The quake, which hit at 3:40 pm local time yesterday (0310 IST Thursday), was 5.4 kilometers (3.4 miles) deep and struck close to Conway Springs in Kansas, the US Geological Survey said.
The epicenter was just 53 kilometers from Wichita, the largest city in Kansas, and 200 kilometers from Oklahoma City.
The quake triggered a torrent of messages on Twitter, with some people saying it shook buildings but others saying they had not even felt it.
"I didn't feel the earthquake, but some folks in my building did," Twitter user @elSicomoro wrote, while @sydneygriffin87 said: "I actually did feel the earthquake and it was very scary."