A record-tying earthquake in the edge of Oklahoma's key energy-producing areas rattled the Midwest from Nebraska to North Texas on Saturday and likely will focus fresh new attention to the practice of disposing oil and gas field wastewater deep underground. The United States Geological Survey said a 5.6 magnitude earthquake happened at 7:02 a.m. Saturday in north-central Oklahoma, on the fringe of an area where regulators had stepped in to limit wastewater disposal. That temblor matches a November 2011 quake in the same region. People in Kansas City and St. Louis, Missouri; Fayetteville, Arkansas; Des Moines, Iowa; and Norman, Oklahoma, all reported feeling the earthquake. Dallas TV station WFAA tweeted that the quake shook their studios, too.