A man looks into a fissure that opened in the desert during a powerful earthquake that struck Southern California, near the city of Ridgecrest

A man looks into a fissure that opened in the desert during a powerful earthquake that struck Southern California, near the city of Ridgecrest, Calif., on Thursday.

California is being rattled by a “swarm” of aftershocks after a 6.4 magnitude earthquake hit during the Fourth of July holiday, the largest the state has experienced in several years.

A 5.4 magnitude aftershock hit the Searles Valley area in the predawn hours on Friday morning, according to the U.S. Geological Survey — strong enough to be felt by communities still shaken from the previous day’s earthquake.

The aftershock was felt in Los Angeles, about 150 miles southwest. The city’s fire department said it had received no immediate reports of damage. The Searles Valley area is between the southern parts of Sequoia and Death Valley national parks.

Aftershocks typically follow larger quakes, and tremors linked to the Independence Day earthquake would probably continue for several days, USGS geophysicist Paul Caruso told The Washington Post. Dozens of smaller aftershocks have struck in the wake of Thursday’s main seismic event, but the USGS forecasts only a very slight chance of any of these tremors matching or exceeding the strength of the original quake.

On Friday, Gov. Gavin Newsom tweeted that officials continued to monitor aftershocks. He approved an emergency proclamation on Thursday evening, and the state’s office of emergency services said it would be supporting the region with fire and rescue resources as it experiences a “swarm of earthquakes.”

The first large shock hit near Ridgecrest at 10:33 a.m. PDT Thursday, ending California’s years-long respite from large quakes. Authorities reported no serious injuries or deaths, though emergency responders throughout the region answered calls for a handful of fires, cracked roads and minor injuries.

Ridgecrest Mayor Peggy Breeden told CNN on Friday that while no deaths had been reported, assessing the damage “is going to take a little bit of time.” She shot down reports that the city had water issues, noting that it was receiving a supply from the water district for the nearby city of Indian Wells.

Breeden said she had “heard from the White House” and that Newsom’s emergency declaration freed funds for emergency services to assist her small city.

Meanwhile, residents had to deal with power failures and damaged infrastructure, while store owners faced daunting cleanups after their products flew off the shelves. Ridgecrest declared a state of emergency and officials evacuated the hospital as a precaution. The local library asked residents for help picking up the books that had been strewn about the building.

The Red Cross set up evacuation centers in Ridgecrest, a local ABC affiliate reported, and was housing 16 guests at an area shelter.

Christina Sanders of Trona, a small town eight miles from the epicenter, told the Los Angeles Times that the earthquake had left her house looking like “a tornado went through there and tore it up.” A pipe had burst, flooding the residence with two feet of water, and items were thrown from the shelves and refrigerator. Several of her neighbors lost power.

The July 4 quake was a “strike-slip,” in which two sides of a fault slide past each other and generate horizontal movement. The shallow quake originated 5.4 miles below the surface, meaning its impact would be felt strongly by people living above.

The earthquake was not on the San Andreas Fault but on one of a large system of associated faults.

California has experienced a handful of earthquakes of similar or greater strength in recent years, according to the USGS, including a magnitude-7.1 quake that hit a remote part of the Mojave Desert near Twentynine Palms in 1999. A 7.2-magnitude earthquake that shook Baja California on Easter Sunday in 2010 was so strong that it was felt throughout Southern California and shifted the earth’s crust by up to 10 feet in Mexico.

Had Thursday’s Searles Valley earthquake quake struck in a more populous area of the state, such as Los Angeles or San Francisco, it could have caused catastrophic damage and deaths, Caruso of the USGS told The Post.

Thursday’s earthquake should jolt people out of any sense of complacency about earthquakes, said Mark Benthien of the Southern California Earthquake Center, which has published a seven-step guide for earthquake preparedness. Though seismic technology has advanced over the years, and the Shake Alert app can provide West Coast residents with a crucial warning about impending earthquakes, it is still nearly impossible to know when the next big one will strike.

“We can have larger earthquakes right underneath Los Angeles at any time,” he told The Post. “We do need to be prepared and know what to do.”