TULSA, Okla. — State regulators Monday asked oil and natural gas producers in central Oklahoma to decrease their waste-water disposal operations to try to temper the sharp increase in the number and severity of earthquakes in the energy-rich state.

The proposal released by the Oklahoma Corporation Commission covers more than 400 wells across 6,000 square miles, and it comes less than a month after the commission issued a similar plan covering nearly 250 wells in northwestern Oklahoma. The state has about 3,800 disposal wells.

The commission wants the central Oklahoma cuts to be phased in over the next two months, and it plans to review the efficacy of the adjustments in about six months.

Commission spokesman Matt Skinner said disposal volumes are about 970,160 barrels a day in the region, and regulators want to get that number down to 724,000 barrels a day.

The number of earthquakes with a magnitude 3.0 or greater has skyrocketed in Oklahoma, from a few dozen in 2012 to more than 900 last year. Last month, a 5.1-magnitude temblor hit the state — the third-largest ever recorded in the state. Scientists have linked the quakes to the underground disposal of waste-water from oil-and-gas production.

It’s too early to tell whether volume limits have been successful in Oklahoma.

Data from the U.S. Geological Survey show that in the 20 days before the 5.1 temblor hit on Feb. 13, there had been 31 earthquakes in northwestern Oklahoma. In the 20 days since regulators asked for the cuts on Feb. 16, there were 30 earthquakes centered in the region.

“Researchers have made it very clear to us that there is no off switch (to seismic activity),” Skinner said. “It will take time.”