By MICHAEL RUBINKAM and MATTHEW BROWN Associated Press
Large parts of Pennsylvania and many other states are littered with old, unstable mines that could cause the earth to suddenly give way, threatening people and property.
That’s what fear led searchers in Westmoreland County, just southeast of Pittsburgh, to the disappearance of 64-year-old Elizabeth Pollard. Pollard and a young granddaughter were looking for a lost cat when she went missing Monday evening. About the same time, a sinkhole appeared about twenty feet from where she had parked her car, in an area above an old coal mine. The granddaughter was found safe in the car hours later.
On Tuesday, December 3, 2024, the Pennsylvania State Police image shows the top of a sinkhole in the village of Marguerite, Pennsylvania, where rescuers were searching for a missing woman. (Pennsylvania State Police via AP)AP
The search for Pollard turned from a rescue to a recovery operation Wednesday as authorities said they did not expect to find her alive.
Mine subsidence has caused billions of dollars in damage in the US. In Pennsylvania, where mining dates back to the late 1700s, coal has been mined in nearly half of the state’s 67 counties and there are at least 5,000 abandoned underground mines, which officials say poses dangers that could arise at any time .
There are as many as 500,000 abandoned mines nationwide — far more than those still active, according to the federal Mine Safety and Health Administration. They are scattered across the landscape of coal country and the vast western states where mining was common. People have died falling for it, and some murderers have tried too hiding the bodies of victims by dumping them in open mine shafts.
The sinkhole in Westmoreland County appears to be the result of a catastrophic collapse, indicating that the roof of an old mine suddenly gave way after years of sagging, said professor Paul Santi of the Colorado School of Mines Geology Department.
“For example, if the temperature drops half a centimeter per year, you can use satellite information to detect that and monitor whether it gets worse or not,” says Santi. “But you can also have very fast things that are more difficult to predict. That is what happened in this case. You have a roof that collapses and overnight a sinkhole forms.”
The Marguerite mine that authorities say led to the sinkhole was last operated in 1952 by the HC Frick Coke Co., according to the Department of Environmental Protection. The coal seam in the area is about 6 meters below the surface.
That’s relatively shallow, which increases the chance of a sudden collapse in areas where the coal had been removed, leaving a void likely filled with air, water or debris that had washed up over time, Santi said.
The sinkhole that emerged was shaped like a teardrop, Santi said, with a small opening above a larger cavern. If the mine collapse had been deeper, it would have been cone-shaped and the disturbance would have taken longer to reach the surface, he added.
Some mines used supports such as steel arches to prevent collapses. Others left coal pillars in place to support the roof, but these don’t always prevent it from settling over time.
The state Office of Abandoned Mine Reclamation will examine the site when the search is completed to see if the sinkhole was indeed caused by subsidence of the mine, spokesman Neil Shader said.
Old mines pose numerous dangersAccording to the U.S. Bureau of Land Management, there were 381 deaths and 152 injuries nationwide between 2000 and 2013.
In many cases, the owners simply abandoned the coal or precious metal mines when their operation became unprofitable and declared bankruptcy, leaving safety risks and costly costs. cleaning up pollution that government agencies have to deal with.
Victims can drown in flooded shafts, get lost in underground tunnels or die from toxic gases present in many old coal mines. Mine shafts can extend hundreds of meters below the surface and are often unmarked.
State and federal agencies have closed many old mines. But more are discovered every year, and officials have yet to conduct basic risk assessments at most abandoned mines on federal land.
Land subsidence is a widespread phenomenon, including: recent sinkhole in a neighborhood north of Rapid City, South Dakota, near where Santi grew up.
“It’s part of population pressure,” he said. “We just have to do our best to map them and then make sure people avoid building on them – or at least know if they are deep enough that it won’t be a problem for sinkholes,” he said.
In addition to the safety risks, millions of gallons of water laden with arsenic, lead and other toxic metals flow from contaminated mine sites every day without being treated.
Pennsylvania’s Abandoned Mines Agency has responded to 75 subsidence this year, and 578 since 2017, said Lauren Camarda of the state Department of Environmental Protection.
Land subsidence has long been a threat to homeowners in the state’s historic coal areas, so much so that Pennsylvania began offering mine subsidence insurance in 1961 to cover damage to homes or buildings. There are currently more than 62,000 such policies in force, and the program has paid out on more than 2,200 claims.
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Rubinkam reported from northeastern Pennsylvania and Brown from Billings, Montana.