Oklahoma

Oklahoma has unexpectedly become the earthquake capital of the United States — with some 240 small earthquakes magnitude 3.0 or more already this year. That's about twice as many as California has gotten. "A new study links the earthquakes to the wastewater disposal wells" And in a new study in Science, researchers say they've pinpointed the culprit: the wastewater disposal wells used by the fracking industry. Back in 2008, energy companies began ramping up the use of fracking for oil and gas in Oklahoma. The fracking process typically involves injecting water, chemicals, and sand underground at high pressures to crack open shale rock and unlock the oil and gas inside. Fracking itself doesn't seem to be causing many earthquakes at all. However, after the well is fracked, all that wastewater needs to be pumped back out and disposed of somewhere. Since it's often laced with chemicals and difficult to treat, companies will often pump the wastewater back underground into separate disposal wells.

When Austin Holland was being considered for his job as the sole seismologist at the Oklahoma Geological Survey in 2009, his interviewer posed a wry question: "Are you going to be able to entertain yourself as a seismologist in Oklahoma?" Back then, the state had a 30-year average of only two earthquakes of magnitude 3.0 or higher per year. As it turns out, though, boredom has been the least of Holland's concerns. Over the last five years, the state has had thousands of earthquakes — an unprecedented increase that has made it the second-most seismically active state in the continental United States, behind California. The state had 109 temblors measuring 3.0 or greater in 2013 — more than 5,000% above normal. There have already been more than 200 earthquakes this year, Holland said. Scientists say the more likely cause of the recent increase is underground injection wells drilled by the oil and gas industry. About 80% of the state is within nine miles of an injection well, according to the Oklahoma Geological Survey.