After several recent Southern California earthquakes left them sensitive to shaking, people around the region thought they felt the ground move earlier this week. But this rumble came from the air.

U.S. Navy Cmdr. Kevin Stephens told the Los Angeles Times on Thursday that the shaking was a sonic boom produced by an F/A-18 Super Hornet fighter jet.

The jet was over the Pacific Ocean about 35 miles southwest of San Diego Wednesday when it broke the sound barrier. Sonic booms move in the direction a jet is flying, and because it was pointed northward the rumble was felt in Orange and Los Angeles counties.

"The sound will propagate in the direction it's flying," Stephens told the paper. The sonic booms have been known in the past to shake buildings.

The F/A-18 was flying as part of a demonstration of the U.S.S. Ronald Reagan aircraft carrier, whose home port is in Coronado.

The Associated Press contributed to this report