RIDGECREST (California) • A strong aftershock shook Southern California early yesterday even as residents were still assessing the damage from a quake a day earlier that was the strongest to hit the region in 25 years.
The temblor, one of many aftershocks predicted by seismologists, struck the same desert region as Thursday's major earthquake with a magnitude of 5.4 about 18km west of Searles Valley at 4.07am local time, the US Geological Survey said.
There had already been more than 80 smaller aftershocks since Thursday's 6.4-magnitude quake near the small desert city of Ridgecrest, which was felt by more than 20 million people from Los Angeles to Las Vegas, USGS seismologist Lucy Jones said. "We should be expecting lots of aftershocks and some of them will be bigger than the (magnitude) 3s we've been having so far," Dr Jones told a news conference. "I think the chance of having a magnitude 5... is probably greater than 50-50," she said.
The initial quake hit the edge of Death Valley National Park about 182km north-east of Los Angeles at about 10.30am on Thursday. It was very shallow, only 10.7km deep, amplifying its effect.
But while it hit a largely sparsely populated area, it was felt throughout Los Angeles, as far north as Fresno, and as far east as Las Vegas on a day when the US celebrated its July 4 Independence Day.
The European quake agency EMSC said the quake shook an area inhabited by 20 million people.
Los Angeles Mayor Eric Garcetti said there was no significant damage there, while the city's international airport said operations continued as normal.
In Ridgecrest, grocery store aisles were littered with smashed bottles, jars and packages.
"I mopped up over 20 gallons (75 litres) of wine that fell over, in addition to the beer, soda (soft drinks) and the cooler that fell over. We have several thousand dollars worth of damage," said shopkeeper James Wilhorn.
Only a few injuries were reported, and two houses caught fire from broken gas pipes, officials said.
Water gushed up from zigzagged cracks in the pavement from busted pipes. Deep fissures snaked across the Mojave Desert, with passers-by stopping to take selfies while standing in the rendered earth.
Although the quake revived fears of the "Big One" - a powerful temblor along the San Andreas Fault that could devastate major cities in Southern California - President Donald Trump was quick to reassure that this was not it. "All seems to be very much under control!" he tweeted two hours after the quake.
The San Bernardino County Fire Department, meanwhile, said that "buildings and roads have sustained varying degrees of damage". This included "buildings with minor cracks, broken water mains, power lines down, rock slides on certain roads".
The Ridgecrest Regional Hospital, where 15 patients were evacuated earlier, appeared intact apart from some new cracks in the walls.
California Governor Gavin Newsom approved an emergency proclamation, and Ridgecrest Mayor Peggy Breeden said she had declared a state of emergency, a step that enables the town to receive help from outside agencies.
Mayor Breeden said she has asked residents to check on their neighbours in the high desert town.
"We're a close-knit community and everybody is working to take care of each other," she told Reuters by telephone.
The quake is the largest in Southern California since the 1994 magnitude-6.6 Northridge earthquake, USGS geophysicist Paul Caruso said. That quake, which was centred in a heavily populated area of Los Angeles, killed 57 people and caused billions of dollars of damage.
REUTERS, AGENCE FRANCE-PRESSE