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

http://www.bloomberg.com

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.