RIDGECREST, Calif. — The second major Southern California earthquake in two days hit the area of Ridgecrest Friday night.

The United States Geological Survey initially reported it as a 7.1 magnitude earthquake at 8:19 p.m. with an updated magnitude of 6.9 immediately after. It has again returned to the initial report of 7.1.

Overnight from Sunday into Monday, Ridgecrest experienced 11 small earthquakes with a magnitude of 3, according to the USGS. The highest magnitude aftershock was a 3.7 at 1:20 a.m. on Monday.

On Monday, President Donald Trump declared an emergency for California. Federal aid will be allocated to help the areas that were impacted by the earthquakes and numerous aftershocks.

According to the Kern County Fire Department, crews responded to calls for service, ordered additional resources in the area affected, and activated the Emergency Operations Center. 

The Ridgecrest area is approximately 150 miles northeast of Los Angeles. The earthquake was also felt in Las Vegas.

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Thursday morning, a 6.4 magnitude earthquake hit the region just after 10:30 a.m. 

"This is the same sequence," tweeted seismologist Dr. Lucy Jones. "You know we say 1 in 20 chance that an earthquake will be followed by something bigger? This is that 1 in 20 time."

The earthquake Thursday was immediately followed by three aftershocks with a 4.7 magnitude and 3.5 in the Ridgecrest-area, as well as a 4.2 magnitude in Searles Valley at 11:30 a.m.

A total of 40 aftershocks were counted by USGS as of 12 p.m. Thursday.

"Yes, we estimate that there's about a 1 in 10 chance that Searles Valley will see another M7. That is a 9 in 10 chance that tonight's M7.1 was the largest," tweeted Jones.