4.0 Magnitude Quake Rattles Northern Oklahoma

An earthquake has shaken parts of northern Oklahoma near the Kansas border.

The U.S. Geological Survey says the preliminary 4.0 magnitude earthquake was recorded at about 4:25 p.m. on Aug. 14 about 3 miles west-northwest of Medford in Grant County. Medford is about 120 miles north of Oklahoma City.

No damage or injuries were immediately reported. Geologists say earthquakes of magnitude 2.5 to 3.0 are generally the smallest that are felt by humans and damage is not likely from earthquakes below magnitude 4.0.

The Oklahoma Geological Survey has said it is likely that many recent earthquakes in the state are being triggered by the injection of wastewater from oil and natural gas drilling operations.