The 3.9-magnitude temblor hit one mile west of San Juan Capistrano at 10:37 a.m. PT. Several communities reported feeling shaking, including Costa Mesa, Anaheim, Rancho Santa Margarita and Huntington Beach.
"I thought a train was going to come through the office, and I braced myself on a door jam, but I was waiting to feel something, and I never felt anything," said Stephanie Espinosa of Dana Point.
There were no immediate reports of damage or injuries. Southern California Edison reported the San Onofre nuclear plant was not affected by the quake.
"Even though it was a quick, small earthquake, it's a good reminder that you should be prepared and have a plan in case we do get a large, damaging earthquake," said Marc Stone of the Orange County Fire Authority.