OKLAHOMA CITY—In Oklahoma, now the country’s earthquake capital, people are talking nervously about the big one as man-made quakes get stronger, more frequent and closer to major population centers. Next door in Kansas, they’re feeling on firmer ground though no one is ready yet to declare victory.
A year ago, the states had a common problem—earthquakes caused by the disposal of wastewater from oil and gas exploration. They chose different solutions. Kansas, following early scientific studies, decided to restrict how much and how fast the wastewater could be pumped back underground. Oklahoma instead initially concentrated on the depth of the wastewater injections.
