Farm Progress

With more than 1 million homes plus other buildings at risk, Pennsylvania DEP urges checking new maps for subsidence risks.

April 27, 2017

2 Min Read
UNDERMINED? Cracks like this in buildings may be due to ground subsidence, not foundation failure.France68/iStock/Thinkstock

Coal mine subsidence is nothing new in Pennsylvania. Many farm homes and buildings have been damaged or lost to it.

Pennsylvania Department of Environmental Protection recently urged checking updated mine maps to determine if your home or other buildings are at risk of mine subsidence. That goes for farms, too, especially if you’re building new structures.

More than 1 million homes in the Keystone State sit atop abandoned mines, according to John Stefanko, deputy secretary of active and abandoned mine operations. “If you’ve checked before and think your property is not at risk, now is the time to check again,” he adds. “We’ve revamped the maps on the Mine Subsidence Insurance website for a more interactive and precise view.”

Mine subsidence occurs when the ground above an old or abandoned mine cavity collapses. A subsidence event can occur at any time and cause sudden, significant damage — often exceeding $100,000 or total loss of the structure. 

Better map data
Mine subsidence is not covered by standard insurance policies. DEP administers low-cost mine subsidence insurance (MSI) coverage through the Commonwealth of Pennsylvania. The average policy of $160,000 costs about $7 a month; senior citizens are eligible for discounted rates.

Using geographic information systems online, DEP combines GIS data with mining data to show where specific properties are in relation to old and abandoned mines. DEP’s MSI program uses the data to identify coverage areas. DEP has completed the process for thousands of maps with thousands more to be entered. The website regularly updates as historical maps and risk areas are discovered. 

Much of the underground mining in Pennsylvania occurred more than a century ago. Many areas that were mined long ago have been mined again. Consequently, the department may have hundreds of maps and a dozen different series for just one area. 

“DEP is continuously improving our maps and data for underground mining. That’s why we recommend property owners need to check back periodically,” says Stefanko. “Our goal is to have the best underground mine mapping easily accessible to anyone who wants to view it.” 

Visit or call 800-922-1678 to check if your home or property is over an abandoned mine, or for more on the Mine Subsidence Insurance Program.

Source: Pennsylvania DEP

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