When small earthquakes rumbled beneath northern Texas in 2008 and again in 2009, scientists were puzzled. While they expect to see seismic activity in active zones like Haiti, Chile, and Turkey, where disasters have already struck this year, the area around Fort Worth, Texas sees only rare and tiny seismic activity. Now, some Texas seismologists are arguing that techniques used in conjunction with natural gas exploration provide a plausible explanation for what's going on. North Texas sits atop the Barnett Shale, one of the several giant layers of shale in the United States believed to hold a truly massive amount of natural gas.
The U.S. Geological Survey estimates that 200 trillion cubic feet of natural gas may reside in shales nationwide [USA Today]
. The reason these giant deposits have remained largely untapped, however, is that shale isn't particularly porous, and so extracting it requires drillers to fracture the rock ...
