The U.S. Geological Survey says two earthquakes centered in central Oklahoma struck Monday.
A magnitude 3.3 earthquake struck 6 miles east-southeast of Edmond around 1:20 p.m. Monday. Shaking could be felt in Oklahoma City.
Earlier in the day, a 3.5-magnitude quake was recorded at 10:30 a.m. It was centered 3 miles south of Guthrie.
Earthquakes above 3.0 are judged to be those felt by residents of the area.
The quakes came the same day an Oklahoma lawmaker and veteran petroleum geologist called for a federal task force to develop an emergency plan in response to the swarm of earthquakes rocking the central part of the state.
Some scientists say the increase is seismic activity could be connected to the oil and gas drilling method known as hydraulic fracturing, and especially the wells in which the industry disposes of its wastewater.