Oklahoma Toughens Oil Fracking Rules After Shale Earthquakes

  • Regulators mandate use of seismic testing at some well sites
  • Level for pausing work lowered to keep events controlled
A fracking oil rig stands behind a home in Oklahoma City.

Photographer: J Pat Carter/Getty Images 

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Oklahoma is tightening its rules for fracking after studying a new cluster of earthquakes in one of the hottest U.S. regions for drilling.

The Oklahoma Corporation Commission announced that all explorers within certain areas must use equipment known as a seismic array, which detects movement underground. The regulators also lowered the quake threshold for pausing work from 3.0 magnitude to 2.5, a level where humans can feel the earth move. The mandated delay is for at least six hours.