Activist Erin Brockovich uses a computer model to display the growing environmental hot spots as she speaks during an Oklahoma Earthquake Town Hall Meeting at the University of Central Oklahoma February 23, 2016.

One of the largest earthquakes in Oklahoma rattled the Midwest on Saturday from Nebraska to North Texas, and likely will turn 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, a key energy-producing region. That matches a November 2011 quake in the same region. No major damage was immediately reported.