There have been no immediate reports of casualties or damage. Local netizens have shared footage showing apartments in California affected by the powerful jolt.
According to San Bernardino County Fire Department, building damage has been reported amid the earthquake.
"Homes shifted, foundation cracks, retaining walls down," the department said on Twitter.
#BREAKING ANOTHER big aftershock or quake just hit! 1400 so far. Really felt the shaking! #Ridgecrestquake@Caltech@CBSLA@CBSNews#pasadena#earthquake#quake seismologists predicted 6% chance quake bigger than 6 mag would hit in the next few days pic.twitter.com/jnsV72lP6q
— JASMINE VIEL (@jasmineviel) 6 июля 2019 г.
Another One Wow!!!!! #earthquakepic.twitter.com/deDzcDwgOP
— Garry Plummer (@Garryplummer) 6 июля 2019 г.
At least 159 aftershocks of magnitude 2.5 or greater were recorded after the first earthquake, according to USGS. The earlier shaking intensity levels had been predicted for the area and were below damaging levels, hence an alert was not triggered, according to local media reports.
The USGS web site was temporarily unavailable Friday night. Local media suggested that the seismic agency's web site was overwhelmed with requests following the significant temblor.
Prelim M7.1 Earthquake 35.767, -117.605 Jul-06 03:19 UTC, updates https://t.co/uVJBfBodUN
— USGS Big Quakes (@USGSBigQuakes) 6 июля 2019 г.
According to media reports, Thursday's lesser quake provoked at least 20 incidents, ranging from medical assistance to structure fires.