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.
For the past three decades, Oklahoma averaged about 50 earthquakes a year. But that number has skyrocketed in the past few years. In 2013 — the state's most seismically active year ever — there were almost 3,000.
The quakes are small, and they're concentrated in the central part of the state, where the Erwins live.