Updated on 09/22/2025 at 7:10am PDT
Published on 09/22/2025 at 3:15am PDT
A magnitude 4.3 earthquake jolted the San Francisco Bay Area from sleep early Monday morning, with its epicenter located in Berkeley's Elmwood neighborhood at the intersection of Dwight Way and Piedmont Avenue. The temblor struck at 2:56 a.m. Pacific Time and was initially reported as a 4.6 magnitude before being downgraded, making it the strongest earthquake felt in the Bay Area since October 2022 and ranking among the 50 largest earthquakes the region has experienced since the Great 1906 San Francisco earthquake.
The earthquake triggered the region's ShakeAlert early warning system, sending alerts to smartphones across Northern California. More than 22,000 residents reported feeling the quake to the U.S. Geological Survey within hours, with shaking felt from Salinas in the south to Santa Rosa in the north and as far east as Stockton, according to SFGATE.
Largest Bay Area Earthquake in Nearly Three Years
This morning's earthquake represents the most significant seismic event to hit the San Francisco Bay Area since the magnitude 5.1 earthquake that struck east of San Jose on October 25, 2022. The 4.3 magnitude quake ranks as the largest earthquake centered directly in Berkeley in recent memory, with its epicenter just blocks from the UC Berkeley campus.
To put this earthquake in historical perspective, it's the approximately 15th largest earthquake to affect the Bay Area since the devastating 6.9 magnitude Loma Prieta earthquake of 1989, and roughly the 50th largest since the great 7.9 magnitude San Francisco earthquake of 1906. The Berkeley Scanner noted that there have been just seven other earthquakes in or near Berkeley since January 1, 2023, making today's event particularly significant for the East Bay community.
Hayward Fault Activity Suspected
While seismologists have not yet officially confirmed which fault produced this morning's earthquake, its location strongly suggests activity along the notorious Hayward Fault system. KTVU reported that the earthquake was located along the Hayward Fault, with its epicenter near The Claremont Hotel, which straddles the Berkeley-Oakland border.
The Hayward Fault runs directly through the UC Berkeley campus, passing underneath Memorial Stadium. UC Berkeley Seismological Lab research indicates that the Hayward Fault has a 33% chance of rupturing in a magnitude 6.7 earthquake or greater before 2043, making it one of the most closely watched fault systems in California.
Widespread Impact Across the Region
The earthquake's moderate magnitude and shallow depth of approximately 4.8 miles meant that shaking was felt across multiple Bay Area counties. ABC7 reported that USGS Seismologist Sarah Minson characterized this as a small earthquake, despite the widespread shaking that woke people throughout the region.
"Shaking is variable and it depends a lot on your location, what kind of building you're in, what kind of land you're standing on," Minson told ABC7. Many residents described the shaking as lasting approximately five seconds, with some on social media calling it "terrifying" and noting they could "still feel the shaking in my bones."
Transportation and Infrastructure Response
While no major damage was reported, the earthquake prompted safety protocols across regional transportation systems. BART announced that trains would run at reduced speeds while engineers completed safety inspections of the tracks, with commuters advised to expect 20-minute delays throughout the morning.
Emergency services across the Bay Area conducted routine post-earthquake assessments, with Berkeley emergency dispatch reporting no immediate local reports of major injury or damage. The earthquake occurred at a depth that, while widely felt, was not strong enough to cause structural damage to buildings designed to modern seismic codes.
Historical Context and Preparedness
This morning's earthquake serves as a reminder of the Bay Area's seismic reality. According to SPUR, the region has a 51% chance of experiencing a magnitude 7.0 earthquake in the next 30 years, and about $80 billion has been invested in earthquake preparedness since the 1989 Loma Prieta earthquake.
The MyShake earthquake early warning app, developed by UC Berkeley and deployed statewide, proved effective for this moderate-magnitude earthquake. Cal OES announced in December 2024 that the app had notified more than 500,000 people following recent earthquakes.
Regional Preparedness Reminder
Seismologists emphasize that today's earthquake, while notable as the largest in nearly three years, represents the kind of moderate seismic activity that Bay Area residents should expect periodically. Historical records from UC Berkeley show that the Hayward Fault last produced a major earthquake in 1868, with scientists estimating that major earthquakes occur along this fault approximately every 138 years on average.
Residents are encouraged to download the MyShake app, secure heavy items in their homes, and maintain emergency supplies including water, food, and first aid materials. Today's earthquake serves as a valuable wake-up call for earthquake preparedness in a region where the next "Big One" is not a matter of if, but when.
