Another piece to this tragedy was reported on my local news here. It seems a lot of the people who are supposed to be the national mine inspectors,have inspsected about "0" to just only 3 mines or so in the last few years!
Worse,these highly paid "professionals" were seen on video partying together in a casino. One inspector was shown to be gambling at the same time there was an important meeting being held elsewhere!
I don't get why they'd go deeper into the mine either,but I'm sure as time goes on,it (and all) will be cleared up.