An earthquake struck east of Los Angeles on Tuesday and was felt hundreds of miles south to the Mexican border and east to Las Vegas, but there were no reports of injuries, major structural damage or power outages.
The earthquake hit at 11:42 a.m. local time (1842 GMT) about 30 miles (48 km) east of Los Angeles in the suburban community of Chino Hills, where it rocked residents shortly before their lunch hour.
The temblor was initially measured by the U.S Geological Survey at magnitude 5.8 but was later downgraded to 5.4, which is considered a moderate quake by the agency. It was followed in the next 90 minutes by at least two dozen aftershocks, the largest registering magnitude 3.6.
In downtown Los Angeles, tall buildings swayed for 10 to 15 seconds, sending office workers pouring into the streets and prompting officials to quickly evacuate City Hall.
"It hit pretty hard. We were in the first floor which is just sort of ground level or just below ground level and we were hit pretty hard, it shook pretty good," Los Angeles County Supervisor Zev Yaroslavsky said.
Airports, ports, power grids and nearby nuclear power plants all reported no structural damage or interruption in service.
"America's second-largest city still appears to have sustained little significant damage. However, our residents appear on edge," Los Angeles Fire spokesman Brian Humphrey said.
The last big quake in the Los Angeles area was the 1994 Northridge earthquake, which registered a magnitude 6.7, killed 57 people, collapsed an apartment building and caused considerable damage.
Chino Hills spokeswoman Denise Cattern said the city of 80,000 people had no reports of damage or injuries despite feeling a strong jolt.
"Most people agreed it was the biggest earthquake they ever felt," Cattern said.
'ROCKING AND ROLLING'
A spokesman for the San Bernardino County Sheriff's Office said there were no reports of injuries, although several water mains broke in the area, flooding streets.
James Destefano, city manager in Diamond Bar, which is adjacent to Chino Hills, said pictures and cabinets fell at City Hall.
"We experienced the same effects as everyone in this immediate area," he said. "We were rocking and rolling for about 15 to 20 seconds."
There were no immediate reports of power outages in the area. Phone service remained operational but AT&T reported a sharp spike in calls that left many customers getting busy signals.
Witnesses reported feeling a strong jolt in neighboring Orange County, and reported shaking far south as San Diego and the Mexican border and as far east as Las Vegas and Flagstaff, Arizona.
"In California, fortunately because of our good building standards we would not expect to see structural damage with a (magnitude) 5.4," said Kate Hutton, seismologist at the California Institute of Technology.
Hutton said there was a five percent chance that the quake was a fore-shock to a larger seismic event.
Some 40 miles (64 km) away in Anaheim, workers at Disneyland removed visitors from rides but the world-famous amusement park remained open and rides were resuming.
The quake did not hinder operations on the state's power grid or damage California's two nuclear plants, utility and state officials said.
Magnitude 5 quakes are considered moderate but are still capable of causing damage. The USGS said Tuesday's quake was shallow, about 8.5 miles (13.6 km) deep.
Los Angeles is the most populous city in California and the second-most populous urban area in the United States. According to 2000 Census Bureau figures, about 3.6 million people live in Los Angeles.