The strongest Southern California earthquake in years jolted residents Tuesday, causing little damage but stirring memories of earlier quakes and underscoring the need to prepare for the massive temblor scientists say is coming.

"We had forgotten what a big earthquake felt like -- at least I did," said Kate Hutton, a seismologist at the California Institute of Technology in Pasadena. "We should probably look at it as an earthquake drill."

The rumble may be a sign the region is entering a more shaky period, said Lucy Jones, chief scientist for the U.S. Geological Survey in Pasadena, in a telephone interview Tuesday.

"I tend to think that Northridge and Landers removed so much energy from the crust that we had a lower level of earthquakes for a while," Jones said. "Maybe this means that we are going back to a higher level, and that we are going to have more earthquakes for a while."

Northridge was the magnitude 6.7 quake that rocked Los Angeles in 1994, toppling freeways and buildings and killing 60 people. Landers was much less deadly by comparison, killing three, but that was largely because it was centered in the desert rather than a populated area. That 1992 quake actually was quite a bit stronger, at magnitude 7.3.

Those giants tend to be relatively rare quakes. The type of quake that struck Tuesday tends to be more common, Jones said.

The magnitude 5.4 temblor rolled across the region at 11:42 a.m. and was centered at Chino Hills in San Bernardino County, about 30 miles east of downtown Los Angeles. It was widely felt across San Diego and Riverside counties, and noticed as far away as Las Vegas.

Only scattered damage was reported in the immediate vicinity of the epicenter, and no damage or injuries were reported in San Diego and Riverside counties, according to law enforcement and public safety officials.

But the quake did shake some people up.

Rides at Legoland California closed for 45 minutes so park employees could conduct a safety inspection, park spokeswoman Julie Estrada said.

Several park visitors asked for ticket refunds and headed north to check on the condition of their Los Angeles-area homes, Estrada said.

The shaking also prompted officials to inspect the condition of the Encina Power Station -- the regional power plant that dominates Carlsbad's coastline -- and the San Onofre nuclear power plant near the San Diego-Orange county line. But power plant owners Cabrillo Power and Southern California Edison officials said those inspections turned up no sign of damage.

Closer to the epicenter, buildings swayed in downtown Los Angeles, prompting the evacuation of offices and disrupting a Los Angeles City Council meeting. And power was cut to about 5,000 Edison customers in the vicinity of Chino Hills, said company spokesman Gil Alexander.

Alexander said the quake sparked a fire at the company's La Habra electric substation, but it was extinguished before major damage was caused.

Besides Legoland, the shaking triggered a temporary closure and inspection at Disneyland.

Clint Hendrickson, 32, a visitor from Texas, was in a Disneyland theater when the shaking started.

"We thought it was part of the show, until people started yelling, 'Get under the tables!' " he said.

Despite the excitement, Jones, the scientist, termed the earthquake "no big deal. It's an every-year sort of earthquake."

But that's only because much of California has been built to survive heavy shaking.

"This size of earthquake would have killed a lot of people in other parts of the world," Jones said.

Earthquake scientists are bracing for, and trying to get Southern Californians to prepare for, something much bigger on the San Andreas fault. That's the fracture in the earth that slices through California on the border of the Pacific and North American plates.

"This is 1 percent of the size of Northridge, and maybe it is one-hundredth of 1 percent of the size of a big earthquake on the San Andreas," Jones said.

She said quakes of roughly magnitude 7.8 hit the southern San Andreas once every 150 years -- and it has been 151 years since the last such geologic twitch. The prospect of that type of quake prompted seismologists to schedule a Nov. 13 drill throughout the region. Jones said Tuesday's shaker turned out to be the best advertising possible for the event that scientists hope will draw at least 5 million participants.

Southern California is home to more than 20 million people.

Big or small, earthquakes tend to occur because over time stress builds up as the two continental plates grind against each other. The shaking can either relieve the stress -- or shift it elsewhere and trigger more quakes.

Mark Benthien, spokesman for the Southern California Earthquake Center in Los Angeles, said it is unlikely the Chino Hills quake relieved any stress on the San Andreas.

Benthien said the quake occurred well south and west of the San Andreas. "And even if it had been close, it was too small to change anything," he said.

Scientists were still trying to answer questions about the quake.

"We're not even sure which fault it's on," said Jones. "It looks like it was on the Whittier fault, but that's not consistent with the aftershocks." About 30 aftershocks, the largest measuring magnitude 3.8, had been reported as of Tuesday night.

The Whittier fault, while far from communities in northern San Diego and southern Riverside counties, has a connection to the Elsinore fault system that runs under Lake Elsinore, Temecula and Julian.

"The Whittier and the Chino (faults) are sort of at the fraying end of the Elsinore," Jones said.

But she said it is unlikely that Tuesday's quake significantly increased or reduced the threat of a major quake on the Elsinore some day. The Elsinore fault is capable of generating a temblor as large as magnitude 7.5.

On Tuesday, the Chino Hills quake generated a lot of office conversation.

Jim Fagelson, a Riverside County planner, was working on the ninth floor of the 13-story county administration building in downtown Riverside when the high-rise swayed back and forth for about 45 seconds.

"The way you feel them up here is usually like a big truck rumbling down the street," Fagelson said. "This time the building was swaying a bit. When it was all over, a bunch of us came out of our offices and said, 'Well, that was a good one.' "

Farther south, a swaying 13-story City Hall building in downtown San Diego prompted the San Diego City Council to call a five-minute recess.

A few blocks away on the eighth floor of a 24-story office tower, Marney Cox, the San Diego Association of Governments' chief economist, recalled an initial rumble and a brief delay, followed by several seconds of robust shaking.

"I thought it was closer," Cox said. "It felt close."

Staff writers Barbara Henry and Dan Simmons and The Associated Press contributed to this report.

Contact staff writer Dave Downey at (760) 745-6611, Ext. 2623, or ddowney@nctimes.com.