Jess Burrow, left, and James Patterson look over damage at Joe and Mary Reneau’s home after a 5.6-magnitude earthquake in November 2011.Sue Ogrocki / AP
It was 5:47 a.m. on June 16 of this year when a 4.5-magnitude earthquake roused Oklahoma City residents from their sleep. The temblor was one of several early-morning quakes felt in the metro area over the course of the week.
During a live morning broadcast, KOCO 5 meteorologist Danielle Dozier covered her mouth with her hand and appeared too stunned to talk. The rattling from the quake could be seen on air. “Forgive me,” she said after a pause. “That actually scared me.”
It’s unlikely to reassure Dozier or other residents, but a recent article by United States Geological Survey (USGS) scientists in The Journal of Geophysical Research has strengthened the temblor uptick’s ties to fracking.
The study suggests a 5.0-magnitude quake that struck the day before the record-breaking 5.6 temblor was induced by fluid injection. That earthquake likely triggered the larger main shock and thousands of aftershocks.
In fracking, or hydraulic fracturing, water, sand and chemicals are blasted into the earth to crack rock and extract oil and natural gas trapped inside. Wastewater is used in the process as well as the volumes of saltwater the earth spits out of the wells are disposed of in injection wells.
State and federal scientists continue to study the Prague sequence in relation to nearby injection activities. The USGS and the Oklahoma Geological Survey analyzed the area’s earthquake activity since 2009 and released a joint statement in May calling wastewater injected into deep geologic formations “a likely contributing factor to the increase in earthquakes.”
The number of injection wells in Oklahoma continues to rise. There are about 10,000 scattered across the state; five years ago, injection wells numbered about 8,000. Reneau said big tank trucks used in the drilling process regularly rumble down the once quiet rural dirt roads near them.
The oil and natural gas industry has decades-long ties to the state. Drilling activity strengthened the Oklahoma economy during the recession and helped residents evade the collapse of the housing market.
In that atmosphere, industry groups as well as residents and politicians have downplayed the links between wastewater injection and earthquakes. But they have become impossible to ignore. Oil and natural gas companies working with scientists and local politicians are calling for forums with industry representatives on behalf of rattled constituents.
The companies have provided the scientists with a deluge of data on injection wells, said Elizabeth Cochran, a geophysicist with the USGS. The statistics involve everything from volume to times and depths of injection. It’s information that will bolster the efforts of scientists studying the links between earthquakes and wastewater injection in Oklahoma and elsewhere.
After all, Oklahoma isn’t the only state experiencing an unprecedented earthquake surge. Ohio, Arkansas, Texas and Colorado have also experienced numerous earthquakes in recent years, which are uncommon historically in those areas.
“All of the earthquakes are in locations where wastewater disposal is going on,” said Lucille Jones, a California-based seismologist for the USGS.