A study by researchers from Cornell University, University of Colorado, Columbia University, and the U.S. Geological Survey believe four waste water wells could be at fault for starting one in five earthquakes in the central and eastern U.S. from 2008 to 2013.
The results are published in the journal Science.
The wells were used to dispose of waste water released from underground rocks during fracking operations. The study goes so far as to suggest the wells could be the reason for a big jump in earthquakes around Oklahoma City. Oklahoma, with twice as many quakes (with a magnitude 3 or higher) as California, is now the state with the most seismic activity this year, outside of Alaska.
The data shows water pumped into waste water wells can affect underground pressures up to 35 kilometers.
(source: Bloomberg Business Week)