The US Geological Survey (USGS) released a report on April 23 confirming that oil and gas drilling triggered man-made earthquakes in eight states. The study discovered that Alabama, Arkansas, Colorado, Kansas, New Mexico, Ohio, Oklahoma and Texas have seen tremors in a degree not witnessed for million years.
The USGS call these tremors “induced earthquakes,” which are indeed “earthquakes triggered by man-made practices.”
“These earthquakes are occurring at a higher rate than ever before and pose a much greater risk to people living nearby,” Chief of the USGS National Seismic Hazard Modeling Project Mark Petersen said in a statement.
“The USGS is developing methods that overcome the challenges in assessing seismic hazards in these regions in order to support decisions that help keep communities safe from ground shaking.”
Campaigners have long accused fracking, or hydraulic fracturing, of being responsible for environmental problems and earthquakes. The process involves injecting large volumes of wastewater deep into to ground by using disposal wells, which is later extracted along with oil and gas during drilling.
The report suggests wastewater injection wells were responsible for causing the earthquakes. Although fracking produces large amounts of wastewater, the report says the procedure itself was only occasionally directly implicated in causing quakes and that the percentage of fracking wastewater was small relative to the total volume of wastewater produced by all types of drilling.
The increase in induced earthquakes is most striking in Oklahoma, which is one of the top energy producing states in US. Seismic activity in 2013 in Oklahoma was 70 times greater than pre-2008. Oklahoma is now seeing an average of 2.5 quakes of magnitude 3.0 or above daily, which is far higher than historical average of 1.5 per year.
In 2011 a 5.6 magnitude quake linked to wastewater injection hit Prague, Oklahoma, and damaged 200 buildings.
The Oklahoma Corporation Commission (OCC), the oil and gas regulatory body of Oklahoma, stressed that the issue is the agency’s top priority. "There will no doubt be more steps to take, and all options available to the OCC are on the table," OCC Spokesman Matt Skinner said in a statement.
Another study from Southern Methodist University (SMU), Dallas, finds that the cause of earthquakes occurring in Azle, Texas from late 2013 through to spring 2014 is “very likely” wastewater injection and saltwater extraction from gas wells.
Azle witnessed 27 magnitude 2.0 or greater earthquakes during this period. According Matthew Hornbach, the leading author of the study, the timing and location of the quakes correlates to the drilling and injection.
The Oklahoma Oil & Gas Association (OKOGA) said further proof is needed.
“There may be a link between earthquakes and disposal wells, but we - industry, regulators, researchers, lawmakers or state residents - still don’t know enough about how wastewater injection impacts Oklahoma’s underground faults,” said OKOGA President Chad Warmington.
But according to the Democrat State Representative Cory Williams, who is one of the most prominent voices advocating stronger action on the earthquake issue, this is not enough.
“I want a moratorium and then an action plan,” Williams said.
“The only way to protect the public is to say, ‘We’re done for now.’”