The quake hit around 2:36 a.m. PT, 88 miles SW of Avalon, Calif., on Santa Catalina Island. It was initially reported that there were two quakes, 6.4 and 6.1, within seconds of each other, but seismologists concluded it was only one temblor.
Experts said an earthquake of that magnitude in that part of the Pacific Ocean, the Cortes Bank, is unusual. They said people will feel the quake differently, depending on where they are.
"It would have been a little bit of a rolling motion for most people to feel. With every earthquake we have shaking and rolling, depending on where you are in relation to the earthquake," said Anthony Guarino, a seismic analyst at Caltech. "With this earthquake, we probably wouldn't expect to have anyone feel any significant shaking, more of a rolling motion."
Eyewitness News viewers across the Southland said they felt some sort of movement, including in Newport Beach, Santa Ana, Temecula and Long Beach.
No tsunami warning was issued, and no reports of damage or injuries were reported on the mainland.