D/FW AIRPORT — Scientists believe they've found the source of several minor earthquakes that rattled neighborhoods around Dallas/Fort Worth International Airport in 2008 and 2009.
After months of study, seismologists at SMU say a saltwater injection well at the southern end of the airport is a "plausible" cause.
The injection well pumps fluids nearly three miles deep into the earth's crust. This is how drilling companies get rid of waste water from gas drilling.
When activity at the D/FW waste well stopped last year, so did the earthquakes. Instruments detected 179 of them.
"The injection well was started in September. The quakes began in October and continued through May," noted SMU's Brian Stump, who was part of team that deployed sensors in the area.
He said the injection well appears to be the source because the timing is right, the location is right, and the well was drilled about two football fields away from a known fault line.
Stump says there is no evidence the tremors are linked to gas drilling itself, or the process called "fracking."
Drilling in the Barnett Shale requires millions of gallons of water to be forced into the ground, fracturing the shale and releasing natural gas.
A map on the wall at SMU puts the incident in context. It shows thousands of gas wells and hundreds of waste water injection wells. But only the one near D/FW Airport is suspected of causing seismic activity.
Stump says this is an opportunity to learn why the drilling operation might have triggered the tremors.
"Understanding interactions of fluids and faults and stress in the crust is a broad important issue for us in society," he said.
Chesapeake Energy, which operated the injection well, issued a statement saying "a direct causal relationship" with the well "has not been scientifically proven." The statement adds that the company agrees with researchers that "natural gas drilling, hydraulic fracturing and production are not related to seismic activity..."