Swaths of Pennsylvania and many other states are honeycombed with old, unstable mines that can cause the earth to suddenly give way — a phenomenon known as 'mine subsidence' that poses a threat to people and property.
Searchers in Westmoreland County, just southeast of Pittsburgh, fear that mine subsidence led to the disappearance of a 64-year-old woman named Elizabeth Pollard. Pollard and her young granddaughter were looking for a lost cat when she went missing Monday evening. A sinkhole appeared roughly 20 feet (6 meters) from where she had parked her car, in an area above an old coal mine. The granddaughter was found safe inside the car hours later, while the search for Pollard continues.
Mine subsidence has caused billions of dollars in damage in areas of the U.S. where mining once took place. In Pennsylvania alone, coal was mined in nearly half of the state’s 67 counties, and there are at least 5,000 abandoned underground mines, leaving behind hazards that officials say can arise at any time.
The Marguerite Mine, believed to have caused the sinkhole, was last operated in 1952 by the H.C. Frick Coke Co., according to the state Department of Environmental Protection. The coal seam in the area is about 20 feet (6 meters) beneath the surface.
The state Bureau of Abandoned Mine Reclamation will examine the scene when the search concludes to determine if the sinkhole was indeed caused by mine subsidence, a spokesperson stated.
There are as many as 500,000 abandoned mines in the U.S., outnumbering those that are still active, according to the federal Mine Safety and Health Administration. Many mine owners abandoned operations when they became uneconomical, leaving behind safety hazards and pollution cleanups for public agencies to address.
Old mines pose various dangers, with hundreds of fatalities and injuries reported at abandoned mine sites nationwide between 2000 and 2013. Victims can fall into hidden shafts, get lost in underground tunnels, or succumb to poisonous gases present in many old coal mines. Mine shafts can extend hundreds of feet beneath the surface and are often unmarked.
State and federal agencies have sealed off numerous old mines, but new ones are discovered annually, and basic risk analyses have not been conducted on most abandoned mines on federal land. In addition to safety hazards, contaminated mine sites release millions of gallons of water loaded with toxic metals daily without treatment.
