A 4.7-magnitude earthquake just north of Malibu shook Southern California on Thursday, and was followed by a 3.4-magnitude aftershock about an hour later.
The quake struck at 7:28 a.m. and was felt throughout the region. An earthquake of this magnitude is not expected to cause significant damage. There were at least three aftershocks of magnitude 2. At 8:40 a.m., an aftershock of magnitude 3.4 occurred.
The epicenter of the quake was closest to the Malibu Fault, said seismologist Lucy Jones, a research associate at Caltech. Early analyses suggest the quake had a 40 percent chance of being associated with the Malibu Fault and a 46 percent chance of being associated with the Anacapa Fault.
Earthquakes of this magnitude rupture only a relatively small section of the fault, perhaps on the order of 100 to a few hundred meters. As a result, these modest earthquakes can often occur on small faults that are not associated with much larger, mapped faults on the Earth’s surface.
“Mild” shaking, defined by the modified Mercalli intensity scale, was felt in Malibu, Thousand Oaks, Agoura Hills and Calabasas. The mild shaking rattles dishes, windows and doors, causes walls to creak and can feel like a heavy truck has hit a building.
In Thousand Oaks, one resident reported the shaking lasted a few seconds, while another resident elsewhere felt about 12 seconds of shaking.
“Mild” shaking was felt across much of the Los Angeles metropolitan area, including downtown Los Angeles, Santa Monica, Long Beach, the San Fernando, San Gabriel and Antelope valleys, Orange County and the Inland Empire. Crowdsourced reports indicated shaking was felt as far away as San Diego and Bakersfield.
Residents along the Los Angeles County coastline felt noticeable shaking. Some people in Redondo Beach and Long Beach felt shaking for 10 seconds. In Redondo Beach, one person felt the shaking start gently and then intensify, but nothing fell off the shelves. In Long Beach, one resident felt a jolt and a rolling motion.
Near Los Angeles International Airport, an El Segundo apartment building shook and curtains swayed.
The most noticeable earthquakes have recently occurred in densely populated areas of Southern California. But that doesn’t predict whether a larger, more damaging quake is likely to occur sooner than expected, earthquake experts said.
Over the past 65 years, Jones said, there have been an average of eight to 10 independent earthquake sequences, with at least one of magnitude 4 or greater. Some years, there have been only one or two; the highest number was 13, in 1988. Thursday’s quake is the 14th magnitude 4 and greater quake to hit Southern California this year, Jones said.
“So this is a more active year than previous years,” Jones said. But, she added, “we can’t say yet whether this is statistically significant or not.”
Another earthquake was felt in the Malibu area on February 9. The 4.6 magnitude quake was felt across a wide swath of Southern California.
Thursday’s quake moved horizontally, from side to side, also known as “strike-slip motion,” Jones said. The other type of motion that can be felt in other earthquakes in Southern California is upward motion on a tilting fault.
Some residents were alerted by the state’s early warning system. In Koreatown, residents were notified about two seconds before the tremors arrived. A free earthquake early warning system app, MyShake, is available for download on the iOS and Google Play app stores.
On the C Line (formerly the Green Line) heading west toward Crenshaw Station, cell phones in the cars began beeping, as phones lit up to warn of an earthquake. Passengers reached for their phones or looked around in alarm, but the train sped along, rocking as usual. Despite the instructions on their phones, no one dropped to the ground or sought shelter under their seats. The audible tremors of an earthquake were not audible on the train, which rocked as it moved down the tracks.
Shortly after the earthquake, Los Angeles Mayor Karen Bass said on X that the city’s fire department had begun its routine inspection of the city to assess the damage. All fire stations are currently conducting inspections and no damage has been reported so far, said Margaret Stewart, a spokeswoman for the fire department.
Ventura County reports “no damage or other impacts to infrastructure.”
The quake was centered in the Malibu Hills off Kanan-Dume Road, around Ramirez Canyon.
Times reporters Luke Money, Iliana Limon Romero, Ruben Vives, Richard Winton, Jon Healey and Steve Henson contributed to this report.
