"Is Drilling To Blame For Texas Quakes?"
"People in North Texas worry about tornadoes, not earthquakes. That's not the case in the small town of Cleburne, just south of Fort Worth. They've had six quakes so far this month.
Cleburne happens to sit on a huge, recently discovered natural gas deposit called Barnett Shale. There's been a lot of drilling, and some people wonder if that has triggered the earthquakes. Here, a four-story drilling rig can pop up in as little as a couple of days. In the past eight years, 2,000 gas wells have been drilled here.
While most of rural America slowly dies on the vine, Cleburne is building civic center additions and opening championship municipal golf courses across the street from lakefront McMansions.
The 18-hole Cleburne Municipal Golf Course was built in part with money that the city received from royalties from natural gas companies that built on city ground.
Nobody thought much about it when a small tremor shook the town in early June. It was 2.8 magnitude quake and was the first in town history. But then a couple of days later, another earthquake. Then another quake. Then another.
Natural gas recovery in the Barnett Shale involves drilling down several thousand feet and then drilling sideways thousands of feet more. Liquid is then pumped down the wells at very high pressures, which fractures the strata releasing the pockets of natural gas. Could this be causing little quakes?"Source: NPR, 07/02/2009