Richard E. Stickler

The mine safety director, Richard E. Stickler, defended his agency’s approval of “retreat” mining at Crandall Canyon. In that technique, pillars of coal that hold up tunnel ceilings are extracted. Mr. Stickler said the cause of the accident was a large “bump” that occurs when mine supports are overstressed, causing cave-ins that redistribute the weight of the mountain. “Inside the mine, the force of the bump was so intense that it blew out the ventilation walls more than a half-mile from the bump area,” he said. “In my nearly 40 years of working in the mine industry, I have never seen a catastrophic mountain bump of this magnitude.”