Blue cave, shattered ice
Lituya explores a cave filled with shattered lake ice, broken up by a calving event a week or so earlier. We have measured the depth of the lake near here, and it's hundreds of feet deep, but to all appearances when you're standing there you might be standing on solid ground.
Wait - you went to a moving glacier face on a frozen with your kids... is that safe?
Well... no. Very few things have zero risk. In my ideal world, I would have a number that described the exact risk, like "The chance of a calving event in these conditions in a given 10 minute period is 0.0015%" That would provide a way of assessing this risk, and considering whether it was acceptable in exchange for the benefit of our explorations. We might compare that risk to other known risks (e.g. the risk of dying while driving 1000 miles is 0.000015% in the US.)
Of course we don't know the number for glacier calving, especially given the very specific conditions we were there in. There are a few things we considered to assess that risk: There was evidence of only two calving events (including the one off the iceberg) in the previous couple weeks (when there was ice). These both appeared to have happened during the warm weather that smoothed the skating ice. Generally calving is much less likely when it's cold, since the ice is stronger, and not being actively weakened by melting.
To further mitigate our risk, we wore helmets, we limited our time by the ice face, and we avoided areas that appeared potentially unstable.
Ultimately, I can't say if we made the right call. But it was pretty awesome...
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