Magnitude 7.1 earthquake hits Southern California

The powerful magnitude 7.1 earthquake rocked the Mojave Desert town of Ridgecrest south of Death Valley National Park as darkness fell on Friday, jolting the area with eight times more force than a 6.4 quake that struck the same area 34 hours earlier.

California Governor Gavin Newsom requested federal assistance and placed the state Office of Emergency Services (OES) on its highest alert.

"We do know there were a number of injuries, but most of them I would characterise in the minor to moderate level, and no reports of any fatalities, so I think we're very lucky there," OES director Mark Ghilarducci said at a news conference.

Mr Ghilarducci said there were reports of building fires, mostly as a result of gas leaks or gas-line breaks.

State officials said all roads damaged by the quakes had been reopened with crews still assessing the aftermath.

Violent shaking also caused water-main breaks and knocked out power and communications to parts of Ridgecrest, home to about 27,000 people some 200km northeast of Los Angeles.

However, emergency officials say the damage is not as bad as they initially feared, with power restored to most who had lost it and food stores trading again.

Mr Ghilarducci said there was sure to be a significant number of aftershocks, including possible powerful ones, and advised residents to ensure they had necessary supplies.

"We want to make sure that people over the next 24 to 48 hours are prepared and cognisant of what to do should more earthquakes occur," Mr Ghilarducci said.

Overnight the centre of Ridgecrest was quiet, except for the occasional rumble of aftershocks. Some residents could be seen sitting on lawn chairs in the darkness outside. The garage doors of many homes were left open with a car parked on the driveway.

The sprawling United States Naval Air Weapons Station China Lake just northwest of town was evacuated of all non-essential personnel following the quake.

The facility, which at more than 445,000 hectares is larger than the state of Rhode Island, reported no injuries. Authorities were assessing any damage to buildings or other infrastructure, according to a post on the base's Facebook page.

Frequent aftershocks 'scary'

Friday's earthquake was widely felt across Southern California, including greater Los Angeles, where shaking in some areas lasted about 40 seconds. Low-level rumbling extended as far north as the San Francisco Bay area and beyond to Reno, Nevada, and as far east as Phoenix, Arizona.

Seismologists said the initial quake on Thursday, and scores of smaller ones that followed it, proved to be foreshocks to Friday's larger temblor, which now ranks as Southern California's most powerful since a 7.1 quake that struck near a US Marine Corps base in the Mojave Desert in 1999.

The US Geological Survey said the quake was immediately followed by at least 16 aftershocks of magnitude 4 or greater and warned of a 50 percent chance of another magnitude 6 quake in the coming days. Geologists put the chance of another magnitude 7 tremor at 10 percent over the next week.

There had been close to 600 aftershocks of 2.5 magnitude or greater in the area surrounding the epicentre, according to USGS data.

Victor Abdullatif was helping clean up broken bottles and other debris inside his father's liquor store, the Eastridge Market, which sustained damage to its ceiling, and found the periodic aftershocks unnerving.

"They're still scary because you almost don't know, 'Is this going to be a full earthquake?' You have to kind of have faith that it's just an aftershock," he said.

South of Ridgecrest, there were reports of a building collapse and gas leaks in the small town of Trona, home to about 2000 residents, Mr Ghilarducci said.

The last major destructive quake to hit Southern California was the 6.7 magnitude Northridge quake in 1994, which struck a densely populated area of Los Angeles. It killed 57 people and caused billions of dollars in property damage.

The comparatively limited damage from Friday's quake, which packed greater force than the Northridge event, was a function of its location in a remote, less developed area.

Its ground motion, however, startled seismically jaded Southern Californians over a wide region.

Pools in Los Angeles sloshed wildly, and TV cameras at Dodger Stadium were shaking as they filmed the night Major League Baseball game between the Los Angeles Dodgers and San Diego Padres.

A television anchorwoman ducked out of sight during a local newscast as shouts of "get under a desk" were heard in the background.

The San Bernadino County Fire Department reported that the quake had caused some damage to buildings.

"Homes shifted, foundation cracks, retaining walls down," the department said on Twitter. "One injury (minor) with firefighters treating patient. No unmet needs currently."

#Earthquake(Update): 911 calls coming in from NW communities of #SBCounty. Homes shifted, foundation cracks, retaining walls down. One injury (minor) with firefighters treating patient. No unmet needs currently. ^eas

— SB County Fire (@SBCOUNTYFIRE) July 6, 2019

Luke Smith, owner of Furys Sports Bar in Ridgecrest, said in a phone interview that the quake shook tiles from the interior ceiling, slightly damaging his bar and knocking down some bottles. Three customers were in the bar at the time but no one was injured, he said.

The Office of Emergency Services gave a media briefing after the earthquake.

- Reuters / BBC