The quake hit at about 4:30 a.m. at a depth of 4.3 miles. The quake was centered 1.3 miles from Pacoima and 1.4 miles north of San Fernando Valley, USGS said. About two hours later, a 3.8-magnitude aftershock rattled the same area.
A strong shaking was felt across the San Fernando Valley region as well as across Los Angeles. It was followed by a 3.3 aftershock a few minutes later.
Pacoima quake: ABC7's David Ono describes feeling 'a sharp jolt'
Caltech said 60 aftershocks have been recorded.
According to a USGS map, the shaking was felt over an area stretching from Palmdale to Anaheim, and from Ontario to Agoura Hills.
Caltech Staff Seismologist Dr. Jen Andrews said Thursday's temblor occurred near the area of the 6.7-magnitude San Fernando earthquake in 1971, and the 6.7-magnitude Northridge earthquake in 1994.
"It's not possible for us to say today's event is related to those, but it's not surprising that we're having seismicity in this area," Andrews said. "We've got a number of fault signs nearby, including the Sierra Madre fault sign ... as well as the Mission Hills and Northridge Hills faults."
WATCH: Caltech seismologist discusses 4.2-magnitude Pacoima earthquake
ABC7's David Ono was at home when his dogs "started barking and running before I felt anything."
"It was a very light rumble for just a few seconds, then a really sharp jolt and that was it," Ono said.
ABC7 entertainment guru George Pennacchio said he too was alerted by his dog.
"I really do feel that dogs feel them first, because she was up on her feet, because I was still awake when that aftershock hit," Pennacchio said. "So it was a little bit jarring."
There were no immediate reports of serious damage or injuries due to the quake. Surveillance cameras at San Fernando restaurant Magaly's Tamales recorded the early morning shaking, showing some pans being knocked over and boxes shaking.
Seismologist Lucy Jones described the earthquake and its aftershocks as "garden variety California quakes," noting that they occurred "in an area with lots of faults and both the 1994 Northridge and 1971 Sylmar quakes."
ABC7's George Pennacchio reacts to 'jarring' 4.2 earthquake centered in Pacoima
"The good (ordinary) life of the Golden State," she mused in a tweet.
The Los Angeles Fire Department said it "concluded the systematic survey of the City of Los Angeles by ground and air" and reported no major infrastructure damage or serious injury due to the quake.
ABC7's Denise Dador recounts being awakened by Pacoima earthquake
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