In a conference Wednesday, MSHA officials provided an update on progress of the ongoing investigation into the accident at the Raleigh County complex.

MSHA said teams evaluating the incident had found no evidence of a “huge floor crack” which could have inundated the mine with methane, a claim MSHA said has been made by Massey.

While federal officials said the investigators have found evidence of heaving in the floor and several small cracks, these measured about six inches deep and eight inches wide.

“We've not seen any massive crack that's 150 feet long underneath the shearing machine," MSHA coal administrator Kevin Stricklin said.

MSHA said Massey had suggested that a large crack under the shearer could have permitted the explosive gas to enter the area just before the April 5 explosion, and had reported similar inundations in 2003 and 2004.

However, MSHA said that mine safety officials with the state of West Virginia had found no sudden methane jumps in its review of preliminary data from UBB.

Massey maintained its stance Wednesday, pointing out that MSHA records confirm the floor crack.

The producer also released a collection of five photographs from the mine which it said were taken by federal investigators, along with a photography log.

Three of the images have a note by MSHA commenting “looking into crack in the floor” and have a date record of July 14 at approximately 11.17am local time.

All of the images were taken at the longwall tailgate, the record also states.

“Records and pictures taken by MSHA’s own officials confirm the presence of a crack in the UBB mine floor,” Massey vice-president and general counsel Shane Harvey said.

“MSHA officials are the only personnel permitted to take photographs and collect evidence from the UBB mine and their own documentation indicates that there is a crack on the longwall tailgate.

“The crack, along with other potential sources in the mine, need to be fully examined by company, federal and state investigators as they continue the ongoing probe into the UBB mine accident.”

Massey also noted that the images were shared with the family members of those killed at UBB prior to their public release.