By David A. Fahrenthold
Washington Post Staff Writer
Thursday, August 12, 2010; A03
Federal regulators said Wednesday that they were more than halfway through their investigations inside West Virginia's Upper Big Branch coal mine but still need to examine more of the mine's equipment and talk to executives at mine owner Massey Energy.
Two top officials at the federal Mine Safety and Health Administration said in a conference call with reporters that they had not reached any conclusions about what caused the explosion that killed 29 miners at Upper Big Branch. The April 5 blast was the worst U.S. mining accident in 40 years.
"There has not been enough evidence and information amassed yet to make any kind of determination as to the cause of the disaster," said Joseph A. Main, who heads the agency.
But the officials disputed a theory put forward by Massey, that a huge crack in the floor of the mine may have allowed an influx of the explosive gas methane.
"Our investigators underground have not taken a picture of a 150-foot crack. What we've seen is floor-heaving," or shifts in the floor of the mine tunnel, said Kevin Stricklin, Main's subordinate. "We've not seen any massive crack that is 150" feet long.
The officials said that they had interviewed 166 people in their investigation so far -- mainly rank-and-file workers at the mine, operated by Massey subsidiary Performance Coal. They said they will begin sending subpoenas to higher-level executives for interviews in the next month.
The regulators said that they have sent specialized teams into the mine, including a "Flames and Forces" team meant to chart the path of the deadly explosion and fire. They said technicians are still testing monitors from machinery inside the mine, which were meant to detect flammable gas. Main declined to answer a question about whether any of these showed signs of tampering.
The two officials said that a pair of key areas, deep inside the mine, had not yet been studied because water had flooded the mine's chambers. Stricklin and Main said they would hold public hearings into the disaster, but declined to say when that might happen.
Main vowed to "scour the earth to determine what happened at the Upper Big Branch mine."