PHILADELPHIA - While the Quecreek mining accident gave Pennsylvanias an edge-of-the-seat introduction to the problem of flooded old coal mines, few are aware of a far more serious menace beneath their feet: fire.
There is Centralia, of course, the luckless Columbia County town that has been slowly incinerated over the last 40 years. But 48 other coal fires - the legacy of two centuries of primitive mining practices - are known to be burning under 1,200 acres across Pennsylvania, more than in any other state.
Several threaten small communities. Others are approaching gas wells, gas lines, and even Pittsburgh International Airport. All are devilishly stubborn, with the largest ones virtually impossible to extinguish.
"These coal fires are like animals: They live in holes, hide from predators like us, and want to eat all the time," said David Philbin, a federal mining engineer who has grappled with several burning mines in the state.
The scenes above ground do not approach the drama of Centralia, where steam pours from bleached tree stumps and the earth is so hot in spots that only lichen grows. Experts worry, however, that disaster - in the form of not only fire, but also toxic pollutants and major cave-ins - could surface at any site.
In Plum, a Pittsburgh suburb, a mine fire has come within 800 feet of natural gas wells on the edge of a public park. Last month, the state began a yearlong, $1.2 million effort to dig out all the burning coal, an estimated 367,000 cubic yards.
In Fayette County, bordering West Virginia, the villages of Youngstown and Percy sit on opposite sides of a fire that has defied many attempts since the 1960s to control it. Fearing coal gas poisoning, the federal government has put carbon monoxide detectors in all 60 homes.
And on the outskirts of Carbondale, 15 miles from Scranton, a mine fire moving faster than Centralia's forced federal engineers two years ago into a costly emergency effort to cut it off. They still monitor the site for a week each month, unsure that the fire is truly contained.
Burning mines such as these threaten more than the people and buildings above them. Scientists are increasingly alarmed that the fires - particularly the huge ones raging in China and India - are spewing so much carbon dioxide that they have become significant contributors to global warming.
They are "a global catastrophe," said Glenn Stracher, a Georgia geologist who is organizing an international symposium on the fires' environmental impact. "We have noxious gases being pumped into the atmosphere at an alarming rate all over the world - Pennsylvania, China, India - and most people, including most scientists, aren't aware of it."
State officials concede they know little about what the fires are doing to Pennsylvania and Pennsylvanians.
"We don't know how bad these things are" for the environment, said Steve Jones, chief of the state Division of Mine Hazards. "I wish we had the time and resources [to] take a typical coal fire and figure out how much carbon dioxide, carbon monoxide, sulfur dioxide it generates in a year."
The state, however, does not have the money to fight the fires, let alone study them. By federal estimates, it would cost $594 million to merely control all of Pennsylvania's fires, and far more to extinguish them.
The state gets about $40 million a year from a federal fund supported by industry fees. The money is supposed to cover all abandoned mine problems.
Only a fraction is spent on the fires - enough to pay for regular checkups on just 10, along with occasional attempts at containment.
Even when well-funded, mine firefighting is uncertain business. Fires that are presumed dead can smolder for decades, then roar back to life.
"The coal is layered like a sandwich. One layer may be connected to another, and the heat in one burning layer can ignite another," said Anupma Prakash, a geologist with the University of Alaska at Fairbanks and one of the world's premier experts on mine fires. "It's difficult to assess at what layer the coal is burning."
At the bottom of the trouble is Pennsylvania's long tradition of scandalous mining practices.
"The older collieries couldn't care less about safety when they shut down," said Philbin, the engineer for the federal Office of Surface Mining. "There wasn't much law, and the laws that did exist weren't enforced."
Miners worked coal seams by carving out rooms supported by pillars of coal left behind. When mines were abandoned but not sealed, oxygen could enter and flow freely in the tunnels - ideal conditions for intense fire.
All it took was a spark. That was provided almost exclusively by burning rubbish dumped into the unsealed mines by individuals and municipalities.
That is how Youngstown and Percy, straddling three old mines, got into trouble in the late 1960s.
Fighting the fire
By 1983, with the fire moving toward homes, engineers cut out 7 acres, 130 feet deep, and slapped clay around the excavation to block airflow. The fire lived on. By 1996, it was not only menacing homes but also three large gas lines.
This time, holes were drilled into the mine, and a goopy mix of fly ash and cement pumped in. The fire was left to burn on the other side of the barrier.
"We think the fire is pretty innocuous now. It's quiet near the town, at least. We monitor it closely," said Jones, of the Division of Mine Hazards.
Residents are skeptical.
"So we've got a hot mine fire on one side of town, huge gas lines on the other, and we're not supposed to live in fear?" asked Lois Minnick, who has two government-supplied carbon monoxide monitors in her Youngstown home because it is less than 200 feet from the barrier.
Another major danger is subsidence. Burned-out mines often collapse, creating cave-ins.
In the longer term, experts say, exposure to pollutants released from the fires could increase the risk of skin or lung cancer for people living nearby.
"Depending on wind direction, any population within a modest distance has the potential to be exposed to sulfuric acid or trace elements like mercury," said Robert Finkelman, a research scientist for the U.S. Geological Survey.
He also has found a "wonderful array of lead minerals, arsenic minerals" where coal fires vent, and these, he said, can easily wash into waterways.
Mindful of the risks, Minnick and her Youngstown neighbors want out. But those who have tried to sell homes say the fire has devastated property values.
As frightening as Pennsylvania's burning mines may be to those living nearby, they are no match for the conflagrations in Asian coalfields, where low-grade coal is prone to spontaneous combustion.
In northern China, "there is a stretch running 5,000 kilometers [3,125 miles] east to west and 700 kilometers [438 miles] north to south where fires are burning all around," said Prakash, who is tracking them via heat-sensing satellites.
Her colleagues estimate that the Chinese fires alone consume as much as 200 million tons of coal annually. That would account for 2 percent to 3 percent of the carbon dioxide emitted globally each year - roughly the same, she said, as that of all passenger vehicles in the United States.
Although less damaging to the global environment, fires in India's Jharia coalfield are no less of a spectacle.
"At night it's like a battlefield. Flames are coming right out of the ground, steam is pouring out," said Stanley Michalski, a geologist with GAI Consultants, a Pittsburgh firm hired by the World Bank to study the fires.
Still, when shown photos of those infernos, Lois Minnick is not awed. She is instead reminded of the time engineers tore into the core of the Youngstown fire and exposed it for all to see.
"Our fire was just as bad, just as big," she said. "They covered it back up. But it's still there, under the ground."