Californians have been spooked by a 5.4 magnitude earthquake that's again raised fears of the long-awaited Big One.
Buildings rumbled, windows rattled and bottles flew off supermarket shelves from Los Angeles to San Diego, when the quake struck about 50 kilometres east of Los Angeles just before midday LA time.
Emergency services say they appear to have dodged a bullet, with no reports of serious injuries or damage.
California Governor Aronld Schwarzenegger says it's a reminder that in California they have to be prepared for anything and everything.
Locals have told of running for cover after the jolt they say seemed to go on for a long time.
Near the epicentre in Chino Hills, 29-year-old office worker Margarita Melo says everything was spinning and she kept wondering when it was going to end.
Truck driver Robert Rosales says he was all shook up, and at Anaheim, south of LA, Jerome Howard says the jolt was so violent he felt his house twist and he fell out of his chair.
A council meeting at City Hall was rudely interrupted by the tremor and many Californians reached for their mobile phones, immediately maxing out phone services.
The quake even affected veteran reality court show Judge Judy, which was filming at the time. (See video)
Geologists have warned that an earthquake capable of causing widespread destruction is 99 per cent certain of hitting California within the next 30 years.
