( CNN ) -- Acting West Virginia Gov . Earl Ray Tomblin will join the families of the 29 men who perished in an explosion at the Upper Big Branch Mine a year ago Tuesday . The April 5 , 2010 , explosion was the worst mining disaster in the United States since 1972 , when 91 miners died in a fire at the Sunshine Mine in Kellogg , Idaho . The Big Branch mine -- owned by Massey Energy -- had a spotty safety record prior to last year 's explosion , with three deaths reported over the previous 12 years . Most of the blast victims were working in an area where long-wall cutting was taking place . The technique uses a large grinder to extract coal and creates large amounts of coal dust and methane gas , both of which are explosive . The remembrance ceremony will take place Tuesday in Whitesville , which is located 30 miles south of Charleston . Tomblin will be joined by other state dignitaries , his office said . Last month , Tomblin unveiled a new , specially equipped truck designed to help rescue trapped miners -- part of that state 's response to the Big Branch explosion . `` I am still saddened by the loss , '' Tomblin said at the time . `` The families of the ( Upper Big Branch ) tragedy have said , 'Do n't let this happen again . ' '' The truck is `` fully equipped to provide mine rescue teams with the tools needed to greatly improve a mine rescue operation if and when called upon in the future , '' according to the acting governor . Tomblin became West Virginia 's chief executive in November , when Gov . Joe Manchin resigned to fill the unexpired term of U.S. Sen. Robert Byrd .
The Upper Big Branch mine explosion killed 29 men . It is the worst mining disaster in the United States since 1972 . The mine had a spotty safety record . Score: 7