2011 Oklahoma Earthquake   Wikipedia
The 2011 Oklahoma earthquake was a 5.6 magnitude intraplate earthquake which occurred on November 5, 2011, at 10:53 pm CDT (03:53 UTC, November 6, 2011) in the U.S. state of Oklahoma. According to the U.S. Geological Survey (USGS), it was the most powerful earthquake ever recorded in Oklahoma.

Many believe Fraking is fracturing the North American plate as swarms of earthquakes continue in Oklahoma.

Oklahoma Quake Stirs Bird, Bug or Bat Swarm Seen on Radars   Live Science - November 7, 2011
For weather watchers in Oklahoma - the heart of Tornado Alley - the weekend's record-breaking earthquake created a curious blip on their radar screens. Weather radars at the National Weather Service in Norman, Okla., spotted what looked like bugs, bats or birds (or all three) swarming in the air just after the 5.6 magnitude earthquake struck the state. The quake hit on Saturday (Nov. 5) and was the largest in the state's history. The damage was minimal, but the quake was felt as far away as Chicago. Earlier in the day, a magnitude 4.8 foreshock rumbled in central Oklahoma. The magnitude 5.6 quake struck about 44 miles (71 kilometers) east-northeast of Oklahoma City, according to the U.S. Geological Survey.

New Madrid Seismic Zone

... between December 1811 and February 1812 the zone had four of the largest
North American earthquakes in recorded history - magnitudes estimated at 8.0 ...