Scientists Say Oil Industry Likely Caused Largest Oklahoma EarthquakeSubmitted by DeMolay on Sat, 03/30/2013 - 02:43
The largest recorded earthquake in Oklahoma history was likely triggered by the injection of wastewater from oil production into wells deep beneath the earth, according to a study published Tuesday in the scientific journal Geology.
The magnitude 5.7 earthquake, which struck in 2011 near Prague in central Oklahoma, is the largest and most recent of a number of quakes scientists have tied to wastewater injection from oil and natural gas production, raising new concerns about the practice.
Advanced methods of oil and gas drilling create massive amounts of toxic wastewater. For example, hydraulic fracturing, also known as fracking, uses high-pressure water to unlock natural gas from shale formations. Drillers also use water to force oil from wells that cannot be captured through traditional methods, part of a practice known as "enhanced oil recovery." (See related interactive: "Breaking Fuel from the Rock.")
The use of such methods has exploded in the United States in recent years, contributing to the domestic boom in shale gas and oil production. Much of the wastewater that emerges as a byproduct is pumped into wells beneath the earth's surface for disposal.
Although the controversial practice of fracking has been directly linked to at least two seismic events (small tremors in Garvin County, Oklahoma and Lancashire, England), the wastewater injection that follows fracking is much more likely to set the earth shaking. That's because injection wells receive far more water than fracking sites, said Katie Keranen, lead author of the Geology study. And unlike at fracking sites, the water is not removed. As pressure builds in these disposal wells, it pushes up against geological faults, sometimes causing them to rupture, setting off an earthquake. (See related blog post: "Tracing Links Between Fracking and Earthquakes.")