A potentially deadly earthquake powerful enough to be felt for several hundred miles rattled and shook Southern California early this morning but did not cause any significant injuries or property damage because its epicenter was in a remote part of the Mojave Desert.

"We are so lucky, we are so lucky," said Jill Andrews, a director at the Southern California Earthquake Center. "It's just incredible."

The quake, with a magnitude of 7.0, was the largest to hit near this densely populated region in eight years. Striking just before 3 a.m., and rumbling for less than a minute, it derailed a crowded Amtrak passenger train as it rolled through the desert to Los Angeles, wobbled hotels along the Pacific Ocean from San Diego to Santa Monica, and even chased all-night gamblers out of casinos along the bustling Las Vegas Strip. Several significant aftershocks could be felt through the night, and more are expected.

If a temblor this size had struck this metropolis directly, officials said, the effects would have been disastrous. Today's quake was even larger than the 1994 Northridge quake in Los Angeles, which had a magnitude of 6.7 and killed 57 people, left 20,000 homeless and caused $20 billion in damage.

But this one could not have occurred in a more isolated area. The earthquake was centered in perhaps the loneliest, most barren quadrant of California, a place of rugged desert mountains, abandoned mines, ghost towns and prehistoric lava beds, just north of the Twentynine Palms Marine Corps Base and 30 miles from the nearest small town, Joshua Tree.

The quake also struck just two days after scientists with the U.S. Geological Survey announced that there is a strong chance in the next 30 years that a temblor of this magnitude will strike the San Francisco Bay area, which exactly 10 years ago was pounded by the 6.9 Loma Prieta quake. The epicenter of that one was 50 miles from the heart of San Francisco and killed 67 people.

This morning's quake caused only ripples of destruction by comparison. It tossed two dozen mobile homes from their foundations near the desert outpost of Ludlow 125 miles east of Los Angeles and left a few cracks along Interstate 40 near there.

Amtrak's Southwest Chief, carrying about 170 passengers overnight from Chicago to Los Angeles, jumped its rails as the quake struck, possibly right beneath it, but its cars did not overturn. All passengers have been accounted for, authorities said, and only four minor injuries were reported. Nearly 100,000 homes and businesses also were left without electricity this morning. By midday, most power had been restored.

"It was, literally, in the middle of nowhere, and thank goodness for that," said USGS seismologist Susan Hough, who was awakened by the temblor at her home in Pasadena and immediately knew what she was feeling was a large but distant earthquake because it was "that long rumble, rumble, rumble, and not that sharp, abrupt jolt that means it's right nearby."

"There was that moment of 'Uh oh, this is a big one and where is it?' and you just hope not someplace like San Diego," Hough said. She immediately dressed and went to her laboratory. Hough and other seismologists from the USGS and the California Institute of Technology believe the epicenter was near the abandoned Hector Mine near Interstate 40, approximately 47 miles east-southeast of Barstow and 32 miles north of Joshua Tree.

This is an area of several fault lines, and the scientists believe the temblor occurred on the Pisgah Fault. What is interesting to them is that this is the same area where in 1992 the Landers earthquake of 7.3 magnitude occurred. Hough and other seismologists are investigating whether the Landers event, while reducing stress along some faults, actually increased the pressure along the Pisgah Fault.

Early this morning, scientists rushed to the site, for an earthquake this big should produce ruptures along the earth's surface. Unfortunately, all the portable seismic recorders in the area probably had been removed recently, to be used on an upcoming experiment in the Los Angeles Basin, where scientists plan to set off a series of small explosions to map the underground structure.

Three minutes after the initial Hector quake, the aftershocks began, and by noon there had been 15 of them 4.0 magnitude or greater.

The earthquake could be felt from Las Vegas to Los Angeles, where citizens bolted upright in bed, dogs howled and hotel guests fled down tall stairwells.

In Los Angeles, electric lines swayed and transformers blew, but there was little damage beyond some shaken nerves.

Closer to the epicenter, cans and bottles flew off the shelves at grocery and liquor stores in Joshua Tree and Twentynine Palms.

"It was a shaky one. It was definitely a roller," said Monique Boneville, a waitress and a granddaughter of the owner of the Sidewinder, where the cult film "Bagdad Cafe" was filmed in Newberry Springs. "I live in a mobile home, and the whole place shook. My kids were terrified. I can't convince my son there's not a monster in the house."

At Joshua Tree National Park, chief naturalist Joe Zarki said, "This was a big one." No injuries or damage were reported at the park. "We dodged a bullet," he said.

At the Roy Rogers and Dale Evans Museum in Victorville, Betty Eubank reported that "Trigger didn't move. We're happy about that." Trigger was Rogers's famous performing horse, now stuffed and on display.

Champ Gabler, owner of Peggy Sue's Nifty '50s Cafe, said, "I came out of bed like everyone else in the area. The TV fell off its hutch. One server here at the cafe said she had to pry her cat out of the carpet. She'd dug in all four claws."

Gabler said he was considering offering a luncheon special to celebrate. What'll it be? "Probably Jell-O," he said.

Special correspondent Cassandra Stern contributed to this report.

Big Temblors

Magnitude

Earthquake magnitudes are measures of earthquake size calculated from ground motion recorded on seismographs. With each scale, an increase in one full number -- from 6.5 to 7.5, for example -- means the quake's magnitude is 10 times as great. There is theoretically no top limit to the scale, but a magnitude 8 quake is considered to be capable of tremendous damage. On Sept. 19, 1985, a magnitude 8.1 earthquake in Mexico left 9,500 people dead. A magnitude 7 quake has the potential to cause widespread damage.

Relative magnitude

5.5

6.5

7.5

Major U.S. Earthquakes

Magnitude Killed

Jan. 17, 1994 Northridge, Calif. 6.7 57

Sept. 20, 1993Southern Oregon 5.4 1

June 28, 1992Landers, Calif. 7.3* 1

June 28, 1991San Gabriel Mountains 5.8 2

Oct. 17, 1989San Francisco Bay area 6.9 67

Oct. 1, 1987Whittier, Calif. 5.9** 8

Jan. 24, 1980Livermore, Calif. 5.8 0

Feb. 9, 1971San Fernando, Calif. 6.5 65

March 27, 1964

Prince William Sound, Alaska 9.2 125

July 21, 1952

Tehachapi-Bakersfield, Calif. 7.5 12

March 10, 1933 Long Beach, Calif. 6.3 115

April 18-19, 1906 San Francisco 7.7 700

(estimated)

World Quakes This Year

Sept. 21 Taiwan 7.6 More than 2,000

Aug. 17 Turkey 7.4 More than 17,000

Jan. 25 Colombia 6.3 At least 1,170

SOURCES: U.S. Geological Survey,Associated Press; Reuters