CHARLESTON, W.Va. -- Federal investigators on Wednesday disputed Massey Energy's description of the size of a crack in the Upper Big Branch Mine's floor, but said they continue to closely examine possible connections between floor fracturing and the April 5 explosion that killed 29 miners.
U.S. Mine Safety and Health Administration officials also disclosed that they have not been able to locate records that describe what preventative steps -- if any -- Massey or MSHA eventually took after a pair of "methane outbursts" from the Upper Big Branch floor in 2003 and 2004.
Kevin Stricklin, MSHA's coal administrator, said agency officials have searched their files and put in a request for potentially relevant documents from government archives, but so far haven't turned up anything.
"We just don't have any information on that yet," Stricklin said in an interview with The Charleston Gazette.
Stricklin discussed the issue in more detail following a telephone news conference in which he and MSHA chief Joe Main updated the media on the ongoing investigation. The news event was scheduled to follow a closed-door meeting Tuesday evening with the disaster victims' families.
Main said investigators had interviewed 166 witnesses, collected 250 pieces of evidence and taken more than 1,800 samples from the Raleigh County mine. Main estimated the probe is about halfway done and emphasized that large portions of the mine, including two active mining sections, have not been examined by the investigation team, making it far too early to draw any serious conclusions about the disaster's cause.
Investigators have begun issuing subpoenas for all future witnesses and are starting to move up to higher level mine managers and Massey corporate officials.
"We are going to scour the Earth to determine what happened at the Upper Big Branch Mine," Main said.
Main said investigators have found eight hand-held methane detectors, along with two methane monitors from the mine's longwall mining section, but said it is far too soon to know if any of the safety equipment was tampered with or malfunctioned.
MSHA officials also confirmed that two executives from Massey's Performance Coal Co. subsidiary were discovered inside the Upper Big Branch Mine after the explosion, but before MSHA took control of access to the operation.
It's not clear what the two men were doing, though Stricklin said mine employees often rush underground after an accident to try to find survivors. Stricklin did not name the two men, but said they did not have mine rescue training and "had no reason to be underground."
Main and Stricklin responded to Massey's theory that the disaster may have been caused by a flood of methane gas from a massive floor crack, an occurrence Massey has suggested it could do nothing to prevent.
During their telephone news conference, Main and Stricklin said family members reported that Massey had told them during a private meeting last week that investigators had found a 100- to 150-foot long crack in mine floor.
But Main said, "I have seen nothing to represent a crack that large, nor have I talked to anybody who has."
Stricklin said investigators have seen floor "heaving," smaller cracks mixed with heaped up rock and earth. Heaving is typically caused by the shifting of ground pressures during highly mechanized longwall mining, and can release methane from coal seams and geologic formations below.