In a February 9 filing with the US Securities and Exchange Commission, Cliffs Natural Resources confirmed its Oak Grove Resources subsidiary received the order from the US Mine Safety and Health Administration for elevated methane and decreased oxygen levels at the Oak Grove mine.

“An existing ventilation line curtain was being adjusted at the time of the order,” it said of the condition recorded on February 7.

“These adjustments lowered the methane readings to an acceptable level within minutes, and resulted in the termination of the MSHA order.”

Cliffs said no accidents or injuries occurred as a result of the condition, and no material adverse impacts on its operations are expected.

Alliance Resource Partners confirmed in its own SEC filing that the Tunnel Ridge mine in northern West Virginia also received an imminent danger order from federal officials on February 4.

“As Tunnel Ridge was in the process of a shift change, an MSHA inspector reported detecting elevated methane levels at the face of an idle entry on the working section,” the company said.

“A roof bolting machine was parked in the idle entry, but had been de-energized prior to the order’s issuance as part of Tunnel Ridge's shift change practices and procedures. Tunnel Ridge adjusted ventilation controls within the idle entry and any existing methane was diluted.”

The order was terminated one hour after it was issued, and Alliance confirmed no miners were injured as a result of the alleged condition.

“Tunnel Ridge is presently reviewing the matter to determine if it will seek judicial review of MSHA's decision to issue the imminent danger order,” the operator said.

Imminent danger orders are issued by MSHA under section 107(a) of the Federal Mine Safety and Health Act, also known as the Mine Act.

Section 1503 of the Dodd-Frank Wall Street and Consumer Protection Act, amended last July, now requires disclosure of all imminent danger incidents as part of new reporting requirements regarding mine safety.