San Ramon has been hit by multiple quakes over the past four days, including magnitudes 2.9, 2.3, and 2.2 on December 13, a 2.8-magnitude quake on December 14 and 2.4 and 2.1 on December 15. There were dozens of other smaller tremors. Read More | San Jose earthquake: Massive jolt in California; tremors in Hollister, Salinas and Dublin

A swarm of at least six earthquakes reaching up to magnitude 2.9 rattled San Ramon near San Francisco, the U.S. Geological Survey reports. The other quakes in the Saturday, Dec. 13, swarm ranged from magnitude 1.3 to 2.3, according to the USGS.

California's seismic risk is increasing with supershear earthquakes, which are faster and more destructive than typical earthquakes.

On Monday morning, around 30 minor earthquakes erupted in a swarm near the Geysers geothermal field south of Clear Lake. The day before, seven quakes rattled Sonoma County, including a 4.0 quake. The recent uptick isn’t out of the ordinary, according to U.S. Geological Survey seismologist Susan Hough.

Major quakes in Japan and Alaska along with a spate of smaller earthquakes in California this fall make folks ask, is the Big One near?

A shake alert went out over the U.S. Geological Survey's early warning system on Dec. 4, warning that a 5.9 earthquake near Carson City in western Nevada could produce heavy shaking in the region. But moments later, the survey announced the alert, which was sent to people as far west as San Francisco, was a false alarm.

We all know the San Andreas Fault is out there. Californians first learn about the looming underground threat during childhood earthquake drills and geology lessons, before growing into anxious adults clicking on headlines about when the next "Big One" could strike along the infamous fault.

A minor, 3.1-magnitude earthquake struck in Southern California on Thursday, according to the United States Geological Survey. The temblor happened at 10:27 a.m. Pacific time about 8 miles northwest of Fillmore, Calif., data from the agency shows.