A magnitude 4.2 earthquake shook several densely populated sections of Los Angeles Sunday evening. 

The U.S. Geological Survey initially reported the quake registered at magnitude 3.8 before revising the measurement upward. The agency said the earthquake struck at 7:36 p.m. local time and was centered in the Santa Monica Mountains about 4 miles northwest of Westwood.

An officer at the Los Angeles Police Department's West Los Angeles station told The Associated Press that there were no immediate reports of damage. Los Angeles Fire Department spokesman Erik Scott said firefighters who inspected the city's infrastructure found no significant damage.

A USGS website for citizen reports of quake intensity showed the shallow quake was felt from Malibu northwest of Los Angeles down to the Manhattan Beach area.

CBS Los Angeles reported that its viewers in Studio Valley, Santa Monica, and Simi Valley on the west side of the city felt the earthquake particularly strongly. 

Dr. Lucy Jones of the USGS told KNX-AM that the shaking was felt by a lot of people because the earthquake was so shallow. 

"It was felt by many people because it happened in a densely populated area," Jones said. "But seismically it’s not a big deal."

The Associated Press contributed to this report.