A 4.7-magnitude earthquake Monday shook buildings in Los Angeles, with US seismologists saying it was the strongest to hit the area since 2010, but there were no reports of damage or casualties.
The epicenter of the quake was some 11 miles (19 kilometers) southeast of Anza, California -- about 100 miles southeast of Los Angeles -- and was felt in San Diego, two hours' drive down the coast from LA.
The temblor revived usually below-the-surface fears of the Big One in California, which is overdue for a massive earthquake.
The quake shook buildings including one housing AFP's offices in Hollywood, northwest of downtown. But there were no immediate reports of people being hurt or property being damaged, according to the Los Angeles Times or other media.
Former tennis world number one Rafael Nadal, who was playing at the Indian Wells tournament near Palm Springs -- about 30 miles (50 km) from the epicenter -- said he was frightened.
"I was very scared. First time in my life," said Nadal, adding he was so alarmed to feel a massage table move beneath him his legs were shaking when he got up.
Angelique Kerber, the women's fourth seed from Germany, was talking with her coach outdoors when things began to shake. "In the first moment we both were thinking, you know, it's like a subway here.
"But actually we are in the desert. No way that there is a subway. That was my first one," she said.
One reporter covering the tennis tournament reported water "sloshing" around in his hotel swimming pool.
The USGS initially put the magnitude of the quake at 5.1, but later downgraded it to 4.7.
It was still the strongest quake in the LA metropolis since since 2010.
"It's been three years since we had anything this size this close to Los Angeles," said USGS seismologist Susan Hough.
The quake on a secondary fault of the San Jacinto fault was followed by more than 100 small aftershocks, most of them smaller than 2.5 in magnitude, said the USGS.
Los Angeles is on the so-called "Ring of Fire," which circles the Pacific and has produced a number of devastating earthquakes, including Japan's March 2011 quake and tsunami, which killed thousands of people.
While major quakes in recent years have shaken Japan, Indonesia, Chile, New Zealand and Mexico, the US West Coast has been spared.