The U.S. Geological Survey says several earthquakes struck central Oklahoma Friday morning, including one with a preliminary magnitude of 4.2.
State and local emergency management officials said there have been no reports of injury or damage as a result of any of the temblors.
The USGS said the quake hit shortly before 9 a.m. near Stroud, about 88 kilometres northeast of Oklahoma City, and was felt in western Arkansas and Wichita, Kansas.
It was followed within about 75 minutes by five more earthquakes of preliminary magnitudes ranging from 2.7 to 3.8.
The quakes struck within about 16 kilometres of a privately run prison, the Cimarron Correctional Facility.
A woman who answered the phone at the prison declined to comment and a spokesman for the parent company, Nashville, Tenn.–based CoreCivic, did not immediately return a phone call for comment.
The oil and gas connection
Scientists have linked some oil and gas production in Oklahoma to an uptick in earthquakes, but the frequency of such earthquakes in the state had dropped recently as the state imposed new restrictions on the injection of wastewater into underground disposal wells.
The Oklahoma Corporation Commission’s induced seismicity department is working with the Oklahoma Geological Survey to investigate the quakes, says commission spokesman Matt Skinner. But the agency has not issued a directive to shut down any disposal wells in the area, which is part of what is known as the Arbuckle formation.
“Everything is still in the initial stages right now,” Skinner said, “but [shuttering some wells] is a distinct possibility.”
Skinner said there are eight disposal wells within 16 kilometres of the preliminary location of the temblors, and that the Oklahoma Geological Survey will determine the precise epicentres of the quakes.
Not a traditional earthquake zone
An open plain better known for tornados, Oklahoma became an earthquake hot zone around 2011, surpassing California in magnitude 3 or greater earthquakes in 2014.
National Geographic reported that the state typically had three or fewer earthquakes annually prior to 2009, when that number jumped to 20, rising to 579 in 2014 and 903 in 2015.
Cracked walls and crumbling brickwork are now common on the state’s historic buildings. Famed environmental lawyer Erin Brockovich is supporting the Pawnee Nation in its lawsuit against Eagle Road Oil LLC, Cummings Oil Company, and 25 other oil and gas companies for damages from alleged human-induced quakes.