One such burst hit the Lucky Friday in 1969 when all of the stopes on a level approached an upper level at the same elevation. Mining theory and ground control are highly complicated, technical and often perplexing facts of life for the industry. And the knowledge of just how to deal with these inherent problems comes as a learning process for us all. There are three basic types of rock bursts known to occur in the district's mines. At the Lucky Friday, and probably at other mines, specific geologic and geometric aspects of a burst site influence the type of burst that occurs.
Tremendous stresses begin building up in the surrounding rock.
Then when the strain becomes greater than the rock can bear, the hard granite explodes, or bursts, thereby relieving that pressure. This article is an account of one of the more ferocious rock bursts to hit the miners of the Lucky Friday. I had been working at the Lucky Friday for six years. In fact, in the early spring of 1986, the mine was experiencing as many as 1000 bursts an hour, of different intensities, of course. Most of them sounded like popcorn popping.