On November 5th, you may recall, the largest earthquake in
Oklahoma's history occurred just 30 miles East of Oklahoma City.
Oklahoma is a hotspot for fracking (hydraulic fracturing to
recover oil in shale formations miles deep). Oklahoma
experienced between two and six earthquakes a year between 1972
and 2008, before fracking. In 2010, after fracking, it
experienced one thousand and forty-seven! [Read more at Reader
Supported News where I got this information from.]