In May of 2014 there was an earthquake in Greeley. This rarely happens, and scientists quickly started monitoring the area. A few quakes later, regulators ended up shutting down a wastewater injection well that took water from nearby drilling operations.
Human-caused earthquakes are not new, but they've become more common, as oil and gas production has ramped up across the U.S., bringing wastewater disposal wells along with it. While most disposal wells don't cause earthquakes, the lubrication they cause can lead to tremors in unexpected places – like the one in Greeley.
A new publication [.pdf] and map produced by the U.S. Geological Survey shows just where that increase in activity is.
As the map below shows, Oklahoma is the epicenter (pun intended) of the new activity. Several spots in Colorado have also seen an increase in earthquake activity. Most recently, those sites have been in Greeley and in southern Colorado's Raton Basin, where disposal of wastewater from coalbed methane has been causing earthquakes (some of them pretty big), for years.
After the wastewater injection site in Greeley that caused the earthquake was shut down for weeks, the bottom of the well was plugged, and eventually injection began again, at lower volumes. The problem of induced earthquakes there seems to be solved for now.
As oil and gas activity continues to produce wastewater, however, continued earthquakes from injection wells are possible. Industry and regulators are now trying to decide just what do about that.
