San Francisco 4.3 Magnitude Earthquake Shakes Bay Area: Sparking Hayward Fault Concerns?

Liputan6.com, Jakarta The San Francisco Bay Area was struck by a magnitude 4.3 earthquake on Monday, September 22, 2025, shortly before 3:00 a.m. PDT.

The earthquake's epicenter was identified southeast of Berkeley, California, about 2 kilometers from the city, at a depth of approximately 7.8 kilometers.

This was the strongest tremor felt in the Bay Area in three years.

Initially reported as magnitude 4.6, the United States Geological Survey (USGS) later revised the magnitude of the earthquake to 4.3.

The event was followed by several aftershocks, including one with a magnitude of 3.0.

A 4.3 magnitude earthquake struck the San Francisco Bay Area at 2:56 a.m. PDT, startling residents who were sleeping.

The epicenter was strategically located near the University of California, Berkeley campus, precisely around the corner of Dwight Way and Piedmont Avenue.

The relatively shallow depth of the earthquake, approximately 7.8 kilometers, contributed to the shaking being felt quite strongly at the surface.

Although the initial magnitude was reported higher, a final revision by the USGS put the quake's magnitude at 4.3.

The shaking was felt widely, from Berkeley, Oakland, and San Francisco, to Albany, Alameda, San Leandro, Piedmont, Orinda, Lafayette, Walnut Creek, and Richmond.

Reports indicated that shaking was felt as far north as Santa Rosa and Sacramento, and south as Santa Cruz and Salinas.

The immediate impact of the earthquake was mild, with no reports of significant injuries or major infrastructure damage.

However, some businesses reported broken windows and merchandise falling from shelves.

“Things were shaking in our newsroom,” posted Dave Clark, a news anchor for KTVU-TV. “It caught everyone off guard.”

Between 22,000 and 30,000 people reported feeling the earthquake to the USGS, indicating a wide range of impacts.

Following the San Francisco earthquake, the United States Geological Survey (USGS) immediately issued a "green alert" for casualties and economic losses.

The San Francisco Department of Emergency Management (DEM) reported an increase in 911 calls following the earthquake, but no reports of injuries were received.

The Bay Area Rapid Transit (BART) public transportation system briefly operated at limited speeds for track safety inspections, causing delays of up to 20 minutes across the system.

However, BART service returned to normal around noon, demonstrating the effectiveness of emergency response procedures.

“As far as earthquakes go, this is kind of the ones where people feel them, but there’s not a whole lot of impacts to them,” said Brayden Murdock of the National Weather Service in Monterey.

The USGS said the last quake of a similar size near Berkeley was a magnitude 4.4 that hit on Jan. 4, 2018.

This earthquake in the San Francisco Bay Area was not isolated, as it was preceded by a magnitude 2.1 earthquake approximately 17 minutes earlier in the same area.

Two significant aftershocks followed, one magnitude 2.6 in the morning and one magnitude 3.0 in the evening on Monday.

The USGS estimates a 16% risk of aftershocks of magnitude 3 or higher in the next week, and a 2% risk of aftershocks of magnitude 4 or higher.

The chance of aftershocks of magnitude 5.0 or higher in the next week is 0.2%.

This data emphasizes the importance of continued vigilance for Bay Area residents.

This earthquake occurred along the Hayward Fault, which the UC Berkeley Seismological Laboratory considers one of the most dangerous faults in the San Francisco Bay Area.

The Hayward Fault has a 33% chance of rupture in an earthquake of magnitude 6.7 or greater before 2043.

Overall, the Bay Area has a 72% chance of experiencing an earthquake of at least magnitude 6.7 in the same timeframe, reminiscent of the Great San Francisco Earthquake of 1906, which had a magnitude of 7.9 and destroyed much of the city.