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 4.2-magnitude earthquake hit the Pacoima area early Thursday morning, according to the U.S. Geological Survey. LOS ANGELES -- A 4.2-magnitude earthquake hit the Pacoima area in Southern California early Thursday morning, according to the U.S. Geological ...

FILLMORE, Calif. (KABC) -- A 3.6-magnitude earthquake struck in Ventura County Saturday, according to the U.S. Geological Survey. The quake struck around 5:03 p.m. at a depth of nearly 7 miles, with its epicenter about 8 miles northwest from Fillmore, USGS said.

The San Jacinto Fault, considered part of the San Andreas Fault system, has a 5% chance of magnitude 6.7 or larger earthquakes. The line begins at Cajun Pass and runs southeast through San Bernardino, Riverside County and Imperial County. Meanwhile, the Elsinore Fault, part of the same system, has a 3.8% chance of earthquakes of that size.