The quake's epicenter was located in the Cajon Pass, seismologist Dr. Lucy Jones said on social media, "where the San Andreas and San Jacinto faults come together. In 1970, there was a M5.2 with a M4.0 foreshock in close to the same location."
[Ads /]
ABC7 viewers in Southern California reported feeling the temblor in Riverside, Rialto, Fontana, and as far away as Watts, Anaheim and downtown Long Beach.
There were no immediate reports of any injuries or major damage.
[Ads /]
The quake was originally measured at a magnitude of 4.6 before being downgraded, the USGS said.
How to make your own earthquake kit