Shortly before 11:00 p.m. on June 8, 1979, a scheduled blast was initiated in the Belle Isle Mine, a salt mine. About ten minutes later a gas explosion occurred, sending intensely hot hurricane-like winds throughout the mine. These gales blew out ventilation controls, including stoppings and doors, and upended trucks and other heavy machinery. Standing at the surface when the explosion occurred, a general mine foreman compared the explosion's sound to that of a dozen freight trains.
Twenty-two miners were underground when the explosion occurred. One group of six miners successfully dialed the surface with a make-shift telephone improvised from two damaged telephones.
Surface workers responded by clearing obstructions from a nearby shaft, and then sending down a mancage, which hoisted the miners to safety. Meanwhile, another group of seventeen miners spent about an hour inching toward a shaft through pitch-dark, intensely hot, debris-filled corridors.
Upon reaching the shaft the survivors banged on its gate, signaling their location to surface workers. Surface workers then freed the shaft's mancage, which had been lodged in the headframe by the explosion's concussive winds, and sent it down to the survivors.
By 2:45 p.m. the stranded miners were lifted to safety. Five other miners were killed in the explosion.
MSHA investigators determined that the scheduled, initial blast had triggered a massive "outburst" of about 15,750 tons of broken salt and flammable gases. Included in these gases were methane and minute quantities of other hydrocarbons, which were ignited by electric arcs, sparks, or burning electric cable insulation.
MSHA identified the causes of the disaster as a general lack of recognition by both MSHA and cargill of the seriousness of the "blow-out" phenomenon, and a lack of recognition of gas problems at Belle Isle - despite a long-standing understanding that positioning mine openings in salt structures that entrained high-pressure gases could trigger outbursts of noteworthy size at Belle Isle and neighboring salt mines.
Historical Summary of Mine Disasters in the United States - Volume III