Oklahoma's oil and gas regulator on Feb. 24 issued a wider directive limiting future increases in wastewater disposal underground in another effort to address temblors in the state.

The guidelines include wells in Oklahoma's Arbuckle Formation that previously were required to restrict disposal volumes, and some potentially high-volume wells not previously covered.

Those wells were not part of earlier orders because there had not been reports of seismic activity in their area.

In total, the directive will cover 654 wastewater disposal wells in the Arbuckle Formation, the vast majority of which have already had volume restrictions, the Oklahoma Corporation Commission (OCC) said.

There are 71 wells included that were not under prior directives, OCC spokesman Matt Skinner said in a telephone interview.

The Arbuckle is popular for wastewater disposal because it is the state's deepest formation and can handle vast amounts of water with little pressure.

Operators have 30 days to make adjustments to comply with the new guidelines. They can dispose wastewater in formations outside of the Arbuckle.

Directives issued by the state to curb wastewater disposal have yielded positive results, the OCC said. So far this year, Oklahoma has experienced an average of 1.38 earthquakes per day of magnitude 2.7 or higher, compared with 5.39 per day in 2015 and 3.61 per day in 2016.