Malibu, California, known for its stretches of beaches and multimillion-dollar mansions, has recently become a seismic hot spot. The latest tremors — a 2.8 magnitude quake on September 28 and a 3.1 magnitude quake the following day — come on the heels of a significant 4.7 magnitude earthquake that rattled the area just weeks earlier, according to the USGS.
Malibu sits alongside the Malibu Coast Fault, a north-dipping reverse fault that runs parallel to Malibu and Pacific Palisades. Mark L. Benthien, the director for communication, education and outreach for the Southern California Earthquake Center, said that while there has been an uptick in Malibu earthquakes, the city does not sit on a major fault and will not experience mass devastation.
“You have to have a longer or greater surface area on a fault to have a larger earthquake. You can’t have a magnitude eight on a small, little local fault,” Benthien explained. “And the faults that these Malibu earthquakes were near, probably the largest earthquake that it could have would be a 7.0 or so.”
John Vidale, a USC professor of earth sciences and the former director of the Pacific Northwest Seismic Network, noted that the recent uptick in earthquakes around Malibu can largely be classified as aftershocks of the larger 4.7 quake.
“There’s sort of a swarm of earthquakes happening there under Malibu,” the expert on seismic hazards explained.
While this increase in aftershocks is noteworthy, Vidale reassured that the overall risk level remains low and doesn’t imply an imminent “big one” is coming. Benthien echoed these sentiments, highlighting that while there are many faults capable of producing large earthquakes, the recent activity does not statistically indicate an increased risk.
“We don’t expect that these earthquakes are increasing the chance of anything or decreasing the chance of anything,” he said.
Instead, Benithen said these earthquakes mark a return to normal seismic behavior after periods of relative calm.
Students at USC are feeling the effects of the recent earthquakes, despite the 30-mile distance. Ricca Yip, a sophomore from Toronto studying public policy, was sleeping when the 4.7 magnitude earthquake hit Malibu.
“I thought I fell off the bed, but I actually thought I dreamed it. We were all like, ‘did you feel that last night? Or was I crazy?,’” Yip said.
Meanwhile, Jose Shaji, a graduate student studying aerospace engineering, reported feeling the ground shake in his Torrance home.
“It was pretty significant,” Shaji said. “I felt the floor move, and my windows rattled.”
Despite the university’s efforts to educate students on earthquake response, students’ awareness of safety protocols varies. Benthien emphasized the importance of participating in drills and other trainings.
“We encourage students to participate in drills to practice drop, cover and hold on. It’s crucial for everyone to be informed and prepared.”
The university is proactive in preparing for seismic events. Benthien praised USC’s earthquake safety measures, including building retrofits and the university’s involvement in the annual Great ShakeOut earthquake drill, which will take place on October 17th this year.
“USC takes earthquake safety very seriously. They have high standards for the buildings being built and continuously assess their safety protocols,” Benthien said.
Despite these measures, five USC buildings still need retrofits, according to the LA Times. Vidale, who has been working at USC since 2017, said old brick buildings pose the greatest danger.
“People in doubtful buildings maybe should be checking into their homes or where they work if there’s not modern construction,” he added.
University preparedness is just one aspect of ensuring students’ safety during seismic events. The state’s first-in-the-nation Earthquake Early Warning System is a new tool that alerts residents to these tremors through the MyShake app. Gov. Gavin Newsom emphasized its importance, saying “Thanks to our Earthquake Early Warning System, millions of people in Southern California received alerts on their mobile phones when shaking began, giving them vital seconds to drop, cover and hold on.”
To help residents prepare for seismic activity, experts recommend several steps, including securing heavy items in homes and establishing communication plans in case of emergencies. The Earthquake Country Alliance recommends its comprehensive guide to earthquake safety which outlines key actions during an earthquake.
Vidale stressed the importance of planning and staying informed, especially about the fault system and earthquake patterns.
“Another thing is to have some supplies, to have some drinking water and to have communication arrangements in case the phone system goes out… So just be prepared — transit arrangements and supplies,” Vidale said.
The recent uptick in earthquakes serves as a reminder that preparedness is not just a protocol, but a vital practice for safety in this seismically active state.
“Stay down and remain vigilant. You never know when the next tremor might hit,” Benthien said.