“While the difference in size between the two events is less than 0.1 magnitude units, rounding magnitudes to one decimal place means that the magnitude of the Prague earthquake is Mw 5.7, and the Pawnee earthquake is Mw 5.8.”

The “Mw” designation stands for “moment magnitude,” a measurement of the maximum motion recorded by a seismograph.

For perspective, Dan McNamara, another USGS research geophysicist, said the magnitude scale is nonlinear. Every additional 0.2 magnitude is a doubling of the energy, he said.

The U.S. Geological Survey’s statement on the magnitude revisions explained that precise ranking of quakes in Oklahoma is difficult because seismic instrumentation has “vastly improved” in recent decades. Magnitude estimates may vary for reasons that include differences in computing methods, uncertainties in data, how data are processed, and assumptions about how seismic waves travel through a region of the Earth.