LOS ANGELES, California (CNN) -- A magnitude-5.4 earthquake shook the Los Angeles metropolitan area Tuesday, leaving residents rattled but causing no serious damage or injuries.



Bricks and other debris clutter an alleyway in Pomona, near Los Angeles Tuesday afternoon.



However, the temblor served as a warning to southern Californians who had not experienced an earthquake in some time: the "Big One" remains a possibility.



"This is a sample, a small sample," said Kate Hutton, a seismologist at the California Institute of Technology.



"This is somewhere between small and moderate." She said there is a 5 percent chance the quake could be a precursor to a larger earthquake. After 24 hours, she said, that chance will drop to 1 percent.



"Every earthquake relieves some stress," Hutton said. "It's usually only a drop in the ocean. In other words, the amount of stress released by this earthquake is minuscule compared to the amount that's built up and is building up for the Big One when it happens some day in the future."  Watch Hutton say Tuesday's quake was a sign of bigger ones to come »



And when will that be?



"From a geologist's point of view, the answer has to be soon," she said. "But geologists are used to thinking on millions of years and thousands of years time scale, so I don't think that gives any useful information for people, except be prepared at any time because it could happen at any time."



A 5.4 magnitude quake is considered by the USGS to be "moderate," which can cause slight damage to buildings and others structures. So far this year, 39 "moderate" earthquakes of between magnitude 5.0 and 5.9 have occurred in the United States, and 790 globally.



The last moderate quake to strike California was a magnitude 5.4 in April in the northern part of the state. A magnitude 4.4 struck the greater Los Angeles area in August 2007.



There is a 99 percent chance of California experiencing a quake of magnitude 6.7 or larger within the next 30 years, according to the Uniform California Earthquake Rupture Forecast, sponsored by the U.S. Geological Survey, the California Geological Survey and the Southern California Earthquake Center and published in Science Daily in April.



"This earthquake reminds us to be prepared," said California Gov. Arnold Schwarzenegger. "We were very fortunate that there were no serious injuries or property damage."



He said he believes the state is "as prepared as anyone can be. We have continuous discussions about that. We are fanatics about emergencies and to be ready."



The largest earthquake in recent years in California was a magnitude 7.1 in 1999, Hutton said. But it was centered in the desert, near Twentynine Palms, in a sparsely populated area.



Tuesday's quake struck about 11:42 a.m., according to the USGS. Its epicenter was about 2 miles southwest of Chino Hills and about 5 miles southeast of Diamond Bar.



The epicenter was about 7.6 miles deep, making it a fairly shallow quake, according to CNN meteorologist Chad Meyers. In general, earthquakes centered closer to the surface produce stronger shaking and can cause more damage than those further underground. But most Southern California earthquakes tend to be fairly shallow, officials said.



More than 30 aftershocks were recorded. Hutton said the largest was a magnitude 3.6.



Los Angeles police said a downtown hotel sustained some structural damage, but no one was injured and the building was not evacuated. There were some unconfirmed reports of minor injuries. The White House was also monitoring the situation, said spokeswoman Dana Perino.



Despite the absence of serious damage or injuries, some Los Angeles-area residents were left rattled. The quake was felt as far south as San Diego, California, and the USGS said it received reports of light shaking as far north as Rosamond, California, about 55 miles north-northeast of Los Angeles.



Reports from those who felt the quake poured into CNN. Did you feel the quake?



"My house was like a fun house. Everything was moving
What was moderate? Who had reports on the damage? Who said the earthquake was a reminder to be prepared? Who said the earthquake is a riminder to be prepared? What time was the earthquake?
earthquake USGS California Gov. Arnold Schwarzenegger. Gov. Arnold Schwarzenegger. 11:42 a.m.,
question: What was moderate?, answer: earthquake | question: Who had reports on the damage?, answer: USGS | question: Who said the earthquake was a reminder to be prepared?, answer: California Gov. Arnold Schwarzenegger. | question: Who said the earthquake is a riminder to be prepared?, answer: Gov. Arnold Schwarzenegger. | question: What time was the earthquake?, answer: 11:42 a.m.,