Oklahoma was shaken by more than 400 earthquakes in the first two months of 2016, the latest in a state that has experienced a marked increase in seismic activity in recent years.

U.S. Geological Survey (USGS) data shows the Sooner State experienced about 430 earthquakes of magnitude 2.5 or greater in January and February, an average of more than seven per day.

About 240 quakes of that magnitude occurred elsewhere in the continental United States during the same time frame, according to a searchable earthquake archive on the USGS website.

Magnitude 2.5 is the minimum strength reported on the USGS’s earthquake tracker.

Oklahoma rarely experienced earthquakes of that size before 2009, when the state’s seismic activity began to surge. USGS data shows the state was hit by about nine earthquakes of magnitude 2.5 or greater in 2008, and that number rose to more than 2,700 last year.

The uptick has been linked to wastewater produced by the oil and gas industries, and state officials have taken steps to limit the amount of wastewater that can be disposed in wells.

Both the USGS and Oklahoma Geological Survey have issued warnings about the increase in earthquakes of magnitude 3.0 or greater, saying the rise in quakes of that size increases the odds that Oklahoma will experience a larger, potentially more damaging earthquake in the future.

USGS data shows Oklahoma felt about 169 quakes of that size in January and February. The rate, an average of more than two per day, places it on pace to break the 2015 total of about 900.

The agency has said that Oklahoma’s average was about two per year between 1978 and 2008.

This year’s events include a magnitude 5.1 earthquake that occurred on Feb. 13 near Fairview. That is the state’s third-largest quake on record, according to the Oklahoma Geological Survey.

Three days later, the Oklahoma Corporation Commission announced it was implementing its biggest plan to reduce wastewater disposal yet, affecting 245 disposal wells across more than 5,200 square miles. Researchers recommended the plan should be implemented gradually over the next two months to avoid sudden pressure changes, the commission said in a news release.

In late January, Oklahoma Governor Mary Fallin announced that $1.4 million would be withdrawn from the state’s emergency fund and given to earthquake researchers and regulators.