Oklahoma experienced just two earthquakes of magnitude 3 or greater from 1978 through 2008. In 2013, it was 109. There have been 145 through May 2 of this year already.
Almost half (45%) of the earthquakes of magnitude 3 or greater in the central and eastern U.S. occurred in the frack-happy state of Oklahoma. The suspicion that fracking may be behind a sudden increase of earthquakes in Oklahoma is not new. But a study just released in Science magazine by University of Cornell researchers enhances the evidence that reinjection can cause seismic swarms.
There is good news: the earthquakes appear to be related to a small minority of reinjection wells. During hydraulic facturing, known as fracking, large volumes of fluid are pumped underground to pressurize and break rock, thereby releasing trapped natural gas. This "fracking water" becomes contaminated during the process and cannot be released back into surface waters, so it is reinjected, often at high pressures and volumes.
Dr. Katie Keranen, of Cornell University, notes that
Four of the highest-volume disposal wells in Oklahoma (~0.04% of wells) are capable of triggering ~20% of recent central US earthquakes in a swarm covering nearly 2000 square kilometers.
Only 4 out of 10,000 of wells causing half of the problems. This could explain why industry representatives continue to protest that fracking and reinjection has been proven safe. More importantly, the the bad actors can be identified and shut down, hopefully significantly minimizing the negative impacts of man-made earthquakes on residents of areas where fracking growth has been embraced for creating jobs and energy independence.
Once the earthquake problem is solved, we can go back to worrying about the potential risk for groundwater pollution. A separate study at Cornell University recently identified yet another mechanism increasing the risk of carrying contaminants from the path of the fracking fluids into clean groundwater reservoirs: the same properties that make the fluids effective at fracking help fracking fluids dissolve contaminants like heavy metals that up until now have clung safely to soils in the form of colloids.
This first principle of risk management requires us to understand the risks so we can maximize the benefits while reducing negative impacts. Fast growing new technologies like fracking often outpace the science needed to ensure safe implementation of the technology. The fracking backers should support this good science more than the TreeHuggers do; it is their best hope to fend off the next NIMBY (not in my back yard) revolution.