Fortunately, all 7 miners are expected to fully recover! It appears that the rock burst might have been caused by seismic activity as was the case in the same area about a month ago according to http://seattletimes.nwsource.com/html/l ... apped.html
. The Lucky Friday Mine has been reaching increasingly deeper depths over the years in order to access multiple silver deposits far beneath the ground. Hecla Mining Company, owner of the mine, is currently undergoing a $200 million project to bring the mine down to almost 9,000 feet below ground in order to access a new vein. With these extreme depths come extreme pressures of rock all around, and the dangerous reality of rock bursts.
On their website, they do have an interesting set of videos which illustrate their operations more clearly:http://www.hecla-mining.com/operations/ ... friday.php
(choose About Lucky Friday for a 3d diagram of the workings)