For many residents of Pennsylvania, hearing of sinkholes being talked about is not an unusual thing. It is very common to see frequent news stories of sinkholes opening up out of nowhere and swallowing homes and cars. 

Pennsylvania is one of the biggest hotbeds in the United States for sinkhole activity. Along with Florida and Tennessee, PA is the leader of the department of sinkhole damage. Due to sinkholes being so unpredictable, it can be difficult for homeowners and real estate agents to predict when and where they will appear, but there is some factual reasoning behind it all. 

Two factors influence the likelihood that a sinkhole will form in a given area–geology and human activity. Their formation comes down to the fact that humans have made the decision to force water to flow through pathways that nature never intended too. 

Because so much of PA has been paved over or built up, stormwater no longer flows where it is intended to, and in turn, has consequences. Pipes that carry our drinking water, runoff or steam for heating, age quickly and leak which then erodes the soil surrounding the pipes and creates large pockets or voids below the surface. Hence, why so many sinkholes form in the middle of city streets. 

The formation of Sinkholes by geology has a completely different process though. Limestone is a very prominent rock in Pennsylvania, and since it is not very durable or resistant to erosion, it experiences a chemical reaction when it comes into contact with the slightest amount of acid in water. When the water reacts to the carbon-based limestone rock, it will emit carbon dioxide and in the process will take away a small part of the solid rock with it. When combining that with acid rain and contaminated water, it is clear why sinkholes are such a problem in areas where there is underlying limestone.

Although there is no one true way to predict with 100% accuracy whether or not a sinkhole will develop under your house or in your backyard, previous geologic studies and past damage reports will give a better idea of how much risk you may be taking on.