PURPOSE:  Reduce ground failure and injuries associated with rock bursts (earthquakes) in deep hard-rock mines.

RESEARCH SUMMARY:  Mines in the Coeur d’Alene Mining District where rock-burst-related roof falls occur have a fatality rate eight times greater than the industry average for all causes of death. Ore from the platinum mines in Montana is being extracted from greater depths, and conditions that favor rock bursts are being encountered. Currently, five underground hard-rock mines in the United States have geologic and mining conditions that could generate rock bursts. These mines employed 2,239 (14%) of the 14,492 workers in metal/nonmetal mining.

In the past, researchers at SRL have developed backfilling, destressing, and underhand mining to alleviate the hazards and protect miners from bursts. Currently, researchers are monitoring rock-burst prone mines to identify hazards before they become a problem. They have developed PC-based, in-mine seismic and electromagnetic monitoring systems to identify rock burst failure mechanisms and an Internet-based seismic monitoring system for real-time surveillance of seismic activity at targeted mines.

For example, wall strain and electromagnetic emissions are being investigated to determine if either can be used to develop a system that could warn of impending bursts. Partners in the research are the Stillwater Mining Co. (Stillwater and East Boulder mines); Hecla Mining Co. (Lucky Friday Mine); Coeur Silver Valley, Inc. (Galena Mine); the Montana Bureau of Mines and Geology, Office of Earthquake Studies; the Montana Tech Foundation; and Gonzaga University. Successful development of an early warning system could reduce injuries caused by rock bursts because miners could be evacuated to safe areas before a burst.