A shop is littered with broken walls after the quake in Ridgecrest, California, the United States, July 4, 2019. A 6.4-magnitude earthquake jolted a remote area in the Searles Valley in the U.S. western state of California on Thursday, causing injuries and damage, and so far there has been no report of casualties in Los Angeles downtown and nearby areas. (Xinhua/Qian Weizhong)

by Huang Heng, Tan Jingjing

RIDGECREST, the United States, July 4 (Xinhua) -- A 6.4-magnitude earthquake jolted a remote area in the Searles Valley in the U.S. western state of California on Thursday, causing injuries and damage, and so far there has been no report of casualties in Los Angeles downtown and nearby areas.

The earthquake, with its focus located at a depth of 8.68 km, was the strongest earthquake in Southern California since 1999.

The quake struck at 17:33:48 GMT and was initially determined to be at 35.70 degrees north latitude and 117.51 degrees west longitude, according to the U.S. Geological Survey (USGS).

The nearest city rocked by the quake is Ridgecrest, which has a population of 28,000 and is located about 18 km southwest of the epicenter and 250 km northeast of Los Angeles downtown.

A video clip posted by a twitter user named Zomo about one hour after the quake showed that bottles fell to the ground from the shelf and alcohol liquid splashed everywhere in her father's liquor store in the city.

All shops in Ridgecrest closed after the quake, and some clerks told Xinhua that workers were repairing the damaged structures and cleaning the messy scene.

"In Walmart there's a lot of damage, they have a whole entire cleaning crew there and I saw pictures of it online and it looks like the damage is pretty extensive," Jeremy Burch, a cashier of local Walmart, told Xinhua outside of the supermarket.

"I was staying at home when it happened, then I called immediately to find out what was going on and they told me it's obvious we have to go back stores because for the rest of the day for repairing," said Burch.

Burch said the quake is scary when it happened.

"It is the first time I've ever seen an earthquake like this. ... but today I noticed this one and it really freaked me out. It was an experience that's scary," Burch added.

"When the quake just started, the sound was just like something roaring in my trench, squeezing and cracking, it is hard to describe but it is scary," said the Walmart cashier.

In an interview with CNN, Ridgecrest Mayor Peggy Breeden declared a state of emergency. She said crews were responding to at least five fires across the city and that crews were assessing broken gas lines.

The quake was felt across the Los Angeles region on Thursday morning. Many local residents tweeted that they felt the shakes and steady sways which lasted for almost 30 seconds but not so strong like in 1994, when a 6.7 magnitude earthquake hit Northridge area of Los Angeles and killed at least 57.

"At this time, the LAPD has not received any reports of damage or calls for service within the City of Los Angeles related to the #earthquake. Remember, 911 is only to report emergencies. This was a strong one, and a good reminder to be prepared," the Los Angeles Police Department tweeted about half an hour after the major earthquake.

"Been fully briefed on earthquake in Southern California. All seems to be very much under control!" U.S. President Donald Trump tweeted later.

In San Bernardino County, the quake broke water mains, downed power lines, cracked buildings and caused rock slides on roads, local ABC 7 news channel reported.

The Chinese Consulate General in Los Angeles issued a note after the major earthquake, reminding Chinese citizens to follow information published by the authority to keep safe.

The consulate said it had not received any call asking for help till noon.

A senior manager of Chinese carmaker BYD told Xinhua that workers in the company's Lancaster factory, located 135 km south of the epicenter, felt shakes but did not stop working.

"It looks everything is as good as normal, our engineers are checking," Patrick Duan, vice president of operations for BYD North America, told Xinhua.

Seismologist Dr. Lucy Jones from California Institute of Technology (CalTech) explained at a news conference Thursday noon that the July 4 quakes' damage is limited since the epicenter was in a remote area.

She said that CalTech received a 48-second warning that the quake was coming, however, users of the Shake Alert, an app designed for earthquake alarm to residents, did not receive an alert because the quake in Los Angeles measured only a magnitude of 4.5, which is under the 5.0 threshold required for an alert.

She also said the quake occurred on a strike fault about 16 km from Ridgecrest instead of the San Andreas fault, an area with a lot of faults but not long fault.

The San Andreas Fault, a continental transform fault that forms the tectonic boundary between the Pacific Plate and the North American Plate, extends some 1,300 km through California. Many researches predicted that it could generate a large-scale earthquake in southern California.

However, Jones warned that aftershocks would likely exceed the magnitude of 5, saying: "We will continue to have a lot of aftershocks. I think the chance of having a magnitude 5 ... it's probably greater than 50-50."

Dozens of quakes have been recorded by the USGS near Searles Valley after the major one.