The report was released Friday by the US Mine Safety and Health Administration.

According to the report, carbon monoxide alarms sounded at the Raleigh County, West Virginia operation at 3.02pm, April 5. The agency said it believed this was also the time of the explosion that killed 29 and left two hospitalized.

“Initial reports indicate that the explosion was massive,” investigators said, and noted that miners in other locations reported strong currents of air as far away as five miles from the most likely explosion site.

MSHA said its initial mine rescue team reports have reflected the most extensive damage was located in and around the active working sections, including severe equipment damage.

“Every miner working in this area was believed to have been killed instantly,” the agency said in the report as it looked to the dangerous mixture of gas and coal dust as a potential cause.

“While the cause of this specific explosion is still being determined, most mine explosions are caused by the combustion of accumulations of methane, combined with combustible coal dust mixed with air,” investigators said.

“Historically, blasts of this magnitude have involved propagation from coal dust. When methane and coal dust levels are controlled, explosions from these sources can be prevented.”

MSHA said that some prevention techniques include methane drainage, methane concentration reduction through adequate ventilation.

Other methods include sufficient rock dust to counter coal dust’s explosive potential, the elimination of ignition sources such as electrical equipment, and the suppression of propagation through barriers.

MSHA reviews Massey’s ‘non-compliance’

MSHA investigators also noted in the preliminary report that the Upper Big Branch operation saw a “marked spike” in its citation numbers for what the agency called an “alarming increase” in the operation’s federal law violations.

“Those violations included an alarming increase in the kinds of serious problems that required miners to be removed from portions of the mine,” the agency said, noting that it warned the operation in December 2007 that it would be placed into pattern of violation (POV) status if it did not reduce its significant and substantial violations.

“This status would have given MSHA a powerful enforcement tool, enabling it to put the mine under more intensive supervision and order the withdrawal of miners from an area with any S&S violation until that violation was fixed.

“However, the mine then reduced its levels of serious violations in a successful effort to avoid being placed into that status.”

UBB has another significant violation spike in 2009, when it issued 515 violations and orders. To date in 2010, the mine has received 124. Fines equaling nearly $US1.1 million have been assessed, but most are being contested by the operator.

“The citations MSHA has issued at Upper Big Branch have not only been more numerous than average, they have also been more serious,” investigators revealed.

“Over 39 per cent of citations issued at Upper Big Branch in 2009 were for S&S violations. In some prior years, the S&S rate at Upper Big Branch has been 10-12 per cent higher than the national average.”

The agency said it is probably most alarmed by the fact that Upper Big Branch was issued 48 federal withdrawal orders in 2009 for repeated significant and substantial violations.

“Massey failed to address these violations over and over again until a federal mine inspector ordered it done,” investigators noted in the report.

“The mine’s rate for these kinds of violations is nearly 19 times the national rate.”

Federal officials have made the preliminary report available in its entirety on the MSHA website.

UBB names released

The West Virginia Medical Examiner’s Office released the names of all 29 miners lost in the April 5 explosion at Upper Big Branch late last week. They include:

• Cory Davis, 20
• Adam Keith Morgan, 21
• Jason Atkins, 25
• Joshua S Napper, 25
• Nicholas Darrell McCroskey, 26
• Ronald Lee Maynor, 31
• Dillard Earl Persinger, 32
• Christopher Bell, 33
• Gary Quarles, 33
• Steven Harrah, 40
• Robert Clark, 41
• Richard K Lane, 45
• Gregory Steven Brock, 47
• Edward Dean Jones, 50
• Rex L Mullins, 50
• James E Mooney, 50
• Ricky Workman, 50
• Charles Timothy Davis, 51
• Carl Acord, 52
• Kenneth Allan Chapman, 53
• Howard D Payne, 53
• William I Griffith, 54
• Joel R Price, 55
• Michael Lee Elswick, 56
• Joe Marcum, 57
• Grover Dale Skeens, 57
• Deward Scott, 58
• William Roosevelt Lynch, 59
• Benny Willingham, 61