The coal is mined by machines that run underground by themselves. The machines leave the tunnels they make to collapse in their wake, causing severe incidences of subsidence on the surface. Water supplies to farms and homes have been disrupted, and the ground cracks open suddenly, causing damage to roads, houses and other buildings.

All this, because private citizens own the rights to the surface, but the mining companies optioned the underground mineral rights long ago. No one anticipated the invention of the underground mining machines that allow a large area to be mined with only limited entry and exit holes and no shaft structure necessary to protect human workers. It's as if Shylock had discovered how to take his pound of flesh without shedding any blood.

The communities in western PA are reluctant to make a big deal about this because the local economy benefits. The people whose property is damaged are understandably upset, and it takes a long time to get their concerns addressed by the mining companies, even though there are agreements in place. This Pittsburgh Post-Gazette article from 2000 outlines the problem. It's still going on. We hear about it every once in a while when someone gets fed up and sues.

Aside to Jody: It would be a really good idea to find out what the compensation arrangements are in case your mother's property is compromised by gas mining activities, and what government agencies are responsible for enforcement. The squeaky wheel that's prepared to squeak for 5 years is the one that gets the grease from mining companies around here. Don't count on any proactive damage control from them.