Utah mine used risky cave-in method of mining.

[Swede]

The mining technique used in Crandall Canyon Mine in Utah, where six miners are trapped, involved collapsing the roof of the mine -- a method that dislodges such tremendous volume of earth with such force that it causes quake activity.

"It's the most dangerous type of mining that there is," said Tony Oppegard, a mining lawyer and former federal mine safety official.

http://www.latimes.com/news/nationworld/nation/la-na-collapse8aug08,1,4610878.story?coll=la-headlines-nation&ctrack=1&cset=true

[flyingfysh]

1. it's risky, but it is very profitable

For the owner. I'm sure ordinary workers don't see a dime of the profit, except for regular pay.

[Sadie4629]

2. Someone on here this a. m.

said he'd work on retreat mining, and that it paid very, very well.