Fracking Tied to Unusual Rise in Earthquakes in U.S.

http://www.bloomberg.com/news/2012-04-12/earthquake-outbreak-in-central-u-s-tied-to-drilling-wastewater.html

Oil pipelines feed into storage tanks in Cushing, Oklahoma.

A spate of earthquakes across the middle of the U.S. is “almost certainly” man-made, and may be caused by wastewater from oil or gas drilling injected into the ground, U.S. government scientists said in a study.

Researchers from the U.S. Geological Survey said that for the three decades until 2000, seismic events in the nation’s midsection averaged 21 a year. They jumped to 50 in 2009, 87 in 2010 and 134 in 2011.

Last month, Ohio officials concluded that earthquakes there last year probably were caused by wastewater from hydraulic fracturing for natural gas injected into a disposal well.

In hydraulic fracturing -- or fracking -- water, sand and chemicals are injected into deep shale formations to break apart underground rock and free natural gas trapped deep underground. Much of that water comes back up to the surface and must then be disposed of.

The Environmental Protection Agency is preparing to release rules on air pollution from gas wells and on the treatment of wastewater. Other state and federal rules could force more disclosure of the chemicals used by the drilling companies.

The Interior Department is considering rules to update well-design standards and require disclosure of the chemicals in fracking on public lands.