Three small earthquakes have been recorded in northern Oklahoma during the weekend.

The US Geological Survey reports the strongest was a magnitude-3.1 quake recorded at 7.22am Sunday six miles east of Medford.

No injuries or damage are reported.

The agency also recorded a magnitude-2.7 quake six miles south-east of Waukomis at 8.13am Sunday and a magnitude-2.7 temblor 12 miles north-east of Helena at 10.22pm Saturday.

On Friday, the USGS reported an 4.0 earthquake at 12.27am, 12 miles north-east of Helena. There were no reports of injury or damage, but the earthquake was felt throughout central Oklahoma and as far away as Junction City, Kansas.

The number of magnitude-3.0 or greater earthquakes has soared in Oklahoma, from a few dozen in 2012 to more than 900 last year. Scientists have linked the increase to the underground disposal of wastewater from oil and gas production and state regulators have asked producers to reduce wastewater disposal volumes.

The Oklahoma Geological Survey has begun a six-month study of oil and gas injection wells to investigate the relationship between fracking and earthquakes.