By Hailey Branson-Potts in the Los Angeles Times
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 have never observed such a dramatic swarm of earthquakes “in what’s considered a stable continental interior,” Holland said. “Whatever we’re looking at, it’s completely unprecedented.”
Oklahoma has always had the potential for earthquakes; it has a complex underlying fault system. But until recently, the most powerful quake of the modern era was a 5.5-magnitude temblor in 1952 that left a 15-meter crack in the state Capitol.
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.
Oklahoma has seen a boom in oil and gas production, including the use of hydraulic fracturing, or fracking — the process of shooting water, sand and chemicals deep into the earth at high pressure to extract oil and natural gas. Scientists from the U.S. Geological Survey and several universities suggest there is a link between the quakes and disposal wells, where wastewater from fracking is forced into deep geological formations for storage.
Read more at the Los Angeles Times