International Coal Group said Tuesday it believes a lightning strike sparked the Jan. 2 explosion that killed 12 workers at its Sago Mine, the worst mining disaster in West Virginia in nearly 40 years.On Tuesday evening, ICG issued a news release saying the company’s internal investigation had determined “the explosion was ignited by lightning and fueled by methane that naturally accumulated in an abandoned area of the mine that had recently been sealed.”ICG said “the precise route by which the lightning electrical charge traveled from a surface strike location to the sealed area remains under investigation.“There is no obvious conduit directly from the surface, such as a borehole with a metal casing, although searches have been conducted on the surface,” the company said.“At this time ... there is no definitive evidence on how the electrical energy was conducted into the sealed area,” the company added.Federal and state inspectors have said they consider lightning a possible cause of the explosion, but that such a strike cannot be conclusively blamed for the blast until a path from the surface to underground is pinpointed.“I believe it’s premature to comment on the cause of the explosion,” Davitt McAteer, Gov. Joe Manchin’s special adviser on the Sago investigation, said Tuesday night. “We don’t know it yet.“We’re not ruling lightning out, but we’re not ruling it in, either,” McAteer said. “The fact that lightning struck is a fact, but what we don’t have, and have no way of knowing, is the path it took and the route of ignition.”Neither the state Office of Miners Health, Safety and Training nor the federal Mine Safety and Health Administration have released their reports on the cause of the Jan. 2 explosion.In its release, ICG said no members of the company’s investigation team were available Tuesday night for comment.ICG said in the release that it revealed its initial findings to the families of Sago miners Tuesday in a series of private meetings conducted at West Virginia Wesleyan College. Employees will receive briefings as they report for regular work shifts that were to begin Tuesday night. The mine is to reopen today.“While our independent investigation is certainly not the final word on the explosion, we are confident that the joint federal-state investigation will reach a similar conclusion,” ICG President Ben Hatfield said in the release.“We hope that the announcement of our preliminary findings as to the cause of the explosion will provide meaningful information to the families and our employees and will answer many of their lingering questions,” he said.The explosion trapped 13 men more than 250 feet underground for more than 40 hours. By the time rescue teams reached them, all but one had perished, most slowly succumbing to carbon monoxide poisoning.Survivor Randal L. McCloy Jr., who is still recovering from severe brain damage and other injuries, visited his Taylor County home Tuesday for the first time since the explosion.In its news release, ICG noted previously reported information that there were three powerful lightning strikes near the mine site just before the time the explosion is believed to have occurred.“All evidence gathered to this point indicates that the ignition occurred due to lightning,” ICG said in a three-page briefing on its investigation.ICG said it believes investigators have ruled out other possible ignition sources for methane accumulated in the sealed area, including roof falls and electrical equipment.“At the location where the ignition is thought to have begun, there are several unusual streaks across the roof on either side of a coal pillar,” the company said. “The streaks across the roof appear to have an associated increase in magnetism, which would suggest the passage of electrical energy across or through the rock.”ICG said that testing of these “unusual features” has not been completed to determine if it was created by the passage of electrical energy from lightning.In a May 2001 report, the National Institute for Occupational Safety and Health studied the issue of lightning strikes triggering mine explosions.NIOSH experts examined the matter following a series of seven explosions over a six-year period in the 1990s. All of those explosions occurred within worked-out, sealed areas — called gobs — of underground mines, according to the NIOSH report.Three of them occurred in one mine in Alabama over a three-year period, according to the report. In its own report on the third of those Alabama blasts, in July 1997, MSHA said the exact “path [of the lightning charge] into the sealed area is undefined.”MSHA recommended “pressure-balancing” the sealed area by removing a water pressure differential to make the air in the sealed area inert.“An inert atmosphere will be unaffected by lightning,” said the MSHA report on the explosion at U.S. Steel Mining’s Oak Grove Mine in Jefferson County, Ala. No one was injured in the Alabama blast.In its report, NIOSH said if lightning is the ignition source, explosions can be prevented by eliminating flammable concentrations of methane or other fuels or reduce the volume of the flammable mixture present in the sealed area.To contact staff writer Ken Ward Jr., use e-mail or call 348-1702.