The agency said Wednesday that all of the mines have histories indicating a significant number of violations and/or conditions that may include methane accumulation problems, ventilation practice issues, rock dust application concerns or inadequate mine examinations.

“The purpose of these inspections is to provide assurance that no imminent dangers, explosions, hazards or other serious health or safety conditions and practices are present at these mines,” MSHA assistant secretary for coal mine safety and health Joe Main said.

“Just last week, we pledged to the president that we will do whatever it takes to make sure another tragedy like the one that claimed 29 miners’ lives at Upper Big Branch never happens again.”

Targeted were operations in 10 states: West Virginia (23 mines), Kentucky (14), Alabama (4), Illinois (3), Utah (3), Indiana (3), Pennsylvania (2), Virginia (2), Tennessee (2) and Colorado (1).

The agency confirmed that more than 275 enforcement personnel participated in the blitz with as many as 10 inspectors sent to each of the 57 mines. Federal officials examined mechanised mining units (MMUs) at the selected mines as well as seals, belt entries and bleeder systems.

The move comes just two weeks after a directive given by Main after the Upper Big Branch explosion for all district managers overseeing US mines to increase focus on mine ventilation, rock dusting, methane monitoring and mine examinations during ongoing regular inspections.

For a table of the coal mines included in the blitz click here.