In their most detailed media briefing to date, U.S. Mine Safety and Health Administration officials investigating last April's explosion at Massey Energy's Upper Big Branch Mine yesterday outlined their evidence, some of which directly contradicts Massey's explanation of the explosion.

Massey has blamed the accident on a huge, uncontrollable burst of methane, saying that the explosion overwhelmed any safety systems they could have had and that no coal dust was involved.

But MSHA said yesterday that they found no evidence of a major explosion in the part of the mine where Massey has said a large floor crack let the huge influx of methane into the mine. Instead, MSHA investigators believe that a smaller ignition of methane expanded through the mine by a trail of coal dust. They said mine operators ignored repeated warnings from workers that more crushed stone needed to be spread to prevent coal dust, which had built up along miles of underground tunnels, from providing fuel for an explosion.

Additionally, MSHA officials described worn-out mining bits on a machine that exposed steel shafts that could easily spark when they hit a piece of rock embedded in the coal seam, and said water sprays were missing or not working, leaving miners without an important protection from methane ignitions.

Investigators told families that their witness interviews are essentially completed and a report will be issued in 60 to 90 days (Ken Ward Jr., Charleston [W.Va.] Gazette, Jan. 19). -- AS