A 7.1-magnitude earthquake hit southern California on Friday at 8:19 pm (0319 GMT Saturday), the United States Geological Survey said.
The latest quake is part of what geologists are calling an "earthquake sequence", and follows a 6.4-magnitude quake that struck the same area the day before.
The USGS said the previous day's tremor was a "foreshock" to Friday's quake, with CNN reporting that the latest tremor was 11 times stronger. Residents on the ground said they were feeling aftershocks.
On Thursday, Caltech seismologist, Lucy Jones had warned a press conference, that there was "about a one-in-20 chance that this location will be having an even bigger earthquake within the next few days, that we have not yet seen the biggest earthquake of the sequence."