This is actually an industry article from Schlumberger which discusses research by Russian scientists which proves a connection between earthquakes and gas drilling activity.
Given this information, I'd like to pose a question: in the event of earthquakes, what happens to the integrity of the concrete casing that supposedly protects our water from the intrusion of chemicals and poisonous gas? Also, if in an earthquake more cracks are created, what protects further migration of poisons? Just asking.
Below is the link: