From what I read, that dam is set ON bedrock, not into it.  That is, no piers extend into solid rock, so blocks making up the dam could be pushed along by the water pressure behind it. 

Aside from the potentially unparalleled loss of life posted by catastrophic failure, the fallout will not be limited to China.  It will be tantamount to nuclear winter for the world economy as so much of their manufacturing capability would be wiped out for years, manufacturing important to us all 

IF, if this were to happen, say goodbye to fiat money as we have known it and many other things currently regarded as stores of value.  The exceptions will be gold and silver, and perhaps gold and silver stocks (maybe after a short-lived wipeout that should be embraced as a buying opportunity if stock markets survive).

But what are the odds?  I don't know.  I would guess that some insurance is better than none, at least until their monsoon season passes...for this year.  Then I would look for China to find some option for anchoring dam segments into bedrock, given it now appears that damn construction was never really completed.  

I am reminded of a lot of soils-distressed housing tracts I investigated in CA long ago.  I saw instances where developers through away soils reports they didn't like and went shopping for ones that they did, the ones they presented to building regulators.  Their thinking was that they would be dead from old age or retired living out of state before problems arose.  And that was so in some cases.  BG, I think, knows something about such games.