An Associated Press statistical analysis shows a dramatic drop in Oklahoma earthquakes since late May, when the state limited wastewater injections into energy wells.

And a new study says the state is on its way back to calmer times that prevailed before a huge jump in man-made earthquakes.

In parts of Oklahoma, the state ordered a 40 percent volume reduction in injection of saltwater – waste from hydraulic fracturing – that scientists generally blame for the massive increase in earthquakes.

An AP analysis of U.S. Geological Survey data of earthquakes magnitude 3.0 or larger shows that before the new rules went into effect, Oklahoma averaged 2.3 quakes a day in 2016. Since then the average dropped to 1.3 a day, though some were large and damaging.