The revolutionary method of natural-gas extraction known as hydraulic fracturing – or “fracking” – has left in its wake a trail of contaminated water supplies, polluted air, health problems, and environmental degradation. But what is potentially the most damaging aspect of the process is just coming to light in the form of a tremendous spate of earthquakes in the heart of the United States.
In the past week, northern Oklahoma and southern Kansas have suffered forty two earthquakes of magnitude 2.5 on the Richter scale – 17% of all earthquakes in the world. This brings the year-to-date count up to 680 such tremors – and this in area that until recently was almost completely seismically dormant. Up until 2009, the area experienced an average of 1.5 of these quakes each year. What has changed since then is the massive influx of fracking operations seeking to take advantage of the Woodford Shale that straddles the two states’ border.
What makes fracking so revolutionary is that it allows oil companies to access natural gas deposits that, due to their position embedded in bedrock as much as a mile below the surface, were previously inaccessible. In a hydraulic fracturing well, a noxious combination of water, sand, and toxic chemicals is shot down into the bedrock at extremely high pressures and then explodes horizontally into tiny fissures in the rock. This frees up the embedded natural gas to flow back to the surface with the water and sand that is pumped back out.
What it also does, however, is seriously destabilize the bedrock and reactivate long-dormant fault lines. In Oklahoma and Kansas, the area that contains the Woodford Shale also happens to sit above the mid-continent rift, a billion-year old fault line buried more than a mile below the surface. The enormous amount of highly pressurized fluid that has been shot into the Earth has now sufficiently destabilized the bedrock to reactivate the fault to an incredible degree.