The San Andreas Fault is the largest fault in the state of California- and it happens to run right through San Juan Bautista. Local geologist Bob Barminski said fault lines across the state are connected like a spider web.
"Movement on one probably influences movement on another section of the fault. We could be entering a period of heighten seismicity,” said Barminski.
However, unlike the San Andreas Fault, not much is known about the smaller faults that shook Napa County early Sunday.
"These smaller earthquake faults are capable of triggering larger earthquakes like we saw today in Napa. And we have similar faults in our area of Salinas, Central Coast, all the way down to the San Luis Obispo area,” said Barminski.
Barminski said more shaking is probably on the way for the Napa area. He said aftershocks there will continue to occur over the next few days.
"There's been numerous aftershocks already. I think the largest was 3.6, according to the United States Geological Survey,” said Barminski.
This is the largest earthquake to hit the San Francisco Bay Area since the 1989 Loma Prieta earthquake. Experts say everyone in California should be on alert- and let this incident serve as a reminder to always be prepared.