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Scientists are increasingly confident about the link between earthquakes and oil and gas production, yet regulators are slow to react
Until 2008 not a single earthquake had ever been recorded by the U.S. Geological Survey from the Dallas–Fort Worth area, where Wallace has lived for more than 20 years. Since then, close to 200 have shaken the cities and their immediate suburbs. Statewide, Texas is experiencing a sixfold increase in earthquakes over historic levels. Oklahoma has seen a 160-fold spike in quakes, some of which have sent people to hospitals and damaged buildings and highways. In 2014 the state’s earthquake rate surpassed California’s.
The rise in quakes coincides with an increase in drilling activity. Wallace’s house, for instance, sits above the Barnett Shale Formation, a layer of hard black rock that holds the U.S.’s second-largest deposit of natural gas. Between 1998 and 2002 companies started drilling this deposit using hydraulic fracturing, or fracking, which involves pumping millions of gallons of water, plus sand and chemicals, into the ground at high pressure to crack the rock and release the gas. As the gas comes up the well so does the fracking fluid, along with volumes of brine so salty it is hazardous. The fluids are pumped back down a different hole drilled far below the shale into porous rock for permanent disposal. As more and more fluid is injected into these wastewater wells, pressure can start to build up on deep geologic faults. Eventually one can slip, causing an earthquake.
Researchers at the USGS and other institutions have tied earthquake surges in eight states, including Texas, Oklahoma, Ohio, Kansas and Arkansas, to oil and gas operations. Some state regulators have been slow to accept scientists’ findings. Residents have become increasingly angry, and environmental groups have sued. “This is a public safety issue, and there’s been a lot of denial and ignoring of the problem,” says Wallace, who has joined neighbors to push for the shutdown of nearby wastewater wells …. http://www.scientificamerican.com
Source: http://luismmx.blogspot.com/2016/03/scientists-are-increasingly-confident.html
