There were no immediate reports of damage or injuries. The earthquake was felt in Long Beach and as far away as Simi Valley and Escondido.
The minor earthquake was centered in Rossmoor.
If the preliminary magnitude is correct, it would be the largest Southern California quake in 20 years.
The epicenter was in Searles Valley, which is about 192 miles from Long Beach.
The first temblor struck at 3:47 a.m. at a depth of 4.3 miles, its epicenter about 38 miles south-southwest of Avalon. The second was around 7:30 a.m.
There were no immediate reports of damage, though several people reported feeling the earthquake.
At least two earthquakes—one of them capable of causing moderate damage—rocked an area of Riverside County near Banning today and was felt in Los Angeles about 90 miles from the epicenter.
A strong earthquake centered off the Ventura County coast rocked parts of the Southland today, swaying buildings in a wide area stretching from Woodland Hills to West Los Angeles to Burbank.
The ground was moving in Long Beach Thursday afternoon, thanks to a small earthquake near Naples Island.
One of the many fears from earthquakes is never knowing when these natural hazards will happen or how disastrous the impacts can be.