Preliminary estimates show there is a 10% chance of a further magnitude 7 or higher earthquake, according to Lucy Jones, a Seismologist with Caltech.

At an overnight news conference, Jones said aftershocks will continue.

She said the earthquakes that struck near Ridgecrest on Thursday and Friday were part of an ongoing sequence of a "very energetic system," Jones said.

The latest 7.1-magnitude earthquake was the mainshock, while Thursday's 6.4-magnitude quake was a foreshock, according to Jones.

Seismologist Lucy Jones speaks at a media briefing at the Caltech Seismological Laboratory in Pasadena, California. Photo: Robyn Beck / AFP

Officials have also warned about the possibilities of more earthquakes. California Gov. Gavin Newsom said he's activated the state emergency operation center to its highest level.

"The state is coordinating mutual aid to local first responders," he tweeted Friday night.