More than a dozen small earthquakes have been recorded in northern Oklahoma and one in south-central Kansas since Friday night, the U.S. Geological Survey said.
No injuries or damage are reported.
The USGS recorded 13 quakes Oklahoma between 6:55 p.m. Friday and 2:21 a.m. Saturday, including a magnitude 3.5 temblor near Fairview and a 3.2 magnitude quake near Cherokee, both about 100 miles northwest of Oklahoma City.
The other Oklahoma quakes range in magnitude from 1.2 to 2.9 and were near Medford and near Pawnee -- the site of a magnitude 5.8 earthquake on Sept. 3.
The Kansas quake was magnitude 2.9 and recorded at 8:18 a.m. Saturday near Belle Plaine, about 27 miles north of the Oklahoma-Kansas state line.
Scientists have linked the quakes to the underground disposal of wastewater from oil and natural gas production.