Tuesday, March 01, 2011

Strongest earthquake to-date in Arkansas swarm recorded; drillers stop doing injection wells

Last month we reported residents of Guy, Ark., suspect that a recent swarm of earthquakes was related to natural-gas drilling in the area. On Sunday the strongest earthquake in Arkansas recorded since 1976 hit the region, centered on nearby Greenbrier, the Arkansas Democrat Gazette reports. No serious damage was recorded after the quake, but some people did report broken windows and cracks in plaster walls. More than 4,100 people reported on the U.S. Geological Survey's website that they felt the quake. (Read more)

The Arkansas quake swarm "has garnered national attention because of its possible connection to natural-gas drilling operations in the area," Campbell Robertson of The New York Times reports. "Researchers with the Arkansas Geological Survey have pointed out spatial and temporal relationships between the earthquakes and the use of injection wells, which are used to dispose of the wastewater left over from gas drilling." No scientific link has been established between the quakes and hydraulic fracturing used in drilling to open up gas and oil deposits.

The Arkansas Oil and Gas Association has halted drilling of new injection wells until the connection is better understood, but injection wells that were drilled prior to the moratorium are still being used. While similar swarms have occurred in the region in the past, "there is also a growing body of research suggesting that injections wells can induce earthquakes, and there is some circumstantial evidence that this might be happening in Arkansas," Robertson writes. (Read more)

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