It’s official (or as close as it can get): Oil and gas operations, like those involved in hydraulic fracturing (fracking), can cause earthquakes. If there was any lingering doubt about whether oil and gas activities are connected to seismic events, then the highly esteemed U.S. Geological Survey (USGS) has pretty much laid it to rest. To quote lead researcher William Ellsworth, a USGS geophysicist, an upsurge in earthquakes occurring in the vicinity of oil and gas operations are “almost certainly man-made.”
Researchers aren’t certain as to the precise cause of the minor earthquakes, but indications point towards the injection of drilling (and fracking) wastewater into underground disposal wells. A combination of factors must take place for seismic events to occur, but scientific evidence since the 1960s has correlated earthquakes with underground fluid injection, especially in association with wastewater wells. These fluids can alter the pressure and lubricate fault lines, initiating slippage in geological formations.
EnergyWire journalist Mike Soraghan interviewed Ellsworth ahead of the USGS report’s presentation, which relied on more than ten years of data in Colorado, Oklahoma and Arkansas. According to Soraghan:
The study found that the frequency of earthquakes started rising in 2001 across a broad swath of the country between Alabama and Montana. In 2009, there were 50 earthquakes greater than magnitude-3.0, the abstract states, then 87 quakes in 2010. The 134 earthquakes in the zone last year is a sixfold increase over 20th century levels.
The surge in the last few years corresponds to a nationwide surge in shale drilling [i.e., fracking technology], which requires disposal of millions of gallons of wastewater for each well. According to the federal Energy Information Administration, shale gas production grew, on average, nearly 50 percent a year from 2006 to 2010.
That fracking-related activities can cause earthquakes is not surprising – the research confirms what others had suspected, as outlined in two November 2011 reports. One was a previously unreleased Oklahoma Geological Survey report that tied fracking to a swarm of 50 microquakes. Days earlier, the United Kingdom energy firm Cuadrilla Resources issued a report stating that it was “highly probable” that minor earthquakes (magnitudes 2.3 and 1.5 ) in Lancashire, England were due to shale-gas test-drilling.
Most recently, shale-gas wastewater disposal wells caused a rash of 11 minor quakes in Youngstown, Ohio since March, 2011 as documented in a preliminary incident report by the state’s Department of Natural Resources. More uncharacteristic seismic events are expected to follow in Ohio.
In the heated debate surrounding fracking and its many associated environmental and health problems, there are at least two aspects that seem certain. Fracking in shale formations use a lot of water, and with that, fracking-related operations can shake the earth.