A 4.7 magnitude earthquake rocked the Southern California coastal city of Malibu at about 7:30 a.m. Sept. 12, the United States Geological Survey (USGS) reported.

The earthquake was centered about 5 miles north of the city, according to the USGS.

Initial estimates registered the quake at a magnitude of 5.1, but it was downgraded as more information was collected by the USGS.

No tsunami was expected from the earthquake, according to the National Weather Service.

Early reports from residents indicated slight shaking of homes and buildings in the town favored by celebrities.

California’s ShakeAlert system, an early earthquake warning system, was activated, alerting millions of residents in Los Angeles County and other areas.

The Los Angeles Fire Department immediately went into “earthquake mode” following the morning temblor, sending out personnel from all 106 of the county’s fire stations to survey the region by land, air, and sea, the department reported.

Fire crews examined infrastructure and other areas of concern, but found no significant damage.

“There are currently no initial reports of structural damage or injuries,” LAFD said in a social media post.

The department completed the assessment by 8:30 a.m.

Local earthquake guru Dr. Lucy Jones, a seismologist in Los Angeles County, said there have been over a dozen earthquakes larger than 4.0 magnitude in the Malibu area this year.

Brian Olson, a California geologist and earthquake hazard scientist in Orange County, said seismic instruments recorded ground movement from the Malibu quake was strongest at Lake Sherwood in Thousand Oaks and Agoura Hills, about 14 miles north of Malibu.

A series of aftershocks, some reaching 3.4 in magnitude, struck the Malibu area throughout the day.

Resident Susan Grant said the quake caused significant shaking.

“That earthquake was the scariest since Northridge!” she wrote on social media platform X. “Not the rolling kind but more like a violent shaking!”

Southern California residents felt the earthquake as far away as Anaheim, according to the city.

Ventura County residents near the quake’s center also experienced the shaking, prompting some officials to warn residents to prepare for future earthquakes.

“Be ready, have a plan,” Ventura County’s sheriff wrote on X.