Authorities in western Pennsylvania are expressing concerns regarding the fate of a woman who went missing while attempting to locate her cat. It is speculated that she may have fallen into a sinkhole, a geological feature likely triggered by ground subsidence linked to previous mining activities.
Search and rescue teams have yet to receive any communication from 64-year-old Elizabeth Pollard, who vanished on Monday evening. Coinciding with her disappearance, a sinkhole emerged approximately 20 feet (6 meters) from her parked car, intensifying fears that she might have slipped into this opening. Fortunately, her granddaughter was located safely in the vehicle several hours later.
Sinkholes can occur independently of mining operations, with a notable incident in 2013 resulting in the death of a man in central Florida. This region is known for its susceptible limestone bedrock, which contributes to thousands of sinkholes forming each year.
While sinkholes are predominantly prevalent in Florida, they also cause issues in several other states, including Texas, Alabama, Missouri, Kentucky, Tennessee, and Pennsylvania. However, fatalities resulting from them are uncommon.
So, what exactly are sinkholes? A sinkhole is a ground area exhibiting no natural surface drainage, forming when the underlying ground can no longer support the weight of the surface above, according to the U.S. Geological Survey. Typically, the land maintains its structure for a while until the underground cavities grow too large, resulting in an abrupt collapse of the surface.
Sinkholes are particularly common in karst terrain, characterized by specific rock types, such as limestone, that can dissolve due to circulating groundwater. They also may develop as a result of old mines.
Florida is especially prone to sinkholes since its land sits atop extensive limestone layers. These geological formations can range widely in dimension, from a few feet across to expansive areas covering hundreds of acres. The sinkhole believed to have ensnared Pollard was roughly the size of a manhole cover when it was first identified on Tuesday.
The depths of these sinkholes can vary significantly, from just inches to more than 100 feet (30 meters). Their shapes can differ, appearing as shallow bowls or deep vertical walls, and some even form water-filled pools.
The sinkhole appearing in Marguerite, Unity Township, where search teams continue to search for Pollard, is located directly above the now-defunct Marguerite Mine, previously operated by H.C. Frick Coke Company until 1952. In this area, the Pittsburgh coal seam lies around 20 feet (6 meters) beneath the surface.
In Pennsylvania, underground coal mining has been conducted across 29 counties, with numerous regions in the southwestern part of the state vulnerable to soil subsidence due to historical mining operations.
Neil Shader, a spokesperson from the Department of Environmental Protection, mentioned that after search efforts conclude, the Bureau of Abandoned Mine Reclamation would conduct an assessment of the area to determine if mining subsidence contributed to the sinkhole’s development.
Other recent sinkhole occurrences include a significant collapse in southern Illinois this past June that swallowed part of a soccer field built on a limestone mine, fortunately with no injuries reported. In 2023, a sinkhole that had previously claimed the life of 37-year-old Jeff Bush in suburban Tampa, Florida, reopened for a third time, cordoned off by fencing to ensure public safety.
Furthermore, a large sinkhole appeared in South Dakota in 2020, discovered near a man mowing his lawn. Investigations found that a large, improperly sealed mine existed under the neighborhood, leading to a 40-foot-deep (12-meter-deep) pit alongside subsequent smaller sinkholes forming. A separate incident in southeastern Texas saw an original sinkhole absorbing oil field equipment and vehicles in 2008, which grew larger this year when additional sinkholes appeared nearby.
