6.4 earthquake rattles Southern California followed by over 30 aftershocks

Southern California was rocked by a magnitude 6.4 earthquake that jolted the Mojave Desert and was widely felt around the region as many prepared to celebrate Independence Day on Thursday.

The temblor hit at 10:35 a.m. and centered about 7 miles southwest Searles Valley, roughly 11 miles east-northeast of Ridgecrest, 109 miles north of San Bernardino and 121 miles north-northeast of Los Angeles, according to the U.S. Geological Survey.

It had a preliminary magnitude of 6.6 before being downgraded.

The “main” quake was proceeded by magnitude 4.2 temblor that shook the area approximately 30 minutes before the large quake, seismologist Lucy Jones tweeted, calling the earlier tremor a foreshock.

A short time after the 6.4 earthquake, aftershocks measuring 4.7, 4.2, 3.8 and 3.5 hit the same area, USGS reported.

Experts warned that more seismic activity is expected throughout the day.

“The #Ridgecrest earthquake is having a robust aftershock sequence. There have been 6 M4+ events and ~30 M3+ in the first 90 minutes,” Jones tweeted. “That means there will be plenty more aftershocks today.”

At a news conference, she said there was a slight chance — about one in 20 — of an even larger quake in the same area within the next few days.

Most likely, there were be an aftershock of magnitude 5 or greater.

“When the probabilities are this high, then you can say, yes, there will probably be a magnitude 5 today,” Jones said.

The quake’s epicenter was within the sprawling Naval Air Warfare Center Weapons Division at China Lake, where a desert test range is located.

The quake was not on the major San Andreas fault but on strikeslip fault in “an area with a lot of little faults but no long fault,” famed seismologist Lucy Jones said on Twitter.

The area had a lot of quakes larger than magnitude 5.0 in the 1980s, she added.

“The chance of having a magnitude 5 [in the area] … is probably greater than 50-50,” Jones said, stressing it was just an off-the-top guess. “Sometime this afternoon, we’re going to be having a larger aftershock within this sequence.”

Thursday’s shaking, which registered in the Los Angeles area as a long, rolling motion, and lasted for at least 20 seconds. It was felt in areas as far as Sacramento, Reno, Las Vegas and Tijuana, according to USGS’s website.

No injuries were immediately reported anywhere, but there appeared to be somewhat extensive damage in parts of Southern California from the quake.

Firefighters battle a house fire in Ridgecrest, California.

The San Bernardino County Fire Department tweeted that buildings and roads have been damaged in Trona, a remote community located about 10 miles northeast of Ridgecrest.

In other northwest areas of the county, some building were found to have minor cracks, according to the Fire Department. There were also broken water mains, downed power lines and rock slides on some roads due to the incident.

In Ridgecrest, which has a population of about 29,000, the Kern County Fire Department was responding to nearly two dozen incidents, everything from structure fires to medical assistance, officials said. Search and rescue teams have been dispatched to the area.

The Ridgecrest Regional Hospital was evacuated early in the afternoon, according to Kern County fire officials.

No damages were immediately reported in the Los Angeles area, though the city’s Fire Department went on earthquake mode in the wake of the temblor.

Thursday’s earthquake was the largest to hit Southern California in nearly 20 years, when a magnitude 7.1 quake struck the Hector Mine area, nearly 50 miles east-southeast of Barstow, in October 1999, according to Jones.

And it was the second largest in the region since the catastrophic 6.6 Northridge quake devastated the region in 1994, killing dozens of people and causing billions of dollars in damages.