The quake hit at a time when the natural gas industry has over 800 wells in Lycoming County which use a process called horizontal slick water hydraulic fracturing, commonly known as fracking, to extract natural gas from the Marcellus Shale.
According to Susquehanna University's Jennifer Elick, Ph.D., "Since 1990, there have been a handful of other low magnitude, shallow earthquakes (approx five) that have shaken the Valley and Ridge Province of central Pennsylvania," Elick, however dismisses any causal connection between fracking and the quake.
Another professor disagrees. "There is a very good possibility that the ground shaking was triggered by natural gas hydraulic fracturing," said Simon Ghanat, Ph.D. of Bucknell University. He pointed out that earthquakes in Williamsport are "very rare." Ghanat said that earthquakes of this magnitude in Williamsport have a "probability of occurrence of 2% in 50 years."
Rowena Lohman, Ph.D., Assistant Professor of geological sciences at Cornell University said, "With events that occur that infrequently, it is very difficult to definitively assign a cause to them." She said, "scientists need to look at the overall statistics of catalogs of earthquakes that span many years before and after the change (in this case due to hydraulic fracturing) to get a clear answer."
Lohman added, "One thing to watch out for in coming years is that a large network of seismometers (part of a project called USARRAY) is moving into the eastern United States." She says that this will increase the ability to detect smaller quakes but that "there is a large group within the seismology community that is carefully examining these records to deconvolve those two effects (for instance, for some of the events in Oklahoma that do seem to be associated with human activity)."