The magnitude 4.4 earthquake that hit near Westwood on Monday morning was 900 times weaker than the 6.7 Northridge earthquake in 1994 and lasted only a fraction of a second, Caltech seismologist Egill Hauksson said.
The Northridge quake killed 57 people and lasted up to eight seconds, Hauksson said.
Monday's quake struck the northern edge of the Santa Monica Mountains, an area that has not seen much recent seismological activity.
"The location is somewhat surprising. It's within the Santa Monica Mountains. We have not seen seismicity in it in recent times," Hauksson said. "It has been dormant for quite some time."
Hauksson said the few earthquakes that have hit underneath the range were weaker.
"Very few of them end up in the Santa Monica Mountains. They're either to the south of the mountains or to the north," Hauksson said.
Historically, scientists viewed the Santa Monica Mountains as a very old and rigid rock formation, a range that was created over thousands of years through earthquakes. In this location, "this is the first magnitude 4.4 we've seen since we started recording earthquakes," Hauksson said.
Hauksson also praised the early warning earthquake system being tested by scientists at the U.S. Geological Survey and at Caltech. He said it gave the Pasadena center about two seconds of warning.
Improving the test system could increase the warning to about four seconds, enough time to send alerts to duck and cover, instructing elevators to open at the nearest floor and alerting surgeons to remove scalpels from patients.
The quake was felt over a large swath of Southern California but especially on the Westside and in the San Fernando Valley.
Aaron Green, 28, a post-doctorate student in chemistry was asleep around 6:30 a.m. at his apartment on Landfair Avenue when he felt a shake: boom-boom, boom-boom.
"I just figured the neighbors upstairs we're gettin' to it," he said. "But it was a little more vigorous than normal. Pretty surprising, and a little scary too."
Green said his building is old and wooden, designed by the famous architect Richard Neutra in the 1920s. Following a run back from the campus gym, he said there didn't appear to be any damage to his building or to any others inside the dense cluster of housing that abutts the
Lilly Chang, 22, a psychobiology major, was sleeping next to Green when she heard the rumbling. Green grabbed her, then jumped out of bed. Once Chang realized what was happening, the college student did what she was taught to do in so many years in school.
"The only reaction I had was to cover myself," she said. "I kind of just grabbed a blanket and hid."
Chang, who grew up in Los Angeles, called the Monday quake "quite a big one."
"This one was really shaking," she said. "It literally woke me up -- and it's hard to wake me up."
Cristina Toth, 26 and Andresa Maia, 25, were among the few that were not shaken awake by the earthquake. The two master's students were making a model for their architecture final so they were up all night.
Still, Toth said the shaking "kind of freaked us out." UCLA's architecture building is old, the students said, a fact they realized after they had fled the scene.
"We looked at each other," Maia said, "and we just sort of ran outside."
The students estimated that the quake lasted two to four seconds, shorter than they expected. To Toth, who is from Los Angeles, it wasn't a big deal.
Monday morning, the two students were waiting for their coffee at a Village
Read more about Southern California earthquakes.
[For the Record, 6:42 p.m. PDT, March 17: An earlier version of this post misspelled the first name of student Cristina Toth as Christina.]