Oklahoma earthquakes decline amid new regulations

There have been fewer earthquakes in Oklahoma this year than last, and federal officials are crediting new regulations on oil and gas drilling operations for the decline. 

Oklahoma has experienced 448 magnitude-3.0 or greater earthquakes this year, USA Today reports, down from 558 through the same time period last year. 

{mosads}State officials in 2015 said wastewater disposal operations at oil drilling and hydraulic fracturing sites were likely to blame for the increase in earthquakes there. Oklahoma was averaging more than two magnitude-3.0 earthquakes a week at the time; before expanded drilling there, it was experiencing only a few such quakes a year. 

Federal officials earlier this year restricted wastewater injections and increased their oversight of the practice. A geophysicist at the United States Geological Survey (USGS) told USA Today the regulations were likely one of the reasons behind the decline in quakes, citing a decrease in oil and gas drilling activity.  

The USGS included man-made earthquakes in its annual seismic activity outlook in March, concluding the quakes were possible in states with heavy oil and gas drilling. 

Seven million Americans live or work in areas threatened by earthquakes induced by human activity, the agency concluded then.