The USGS is reporting a M5.6 earthquake north of Oklahoma City, very near Pawnee, OK - which if the magnitude doesn't change - ties with the November 2011 quake as the strongest ever reported in that state.
Since 2009 Oklahoma has seen a major up tick in seismic activity (see USGS/OGS Joint Statement On Increased Earthquake Threat To Oklahoma).
Prior to 2009, earthquakes in Oklahoma were rare events, averaging 2 to 5 small >3.0 quakes per year. In 2009, there were 10 such quakes, followed by 40 in 2010, and then 60 in 2011. The number broke 100 in 2013, and has been climbing substantially every year since.
Now, Oklahoma residents can easily see 100+ quakes a month and the USGS 2016 one-year seismic hazard forecast for the Central and Eastern United States from induced and natural earthquakes, finds Oklahoma's risk of seeing damaging quakes is now on par with California.
Although preliminary reports are of only light damage from this quake, this is another reminder that Half Of All Americans Need An Earthquake Plan.
UPDATED: Local news now reporting . . .
And a M3.6 aftershock in the past few minutes. More may be expected.
For more on earthquake risks, and preparedness, you may wish to revisit: