The Mine Safety and Health Administration targeted 43 mines formerly owned by Massey Energy for surprise inspections this week, as NPR's Howard Berkes reports. The mines, in Kentucky, West Virginia and Virginia, are all now owned by Alpha Natural Resources.Berkes reports that the inspection blitz was prompted by a recent incident at an Alpha mine in Wyoming County, WV. A source familiar with the inspections says they were focused on conveyor belts used to transport coal underground. The source is not authorized to discuss the inspections publicly and spoke on the condition of anonymity. A fire involving a conveyor belt in Massey's Aracoma Alma Mine [ PDF] in West Virginia in 2006 led to the deaths of two coal miners, corporate criminal charges against the company and more than $4 million in civil and criminal fines. MSHA spokeswoman Amy Louviere confirms that Wednesday's inspection blitz was prompted by a recent incident involving a burning conveyor belt at Alpha's Road Fork No. 51 mine in Wyoming County, W. Va., which was also once owned by Massey. That incident included smoke but no fire, according to NPR's source. MSHA decided to then quickly target the other former Massey mines for surprise inspections "because of the serious nature of the incident," according to Louviere.Luckily--both for the miners working in the mines and for Alpha--Louviere says there weren't any incidences as serious as that burning conveyer belt found in Wednesday's inspections. MSHA has been routinely conducting impact inspections since the explosion at Massey's Upper Big Branch Mine in April 2010 killed 29 coal miners, but Berkes notes "none have focused on so many mines owned by a single company on a single day." Read more here.