A 7.1 magnitude earthquake has rattled parts of Southern California, US meteorologists say, in the biggest tremor to strike in two decades.

It struck at the shallow depth of 0.9km (0.6 miles) and its epicentre was near the city of Ridgecrest, about 240km north-east of Los Angeles.

A 6.4 magnitude quake hit the same region on Thursday at a depth of nearly 11km.

Seismologist Dr Lucy Jones said the quakes could continue.

"This is an earthquake sequence," she said at a press conference. "It will be ongoing."