West Virginia The miners union Thursday blamed last year's deadly Sago Mine explosion on friction between rocks and a metal roof-support system, rather than lightning.
The United Mine Workers report said the chance that lightning caused the methane gas blast is "so remote as to be practically impossible."
The union's report differs from the conclusions of state investigators and the mine's owner that a lightning strike somehow traveled two miles and ignited gas that had accumulated naturally in a mined-out and sealed-off area. A third report, by a former federal Mine Safety and Health Administration chief and special adviser to Gov. Joe Manchin, said lightning could not be ruled out.
The January 2006 explosion killed one miner and left 12 others trapped underground for more than 40 hours. By the time rescuers reached them, carbon monoxide poisoning had killed all but one of the remaining men.