Since late 2013, the overall rate of earthquakes in Oklahoma has increased by about 50 percent. Between October 2013 and April 2014, there were 183 quakes of magnitude 3.0 or stronger. By contrast, the long-term average between 1978 and 2008 was about two such quakes each year.
Oklahoma’s escalating earthquake activity since 2009 included 20 magnitude 4.0 to 4.8 quakes, including one of the two largest recorded quakes in Oklahoma’s history—a magnitude 5.6 earth quake near Prague on Nov. 5, 2011, which damaged a number of homes and a historic St. Gregory’s University hall in Shawnee.
The U.S. Geological Survey (USGS) blames hydraulic fracturing or “fracking” for the increased earthquake activity in the Sooner State—pumping millions of gallons of chemically-treated water and sand below ground to extract oil. Such deep injections into geological formations can boost pressure underground and even lubricate faults, in a process known as “injection-induced seismicity.”
Whether fracking causes earthquakes is a matter of argument and controversy, with ranchers reluctant to take sides. For them, the jury is still out. They can see the need for energy independence brought about by increased drilling, but they also do not want their water wells contaminated.
“As an association, our members have not taken a position on fracking,” Chancey Hanson, Communications Director for the Oklahoma Cattlemen’s Association, told the Western Livestock Journal, declining to discuss it further.
The swarms of small and moderate quakes in the state make it more likely damaging earthquakes will jolt central and north-central Oklahoma in the future. The Oklahoma Geological Survey operates a seismograph network of 15 permanent stations and 17 temporary stations.
In early May, the USGS and Oklahoma Geological Survey issued a joint statement stating they found “a likely contributing factor to the increase in earthquakes is wastewater disposal by injection into deep geologic formations.” Last October, the USGS issued a similar warning, attributing Oklahoma’s increased seismic activity to fracking.
NBC News in 2012 reported on a peer-reviewed report by a New York veterinarian and a Cornell molecular medicine professor that suggested a link between fracking and illness in farm animals.
“The authors compiled 24 case studies of farmers in six shale-gas states whose livestock experienced neurological, reproductive and acute gastrointestinal problems after being exposed—either accidentally or incidentally—to fracking chemicals in the water or air,” NBC said, citing Louisiana, New Mexico, Pennsylvania, Colorado, West Virginia and Texas.
Critics challenged the study because the authors neither identified the farmers nor ran controlled experiments to determine how specific fracking compounds might affect livestock.
In early May at its annual meeting, the Seismological Society of America declared fracking may cause earthquakes much farther from the sites of wastewater wells than previously thought. In central Oklahoma, a cluster of four high-volume wastewater injection wells triggered quakes up to 30 miles away, it was stated.
According to a study published last year in Earth and Planetary Science Letters, a series of small earthquakes in the Texas’ Eagle Ford shale formation was in part “associated with fluid extraction.” The Eagle Ford accounts for 6 percent of southern Texas’ economic output and supports 12,000 full-time jobs.
More than 30 earthquakes have been experienced northwest of Fort Worth since early November. Area seis mologists have recorded more than 300 quakes in the area since December, many barely detectable, all clustered around area injection wells.
Oil companies have long been exempt from most Texas state water rules and permitting requirements. Each fracking well requires about six million gallons of water to break open rocks far below the surface and release hydrocarbons. Ranchers and oil companies compete for underground water in droughtravaged Texas.
“North Texas isn’t alone. Earthquakes in Colorado, Oklahoma, Ohio and Arkansas over the past few years have all been tied to wastewater injection wells. New research presented at the Seismological Society of America annual meeting last month showed that disposal wells may be changing stress on faults and inducing earthquakes,” the Shreveport Times reported.
Earthquakes in Texas are historically rare. But in 2008, they began in the Dallas-Fort Worth area near where energy companies were fracking for natural gas. More than 60 quakes were recorded over two years, all near injection wells, the newspaper said.
In April, a Dallas jury awarded a Texas ranching family nearly $3 million from Aruba Petroleum Inc., a large natural gas company whose drilling the family said caused years of sickness, killed pets and forced them out of their home for months.
Oil and natural gas companies dispute a direct link between earthquakes and fracking, citing a lack of conclusive evidence. The vast majority of 35,000 disposal wells throughout Texas have reported no seismic activity, the Texas Alliance of Energy Producers says. In March, the Texas Railroad Commission, overseer of the oil and gas industry, hired a seismologist to study the issue.
In 2011, the U.S. Environmental Protection Agency issued a report marking the first time the agency publicly linked fracking and groundwater contamination, causing a stir on both sides of the issue. — Mark Mendiola, WLJ Correspondent