Despite technological innovations and regulations which have made the industry much more safe than it once was, mining is still inherently dangerous.

For every 100,000 mine workers, 30 died in 2000 — the highest rate of any industry and about seven times the rate of other industries, according to the U.S. Department of Labor.

One of the leading dangers is inaccurate maps or no maps at all documenting the location of old mines, mine experts say.

"Mines in general have become safer over the years from hazards such as explosions (and) coal dust, but there are problems when you have very old mines and abandoned mines and the maps are not in the best of shape or nonexistent," said Raja Ramani, a mining engineer and professor emeritus of mining engineering at Penn State University.

Without accurate maps, miners can come too close to old mines, causing an "inundation" — a sudden inrush of water or gas, Ramani said.

That may have been what happened Wednesday night at Quecreek Mine.

The Department of Environmental Protection, which issues mining permits, requires 200 feet of solid rock between mines. The miners at Quecreek thought they had about 300 feet, said David Hess, DEP secretary. Millions of gallons flooded the mine, trapping nine workers.

"The mine maps we were relying on were apparently wrong. But there will be an investigation into that," Hess said.

"Pennsylvania has a 100 year history of mining and those maps are not 100 percent accurate," Hess said. Still, he said, "Pennsylvania probably has the best collection of old mine maps, bar none."

Mapping problems are more common with mines 30 years and older, Ramani said.

"By 1970, people realized we have to have maps and we have to have an inventory of maps" with government agencies, Ramani said.

Rodney Brown, a spokesman with the federal Mine Safety and Health Administration, said improved government regulations have led to safer mines. In the early 1900s, he said, it wasn't uncommon for more than 3,000 people die annually in mines.

Safety regulations often followed tragedy.

"It's been these disasters. That really is what prompts the passage of regulations and laws," said Mark Radomsky, director of field services for Penn State's Miner Training Program.

Fatal collapses in the United States are generally rare nowadays, Radomsky said, attributing that to improved regulations and safety training.

Joseph Main, health and safety administrator for the United Mine Workers of America, said the 1969 mine act, triggered by a disaster in Farmington, W.Va., which killed 78 people, had a dramatic impact on safety. It establish rigid safety standards which were backed up by enforcement and stiff penalties.

Besides the danger of the unforeseen, there is also a human element to safety.

"Safety's a struggle because you're dealing with human nature, you're dealing with people who are tempted to take shortcuts. That's the human way, which may not be the safest," Radomsky said.

"You are dealing with an environment that is not a natural environment" for people, Raja said. Mining is often done hundreds of feet underground in confined, dusty and watery locations.

A decrease in the number of miners also plays a role in safety.

There are about 75,000 coal miners working today; in 1902, there were 489,000 coal miners, said UMWA spokesman Pete McCall. According to the Mine Safety and Health Administration, there are 350,000 people working in all types of mining.

At the same time, productivity has about tripled, from 302 million tons of coal extracted in 1902 to 1.1 billion tons mined in 2000, McCall said.

Ramani said the United States is the most productive country.

Over the last 11 years, 59 miners have been killed in Pennsylvania, according to the Mine Safety and Health Administration.

The last miner killed in Pennsylvania was George Shirley, who was apparently electrocuted by a loading machine on May 11 in the Eighty Four Mine in Washington County.

Pennsylvania's worst mining disaster was the Dec. 19, 1907, explosion at the Darr Coal mine near Van Meter, Westmoreland County, that killed 239 miners.

The nation's worst United States mine disaster occurred in Dec. 6, 1907, when 361 to 370 miners were killed as electrical sparks apparently ignited an explosion in a network of coal mines at Monongah, W.Va.

The world's worst mining disaster was the Apr. 25, 1942 coal mine explosion that killed 1,549 workers in the region of China formerly known as Manchuria.