Earthquakes and Fracking connection

The recent uptick in the area's temblors has been dramatic. From 1972 to 2008 only two to six earthquakes were reported per year in Oklahoma, and were often too small for people to notice. However, in 2009 nearly 50 earthquakes were recorded (pdf), and that number more than doubled in 2010 to 1,047, with 103 powerful enough to be felt.

Fracking has been linked to two minor earthquakes in northwest England, very likely by lubricating an already stressed fault zone and thus making it easier for the land to shift. A report in August by seismologist Austin Holland at the OGS also suggested that a swarm of nearly 50 small quakes of magnitude 1.0 to 2.8 near the center of the state might have been triggered by nearby fracking.

Still, researchers say it seems unlikely that fracking had anything to do with last weekend's magnitude 5.6 quake. "I won't say that man's activity never ever caused the release of seismic stress, but hydro-fracks are such small things," Keller adds. "If we were talking a magnitude 1 or 2 earthquake, that'd be different, but it's awfully hard to imagine a hydro-frack being involved with one of this size. We also have to determine if there were any frack jobs going on there right now, but I don't think there were—it didn't happen in an area of particularly active oil and gas exploration."