In a surprising turn of events, Cuadrilla Resources, a British energy company, recently admitted that its hydraulic fracturing operations "likely" caused an earthquake in England. Predictably, this news quickly sent a shockwave through the U.K., the oil and natural gas industries, and the environmental activist community. And it certainly feeds plenty of speculation that the same phenomenon could be occurring elsewhere.
Speculation that would be well-founded, evidently. Right on the heels of Cuadrilla's announcement, news is spreading that the United States Geological Survey has released a report (pdf) that links a series of earthquakes in Oklahoma last January to a fracking operation underway there. Evidently, a resident reported feeling some minor earthquakes, spurring the USGS to investigate. They found that some 50 small earthquakes had indeed been registered, ranging in magnitude from 1.0 to 2.8. The bulk of these occurred within 2.1 miles of Eola Field, a fracking operation in southern Garvin County.
The U.S.G.S. determined that "from the character of the seismic recordings indicate that they are both shallow and unique."
Our analysis showed that shortly after hydraulic fracturing began small earthquakes started occurring, and more than 50 were identified, of which 43 were large enough to be located. Most of these earthquakes occurred within a 24 hour period after hydraulic fracturing operations had ceased. There have been previous cases where seismologists have suggested a link between hydraulic fracturing and earthquakes, but data was limited, so drawing a definitive conclusion was not possible for these cases.
The report is still under peer-review, and even then, the correlation between fracking and the quakes is inconclusive. The U.S.G.S. notes that region has historically been seismically active, though the summary states that the "strong correlation in time and space as well as a reasonable fit to a physical model suggest that there is a possibility these earthquakes were induced by hydraulic fracturing."
Needless to say, it's become much less far-fetched to presume that fracking has a serious impact on seismic activity. And so, yet another reason emerges to be wary of the secretive processes that underly the nation's most controversial gas-extraction process: Fracking earthquakes.