Mine Explosion Cause Still Unknown

Federal mining officials say it’s still too soon to say what caused the worst U.S. mining disaster in several decades where 29 miners died.

Federal Mine Safety and Health Administration chief Joe Main said Wednesday that investigators are still collecting information, but they have yet to reach all parts of the Upper Big Branch mine in Raleigh County.

MSHA coal administrator Kevin Stricklin says about half of the Massey Energy mine has been searched, but teams have yet to reach its deepest parts.

Main says teams have found no evidence yet to confirm Virginia-based Massey’s claim that a large crack in the mine floor may have released a sudden rush of explosive methane gases.

Main says investigators also are issuing subpoenas for witness interviews.