A new federal investigation reveals a spate of earthquake activity in certain regions of the U.S. is likely the cause of localized hydraulic fracturing (fracking) drilling for natural gas and oil.
A report from the advocacy organization Environmental Working Group indicates the results of a U.S. Geological Survey study indicate earthquake activity since 2001 near gas and oil fields is due to drilling and other man-made causes, not any natural seismic activity. The study found the seismic activity is “almost certainly” a result of drilling.
In the last few years, especially, there has been a rise in seismic activity in areas not typically the site of earthquakes. The location of this activity appeared to be running parallel with new fracking drilling and specifically in places where the wastewater from that process is disposed of in underground injection wells. These wells are dug near fracking wells. The toxic and briny wastewater is rushed into these wells deep underground.
Underground injection wells for disposing fracking wastewater have been used since the 1960s but only recently has more and more fluid been used in the process. This has created a massive amount of wastewater and a need for more disposal sites. USGS researchers do not theorize why disposing of the wastewater underground is responsible for the earthquakes but other studies suggest the briny, salty nature of the drilling fluid causes lubrication of underground rock. If the site of the underground well is near a natural fault line, the wastewater may eventually cause the rocks to move.
The USGS study did find a recent wave of seismic activity and each site “across a broad swath of the country between Alabama and Montana.” The amount of earthquakes – usually registering around 3.0 on the Richter scale – rose sharply just as fracking drilling did the same. The intensity and frequency of these quakes has increased in recent years, USGS researchers found. According to its study, 50 earthquakes greater than 3.0 on the scale were measured in that area in 2009. That number grew to 87 in 2010 and hit 134 last year.
Since 2000, nearly double the amount of fracking wells are active in the U.S. and in many places, the wastewater is disposed of in underground wells instead of being transported to a special water treatment facility. In the 1990s, there were 245,00 wells dug in the U.S. In 2010, that number hit 405,000, according to the study.
Previous reports on possibly fracking-related earthquakes note a recent rise in activity in Arkansas, West Virginia, Ohio, and California, all the sites of new fracking drilling. This has led some local governments to ban the use of underground injection wells, at least until they conduct studies to determine if they’re the root of the earthquakes. In some areas, thousands of minor earthquakes have been reported.