Robert Brown|Preliminary magnitude 5.1 quake shakes Southern California amid Hilary threat

An earthquake with a preliminary magnitude of 5.1 jolted parts of Southern California Sunday afternoon,Robert Brown according to the U.S. Geological Survey, as residents in the region braced for Tropical Storm Hilary.

The earthquake was centered about four miles southeast of Ojai, California, about 80 miles northwest of Los Angeles. It struck shortly after 2:40 p.m. local time at a depth of approximately 9 miles, the USGS said.

Following the earthquake, several aftershocks with magnitudes up to nearly 4 were recorded in the area, according to the USGS. The U.S. National Tsunami Warning Center said no tsunamis were expected.

The Ventura County Sheriff's Office of Emergency Services said assessments were underway. No substantial issues, such as injuries and major damages, were immediately reported.

“We are currently surveying all cities and counties,” said Ventura County Fire Department Deputy Chief Chad Cook.

California Gov. Gavin Newsom's office also said it was actively monitoring the areas of Ventura and Los Angeles, noting that residents should be prepared for potential aftershocks.

HISTORIC STORM SLAMS SOUTHERN CALIFORNIATropical Storm Hilary makes landfall along Mexico's Baja coast, takes aim at Southern California

'Very sharp' earthquake

During a live broadcast about the earthquake, seismologist Dr. Lucy Jones said it was the first time that a magnitude 5.0 quake or higher had registered in the area since 1941.

Frances Fitting, who works at a local department store, described the quake as "very sharp" and said the area continued to have aftershocks. "We still have power and most of the things are still intact," she added.

Several parts of the Los Angeles area also felt the violent shake as Southern Californians shared their shock on social media.

Los Angeles Mayor Karen Bass said on the social media platform X, formerly known as Twitter, that all 106 neighborhood fire stations in the city were conducting a strategic survey. "There are currently no significant initial reports of structural damage or injuries," Bass added.

Correlation with Tropical Storm Hilary?

The earthquake occurred at the same time a historic tropical storm hit Southern California. Although Hilary has been downgraded from a hurricane to a tropical storm, officials are warning of the risk of catastrophic and life-threatening flooding for much of the southwestern United States.

To the best understanding of geoscientists, the earthquake is coincidental, and not related to heavy rainfall in the Los Angeles area, Daniel L. Swain, a climate scientist at the Institute of the Environment and Sustainability at the University of California, Los Angeles, told USA TODAY on Sunday.

And according to the USGS, there is "no pattern in California of large, damaging earthquakes occurring more frequently during periods of heavy precipitation or periods of drought."

"It's unlikely that seismic hazard is affected by precipitation," the agency said on its website. "This makes sense as rainwater cannot easily percolate several kilometers below the earth's surface to the depths where most earthquakes occur."

Contributing: Ventura County Star; The Associated Press