A swarm of 20 earthquakes has jolted Southern California, shaking communities just miles from Los Angeles. The largest quake reached a magnitude of 3.3, and all struck within a tight two-hour window near the city of Fillmore.

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.

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?

Residents in Nevada woke up to a shocking 5.9 magnitude earthquake alert, but after the panic settled, the whole thing turned out to be a fake quake alert sent by USGS.

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.

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.

The ShakeAlert system that warns about imminent shaking arriving from earthquakes sent a false alarm across California on Thursday morning for a magnitude 5.9 temblor that did not happen.

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.