ENID, Okla. (AP) — Three small earthquakes have been recorded in northern Oklahoma.

The U.S. Geological Survey reports a magnitude 3.6 quake was recorded at 1:01 a.m. Sunday 12 miles northeast of Enid and a 3.3 magnitude temblor was recorded in the same area eight minutes later.

A 2.7 magnitude quake was recorded at 2:20 a.m. near Blackwell, near the Oklahoma-Kansas state line.

No injuries or damage are reported.

The number of magnitude 3.0 or greater earthquakes has skyrocketed 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 want oil and gas companies to reduce their wastewater disposal operations.