SMU, UT Researchers Think They've Found Cause of North Texas Quakes

SMU just sent word: Its seismologists, Brian Stump and Chris Hayward, joined by researchers from the University of Texas, have found evidence that could very well link those North Texas earthquakes in '08 and '09 to the re-injection of saltwater into natural-gas wells. From the report summary:

The incidents under study occurred in an area of North Texas where the vast Barnett Shale geological formation traps natural gas deposits in subsurface rock. Production in the Barnett Shale relies on the injection of pressurized water into the ground to crack open the gas-bearing rock, a process known as "hydraulic fracturing." Some of the injected water is recovered with the produced gas in the form of waste fluids that require disposal.

The earthquakes do not appear to be directly connected to the drilling, hydraulic fracturing or gas production in the Barnett Shale, the study concludes. However, re-injection of waste fluids into a zone below the Barnett Shale at the nearby saltwater disposal well began in September 2008, seven weeks before the first DFW earthquakes occurred and none were recorded in the area after the injection well stopped operating in August 2009.

Here's the full report, in which the researchers also address the issue of 11 additional "non-felt quakes" no one ever noticed, which must make those quakes feel very inadequate.