A quarterly research and development magazine
What ignited the explosion that killed 12 miners the morning of Jan. 2, 2006, at the Sago Mine in West Virginia? Since the tragedy struck nearly 18 months ago, several theories have been put forward, ranging from a gas-well rupture to a roof fall to a lightning strike.
Among evidence for the lightning theory were three strikes recorded by national detection networks, along with eyewitness accounts of other strikes near the mine. The bolts struck nearly simultaneously with the explosion, registered by seismographs.
Thirteen miners were in close proximity to the underground blast when it occurred. The force of the explosion killed one, and 12 others retreated behind a curtain at the working face of the mine in an attempt to barricade themselves against the smoke and carbon monoxide. They awaited rescue, which would come too late for all but one of them.
In early November 2006, a Sandia team spent 10 days at the Sago Mine analyzing the likelihood that electric current produced by a lightning strike could transmit effects deep into the coal mine. Their findings became part of the final MSHA accident investigation report delivered to Congress on May 9, 2007.
“We never expected to discover a smoking gun,” says Sandia senior manager Larry Schneider. “However, we pursued and characterized a coupling mechanism that the team of accident investigators hadn’t previously considered — that current from a surface lightning strike can generate electromagnetic fields that can propagate through the earth, as opposed to current being driven into conductors entering the mine such as metal rails or power lines.”