U.S. Seismicity: 1980-2015 USGS Seismic Hazard Mapping Project

The central U.S. has undergone the most dramatic increase in seismicity over the past six years. From 1973 to 2008, there was an average of 24 earthquakes of magnitude 3.0 and larger per year. From 2009 to 2015, the rate steadily increased, averaging 318 per year and peaking in 2015 with 1,010 earthquakes. Through mid-March in 2016, there have been 226 earthquakes of magnitude 3.0 and larger in the central U.S. region. To date, the largest earthquake located near several active injection wells was a magnitude 5.6 in 2011 near Prague, Oklahoma.