Updated

A larger-than-usual joint federal and state investigation into the mining accident that jeopardized the lives of nine men will focus on how mining permits are issued in Pennsylvania and how old mining maps are evaluated, officials said Sunday.

Pennsylvania's Bureau of Deep Mine Safety and the federal Mine Safety and Health Administration in Washington were planning to announce the enhanced investigation in the next week, said David Hess, secretary of the state Department of Environmental Protection.

He promised something "clearly more than an accident investigation," which was needed because "it was huge high-profile accident with some very complex issues." He said, however, the probe would not be focused on assigning blame.

"This is an accident, pure and simple," Hess said. "What you do with an accident is you learn from them."

Hess said it was important to learn exactly how the men became trapped 240 feet beneath the ground when water from a mine that was not supposed to be so close to them spilled in.

"Those guys didn't deliberately poke a hole in that mine and we certainly didn't want to issue a permit that didn't meet our minimum 200-foot separation requirement between mines," he said.

Hess said the probe would focus on the mining permit process, how old maps are evaluated and safety issues.

Old, sometimes faulty, maps are an important focus, especially since 10,000 or so mine maps are archived by the state, some of them so crude that they are hand-drawn and some made more than 100 years ago.

"The older they are, the more inaccurate they can be," he said.

But Hess cautioned that it was "not just a map issue," since proper procedures can help prevent accidents. For instance, he said, miners can drill small holes ahead of them to make sure they are not about to flood themselves.

Richard Stickler, the state's director of the Bureau of Deep Mine Safety, said any changes would have to be carefully thought out.

"You have to look at what's practical," he said Sunday, noting that drilling ahead can slow miners substantially. "There's a lot of issues. It's not a simple solution."

Stickler said he will begin the investigation into the Somerset accident "like every investigation, with a look at the root cause of the accident, leading you to remedies."

He said the state has many measures in place to prevent the kind of accident that risked nine lives, and authorities will have to learn if they were followed.

For instance, he noted that the mining company was required to have someone certify that the maps of the mines were accurate.

"The maps are going to be a major issue," he said.

The map of the adjacent mine assured that there was no threat to the miners, but Stickler said no mining had occurred there since the 1950s.