The company held a press conference late last week following a briefing with the UBB family members, reviewing rock dust analyses as well as data readings and photos of the longwall’s shearer and water sprays.

“Mine Safety and Health Administration gas data readings indicate the mine experienced a massive inundation of natural gas into the mine from an external source,” Massey said.

While federal officials made claims last week that missing water sprays may have played a role in the explosion, the producer said that was not a factor. It also noted that the shearer was equipped with 44 more water sprays than MSHA required.

Photos of a broken shearer bit were also shown during the agency’s conference; Massey general counsel Shane Harvey showed the same photo in Friday’s briefing but panned out to reveal the condition of other installed bits, each with carbide tips intact. According to the producer’s investigators, the bit was a lead bit on the head, and therefore would be expected to sustain greater levels of interaction with the coal and rock.

Massey has maintained for some time that there was a sizeable crack in the mine floor directly beneath the shearer, which it reiterated yesterday. That crack, Harvey noted, continues to emit natural gas today.

As for a possible ignition source that may have sparked the elevated gas, Massey is citing the shearer’s interaction with sandstone. The company also noted that, despite federal claims, UBB was well rock dusted prior to the accident.

“The area affected by the explosion shows poor rock dusting; the area affected shows good rock dusting,” Harvey told the conference attendees, countering MSHA’s claims.

“We think the difference is the explosion.”

Harvey also noted that, like MSHA’s assessment of conditions and the timeline of events leading up to the blast, Massey’s evaluation was preliminary. He confirmed that the company would probably not release its report until the state and federal investigations had been released.

The US coal industry reported 48 deaths in 2010; 29 of those were in the Upper Big Branch explosion.