Federal mine safety officials say they will digitally reconstruct the Jan. 2 explosion at West Virginia's Sago mine to determine the force that destroyed 10 seals blocking off an abandoned portion.

The explosion killed one miner outright and trapped 12 others. Only one of the 12, Randal McCloy Jr., survived.

With help from the Army Corps of Engineers, the Mine Safety and Health Administration will make a mathematical model of the mine, including seals, crosscuts, entries and variations in the height of the roof and floor.

"This precise modeling of the Sago mine will allow investigators to better calculate the strength of the explosive pressures needed to create the damage investigators found following the accident," MSHA officials said yesterday in a news release.

MSHA also has been overseeing a series of test blasts in the Lake Lynn Laboratory experimental mine in Fayette County, subjecting seals to different explosive forces. The third test blast is scheduled for today.

The Omega Block seals at Sago, completed about a month before the explosion, were built to withstand a force of 20 pounds per square inch, or psi.

Two weeks ago, MSHA officials announced that all new seals must be able to withstand a force of up to 50 psi, bringing the U.S. standard in line with those of most other industrialized nations.