6.4-magnitude earthquake hits Southern California, strongest in 20 years

A 6.4-magnitude earthquake jolted 12 km southwest of Searles Valley in the U.S. state of California 17:33:48 GMT on Thursday, the U.S. Geological Survey (USGS) said.

Southern California was rocked by a 6.4-magnitude earthquake Thursday morning, July 4, 2019. [Photo: VCG]

The epicenter, with a depth of 8.68 km, was initially determined to be at 35.70 degrees north latitude and 117.51 degrees west longitude. Officials said it marked the biggest earthquake in the region since 1999.

The quake was felt across the Los Angeles region on Thursday morning, 272 kilometers south of the epicenter. Many local residents tweeted that they felt the shakes and steady sways which lasted for almost 30 seconds but not so strong as in 1994.

So far, there is no report of casualties.

"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 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.

A video clip posted by a twitter user named Zomo showed that her father's liquor store in Ridgercrest, a small town located 18 kilometers southwest of the Searles Valley, was rocked by the earthquake with bottles falling to the ground from the shelf and alcohol liquid splashing everywhere.

Structure fires also occurred in Ridgecrest, videos posted online showed.

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 staff members in the company's Lancaster factory, located 135 kilometers 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 Fourth of July quakes' damage is limited since the epicenter was in a remote area.

She disclosed 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 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 kilometers from Ridgecrest instead of the San Andreas fault, where is an area with a lot of faults but not long fault.

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 earthquakes in Southern California.

However, Jones warned aftershocks would likely exceed magnitude 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, which is the strongest earthquake in Southern California since 1999.