"The U.S. Geological Survey says it recorded seven small earthquakes in central Oklahoma in 14 hours over Saturday and Sunday," AP reports.
"The quakes ranged in magnitude from 2.6 to 2.9 on the Richter Scale. Earlier on Saturday, four quakes were recorded in the same area of central Oklahoma. One of those quakes registered 4.3 on the Richter Scale. No injuries or damage were reported."
"Some residents in the area say they believe that drilling for oil may be the reason for an increase in seismic activity in the region."