Earthquake Rattles Foothills (Update)

UPDATE: The Southern California Seismic Network, a joint project between the U.S. Geological Survey and the Pasadena California Caltech Seismological Laboratory, now reports that Thursday's earthquake in the San Fernando Valley was of 4.2 magnitude—not 4.3 as initially reported.

Eagle Rock residents in their homes are more likely than those in bigger buildings to have felt a magnitude 4.2 earthquake that rocked the Greater Los Angeles area Thursday afternoon, according to the U.S. Geological Survey.

The tremors, some 4.6 miles beneath the earth, began at 1:47 p.m., about five miles from the San Fernando Valley, the USGS reported. The quake's epicenter also lay about four miles from Newhall, a densely populated district in Santa Clarita named after silent movie mogul Henry Newhall.

At least 19 people in the Santa Clarita area said they felt the earthquake, according to the geological survey.

But tremors from the quake were evidently too small to be felt—let alone cause any damage—at a large complex such as .

“We didn’t even feel it,” said Rachel Vaughan, an administrative officer at the sprawling plaza’s management office. “Nobody felt it in our office.”

No books fell off the shelves at , where, too, the quake apparently went unnoticed. “Everyone’s fine here,” said a substitute librarian who identified herself only as April.

If you felt the earthquake, click here to join more than 7,000 others in 358 zip codes who told the U.S. Geological Survey about it.