A noticeable 3.6-magnitude earthquake occurred on Thursday at 12:41 PM, with its epicenter located two miles southeast of Vallejo. According to the US Geological Survey, this earthquake elicited mild shaking that was felt in San Francisco, the East Bay, and various areas in the North Bay.
The temblor appears to have occurred along the Southampton Fault, which is recognized as a northern extension of the Calaveras Fault. This particular fault runs beneath the East Bay and stretches down to Hollister, situated just east of the more well-known Hayward Fault.
Interestingly, just days prior to this earthquake, a swarm of smaller quakes rattled the region along the Calaveras Fault, the most significant of which registered at 3.8 magnitudes. The Calaveras Fault is known for having the potential to generate larger earthquakes, with estimates suggesting it could produce quakes around 6.7 magnitudes.
Mapping the complexities of the Bay Area’s geological structure, the Southampton Fault is marked in yellow on a fault map as number 11. It intersects with the Franklin Fault, which connects to the Calaveras Fault and lies directly beneath Vallejo.
Experts warn that interconnected faults might trigger larger seismic activities together, heightening the concern for the region. A study conducted nearly a decade ago highlighted the interconnectivity of the Rodgers Creek and Hayward faults, indicating that they could jointly induce a quake across a stretch of 115 miles.
The recent activity serves as a reminder of the active seismic nature of the Bay Area and the importance of preparedness in the face of potential larger earthquakes in the future.