What’s Causing the Huge Spike in Earthquakes in Oklahoma? | The Nation
"The US Geological Survey found that from 1975 to 2008, central Oklahoma experienced one to three 3.0-magnitude earthquakes a year, compared with an average of forty per year from 2009 to 2013. And it looks like that number is going to get bigger. It's only February, and the state has already logged more than twenty-five quakes of 3.0-magnitude or larger this year, and more than 150 total quakes in the past week alone."
