Geologic Hazards of Pennsylvania

Most people would agree that the Latin term terra firma (meaning “solid earth”) applies to Pennsylvania.

Yet there are many Pennsylvanians who could point to events that have shaken foundations -- literally.

• Earthquakes -- although rarely felt in Pennsylvania, over the years, a few earthquakes have caused minor damage to structures
• Landslides -- whether caused by changes in the weather or land interference by man, houses and roads are no match for thousands of tons of rock and debris seeking its own equilibrium
• Sinkholes -- most common in areas underlain by limestone, sinkholes can impact roadways and buildings, and disrupt utility services

There are other hazards in Pennsylvania that have a geologic component:

• Radon -- a gas derived from the decay of uranium, which is found in many rocks and soils, radon is the second leading cause of lung cancer in the United States
• Carbon dioxide and methane -- subsurface migration of these gases are of particular concern in areas where coal and petroleum resources underlie the land surface
• Floods -- a well-known danger in our state, floods are influenced mainly by precipitation, topography, and surface materials
• Mine collapse -- an underground mine collapse can cause subsidence of the overlying land surface