The U.S. Geological Survey says a 3.1 magnitude earthquake has been recorded near Medford in northern Oklahoma.
The quake struck at 3:51 a.m. Friday and is the third small earthquake in the area since Wednesday. A magnitude 3.4 quake was recorded near Enid on Thursday and a 2.7 magnitude temblor occurred Wednesday night near Medford.
No injuries or damage are reported. Geologists say damage is not likely in earthquakes below magnitude 4.0.
Thousands of earthquakes have been recorded across Oklahoma in recent years, and many have been linked to the underground disposal of wastewater from oil and natural gas operations.
Regulators have asked oil and natural gas producers to close injection wells in certain areas or reduce the volume of fluids they inject.