and it would be questionable to build a labaz on an exposed slope . How easy would it be to find on your return , especially when the weather could be doing anything? . when building the labaz and then digging and retrieving the stored goods , first you have to unpack the back packs which would be slightly easier , but then on your return you have to pack your kit again. These are two unefficient extra stops with variables( finding the labaz in poor weather condition s for example) , it would make more sense to build a labaz at a campsite when you have all your kit out for the evening , when cutting wood for a fire at that campsite and building the labaz it would also be good to have ready chopped wood for your return , this would then be a good rest night , all that's needed is to pitch the tent .