power outage and yeast bank

well, i live outside of philly and we managed to get 12 inches of snow in october. our power was out for 4 days and i'm worried about my frozen yeast bank that took 2 years to build up. i burried all of the vials outside in a pile of snow and dug them up as soon as the power came back on and got them back in the freezer, so i don't think they warmed up to much. they definitely didn't stay frozen solid though. anybody ever have this happen? can somebody explain why freezing/thawing/freezing yeast has detrimental effects on the cells? any advice is appreciated.

thanks in advance

Freeze thaw cycles typically are only detrimental, ie break the cell membrane, if there is no cryopreservative. Since they were in snow, I bet they didn't warm up enough to make a difference. I've refrozen yeast after a vial was left out overnight, and it came back just fine. Worst case they may have lost some viability, but doubtful. Also, most of my yeast are not frozen solid, too much glyercine. Doesn't seem to make any difference in viability there.