According to some researchers, yes, fracking is tied to earthquake activity in the U.S.
The central portion of the United States has seen six times more earthquakes than it did in the 20th century. Over a two-year period, from 2010 to 2012, 300 earthquakes were reported that registered at least 3.0 in the Central U.S. From 1967-2000, the same area averaged around 21 earthquakes per year.
The increase in seismic activity may be connected to the introduction and increase in fracking activity in Texas, North Dakota and elsewhere in the middle U.S., according to a recent study published in Science magazine. The result is that large quakes in far-away places are causing tremors and small earthquakes here in the continental United States.
Researchers studied earthquakes that were reported after three larger quakes in distant countries: Chile, Indonesia and Japan. They found that Oklahoma, Texas and Colorado were the most sensitive to these distant quakes, experiencing seismic activity themselves.
Specifically, areas that had been sites for hydraulic fracturing for years were more likely to experience a dynamically-triggered quake after a large quake elsewhere. The injection of wastewater back into the ground as part of the fracking process has been linked to increasing the odds that a dynamically-induced earthquake will occur at that spot in the future. Some research even points to wastewater disposal during fracking as an actual cause of earthquakes, like the 2011 quake that hit Prague, Oklahoma.
Source: National Geographic, “Fracking Wastewater Disposal Linked to Remotely Triggered Quake,” July 11, 2013