The quake struck at 12:51 p.m. and was centered about 6 miles west of Chatsworth, the USGS said.
There were no immediate reports of injuries or structural damage.
The depth of the temblor was measured at about 6.5 miles. Residents reported shaking in Cypress, West Hills and Thousands Oaks.
"Quick jolt in Simi Valley," Michelle Ramstead McAteer wrote on Facebook. "Hanging lights didn't even sway! Pool water wasn't moving. Strangest earthquake I've ever felt!"